Ceip.us

Poster Abstract Session:
51. C. difficile Diagnostics
Presenters:
Increased Clostridium difficile (CD) Detection and Decreased Empiric
Treatment/Ancillary Testing after switch from Toxin A/B Immunoassy to PCR
for Diagnosis of CD Infection
LAURIE LABUSZEWSKI, PHARMD1, URVASHI THAKKAR, PHARMD2, STUART JOHNSON,
MD, FIDSA3, PAUL SCHRECKENBERGER, PHD1 and JORGE PARADA, MD, MPH1; 1Loyola
University Medical Center, Maywood, IL, 2Western University Col ege of Pharmacy, Pomona,
CA, 3Edward Hines Jr. VA Hospital, Hines, IL
Utility of Perirectal Swab Specimens for Diagnosis of Clostridium difficile
Infection
SIRISHA KUNDRAPU, M.D.1, VENKATA SUNKESULA, M.D, M.S2, LUCY JURY, N.P.2, AJAY
K. SETHI, PHD3 and CURTIS J. DONSKEY, MD2; 1Case Western Reserve University,
Cleveland, OH, 2Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH,
3University of Wisconsin-Madison, Madison, WI Commercial Clostridium difficile Toxin PCR Assay of Stools from Pediatric
Inpatients with Diarrhea with Cytotoxicity Confirmation of Positives
JILL LEIBOWITZ, MD; Steven and Alexandra Cohen Children's Medical Center of New York
of the North Shore-LIJ Health System, New Hyde Park, NY, VIJAYA SOMA, MD; Seattle Children's Research Institute, Seattle, WA and LORRY RUBIN, MD; Hostra North Shore-LIJ Stools from Asymptomatic Pediatric Inpatients at Risk for Clostridium difficile-
Associated Diarrhea Frequently Test Positive Using a Commercial PCR Assay
JILL LEIBOWITZ, MD; Steven and Alexandra Cohen Children's Medical Center of New York
of the North Shore-LIJ Health System, New Hyde Park, NY, VIJAYA SOMA, MD; Hofstra North Shore-LIJ School of Medicine, New Hyde Park, NY and LORRY RUBIN, MD; Hostra North Shore-LIJ School of Medicine, New Hyde Park, NY Regional Differences in Vancomycin-resistant enterococcus and C difficile co-
Colonization Rates in Critically Ill Veterans
LINDA MCKINLEY, RN, BSN, MPH, CIC; Madison VA Medical Center, Madison, WI, MARY
HAGLE, RN, PHD; Milwaukee VA Medical Center, Milwaukee, WI, HELENE MORIARTY, RN, PHD; Phiadelphia VA Medcial Center, Philadephia, PA, TOM SHORT, PHD; John Carrol University, University Heights, OH and NASIA SAFDAR, MD, PHD; University of Wisconsin School of Medicine and Public Health, Madison, WI Changes in Clostridium difficile Testing Practices and their Impact on Stool
Rejection Policies across Multiple U.S. Laboratories
JESSICA COHEN, MPH1, DUNCAN MACCANNELL, PHD1, LEIGH ANN CLARK, MPH2,
WENDY BAMBERG, MD3, REBECCA PERLMUTTER, MPH4, JOHN DUNN, DVM, PHD5, JOELLE
NADLE, MPH6, STACY HOLZBAUER, DVM7, CAROL LYONS, MPH8, ERIN PHIPPS, DVM9,
GHINWA DUMYATI, MD, FSHEA10, ZINTARS G. BELDAVS, MS11 and FERNANDA LESSA,
MD1; 1Division of Healthcare Quality Promotion, Centers for Disease Control and
Prevention, Atlanta, GA, 2Georgia Emerging Infections Program, Decatur, GA, 3Colorado
Dept. of Public Health and Environment, Denver, CO, 4Maryland Dept. of Health and Mental
Hygiene, Baltimore, MD, 5Tennessee Department of Health, Nashvil e, TN, 6California
Hygiene, Baltimore, MD, Tennessee Department of Health, Nashvil e, TN, CaliforniaEmerging Infections Program, Oakland, CA, 7CDC CEFO assigned to the MN Dept. of Hlth,St. Paul, MN, 8Connecticut Emerging Infections Program, New Haven, CT, 9New MexicoEmerging Infections Program, Albuquerque, NM, 10University of Rochester, Rochester, NY, The Nose Knows Not: Poor Predictive Value of Stool Sample Odor for
Detection of Clostridium difficile
KRISHNA RAO, MD1, DANIEL BERLAND, MD1, CAROL YOUNG, MT(ASCP)2, SETH WALK,
MS, PHD3 and DUANE NEWTON, PHD3; 1University of Michigan Health Systems, Ann Arbor,
MI, 2University of Michigan Health System, Ann Arbor, MI, 3University of Michigan, Ann
Evaluation of a Commercial PCR Assay for Detection of Environmental
Contamination with Clostridium difficile
ABHISHEK DESHPANDE, M.D., PH.D.1, JENNIFER CADNUM, B.S.2, BRETT SITZLAR,
B.S.2, SIRISHA KUNDRAPU, M.D.2 and CURTIS J. DONSKEY, MD2; 1Case Western Reserve
University, Cleveland, OH, 2Louis Stokes Cleveland Veterans Affairs Medical Center,
Severe Clostridium difficile Infection in Patients with Negative Results for tcdB
by the Xpert® C. difficile assay
JEROME LEIS, MD1, WAYNE GOLD, MD, FRCPC1, JOHN NG, PHD1, ZAHIR HIRJI1, DYLAN
PILLAI, MD, PHD2, GEORGE BROUKHANSKI, PHD1, PAUL RAGGIUNTI1, SUSY HOTA, MD1,
ALLISON MCGEER, MD, FSHEA1 and SUSAN POUTANEN, MD, MPH1; 1University of Toronto,
Toronto, ON, Canada, 2University of Calgary, Calgary, AB, Canada
Does Empirical Clostridium difficile Infection (CDI) Therapy Result in False-
Negative CDI Diagnostic Test Results?
VENKATA SUNKESULA, M.D, M.S1, SIRISHA KUNDRAPU, M.D.2 and CURTIS J. DONSKEY,
MD1; 1Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH, 2Case
Western Reserve University, Cleveland, OH Prospective Evaluation of the Epidemiology of Clostridium difficile
Colonization and Infection among Hematopoietic Stem Cell Transplant
Recipients
VARINIA URDAY-CORNEJO, MD1, CHRISTOPHER CROSWELL1, TEENA CHOPRA, MD,
MPH2, ALYSSA LIUBAKKA1, JESSICA CUTRIGHT, BS1, HOSSEIN SALIMNIA, PHD3, PAUL
LEPHART, PHD3, SANJAY REVANKAR, MD1, PRANATHARTHI CHANDRASEKAR, MD1 and
GEORGE ALANGADEN, MD4; 1Wayne State University, Detroit, MI, 2Detroit Medical Center/
Wayne State University, Detroit, MI, 3Detroit Medical Center University Laboratories,
Detroit, MI, 4Henry Ford Health System, Detroit, MI
Multilocus sequence typing analysis of 85 C. difficile strains isolated from a
teaching hospital in Houston Texas, September through December 2011
ZHI-DONG JIANG; The University of Texas, School of Public Health, Houston, TX, RAVI
PANCHUMARTHI; UNIVERSITY OF TEXAS SCHOOL OF PUBLIC HEALTH, HOUSOTN, TX, KEVIN W. GAREY, PHARMD, M.S.; University of Houston Col ege of Pharmacy, Houston, TX, TODD M. LASCO, PHD; Saint Lukes Episcopal Hospital, Houston, TX, JANE CHEN; UNIVERSITY OF TEXAS SCHOOL OF PUBLIC HEALTH, HOUSTON, TX and HERBERT DUPONT, MD, FIDSA; St.
