Antimicrobial susceptibility of 51 Campylobacter strains isolated from diarrheic and diarrhea-free dogs.
ANTIMICROBIAL SUSCEPTIBILITY OF 51 CAMPYLOBACTER STRAINS
ISOLATED FROM DIARRHEIC AND DIARRHEA-FREE DOGS*
J.R. Modolo1, R. Giuffrida2, C.A. de M. Lopes3
1Faculdade de Medicina Veterinária e Zootecnia, UNESP/Botucatu, CP 524, CEP 18618-000, Botucatu, SP,
The minimum inhibitory concentrations (MICs) were determined by agar dilution for six
antimicrobial agents (cephalexin, eythromycin, gentamicin, enrofloxacin, chloramphenicol, and
oxytetracyline) using 51 Campylobacter strains (29 Campylobacter jejuni subsp. jejuni, 14 Campylobacterjejuni subsp doylei, 5 Campylobacter upsaliensis, 2 Campylobacter coli, and 1 Campylobacter lari) isolated
from 29 diarrheic and 22 diarrhea-free dogs. Percentages corresponding to 50% and 90% strain
inhibition (MIC 50% and MIC 90%) were determined. The results show that erythromycin,
enrofloxacin, and gentamicin can be recommended for the treatment of campylobacteriosis in dogs;
this opens the possibility of their therapeutic use in human medicine.
KEY WORDS: Campylobacter, dogs, minimum inhibitory concentration, antimicrobials, public
SUSCEPTIBILIDADE ANTIMICROBIANA DE 51 AMOSTRAS DE CAMPYLOBACTER ISOLA-
DOS DE CÃES COM E SEM DIARRÉIA. As concentrações inibitórias mínimas de seis antimicrobianos
(cefalexina, eritromicina, gentamicina, enrofloxacina, cloranfenicol e oxitetraciclina) para 51 estirpes
de Campylobacter (29 de Campylobacter jejuni subsp. jejuni, 14 de Campylobacter jejuni subsp doylei, 5
de Campylobacter upsaliensis, 2 de Campylobacter coli e 1 de Campylobacter lari), isoladas de 29 cães com
diarréia e 22 cães sem diarréia foram determinadas pelo método de diluição em ágar. Foram
determinadas as percentagens correspondentes à inibição de 50% e 90% das estirpes isoladas (CIM
50% e CIM 90%). De acordo com os resultados, a eritromicina, a enrofloxacina e a gentamicina podem
ser recomendadas como drogas de eleição para o tratamento da campilobacteriose em cães,
ampliando também as possibilidades terapêuticas para o uso em medicina humana.
PALAVRAS-CHAVE: Campylobacter, cães, concentração inibitória mínima, antimicrobianos, saúde
with clinical campylobacteriosis reduces the duration
and severity of the disease, decreases microorganism
Over the past few decades, Campylobacter species
shedding time, minimizing the risk of human exposure
have emerged as the common cause of enteritis in
to the bacteria (BOOSINGER & DILLON, 1992).
humans and animals. Enteric campylobacteriosis has
Antimicrobial resistance studies of Campylobacter
been considered as a highly prevalent worldwide
strainsisolated from dogs are rare. Most studies deal
zoonosis in developed countries (NACHAMKIN, 1997)
with strains isolated from humans and animals used
Dogs are contaminated by oral-fecal contact, and
by manifesting gastroenteritis or acting as healthy
Erythromycin and chloramphenicol, the most
carriers, represent a potential infection source to
common antibiotics used to treat dogs have sometimes
humans (BLASER et al., 1978; BRUCE & FLEMING, 1983;
failed to eliminate the organism from the stool
GOOSSENS et al., 1991). Antimicrobial therapy for dogs
2Pós-graduando, área de Vigilância Sanitária, Faculdade de Medicina Veterinária e Zootecnia, UNESP/Botucatu,
Botucatu, SP, Brasil3Instituto de Biociências, UNESP/Botucatu, SP, Brasil. Arq. Inst. Biol., São Paulo, v.70, n.3, p.283-286, jul./set., 2003
The aim of this study was to evaluate minimum
1996). Cephalosporins are useful in selective media
inhibition concentrations (MICs) of six antimicrobial
for primary bacterial isolation; however, studies report
agents (cephalexin, chloramphenicol, enrofloxacin,
2-25% susceptibility of these bacteria to cephalexin
erythromycin, gentamicin, and oxytetracyline) on
(ABRAHANS et al., 1990; MODOLO et al., 1991). It is therefore
Campylobacter strains isolated from both diarrheic
important that cephalosporin selective media are not
exclusively used for the primary isolation of this
bacterium; the concomitant use of filtration techniques
is recommended (MODOLO, 2000). Chloramphenicol
showed higher MIC values in diarrheic dogs (2-32
µg/mL) than diarrhea-free (2-8 µg/mL). Considering
Fifty-one Campylobacter strains were isolated from
the cloramphenicol cut-off point of 8 µg/mL for
dogs: 29 Campylobacter jejuni subsp. jejuni , 14
Campylobacter, it is significant that 27.4% of the diarrheic
Campylobacter jejuni subsp doylei, 5 Campylobacter
strains were susceptible to the antibiotic. In contrast,
upsaliensis, 2 Campylobacter coli, and 1 Campylobacter
all diarrhea-free strains were susceptible to the drug.
