Antimicrobial resistance of Gram-negative bacteria isolated from domestic and food-producing animals: potential reservoirs of plasmid-mediated quinolone resistance genes

Abstract number: P766

Objective: The aim of the study was to evaluate the antimicrobial resistance of domestic and food-producing animals' Gram negative bacteria and to screen for the presence of plasmid-mediated quinolone resistance genes (qnr) as few data on the prevalence of these determinants in strains from animals are available.

Methods: Gram negative bacteria were isolated from domestic (cat, dog and jennet) and food-producing (chicken, rabbit, trout and gilt-head bream) animals. Antimicrobial susceptibility was performed using the disc diffusion method according to CLSI guidelines. The presence of qnr genes was determined by Multiplex-PCR and DNA sequencing.

Results: Of the 53 strains studied, 22 were isolated from domestic animals (DA) and 31 from food-producing animals (FPA). The majority of isolates were Enterobacteria (70%) and 46% were Escherichia coli. Isolates of both groups showed high resistance to amoxicillin: 87% for FPA and 91% for DA, whose activity were recovered in the presence of clavulanic acid (26 and 67% of resistance, respectively). All FPA isolates were susceptible to ceftazidime, cefotaxime and imipenem. In contrast, 23%, 45% and 9% of DA isolates showed decrease susceptibility or resistance to these b-lactams, respectively. Isolates were more susceptible to gentamicin (100 and 91% for FPA and DA isolates, respectively) than to kanamycin (32 and 23% for FPA and DA isolates, respectively). For cloramphenicol and SXT, FPA and DA isolates showed 35% and 41% of resistance, respectively, while tetracycline resistance was higher for FPA (52%) than for DA group (41%). Both groups were more resistant to nalidixic acid (55% for FPA and 59% for DA) than to ciprofloxacin (19 for FPA and 27% for DA). In DA isolates were found 3 isolates with QnrB and 1 with QnrS, none susceptible to quinolones. One isolate with QnrB (quinolone resistant) and 6 with QnrS were found in FPA group, susceptible to quinolones. The six isolates were collected from rabbits.

Conclusion: This work shows differences in antibiotic resistance between isolates of DA and FPA. Noteworthy is the appearance of resistant isolates to broad spectrum b-lactams, including imipenem in isolates from DA group. qnr genes were detected in both groups, suggesting that animals may act as reservoirs of these genes, even in strains susceptible to nalidixic acid. Resistant bacteria present in DA and FPA can be transmitted to humans by contact or food-chain, an increasing risk for human health.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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