Luke's Episcopal Hospital and Kelsey Research Foundation and Kelsey-Seybold Clinic, Clostridium difficile Whole Genome Sequencing Suggests Limited
Transmission Arising From Mixed Infection
DAVID EYRE, BM, BCH1, MADELEINE CULE, PHD2, DAVID GRIFFITHS, BSC3, TIM PETO,
MB BS, DPHIL4, A. SARAH WALKER, PHD2 and DANIEL WILSON, DPHIL2; 1Nihr Oxford
MB BS, DPHIL , A. SARAH WALKER, PHD and DANIEL WILSON, DPHIL ; Nihr OxfordBiomedical Research Centre, Oxford, United Kingdom, 2NIHR Oxford Biomedical ResearchCentre, Oxford, United Kingdom, 3National Institute for Health Research Oxford BiomedicalResearch Centre, Oxford, United Kingdom, 4University of Oxford, Oxford, United Kingdom Title: Safety of Clostridium Difficile Testing Algorithm using Glutamate
Dehydrogenase Antigen and Toxin Enzyme Immunoassay with Reflex PCR for
Discordant Test
CECILIA BIG, MD, DAVID SENGSTOCK, MD, MS, NATASHA BAGDASARIAN, MD, MPH, VIJAYALAKSHMI NAGAPPAN, MD, PADMAJA VEMURI, MD, DAVID WEIDENDORF, MD and RAMA THYAGARAJAN, MD; Oakwood Hospital and Medical Center, Dearborn, MI
Prevalence and Molecular Epidemiology of Clostridium difficile (CD) in Food
and Companion Animals, Retail Meats, and Humans in Minnesota
MEGAN K. SHAUGHNESSY, MD1, TIM SNIDER, DVM2, ROCIO SEPULVEDA2, DAVID
BOXRUD, MS3, ELIZABETH CEBELINSKI, BS3, STACY HOLZBAUER, DVM4, KIRK SMITH, DVM,
PHD3, JEFF BENDER, DVM MS DACVPM5, FRANCISCO DIEZ-GONZALEZ, PHD5 and JAMES R.
JOHNSON, MD1; 1University of Minnesota, Minneapolis, MN, 2University of Minnesota, St
Paul, MN, 3Minnesota Department of Health, St. Paul, MN, 4CDC CEFO assigned to the
Minnesota Department of Health, St. Paul, MN, 5University of Minnesota, St. Paul, MN
Screening for Vancomycin Resistant Enterococcus (VRE) Colonization During
Clostridum difficile Testing is Not Cost Effective at a Canadian Teaching
Hospital
SUNIL VARGHESE, MD, MA1, KATHRYN SUH, MD, MSC, FRCPC1, NATALIE BRUCE, RN,
BSCN, CIC1, KARAM RAMOTAR, PHD1 and VIRGINIA ROTH, MD2; 1The Ottawa Hospital,
Ottawa, ON, Canada, 2The Ottawa Hosp, Ottawa, ON, Canada
Toxin A/B EIA Compared to Molecular Amplification Testing for Clostridium
Difficile: Cost and Resource Utilization Analyses
REDA A. AWALI, MD1, BRINDHA GOPALA KRISHNAN, MD1, HARLEEN KAUR, MD1, INDU K.
CHALANA, MD2, PAULA ROBINSON, RN1, SANJAY REVANKAR, MD3, JUDY MOSHOS, BS,
MT4, PAUL LEPHART, PHD5, RICHARD FACKLER, BBA1, KEITH KAYE, MD, MPH, FIDSA,
FSHEA6 and TEENA CHOPRA, MD, MPH7; 1Detroit Medical Center, Wayne State University,
Detroit, MI, 2Wayne State University / Detroit Medical Center, Detroit, MI, Detroit, MI,
3Wayne State University, Detroit, MI, 4Sinai-Grace Hospital, Detroit Medical Center, Detroit,MI, 5DMC University Laboratories, Detroit, MI, 6Detroit Medical Center (DMC) / Wayne StateUniversity, Detroit, MI, 7Detroit Medical Center/ Wayne State University, Detroit, MI Comparative Analysis of Two Culture Media and PCR for the Detection of
Toxigenic and Non-Toxigenic C. difficile
CHRISTOPHER CROSWELL1, VARINIA URDAY-CORNEJO, MD1, ALYSSA LIUBAKKA1,
JESSICA CUTRIGHT, BS1, HOSSEIN SALIMNIA, PHD2, PAUL LEPHART, PHD3, TEENA
CHOPRA, MD, MPH4, PRANATHARTHI CHANDRASEKAR, MD1 and GEORGE ALANGADEN,
MD5; 1Wayne State University, Detroit, MI, 2Detroit Medical Center/Wayne State University,
Detroit, MI, 3Detroit Medical Center University Laboratories, Detroit, MI, 4Detroit Medical
Center/ Wayne State University, Detroit, MI, 5Henry Ford Health System, Detroit, MI
Session #51 Presentations:
320. Increased Clostridium difficile (CD) Detection and Decreased Empiric
Treatment/Ancillary Testing after switch from Toxin A/B Immunoassy to PCR
for Diagnosis of CD Infection
Part of Session: 51. C. difficile Diagnostics LAURIE LABUSZEWSKI, PHARMD1, URVASHI THAKKAR, PHARMD2, STUART JOHNSON, MD, FIDSA3, PAUL
SCHRECKENBERGER, PHD1 and JORGE PARADA, MD, MPH1; 1Loyola Univers ity Medical Center, Maywood, IL, 2Wes tern
Univers ity College of Pharmacy, Pomona, CA, 3Edward Hines Jr. VA Hos pital, Hines , IL
Background: Polymeras e chain reaction (PCR) as s ays have s uperior s ens itivity compared to toxin A/B Enzyme
Immunoas s ay (EIA) tes ting for the detection of C. difficile (CD). Low s ens itivity tes ting methods may lead to diagnos tic
uncertainty and impact us e of ancillary s ervices , s pecialty cons ultations and antibiotics (ABX). We as s es s ed how s witching
from EIA to PCR tes ting affected ABX pres cribing practices and other as pects of patient management at our ins titution.
Methods: We conducted a retros pective chart review of adult inpatients tes ted for CD between 7/1/09-12/31/09 (EIA group)
and 07/01/11-12/31/11 (PCR group) and treated with oral/IV metronidazole (metro) or oral vancomycin (vanc). We excluded
patients receiving metro for non-CD indications or receiving oral vanc tapers for previous CD. Us e of ABXs , diagnos tic
tes ting and s pecialty cons ultations were examined for CD-negative patients in both groups .
Results: Overall, 1,003 CD tes ts were performed on 664 patients in the EIA group, and 12.6% (n=97) were pos itive, while
955 tes ts were performed on 668 patients in the PCR group and 25% (n=167) were pos itive (p<0.001). The PCR group had
fewer repeat CD tes ts (p<0.001). After exclus ions there were 246 patients in the EIA group and 237 patients in PCR group.
1418 vs 636 dos es of metro were adminis tered to CD-negative patients in the EIA vs PCR groups (p=0.23). 388 vs 43
dos es of oral vanc were adminis tered to CD-negative patients in the EIA vs PCR groups (p=0.007). Compared to the EIA
group, the PCR group had s ignificantly decreas ed ABX treatment days (p=0.004), abdominal radiologic imaging s tudies
(abdominal x-ray p=0.013, abdominal/pelvic CT s can p=0.002), s igmoidos copy/colonos copy (p=0.006), and infectious
dis eas e cons ults (p=0.033).
Conclusion: With PCR tes ting s ignificantly more CD was detected. There was a marked decreas e in total ABX treatment
days , overall oral vanc us e, us e of radiologic tes ting, s igmoidos copy/colonos copy, and infectious dis eas es cons ultations
amongs t patients who tes ted CD-negative by PCR vs EIA. We pos tulate that lack of confidence in a negative res ult by the
lower s ens itivity EIA drove phys icians to continue CD treatment and obtain more ancillary tes ts and s ervices in order to
obtain an accurate CD diagnos is .
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
321. Utility of Perirectal Swab Specimens for Diagnosis of Clostridium difficile
Infection
Part of Session: 51. C. difficile Diagnostics SIRISHA KUNDRAPU, M.D.1, VENKATA SUNKESULA, M.D, M.S2, LUCY JURY, N.P.2, AJAY K. SETHI, PHD3 and CURTIS J.