There is no solid explanation for this discrepancy,
Serial dilutions in solid medium, according to the
since feces were not collected from diarrheic dogs after
National Committee for Clinical Laboratory Standards
receiving medication. Variations in sensitivity
recommendations (NCCLS,1998), were used to study
the susceptibility of these strains to antimicrobial
Campylobacter genus (ALEKSANDROVA et al., 1990).
agents and to determine each agent's MIC. The
However, many studies have reported high sensitivity
antibiotics cephalexin, erythromycin, gentamicin,
to the drug when considering strains isolated from
enrofloxacin, cloramphenicol, and oxytetracycline
humans (SHANKER & SORRELL, 1983) and dogs (FOX et
were submitted to the following procedures: each one
was first diluted in 1,000 µg/mL saline, then new
Cloramphenicol was effective in the treatment of
dilutions were made on Petri dishes with thioglycolate
dogs with campylobacteriosis, but failed in the
elimination of chronic fecal excretion (DAVIES et al.,
corresponding to the following concentrations per
1984; MONFORT et al., 1990). In contrast, due to good
plate: 0.06 µg/mL, 0.125 µg/mL, 0.25 µg/mL, 0.5 µg/
liposolubility that can enhance body tissue
mL, 1 µg/mL, 2 µg/mL, 4 µg/mL, 8 µg/mL, 16 µg/mL,
penetration, it can be recommended for treating extra-
32 µg/mL, 64 µg/mL, and 128 µg/mL. The final
intestinal infections in dogs, as long as the animals
volume of each plate was 20 mL. Bacterial colonies
show no Campylobacter fecal excretion.
were suspended in saline to 0.5 MacFarland standard
Enrofloxacin showed very similar MIC variations
turbidity (1.5 x 108 CFU/µL) and inoculated in culture
in diarrheic (1-4 µg/mL) and diarrhea-free dogs (1-8
medium using a 3-mm replicator. Escherichia coli,
µg/mL). It was active against isolated Campylobacter
ATCC 25922, inoculated in one of the plates was used
strains demonstrated by the low concentrations, at
as a control. The plates were kept at 35° C under
which 90% of strains were susceptible (2-4 µg/mL,
microaerophilic conditions; readings were made 48
diarrheic dogs and 4-8 µg/mL, diarrhea-free dogs). Campylobacter is frequently sensitive to quinolones;
From these results, MICs corresponding to 50%
however, an increased resistance to these drugs is
and 90% inhibition of Campylobacter (MIC and MIC )
seen, probably due to genetic mutations interfering
with bacterial DNA girase (GREIG et al., 2003). Selective
pressure caused by the indiscriminate use of these
drugs in aviculture is a contributary factor. Considering
the existence of cross resistance between quinolones,
the occurrence of nalidixic acid resistant Campylobacter
Tables 1 and 2 show the results of the different
jejuni may interfere with tests for this bacterium
Different results were observed for each drug,
Erythromycin was the most effective against
which were also considered in other investigations. Campylobacter, with total strain sensitivity from both
The variability can be used as an important marker in
groups at very low concentrations (lower or equal to
epidemiological research (ABRAHANS et al., 1990)
0.06 µg/mL). This is corroborated by several authors
The strains isolated from both diarrheic and
(FOX et al., 1984; REINA et al., 1984; SKIRROW, 1994;
diarrhea-free dogs were highly resistant to cephalexin
GANDREAU & GILBERT, 1998). Erythromycin is effective in
(MIC 50 > 128 µg/mL for both). This is due to the high
treating dogs, but was not able to eliminate the passive-
resistance of these bacteria to cephalosporins and β-
carrier status of some treated dogs (MONFORT et al., 1990;
lactamic in general (ABRAHANS et al., 1990; TAJADA et al.,
BOOSINGER & DILLON, 1992; BURNENS et al., 1992). Arq. Inst. Biol., São Paulo, v.70, n.3, p.283-286, jul./set., 2003
Antimicrobial susceptibility of 51 Campylobacter strains isolated from diarrheic and diarrhea-free dogs.
Table 1 - Antimicrobial drug concentration variations
In view of the heterogeneity in the results reported
and minimum inhibitory concentrations (MIC) capable
in the literature in comparison to data in this study, we
of inhibiting 50% and 90% of the 29 thermophilic
recommend that Campylobacter antimicrobial
Campylobacter strainsisolated from diarrheic dogs.
susceptibility tests be performed for therapeutic
purposes. Our results indicate erythromycin,
enrofloxacin, and gentamicin as drugs suitable for the
treatment of canine campylobacteriosis. This also
opens up therapeutic possibilities for these drugs in
for financial support; the staff from the Infectious
Diseases Discipline at Botucatu School of
Table 2 - Antimicrobial drug concentration variations
Veterinary Medicine and Animal Husbandry; and
and minimum inhibitory concentrations (MIC) capable
Tânia Maria Martins, Adriana Cristina Pavan
of inhibiting 50% and 90% of the 29 thermophilic
Vieira, and Fernando Paganini Listoni for their
Campylobacter strainsisolated from diarrhea-free dogs.
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BLASER, M.; POWERS, B.W.; CRAVENS, J.; WANG, W.L.
mL). Campylobacter is frequently sensitive to gentamicin
Campylobacter enteritis associated with canine infection.
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Journal of the Korean Magnetic Resonance Society 2006 , 10, 126 - 140 Quantification of Metabolic Alterations of Dorsolateral Pre-Frontal Cortex in Depression SD Rat by MR Spectroscopy Sung-Tak Hong1, Bo-Young Choe1*, Chi-Bong Choi1, 1Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 505 Banpo-Dong, Seocho-Gu, Seoul 137-040, Korea 2MRI