International Journal of Antimicrobial Agents 21 (2003) 267 Á/273
b-lactamase production in Provotella and in vitro susceptibilities to
L. Dubreuil a,, J. Behra-Miellet a, C. Vouillot a, S. Bland b, A. Sedallian b, F. Mory c
a Faculte´ de Pharmacie, 3, rue du Professeur Laguesse, BP83, Lille Cedex 59006, France
Received 21 May 2002; accepted 1 July 2002
This study looked for b-lactamase production in 100 Provotella isolates. MICs were determined for amoxycillin, ticarcillin,
amoxycillin'/clavulanate, cephalothin, cefuroxime, cefixime, cefpodoxime and cefotaxime using the reference agar dilution method(standard M11 A4, NCCLS). Beta-lactamase activity was detected in 58 of the 100 isolates, 24 of 46 black-pigmented Provotella and34 of 54 non-pigmented Provotella. All b-lactamase-negative strains were susceptible to all b-lactam antibiotics with the exception ofcefuroxime and cefixime. Overall, resistance rates of Provotella strains were lower for ticarcillin (8%) and celefotaxime (12%) thanfor the other cephalosporins. All Provotella isolates were susceptible to amoxyillin and were all inhibited by 2 mg/l or less amoxcillin. # 2002 Elsevier Science B.V. and the International Society of Chemotherapy. All rights reserved.
Keywords: Provotella ; b-lactamase production; Antibiotic resistance
Beta-lactamase production steadily increased duringthe 1980s. Clinical failures of penicillin treatment for
Anaerobic Gram-negative bacilli other than the
orofacial infections have been documented to-
Bacteroides fragilis group have been shown to be
gether with reports suggesting that previous penicillin
involved in clinical infections, either alone or mixed
therapy increases the incidence of penicillin-resistant
with other species. Although Fusobacterium and Pro-
Provotella . Resistance to metronidazole, combina-
votella are the main anaerobic bacilli isolated from
tions of penicillins and b-lactamase inhibitors or imipe-
human pathological samples, b-lactamase production
nem is rare and many laboratories now consider
identification and susceptibility testing of Provotella to
be unnecessary. Oral cephalosporins have a limited anti-
in pyogenic orofacial and upper respiratory tract infec-
anaerobic activity, especially against the B. fragilis
tions (chronic sinusitis and otitis). In elderly people,
group, but this activity may vary for other species.
micro-aspiration of saliva may inoculate the lungs and
Some oral cephalosporins are used to treat community-
cause pulmonary infections. There have been scattered
acquired anaerobic infections, although their anti-anae-
reports on the antibiotic susceptibility of Provotella
robic activities have not been recently reviewed. The
species, but only rare studies have been based on a large
activity of b-lactam antibiotics is decreasing due to the
number of Provotella strains apart from strains
increasing incidence of b-lactamase-producing isolates.
derived from periodontal isolates. Until the latter half of
It is, therefore, important to monitor resistance both to
the 1970s, penicillins and cephalosporins were generally
new drugs but also to widely prescribed antibiotics in
still effective against oral Gram-negative anaerobes.
community-acquired infections in order to guide theirempirical use.
In this study, we collected strains of Provotella and
tested the susceptibility of a sufficient number of isolates
* Corresponding author. Tel./fax: '/33-3-2096-4008E-mail address: (L. Dubreuil).
to antimicrobial agents marketed in the community. As
0924-8579/02/$30 # 2002 Elsevier Science B.V. and the International Society of Chemotherapy. All rights reserved. PII: S 0 9 2 4 - 8 5 7 9 ( 0 2 ) 0 0 3 5 2 - 7
L. Dubreuil et al. / International Journal of Antimicrobial Agents 21 (2003) 267 Á/273
Table 1b-lactamase production in Provotella isolates
the b-lactamase of Provotella has been reported to be a
fold dilutions of antimicrobial agents were prepared on
cephalosporinase ticarcillin was added to this
the day of the test and added to the media in various
study, although this drug is available only in hospitals.
Beta-lactamase production was tested by using the
(Cefinase†, Biome´rieux, France). According to Appel-
A total of 100 Provotella strains were isolated from
baum’s recommendations disks which did not turn
human clinical sources (blood culture, pleural fluid,
from yellow to red within 15 min at room temperature
chronic sinusitis and otitis, lung abscess, etc.). and from
vaginal samples for P. bivia and P. disiens . Strainsisolated from stools were excluded. The 100 isolates
were studied together with appropriate reference andcontrol strains (B. fragilis ATCC 25285, B. thethaiotao-
Susceptibility testing was performed by the reference
micron ATCC 29741, Eggerthella lenta ATCC 43055
agar dilution method according to the standards of
and C. perfringens ATCC 13124). All isolates were
the National Committee for Clinical and Laboratory
identified by standard criteria The P. intermedia
Standards (M11-A4). Brucella blood agar (Difco,
group includes three phenotypically indistinguishable
France) with 5% lysed horse blood (Eurobio, Les Ulis,
species: P. intermedia , P. nigrescens and P. pallens
France) was the basic medium. Amoxycillin and ticar-
this group is referred to as P. intermedia in this
cillin were diluted with clavulanate tested at a constant
paper. The numbers and species of isolates tested are
concentration of 2 mg/ml, as is usual in most European
countries. To comply with the interpretative categoriesof the NCCLS, we added two plates containing 8/4 and
16/8 mg/ml of amoxycillin and clavulanate combinations,respectively. A Mast multipoint inoculator was used to
Standard laboratory powders were obtained from the
deliver inocula of approximately 105 CFU per spot.