DONSKEY, MD2; 1Cas e Wes tern Res erve Univers ity, Cleveland, OH, 2Louis Stokes Cleveland Veterans Affairs Medical
Center, Cleveland, OH, 3Univers ity of Wis cons in-Madis on, Madis on, WI
Background: Nearly all tes ting for Clos tridium difficile infection (CDI) is accomplis hed through collection of s tool
s pecimens . However, patients with s evere dis eas e complicated by ileus may be unable to produce s tool s pecimens and a
variety of factors may res ult in delays in s pecimen collection. We hypothes ized that collection of perirectal s wabs might
provide an accurate and efficient tes ting s trategy for CDI.
Methods: We conducted a 4-month pros pective s tudy of inpatients being tes ted for CDI. Perirectal s wabs collected by
res earch s taff and s tool s pecimens collected by clinical nurs es were tes ted by polymeras e chain reaction (Xpert C. difficile,
Cepheid) and by culture for toxigenic C. difficile. The s ens itivity, s pecificity, pos itive predictive value (PPV), negative
predictive value (NPV), and time to diagnos is of CDI (i.e., from order placement to completion of lab res ult) were
determined for perirectal s wabs in comparis on to s tandard tes ting of s tool s pecimens .
Results: Of 139 patients with s tool s pecimens tes ted, 23 (17%) were diagnos ed with CDI. The s ens itivity, s pecificity, PPV,
and NPV of perirectal s wabs for diagnos is of CDI were 95.7%, 100%, 100%, and 99.1%, res pectively. The median time from
CDI tes t order to tes t res ult was 0.5 days (interquartile range; 0, 1 days ) for perirectal s wab s pecimens vers us 1.2 days
(interquartile range, 1.2, 2.1) for s tool s pecimens (P <0.0001). The one patient with pos itive s tool tes t res ults but negative
res ults of perirectal PCR tes ting als o had negative culture res ults from the perirectal s wab.
Conclusion: Tes ting of perirectal s wabs by PCR is an accurate and efficient method to diagnos e CDI. This tes ting
method will be us eful in s ettings where it is impos s ible or impractical to collect s tool s pecimens and when rapid diagnos is
is required to expedite infection control and management decis ion-making.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
322. Commercial Clostridium difficile Toxin PCR Assay of Stools from Pediatric
Inpatients with Diarrhea with Cytotoxicity Confirmation of Positives
Part of Session: 51. C. difficile Diagnostics JILL LEIBOWITZ, MD; Steven and Alexandra Cohen Children's Medical Center of New York of the North Shore-LIJ Health
Sys tem, New Hyde Park, NY, VIJAYA SOMA, MD; Seattle Children's Res earch Ins titute, Seattle, WA and LORRY RUBIN, MD;
Hos tra North Shore-LIJ School of Medicine, New Hyde Park, NY
Background: Commercial PCR-bas ed as s ays for C. difficile have been s tudied in adults , but experience in pediatric
patients is limited. Pediatric patients may have a higher rate of as ymptomatic carriage than adults . We determined the
frequency of pos itive s tool PCR as s ays for C. difficile toxin DNA among tes ted pediatric inpatients with diarrhea & des cribe
their epidemiologic features .
Methods: The s tudy population was inpatients 1-18 years of age with diarrhea who had s tool s pecimens s ubmitted for
tes ting over a 5 month period. Stools were tes ted us ing a C. difficile toxin DNA PCR as s ay (Xpert C. difficile, Cepheid,
Sunnydale, CA). A cytotoxicity as s ay (Cytotoxicity As s ay for Clos tridium difficile Toxin, Bartels , Carls bad, CA) was
performed on PCR-pos itive s amples . Demographic and clinical data were abs tracted. Proportions were compared us ing
Fis her’s Exact tes t. Medians were compared us ing the Mann-Whitney tes t.
Results: Of 121 s tools , PCR was pos itive in 25 (21%). Samples were pos itive in 27%, 16%, & 21% of patients ages 1-3y, 4-
11y & 12-18y, res pectively; differences were not s ignificant. Of the 25 PCR-pos itive s pecimens , 17 (68%) were clas s ified as
nos ocomial. The PCR-pos itive & -negative groups did not differ s ignificantly with res pect to median age (10y vs . 11y,
p=0.44), median hos pital days prior to s tool collection (5 vs . 2.5, p=0.33), receipt of antimicrobials in the preceding 30 d
(84% vs . 69%; p=0.21), or median antibiotic days in the preceding 30 d (10 vs . 5, p=0.30). Of the 23 PCR-pos itive s tools
tes ted, 14 (61%) demons trated cytotoxin activity. The cytotoxicity-pos itive and negative groups did not differ s ignificantly
with res pect to median age (8.5y vs . 7y, p=0.75), median hos pital days prior to s tool collection (5.5 vs . 2, p=0.19), receipt
of antimicrobials in the preceding 30 d (79% vs . 89%, p=1.0), or median antibiotic days in the preceding 30 d (10 vs . 10,
p=0.57). Of the PCR-pos itive, cytotoxicity-pos itive s pecimens , 11 of 14 were clas s ified as nos ocomial compared to 4 of 9 of
the PCR-pos itive, cytotoxicity-negative s pecimens (p=0.18).
Conclusion: Stool C. difficile PCR as s ays are frequently pos itive in hos pitalized children with diarrhea, but s pecimens are
frequently negative by cytotoxicity tes ting. Further s tudies are needed to determine the s ignificance of this tes ting
dis crepancy.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
323. Stools from Asymptomatic Pediatric Inpatients at Risk for Clostridium
difficile-Associated Diarrhea Frequently Test Positive Using a Commercial PCR
Assay
Part of Session: 51. C. difficile Diagnostics JILL LEIBOWITZ, MD; Steven and Alexandra Cohen Children's Medical Center of New York of the North Shore-LIJ Health
Sys tem, New Hyde Park, NY, VIJAYA SOMA, MD; Hofs tra North Shore-LIJ School of Medicine, New Hyde Park, NY and LORRY
RUBIN, MD; Hos tra North Shore-LIJ School of Medicine, New Hyde Park, NY
Background: Many laboratories us e polymeras e chain reaction (PCR)-bas ed s tool as s ays to detect Clos tridium difficile
toxin DNA, but experience in pediatric patients is limited. We compared the detection rate of C. difficile by PCR in high-ris k
pediatric patients without diarrhea to thos e with diarrhea who were tes ted for C. difficile.
Methods: Stool s pecimens from inpatients ages 1-18y with diarrhea and from cons ented inpatients without diarrhea were
tes ted for C. difficile toxin DNA us ing a commercial PCR as s ay (Xpert C. difficile/Epi, Cepheid, Sunnydale, CA). A cytotoxicity
as s ay was performed on pos itive s amples . Demographic, clinical & laboratory data were abs tracted. Proportions were
compared us ing Fis her’s Exact tes t. Medians were compared us ing Mann-Whitney tes t.
Results: Of 53 pediatric inpatients without diarrhea, a s tool s ample tes ted pos itive for C. difficile toxin DNA in 13 (25%).
Included were patients in the pediatric ICU, 7 (29%) pos itive of 24; oncology unit, 1 (11%) pos itive of 9; other units , 5 (25%)
pos itive of 20. Among the age groups , 1-3y, 4-11y, 12-18y, the percent pos itive did not differ s ignificantly. Of the 13 PCR-
pos itive s tools , 1 (9%) demons trated cytotoxin activity. The PCR-pos itive and negative groups did not differ s ignificantly with
res pect to median age (7y vs . 6.5y, p=0.71), hos pital days prior to s tool collection (5 vs . 4, p=0.6), receipt of
antimicrobials in the preceding 30 days (77% vs . 78%; p=1.0), or antibiotic days in the preceding 30 days (4 vs . 3.5,
p=0.87). From pediatric inpatients with diarrhea tes ted by PCR, 25 (21%) of 121 s tool s amples were pos itive; of 23 PCR-pos itive s pecimens tes ted, 14 (61%) demons trated cytotoxin activity. The proportion of PCR-pos itives between s ymptomatic& as ymptomatic patients did not differ s ignificantly (p=0.56). Of the PCR-pos itive s pecimens , the proportion that exhibitedcytotoxicity was s ignificantly higher in the group with diarrhea (p=0.0039).
Conclusion: C. difficile PCR as s ays are frequently pos itive in hos pitalized children both with & without diarrhea. Stools
pos itive by PCR are frequently negative by cytotoxicity tes ting. Our findings s ugges t that a pos itive C. difficile PCR tes t
res ult in a hos pitalized child with diarrhea s hould be interpreted with caution.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
324. Regional Differences in Vancomycin-resistant enterococcus and C difficile
co-Colonization Rates in Critically Ill Veterans
Part of Session: 51. C. difficile Diagnostics LINDA MCKINLEY, RN, BSN, MPH, CIC; Madis on VA Medical Center, Madis on, WI, MARY HAGLE, RN, PHD; Milwaukee VA
Medical Center, Milwaukee, WI, HELENE MORIARTY, RN, PHD; Phiadelphia VA Medcial Center, Philadephia, PA, TOM SHORT,
PHD; John Carroll Univers ity, Univers ity Heights , OH and NASIA SAFDAR, MD, PHD; Univers ity of Wis cons in School of Medicine
and Public Health, Madis on, WI
Background: In 2007, the Department of Veterans Affairs (VA) implemented a nationwide Methicillin-res is tant
Staphylococcus aureus (MRSA) initiative that included active screening for MRSA colonization on all patient admissions.
Identification and s ubs equent is olation of thes e patients have lead to a reduction in overall MRSA infections . Screening andis olation for other multi-drug res is tant organis ms (e.g., Vancomycin-res is tant enterococcus , VRE) has not beenimplemented.
Methods: A pros pective s tudy was conducted to identify the admis s ion prevalence rate of VRE in patients admitted to the
intens ive care unit (ICU) in two VA facilities in Milwaukee and Madis on, WI. VRE colonization was identified from perirectal
s wabs us ing rapid PCR as s ay.
Results: Over a period of three months , we found 15 of 61 s ubjects (26%) colonized with VRE upon ICU admis s ion at the
Madis on VA Medical Center and 7 of 94 s ubjects (7%) at the Milwaukee VA Medical Center. We found 5 of 17 (29%) VRE
pos itive s ubjects co-colonized with CDI during ICU admis s ion at the Madis on VA Medical Center and 0 of 5 s ubjects (0%) at
the Milwaukee VA Medical Center; total of 5 of 22 (23%). Patients at both facilities were comparable regarding average
s everity of illnes s and demographics . During the s ame time period, MRSA prevalence rates upon ICU admis s ion at Madis on
and Milwaukee VA were comparably lower at 10% and 13% res pectively. The rate of VRE infections was 1.0 per 1000
patient days at Madis on and 0.5 per 1000 patient days at Milwaukee.
Conclusion: Patients at the Madis on VA ICU have a greater prevalence of VRE on admis s ion compared with a s imilar
facility in Milwaukee. VRE colonization will be mis s ed in two-thirds of this population when relying on s creening in CDI
patients alone. Further s tudies are needed to account for regional differences in VRE admis s ion prevalence and their
relations hip to targeted infection control interventions .
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
325. Changes in Clostridium difficile Testing Practices and their Impact on
Stool Rejection Policies across Multiple U.S. Laboratories
Part of Session: 51. C. difficile Diagnostics JESSICA COHEN, MPH1, DUNCAN MACCANNELL, PHD1, LEIGH ANN CLARK, MPH2, WENDY BAMBERG, MD3, REBECCA
PERLMUTTER, MPH4, JOHN DUNN, DVM, PHD5, JOELLE NADLE, MPH6, STACY HOLZ BAUER, DVM7, CAROL LYONS, MPH8, ERIN
PHIPPS, DVM9, GHINWA DUMYATI, MD, FSHEA10, Z INTARS G. BELDAVS, MS11 and FERNANDA LESSA, MD1; 1Divis ion of
Healthcare Quality Promotion, Centers for Dis eas e Control and Prevention, Atlanta, GA, 2Georgia Emerging Infections
Program, Decatur, GA, 3Colorado Dept. of Public Health and Environment, Denver, CO, 4Maryland Dept. of Health and
Mental Hygiene, Baltimore, MD, 5Tennes s ee Department of Health, Nas hville, TN, 6California Emerging Infections Program,
Oakland, CA, 7CDC CEFO as s igned to the MN Dept. of Hlth, St. Paul, MN, 8Connecticut Emerging Infections Program, New
Haven, CT, 9New Mexico Emerging Infections Program, Albuquerque, NM, 10Univers ity of Roches ter, Roches ter, NY,
Background:
At leas t five nucleic acid amplification as s ays (NAAT), with higher s ens itivity than traditional enzyme immunoas s ays (EIA),have been approved for Clos tridium difficile tes ting. Laboratory practice guidelines dis courage C. difficile tes ting of formeds tools and repeat tes ting regardles s of as s ay type. We s urveyed laboratories participating in the C. difficile infectionpopulation-bas ed s urveillance s erving a population of 11.2 million in 10 US s ites to as s es s differences in s tool rejectionpolicies bas ed on NAAT adoption.
Methods:
Laboratories were s urveyed in December 2011. Data collection included current tes ting practices , changes to tes tingalgorithms and s tool rejection policies in the pas t year, and number of s tool s pecimens tes ted and number of s toolspos itive for C. difficile in the 3 months pre- and pos t- NAAT implementation. Chi-s quare and Wilcoxon rank s um tes ts wereus ed to evaluate differences in categorical and continuous variables , res pectively.
Results:
Surveys were completed by 107 (91%) of the 118 labs s urveyed; repres enting 79 inpatient and 28 outpatient labs . A totalof 47 (44%) labs were us ing NAAT, of thes e 23 (50%) s witched to NAAT as either firs t line (n=17) or s econd line (n=6) in2011. EIA was us ed by 22 (96%) labs while EIA/GDH was us ed by 1 lab prior to the s witch. Labs us ing NAAT were morelikely to reject formed s tools than labs that do not (89% vs . 52%, P < .001). More s tringent policies were implemented by20 labs after the s witch; 11 of the 12 labs that did not reject formed s tools previous ly began rejecting formed s tools afteradoption of NAAT and 12 res tricted tes ting of multiple s pecimens within 48 hours . Data from 16 labs s how the mediannumber of s pecimens tes ted decreas ed from 345 to 247 (P<.001) and percent of pos itive s pecimens increas ed from 10%to 20% (P <.001) in the 3 months after NAAT implementation.
Conclusion:
Rejection policies varied s ignificantly depending on tes t us ed. Labs us ing NAAT reported rejecting formed s tools morecommonly than labs us ing toxin as s ays , and a higher C. difficile pos itivity rate. The implementation of NAAT will likelyimprove compliance with recommended s tool rejection policies , improve detection and, depending on relative cos tcompared to EIA, reduce cos ts by performing fewer tes ts .
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
326. The Nose Knows Not: Poor Predictive Value of Stool Sample Odor for
Detection of Clostridium difficile
Part of Session: 51. C. difficile Diagnostics KRISHNA RAO, MD1, DANIEL BERLAND, MD1, CAROL YOUNG, MT(ASCP)2, SETH WALK, MS, PHD3 and DUANE NEWTON, PHD3;
1University of Michigan Health Systems, Ann Arbor, MI, 2University of Michigan Health System, Ann Arbor, MI, 3University of
Michigan, Ann Arbor, MI
Background:
C. difficile is a major cause of nosocomial infection and poses a challenge to infection control procedures. A nurse-drivenprotocol may res ult in earlier is olation and decreas ed trans mis s ion. Gas chromatography has s hown that unique volatilecompounds differentiate C. difficile pos itive and negative s tool s amples and other s tudies have s hown that nurs es in theclinical s etting may be able to identify C. difficile pos itive s tool s amples by odor. Our s tudy examined this hypothes is in acontrolled laboratory s etting.
Methods:
Nurs es were recruited from inpatient wards at our hos pital. Our microbiology lab randomly s et as ide 5 pos itive and 5negative s tool s amples bas ed on res ults from 2-s tep tes ting (GDH/toxin EIA followed by PCR for EIA dis cordants ) for Clostridium difficile toxin (CDTOX) from patients with liquid stool. We surveyed nurses on age, work experience, and if theyfelt they could detect C. difficile by odor. They were ins tructed to s niff each s ample, 10 total s amples per nurs e, andrecord their opinion if CDTOX pos itive s tool was pres ent. Fis her’s exact and Mann-Whitney tes ts were us ed to as s es ss tatis tical s ignificance.