following sources: amoxycillin, ticarcillin, clavulanic
Plates were incubated in an anaerobic chamber (Don
Whitley†, AES, Combourg, France) and MICs were
Marly-le-Roi, France), cefotaxime, cefixime, cefpodox-
determined after 48 h of incubation at 35 8C and then
ime (Aventis, Paris). Antimicrobials were reconstituted
examined. Resistance rates were calculated at the
according to each manufacturer’s instructions. Serial 2-
NCCLS breakpoints. French (CA-SFM) breakpoints
L. Dubreuil et al. / International Journal of Antimicrobial Agents 21 (2003) 267 Á/273
were used for some oral cephalosporins, due to the lack
Beta-lactamase production was detected in 58 of the
100 isolates, including 24 of 46 black-pigmented Provo-
tella (52%) and 34 of 54 non-pigmented Provotella(63%). Beta-lactamase production varied according to
the species (Beta-lactamase production wasmore frequent for P. melaninogenica (14/21) , P. bivia(15/20), and P. intermedia (7/11). The amoxycillin MIC
breakpoint separating b-lactamase-positive and b-lacta-mase-negative isolates was ]/0.5 mg/l (
3.2. In vitro susceptibility to b-lactam antibiotics
Most antimicrobial agents were more active against b-
lactamase-negative isolates than against b-lactamase-
positive isolates (). All b-lactamase-negative
strains were susceptible to all b-lactams, with theexception of one strain of P. oris and one strain of P. bivia that were resistant to both cefuroxime and
cefixime. Beta-lactamase-negative strains were all in-hibited by either 0.25 mg/l of amoxycillin'/clavulanate,1 mg/l of ticarcillin or cefpodoxime, or 2 mg/l of
Amoxycillin-resistant isolates were detected in all
species of Provotella with the exception of P. denticola ;the highest resistance rate was observed for Provotella
bivia . Among b-lactamase-positive strains, amoxycillin
MICs were higher for non-pigmented Provotella than
for black-pigmented isolates (Amoxycillin
MIC90 for b-lactamase-positive isolates was 9 dilutionshigher than that for b-lactamase-negative isolates.
All isolates in this study were susceptible to
amoxycillin'/clavulanate. Most isolates were suscepti-
ble to 64 mg/l of ticarcillin. Although the MICs ofcefpodoxime and cefotaxime were generally fairly simi-
lar, cefpodoxime, which has lower antibiotic break-
points, had poor activity against b-lactamase-positive
for cefixime. Among the black-pigmented isolates, only
one strain of P. intermedia was resistant to cefotaxime;
most cefotaxime-resistant strains were, therefore, notpigmented (P. oralis , P. buccae and P. bivia ).
On the whole, resistance rates of Provotella strains
were lower for ticarcillin (8%) and cefotaxime (12%)
than for the other cephalosporins. All Provotella isolates
inhibited by 2 mg/l or less of amoxycillin'/clavulanate
were susceptible to this combination.
L. Dubreuil et al. / International Journal of Antimicrobial Agents 21 (2003) 267 Á/273
Table 3Activity of three penicillins against 100 strains of Provotella : distribution of MICs
Amoxycillinb-lactamase negative Provotella
Amoxycillin-clavulanateb-lactamase negative Provotella
Ticarcillinb-lactamase negative Provotella
Table 4Activity of five cephalosporins against 100 strains of Provotella : distribution of MICs
Cephalothinb-lactamase negative Provotella
Cefuroximeb-lactamase negative Provotella
Cefpodoximeb-lactamase negative Provotella
Cefotaximeb-lactamase negative Provotella
However, several studies have also reported lowerprevalences The various frequencies observedin other reports could be explained by geographical
differences and isolate sampling differences .
Most studies of antimicrobial susceptibility of anae-
robic bacteria are based on serial isolates from clinical
4.2. In vitro susceptibility to b-lactam antibiotics
material and, therefore, focus on the more commonspecies and combine the results for less common
The amoxycillin MIC distribution clearly distin-
isolates. Consequently, little information is available
guished Provotella isolates into two groups according
about the susceptibility of less commonly isolated
to b-lactamase production (breakpoint ]/0.5 mg/l). This
Provotella species. Beta-lactamase production was low
value was identical to the penicillin G breakpoint
(19 Á/40%) in the 1980s and subsequently in-
previously proposed by Matto et al. . Beta-lactamase
creased to reach 70% of strains in 1994 . Since then,
detection is relatively difficult and could be replaced in
the frequency of b-lactamase-producing strains has
routine by determination of amoxycillin MICs using the
remained in the 60 Á/70% range . The prevalence
E -test and the 0.38 mg/l breakpoint. As recommended
of b-lactamase production of Provotella species is in
by the NCCLS, all Gram-negative anaerobes should be
agreement with several previous French studies .
screened for b-lactamase production with nitrocephin
L. Dubreuil et al. / International Journal of Antimicrobial Agents 21 (2003) 267 Á/273
Table 5Comparative in vitro activity of b-lactam antibiotics against Provotella species according to b-lactamase production
Organism (number tested) and antimicrobial agent
L. Dubreuil et al. / International Journal of Antimicrobial Agents 21 (2003) 267 Á/273
Organism (number tested) and antimicrobial agent
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A novel two-step kit for topical treatment of tinea pedis –an open studyA Shemer,† MH Grunwald,‡ B Davidovici,§ N Nathansohn,† B Amichai†,*†Department of Dermatology, Sheba Medical Center, Tel-Hashomer, ‡Soroka University Medical Center, Ben-Gurion University,Beer-Sheva, and §Dermatology Unit, Kaplan Medical Center, Rehovot, Israel*Correspondence: B Amichai. E-mail: boazam@clali