Results:
18 nurs es participated. Experience ranged from 1 to 30 yrs (8 had > 10 yrs of experience). 11 felt confident they could tellif CDI was pres ent by odor (61%). The median percent correct per individual was 45%. However, the median percent ofcorrect ans wers for CDTOX pos itive s amples was 31% vs . 74% for CDTOX negative s amples (p=0.0119). By Fis her’s exacttes ts , no s ingle individual’s s niffing ability was better than that predicted by chance (mean s ens itivity / s pecificity =0.26/0.69). Thos e with confidence in s niffing ability did not perform better than others bas ed on median percent correct(40% vs . 50%; p=0.2471) and more experienced nurs es were no different than les s experienced nurs es in identifying CDTOX s tatus bas ed on median percent correct (both 45%; p= 0.8887).
Conclusion:
In the controlled laboratory s etting of our s tudy, nurs es were unable to identify C. difficile pos itive s tool s amples by odor,but CDTOX negative s amples elicited more correct ans wers than CDTOX pos itive s amples . More experience and confidencein the ability to diagnos e CDI by odor do not improve performance.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
327. Evaluation of a Commercial PCR Assay for Detection of Environmental
Contamination with Clostridium difficile
Part of Session: 51. C. difficile Diagnostics ABHISHEK DESHPANDE, M.D., PH.D.1, JENNIFER CADNUM, B.S.2, BRETT SITZ LAR, B.S.2, SIRISHA KUNDRAPU, M.D.2 and
CURTIS J. DONSKEY, MD2; 1Cas e Wes tern Res erve Univers ity, Cleveland, OH, 2Louis Stokes Cleveland Veterans Affairs
Medical Center, Cleveland, OH
Background: Contaminated environmental s urfaces are an important s ource for trans mis s ion of Clos tridium difficile.
However, there are currently no efficient and eas y to us e methods to as s es s the effectivenes s of environmental
dis infection.
Methods: We tes ted the hypothes is that a commercial real-time polymeras e chain reaction (PCR) for the toxin B gene tcdB
(Xpert® C. difficile, Cepheid) would provide a s ens itive and efficient method to detect toxigenic C. difficile in the
environment. Pre-mois tened s wabs and gauze pads were us ed to culture high-touch s urfaces (toilet s eat/hand rail,
table/bed rail, phone/call button) in C. difficile infection (CDI) rooms before and after pos t-dis charge cleaning by
hous ekeeping. The s ens itivity, s pecificity, pos itive predictive value (PPV), and negative predictive value (NPV) of PCR from
s wabs was compared to toxigenic culture by direct plating of s wabs .
Results: Of 22 CDI rooms , 9 were s ampled before and 13 were s ampled after pos t-dis charge cleaning. One or more C.
difficile swab cultures were positive for 6 of 9 active CDI rooms and 6 of 13 (46%) cleaned rooms. PCR testing of swabswas s pecific but had low s ens itivity in comparis on to culture (Table). Lowering the PCR cycle thres hold (Ct) value to 45increas ed s ens itivity without decreas ing s pecificity. PCR pos itivity correlated with greater levels of contamination (5/5 s itespos itive when ≥10 colonies (range: 11-215) pres ent vers us 0/6 when < 10 colonies recovered (P<0.001). In comparis on tos wabs , gauze cultures had 50% higher s ite pos itivity in both active CDI and cleaned rooms .
Conclusion: In comparis on to culture, we found that a commercial PCR as s ay had good s ens itivity for detection of heavy
environmental contamination, but poor s ens itivity for detection of low levels of contamination that were typically pres ent
after rooms were cleaned. Modifications of the as s ay s uch as lowering the PCR Ct or increas ing the s urface area s ampled
may res ult in improved s ens itivity.
Table. Diagnos tic accuracy of PCR for detection of environmental C. difficile Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
328. Severe Clostridium difficile Infection in Patients with Negative Results for
tcdB by the Xpert® C. difficile assay
Part of Session: 51. C. difficile Diagnostics JEROME LEIS, MD1, WAYNE GOLD, MD, FRCPC1, JOHN NG, PHD1, Z AHIR HIRJI1, DYLAN PILLAI, MD, PHD2, GEORGE
BROUKHANSKI, PHD1, PAUL RAGGIUNTI1, SUSY HOTA, MD1, ALLISON MCGEER, MD, FSHEA1 and SUSAN POUTANEN, MD,
MPH1; 1Univers ity of Toronto, Toronto, ON, Canada, 2Univers ity of Calgary, Calgary, AB, Canada
Background:
C. difficile (CD) real-time polymerase chain reaction (PCR) for tcdBis more sensitive and reduces turnaround time whencompared to toxin immunoas s ay. We noted typical amplification curves with high cycle thres holds (Ct) and low endpoints(Ept) that are labeled negative by the Xpert® as s ay (Cepheid) and undertook this project to determine their s ignificance.
Methods:
An indeterminate (IND) Xpert® CD as s ay res ult was defined as detection of a typical PCR amplification curve with a non-zero numeric Ct and Ept >10, and interpreted as negative by the Xpert® as s ay. For 5 months after implementation ofXpert® in our laboratory, non-duplicate s tools with an IND res ult were retes ted by Xpert®, cultured for toxigenic CD, andis olates were s ubjected to PCR ribotyping, toxin genotyping and multilocus variable-number tandem repeat analys is (MLVA)typing. Chart reviews were completed to as s es s if patients met the SHEA/IDSA CD infection (CDI) cas e definition andillnes s s everity was compared with Ct and culture res ults .
Results:
During the firs t year after implementation of the Xpert® as s ay, 14% (1151/8413) of s pecimens were pos itive and 1%(97/8413) were IND. IND res ults were not as s ociated with one us er or one machine module, and the percentage was s tableover time. Of the 48 patients with IND res ults in the firs t 5 months , 39 (81%) met the CDI cas e definition, and 7 (18%) metcriteria for s evere CDI. Toxigenic s tool cultures were pos itive for 86% (6/7) of patients with s evere CDI, 19% (6/32) ofpatients with non-s evere CDI, and 44% (4/9) of patients who did not meet CDI cas e definition (p=0.002). Lower Ct andhigher Ept were as s ociated with greater likelihood of toxigenic culture pos itivity (p=0.03) and more s evere s ymptoms(p=0.06). Typing of CD is olates confirmed that IND res ults were not as s ociated with a particular s train. Conclusion:
One-third of res ults that have typical amplification curves , but are interpreted as negative by Xpert®, are pos itive bytoxigenic culture and mos t meet the cas e definition of CDI. The mechanis m of thes e fals e-negative res ults is nottechnique-related, equipment-related, or due to particular CD s trains . IND res ults s hould be reported to clinicians as theymay impact patient care decis ions .
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
329. Does Empirical Clostridium difficile Infection (CDI) Therapy Result in False-
Negative CDI Diagnostic Test Results?
Part of Session: 51. C. difficile Diagnostics VENKATA SUNKESULA, M.D, M.S1, SIRISHA KUNDRAPU, M.D.2 and CURTIS J. DONSKEY, MD1; 1Louis Stokes Cleveland
Veterans Affairs Medical Center, Cleveland, OH, 2Cas e Wes tern Res erve Univers ity, Cleveland, OH
Background: Patients with s us pected Clos tridium difficile infection (CDI) often receive empirical CDI therapy while awaiting
diagnos tic tes t res ults . Becaus e CDI treatment s uppres s es C. difficile in the colon, we hypothes ized that empirical therapy
might res ult in fals e-negative CDI diagnos tic tes t res ults .
Methods: We conducted a 6-month pros pective s tudy of inpatients being tes ted for CDI. We determined the frequency of
empirical therapy for CDI and calculated the time on empirical therapy prior to collection of a s tool s ample for tes ting. For
a cohort of CDI patients , we tes ted multiple s tool s amples during therapy to determine the impact of CDI therapy on
res ults of polymeras e chain reaction (PCR) for toxin B genes .
Results: Of 151 patients being tes ted for CDI, 29 (19%) patients were empirically treated, of whom 27 tes ted negative.
The median duration of empirical CDI therapy prior to collection of a s tool s ample was 24 hours (range, 6 hours to 9
days ). For 26 CDI patients with s erial tes ting, PCR res ults converted to negative within 7 days in 7 of 11 (64%)
metronidazole-treated patients and 14 of 15 (93%) vancomycin or vancomycin plus metronidazole-treated patients (P=0.11)
(Figure). There were no differences between patients who did or did not convert to negative PCR with regard to age, ATLAS
s core, age adjus ted Charls on comorbidity index, infection with the NAP1 epidemic s train, or clinical treatment res pons e.
Within 1 and 2 days of treatment, 1 (4%) and 7 (27%) of 26 CDI patients had converted to negative PCR res ults ,
Conclusion: Empirical treatment of patients with s us pected CDI res ulted in negative s tool PCR res ults in only 4% of
patients after 1 day of therapy, but negative res ults occurred in 27% or more of infected patients when s tool collection was
delayed ≥2 days . Pos itive PCR res ults often pers is ted for s everal days after s tart of CDI therapy.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
330. Prospective Evaluation of the Epidemiology of Clostridium difficile
Colonization and Infection among Hematopoietic Stem Cell Transplant
Recipients
Part of Session: 51. C. difficile Diagnostics VARINIA URDAY-CORNEJO, MD1, CHRISTOPHER CROSWELL1, TEENA CHOPRA, MD, MPH2, ALYSSA LIUBAKKA1, JESSICA
CUTRIGHT, BS1, HOSSEIN SALIMNIA, PHD3, PAUL LEPHART, PHD3, SANJAY REVANKAR, MD1, PRANATHARTHI CHANDRASEKAR,
MD1 and GEORGE ALANGADEN, MD4; 1Wayne State Univers ity, Detroit, MI, 2Detroit Medical Center/ Wayne State Univers ity,
Detroit, MI, 3Detroit Medical Center Univers ity Laboratories , Detroit, MI, 4Henry Ford Health Sys tem, Detroit, MI
Background:
Clostridium difficile infection (CDI) occurs in 4-20% of Hematopoietic Stem Cell Transplant (HSCT) recipients. Asymptomaticcarriage of Clos tridium difficile (C. diff) is believed to occur in about 7% of healthy adults and 11-25% of hos pitalizedpatients (pts ). We performed a pros pective s tudy to examine the rates of as ymptomatic carriage of C. diff and s ymptomatic CDI in theHSCT recipients to better unders tand the epidemiology of CDI in this population.
Methods:
This s tudy began in December 2010 and was performed at the Karmanos Cancer Center, a 100 bed tertiary care hos pitalin Detroit, Michigan. Informed cons ent was obtained from all pts admitted to the HSCT unit before s tudy enrollment. Stools amples were collected within 72 hours of hos pital admis s ion and weekly thereafter until hos pital dis charge. Sampleswere anaerobically cultured for C. diff us ing two different culture media: CCFA-VA and CCFA-HB media. All culture pos itives tool s amples were tes ted by PCR for confirmation of toxigenic C. diff. Medical data on pt demographics and clinicaloutcomes was collected.
Results:
Data on the firs t 50 pts (planned s tudy enrollment of 200 pts ) is pres ented. The median follow up was 284 days (range = 196-372 d). The overall s tudy population had a mean age of 50 yr, 48% were women, 92% were allogeneic HSCTrecipients , 52% had been hos pitalized within the las t 30 d. Of the 50 pts , 21 (42%) were colonized with C. diff at hos pitaladmis s ion of which 7 (33%) were colonized with a toxigenic s train. All 7 (100%) pts colonized with a toxigenic s traindeveloped CDI during the hos pital s tay compared to 1/14 (7%) colonized with a non-toxigenic s train at admis s ion. Of the 29pts not colonized at admis s ion 6 (29%) s ubs equently became colonized with C. diff; 3 toxigenic and 3 non-toxigenic s trains .
Overall 14/50 pts developed CDI during the period of follow-up, of thes e 36 % had a recurrent epis ode of CDI.
Conclusion:
CDI occurs frequently in the HSCT population at our ins titution and recurrent CDI occurs in a third of pts with CDI.
As ymptomatic colonization with C. diff at time of hos pitalization is common. Colonization with a toxigenic s train atadmis s ion is predictive of CDI. Additional s tudies are needed to elucidate the clinical and infection control implications ofthes e findings .
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
331. Multilocus sequence typing analysis of 85 C. difficile strains isolated from
a teaching hospital in Houston Texas, September through December 2011
Part of Session: 51. C. difficile Diagnostics ZHI-DONG JIANG; The Univers ity of Texas , School of Public Health, Hous ton, TX, RAVI PANCHUMARTHI; UNIVERSITY OF
TEXAS SCHOOL OF PUBLIC HEALTH, HOUSOTN, TX, KEVIN W. GAREY, PHARMD, M.S.; Univers ity of Hous ton College of
Pharmacy, Hous ton, TX, TODD M. LASCO, PHD; Saint Lukes Epis copal Hos pital, Hous ton, TX, JANE CHEN; UNIVERSITY OF
TEXAS SCHOOL OF PUBLIC HEALTH, HOUSTON, TX and HERBERT DUPONT, MD, FIDSA; St. Luke's Epis copal Hos pital and
Kels ey Res earch Foundation and Kels ey-Seybold Clinic, Hous ton, TX
Background: In epidemiological res earch, genotyping of s trains plays an important role in tracing potential s ource(s ),
identifying infection clus ters , and defining mode(s ) of trans mis s ion. Multilocus s equence typing (MLST) facilitates the
s eparation of is olates by indexing variation in intragenic s equences of a s et (generally, 5 to 7) of hous ekeeping genes .
Methods: A total of 85 C. difficile (CD) clinical is olates collected between September and December of 2011 from a large
teaching hos pital in Hous ton, Texas were analyzed by MLST analys is of s ix hous ekeeping genes (aroE, dutA, tpi, recA, gmk,
and s odA).
Results: The number of alleles ranged from 7 (recA and gmk) to eleven (s odA). Allelic profiles revealed 20 different
s equence types (STs ). All STs lacked correlation with geographic s ource, but correlated to CD toxigenic type. The
dendrogram generated from a matrix of pairwis e genetic dis tances s howed no hypervirulent lineage within the population
of toxigenic human is olates . However, A− B+ variant is olates s hared the s ame STs that appeared as a divergent lineage
in the population s tudied, indicating a s ingle evolutionary origin.
Conclusion: This s tudy focus ed on human clinical is olates collected from a s ingle geographic location. It s ets a bas eline
of MLST data for epidemiologic s tudies underway des igned to identify clus tering and hos pital trans mis s ion of s trains of
CD, and the relations hip between genotype pattern and dis eas e s everity us ing clinical s everity data from infected patients .
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
332. Clostridium difficile Whole Genome Sequencing Suggests Limited
Transmission Arising From Mixed Infection
Part of Session: 51. C. difficile Diagnostics DAVID EYRE, BM, BCH1, MADELEINE CULE, PHD2, DAVID GRIFFITHS, BSC3, TIM PETO, MB BS, DPHIL4, A. SARAH WALKER,
PHD2 and DANIEL WILSON, DPHIL2; 1Nihr Oxford Biomedical Res earch Centre, Oxford, United Kingdom, 2NIHR Oxford
Biomedical Res earch Centre, Oxford, United Kingdom, 3National Ins titute for Health Res earch Oxford Biomedical Res earch
Centre, Oxford, United Kingdom, 4Univers ity of Oxford, Oxford, United Kingdom
Background: Whole genome s equencing (WGS) offers the pros pect of high precis ion outbreak inves tigation us ing genetic
data. However, potentially undetected mixed infection impairs exclus ion of trans mis s ion with certainty. Clos tridium
difficile (CD) mixed infection rates of ~7% are described, but their significance in transmission is unclear.
Methods: Hos pital admis s ion / ward movement data on 1276 CD cas es in Oxfords hire, UK (Sep07 – Mar10) were analys ed
in a s tochas tic compartmental trans mis s ion model. Independently, is olates were multi-locus s equence typed (MLST). 15
high probability trans mis s ions (p>0.45) had putative donors and recipients with dis cordant s equence types (STs ). WGS of
primary s tool cultures from each putative donor and recipient was undertaken us ing Illumina HiSeq. Reads were mapped to
the CD630 reference. As s uming each culture contained a mix of 1 or 2 STs , a maximum likelihood es timate of the identity,
and relative proportions , of each ST pres ent was obtained us ing Illumina bas e counts at the MLST loci. Es timator
performance was as s es s ed us ing 100 s equences from s ub-culture of a s ingle colony, and 10000 s imulated mixes of thes e
s equences .
Results: Sequences were obtained from 13 putative donors and 15 putative recipients (2 donors had 2 putative
recipients ). In 27/28 s amples the es timated dominant ST matched the original ST from MLST PCR. The remaining s ample
was s ignificantly contaminated with another Clos tridium s pecies . Only 1/28, a recipient, had a minor ST recovered (8.4% of
the s ample) that created a new donor-recipient ST match. The minor ST was that predicted by the trans mis s ion model.
In 100 s equences each derived from a s ingle colony, thus expected not to be mixed, the known ST was recovered on alloccas ions and accounted for median 99.9% (IQR 99.0-100%) of the s ample. In 10000 s imulated mixed ST infections themixture proportion was es timated with a root mean s quare error of 0.068, and the correct STs were obtained on9706/10000 occas ions .
Conclusion: WGS can detect mixed ST infection without labor-intens ive multiple colony typing. In this s ample of cas es
s ignificantly enriched for the pos s ibility of mixed infection only 1/15 putative donor-recipient pairs s howed evidence of a
mixed infection that might have been mis s ed on initial typing and s upported trans mis s ion.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
333. Title: Safety of Clostridium Difficile Testing Algorithm using Glutamate
Dehydrogenase Antigen and Toxin Enzyme Immunoassay with Reflex PCR for
Discordant Test
Part of Session: 51. C. difficile Diagnostics CECILIA BIG, MD, DAVID SENGSTOCK, MD, MS, NATASHA BAGDASARIAN, MD, MPH, VIJAYALAKSHMI NAGAPPAN, MD, PADMAJA
VEMURI, MD, DAVID WEIDENDORF, MD and RAMA THYAGARAJAN, MD; Oakwood Hos pital and Medical Center, Dearborn, MI
Background:
Introduction & background: Clos tridium difficile infections (CDI) are a s ignificant caus e of hos pital-as s ociated morbidity andmortality. PCR tes ts for CDI are s ens itive but expens ive. At a community hos pital s ys tem compris ed of four teachingcenters , s tools from s ymptomatic patients are tes ted with a combined Glutamate Dehydrogenas e Antigen (GDH) andClos tridium Difficile Toxin Enzyme Immunoas s ay (toxin EIA); s ubs equently, PCR is done when GDH is pos itive but toxin EIAis negative. The combination GDH/toxin EIA has a reported 90.5% s ens itivity with a negative predictive value of 97.6%. Thecurrent s tudy aimed to determine whether patients with negative tes ting for CDI by GDH/toxin EIA s uffered advers e clinicalcons equences due to undiagnos ed CDI, as meas ured by death or readmis s ion for CDI within 7 days .
Methods:
Methods : We queried the hos pital microbiology databas e for all firs t-time s tool tes ts during hos pitalization for CDI in adultinpatients during the month of September 2011. All initial pos itive GDH/toxin EIA tes ts were excluded. Charts from the firs t100 patients with initial negative tes ts were examined for repeat CDI tes ting, death, or re-admis s ion within 7 days .
Results:
Res ults : 18 of the firs t 100 patients with initial negative tes ts had one or more repeat tes ts ; only one of the repeat tes twas pos itive (1% fals e negative rate). That pos itive repeat tes t was ordered the following day and the patient wass ucces s fully treated. Three patients expired due to unrelated caus es ; 18 were dis charged without any further medical careat our facility; laboratory data confirmed that the remaining 79 patients were alive after 7 days . No patient with a negativetes t was re-admitted or died within 7 days due to CDI.
Conclusion:
Conclus ion: Preliminary res ults s ugges t that after a negative GDH/toxin EIA, poor outcome as a res ult of undiagnos ed CDIis rare. The GDH/toxin EIA combination is a s afe and effective method to rule out clinically s ignificant CDI.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
334. Prevalence and Molecular Epidemiology of Clostridium difficile (CD) in Food
and Companion Animals, Retail Meats, and Humans in Minnesota
Part of Session: 51. C. difficile Diagnostics MEGAN K. SHAUGHNESSY, MD1, TIM SNIDER, DVM2, ROCIO SEPULVEDA2, DAVID BOXRUD, MS3, ELIZ ABETH CEBELINSKI,
BS3, STACY HOLZ BAUER, DVM4, KIRK SMITH, DVM, PHD3, JEFF BENDER, DVM MS DACVPM5, FRANCISCO DIEZ -GONZ ALEZ ,
PHD5 and JAMES R. JOHNSON, MD1; 1Univers ity of Minnes ota, Minneapolis , MN, 2Univers ity of Minnes ota, St Paul, MN,
3Minnesota Department of Health, St. Paul, MN, 4CDC CEFO assigned to the Minnesota Department of Health, St. Paul, MN,
5University of Minnesota, St. Paul, MN
Background: Community as s ociated Clos tridium difficile infection (CA-CDI), i.e., CDI in patients who lack clas s ic CDI ris k
factors (recent hos pitalization or antibiotic us e), is increas ing and accounts for approximately 50% of CDI cas es in central
Minnes ota. Some have s peculated that animals and food may s erve as CA-CDI s ources . We collected s amples from
humans , animals , and meat products to explore this hypothes is .
Methods: Since 2007, the Minnes ota Department of Health (MDH) has collected and genotyped CD is olates from central
Minnes ota as part of human CDI s urveillance. In November 2011, we began collecting food and companion animal fecal
s amples (goal n = 600) and retail meat products (goal n = 300) from the s ame geographic region. Sample characteris tics
for fecal s amples (geographic region, animal diarrhea s tatus , age, antibiotic us e) and retail meats (geographic region,
antibiotic-free labeling) are recorded. Animal fecal and retail meat s amples are cultured us ing a s ingle alcohol s hock
method. CD-like colonies are confirmed as CD us ing egg yolk agar, blood agar, PRO dis k, and Gram s tain. Confirmed CD
is olates undergo binary toxin PCR, toxinotyping, and tcdCgene s equencing.
Results: Sample collection is ongoing. Of 164 animal fecal s amples tes ted to date, 17 (10%) yielded CD; the majority
porcine (n = 10) and bovine (n = 4). Preliminary res ults s howed a higher trend in the CD pos itivity rate among diarrhetic
(26%) vers us healthy animals (5%), (P = .15). To date, of 129 retail meat s amples tes ted, none were CD-pos itive.
Molecular analys is s hows that mos t CD is olates are binary toxin pos itive (81%), toxinotype V (75%), with a 39 bas e pair
deletion in tcdC(81%). In parallel, MDH’s human CDI s urveillance project has yielded 138 human CD is olates during the
s ame time frame.
Conclusion: CD has been recovered from food animals in Minnes ota, but not from retail meats . Future plans include (i)
completing collection and CD tes ting of animal fecal and retail meat s amples , (ii) comparative molecular analys is of CD
is olates from animals , meats , and humans including puls ed field gel electrophores is , (iii) and s tatis tical analys is of CD
prevalence in relation to s ample characteris tics . Preliminary data from retail meat currently does not s upport the
hypothes is that meat products are a key s ource of CA-CDI.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
335. Screening for Vancomycin Resistant Enterococcus (VRE) Colonization
During Clostridum difficile Testing is Not Cost Effective at a Canadian Teaching
Hospital
Part of Session: 51. C. difficile Diagnostics SUNIL VARGHESE, MD, MA1, KATHRYN SUH, MD, MSC, FRCPC1, NATALIE BRUCE, RN, BSCN, CIC1, KARAM RAMOTAR, PHD1
and VIRGINIA ROTH, MD2; 1The Ottawa Hos pital, Ottawa, ON, Canada, 2The Ottawa Hos p, Ottawa, ON, Canada
Background: From January-December 2010, The Ottawa Hos pital (TOH) was s creening all patients on admis s ion for
VRE colonization. As part of outbreak management, s creening roommates of patients with VRE (contact
tracing), point prevalence s urveys , and dis charge/trans fer s creening were routinely performed. VRE s creening was als o
s imultaneous ly performed on all s tool s amples s ubmitted for C. difficile tes ting. This retros pective review as s es s ed
the cos ts and incremental yield of VRE detection from s tool s amples s ubmitted for C. difficile tes ting.
Methods: Data from January - December 2010 were collected retros pectively. Information was obtained from s urveillance
data available through the Departments of Microbiology, Clinical Quality and Performance Meas urement, and Infection
Control.
Results: 44616 VRE s creening tes ts were performed during the s tudy period. 403 s eparate patients were identified with
VRE. From 7071 s tool s pecimens s ubmitted for C. difficile tes ting, 41 s eparate patients were identified with VRE. Of thes e
41 patients , 24 (59%) would have been s ubs equently identified by VRE s creening that was performed for other infection
control indications . Time from initial pos itivity (at the time of C. difficile tes ting) to s ubs equent pos itive tes t was 0-281 days
(mean 22.5 days , median 5.5 days , mode 4 days ). VRE tes ting of C. difficile s pecimens identified only 17 patients (4.2% ofall patients with VRE) who would not otherwis e have been detected. The total cos t for VRE s creening with C. difficile tes tingwas approximately $35,000 CDN.
Conclusion: The overall yield of VRE tes ting on s amples s ent for C. difficile tes ting is low at TOH. Only 4.2% of patients
with VRE were identified s olely through s creening of s tool s pecimens s ubmitted for C. difficile tes ting. Given the low
morbidity as s ociated with VRE colonization, this calls into ques tion the cos t effectivenes s of routinely tes ting C.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
336. Toxin A/B EIA Compared to Molecular Amplification Testing for Clostridium
Difficile: Cost and Resource Utilization Analyses
Part of Session: 51. C. difficile Diagnostics REDA A. AWALI, MD1, BRINDHA GOPALA KRISHNAN, MD1, HARLEEN KAUR, MD1, INDU K. CHALANA, MD2, PAULA ROBINSON,
RN1, SANJAY REVANKAR, MD3, JUDY MOSHOS, BS, MT4, PAUL LEPHART, PHD5, RICHARD FACKLER, BBA1, KEITH KAYE, MD,
MPH, FIDSA, FSHEA6 and TEENA CHOPRA, MD, MPH7; 1Detroit Medical Center, Wayne State Univers ity, Detroit, MI, 2Wayne
State Univers ity / Detroit Medical Center, Detroit, MI, Detroit, MI, 3Wayne State Univers ity, Detroit, MI, 4Sinai-Grace Hos pital,
Detroit Medical Center, Detroit, MI, 5DMC Univers ity Laboratories , Detroit, MI, 6Detroit Medical Center (DMC) / Wayne State
Univers ity, Detroit, MI, 7Detroit Medical Center/ Wayne State Univers ity, Detroit, MI
Background: Since molecular amplification tes ting has only recently been adopted for CDI diagnos is , its cos t-
effectivenes s in detecting CD in a hos pital s etting is s till unclear. We did this s tudy to evaluate the cos t-effectivenes s of
diagnos is of CDI by molecular amplification (MA) as compared with Toxin A/B EIA.
Methods: Data on 229 CDI pos itive patients (tes ted by either EIA or llumigene as s ay) were obtained from the microbiology
laboratory at one of the Detroit Medical Center hos pitals between July 2009 and December 2011. Additional data on
is olation days and cos ts of contact is olation were acquired from the infection control department of the participating
hos pital. Outcome meas ures were number and type of CD tes ts ordered per patient and duration of contact is olation and
as s ociated cos ts . Cos ts were calculated from the private payer pers pective and analyzed us ing Wilcoxon rank-s um tes t.
Statis tical analys is was done us ing IBM SPSS Statis tics 20.0.
Results: Fifty-three CDI patients were admitted to the hos pital during the firs t 15 months of the s tudy and were tes ted
us ing the EIA. The 176 patients admitted during the s econd 15 months of the s tudy were diagnos ed by MA. The mean age
of EIA patients was higher than that of MA patients (67±15 vs 60.4 ± 20; p=0.016). There was a female predominance in
both groups (53% in EIA group and 59% in PCR group).
The median number of tes ts ordered per patient was much higher in the EIA group than the MA group (2, IQR [1-3] vs 1,IQR [1-1]; p<0.0001). Als o, the median number of is olation days per patient was greater in the EIA group than in MA group(8, IQR [5-10] vs . 7, IQR [4-9]; p=0.082). Although not s tatis tically s ignificant, the es timated median of cos ts attributable tocontact is olation of CDI patients (i.e. private room, gowns , gloves ) was higher in EIA group than in MA group ($8539, IQR[5355-10710] vs $7497, IQR [4284-9639]; p=0.082) Conclusion: Patients in the MA group were younger than thos e in the EIA group, pos s ibly due to the increas ed s ens itivity
of the MA tes t. Us e of MA was as s ociated with decreas ed number of CDI tes ts performed, s horter durations of contact
is olation for patients with CDI and fewer cos ts related to contact is olation.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.
337. Comparative Analysis of Two Culture Media and PCR for the Detection of
Toxigenic and Non-Toxigenic C. difficile
Part of Session: 51. C. difficile Diagnostics CHRISTOPHER CROSWELL1, VARINIA URDAY-CORNEJO, MD1, ALYSSA LIUBAKKA1, JESSICA CUTRIGHT, BS1, HOSSEIN
SALIMNIA, PHD2, PAUL LEPHART, PHD3, TEENA CHOPRA, MD, MPH4, PRANATHARTHI CHANDRASEKAR, MD1 and GEORGE
ALANGADEN, MD5; 1Wayne State Univers ity, Detroit, MI, 2Detroit Medical Center/Wayne State Univers ity, Detroit, MI, 3Detroit
Medical Center Univers ity Laboratories , Detroit, MI, 4Detroit Medical Center/ Wayne State Univers ity, Detroit, MI, 5Henry Ford
Medical Center Univers ity Laboratories , Detroit, MI, Detroit Medical Center/ Wayne State Univers ity, Detroit, MI, Henry FordHealth Sys tem, Detroit, MI Background:
Clostridium difficile (C. diff) is an anaerobic gram positive bacillus that causes C. diff infection (CDI). Epidemiologicals tudies utilize s pecial culture media to is olate C. diff, in order to determine rates of as ymptomatic carriage of C. diff or toevaluate environmental contamination with C. diff. The goal of this s tudy was to compare the effectivenes s of two differentculture media us ed to is olate toxigenic and non-toxigenic C. diff. The two media tes ted were a new modified cyclos erine-cefoxitin, fructos e agar enriched with hors e blood (CCFA-HB) and the commonly us ed pre-reduced cyclos erine-cefoxitinagar with vancomycin (CCFA-VA). Culture res ults were confirmed by C. diff real-time PCR (TIB, MolBiol) for the identificationof toxigenic C. diff.
Methods:
Pros pective s tool s amples from 50 as ymptomatic hematopoietic s tem-cell trans plant recipients from an ongoing s tudy ofCDI were cultured on both CCFA-HB and CCFA-VA media, followed by incubation in an anaerobic chamber. The C. diff real-time PCR as s ay was performed on all s amples to identify toxigenic C. diff and to confirm culture res ults . Sens itivity,s pecificity, negative predictive values , and pos itive predictive values were calculated.
Results:
C. diff was isolated from 21 of the 50 samples using CCFA-HB, and 7 of these tested positive by PCR for toxigenic C. diff. In contras t, C. diff was is olated from 6 of the 50 s amples us ing CCFA-VA media, and 4 of thes e tes ted pos itive by PCR. The s ens itivity, s pecificity, negative predictive value and pos itive predictive value for CCFA-HB compared to PCR were 100%,67%, 100%, and 33%. The s ens itivity, s pecificity, negative predictive value, and pos itive predictive value for CCFA-VA were57%, 95%, 93%, and 67%. Conclusion:
CCFA-HB media s upports the growth of both toxigenic and non-toxigenic C. diff s trains , and is cons iderably more s ens itivethan the CCFA-VA media. Convers ely, the CCFA-VA media offers more s pecificity for the is olation of toxigenic C. diff. Bas ed upon this s tudy, CCFA-HB is the preferred media for population s tudies evaluating as ymptomatic carriage rates oftoxigenic and non-toxigenic C. diff. The us e of the current s tandard media, CCFA-VA, for this purpos e may res ult in anunderes timation.
Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.

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