Dataset Information

Dynamics of quinolone resistance in fecal Escherichia coli of finishing pigs after ciprofloxacin administration.

ABSTRACT: Escherichia coli resistance to quinolones has now become a serious issue in large-scale pig farms of China. It is necessary to study the dynamics of quinolone resistance in fecal Escherichia coli of pigs after antimicrobial administration. Here, we present the hypothesis that the emergence of resistance in pigs requires drug accumulation for 7 days or more. To test this hypothesis, 26 pigs (90 days old, about 30 kg) not fed any antimicrobial after weaning were selected and divided into 2 equal groups: the experimental (EP) group and control (CP) group. Pigs in the EP group were orally treated daily with 5 mg ciprofloxacin/kg of body weight for 30 days, and pigs in the CP group were fed a normal diet. Fresh feces were collected at 16 time points from day 0 to day 61. At each time point, ten E. coli clones were tested for susceptibility to quinolones and mutations of gyrA and parC. The results showed that the minimal inhibitory concentration (MIC) for ciprofloxacin increased 16-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin administration for 3 days and decreased 256-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin withdrawal for 26 days. GyrA (S83L, D87N/ D87Y) and parC (S80I) substitutions were observed in all quinolone-resistant E. coli (QREC) clones with an MIC ?8 µg/ml. This study provides scientific theoretical guidance for the rational use of antimicrobials and the control of bacterial resistance.

SUBMITTER: Huang K

PROVIDER: S-EPMC4197147 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Dynamics of quinolone resistance in fecal Escherichia coli of finishing pigs after ciprofloxacin administration.

Huang Kang K Xu Chang-Wen CW Zeng Bo B Xia Qing-Qing QQ Zhang An-Yun AY Lei Chang-Wei CW Guan Zhong-Bin ZB Cheng Han H Wang Hong-Ning HN

The Journal of veterinary medical science 20140612 9

Escherichia coli resistance to quinolones has now become a serious issue in large-scale pig farms of China. It is necessary to study the dynamics of quinolone resistance in fecal Escherichia coli of pigs after antimicrobial administration. Here, we present the hypothesis that the emergence of resistance in pigs requires drug accumulation for 7 days or more. To test this hypothesis, 26 pigs (90 days old, about 30 kg) not fed any antimicrobial after weaning were selected and divided into 2 equal g ...[more]

PMID: 24919413

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Project description:The overall aim of the current study was to test the hypotheses that (i) antibiotic resistance in bacteria were more frequent in clinically health pigs in intensified company owned, medium-scale farms (MSFs) (100-500 sows) than in pigs in family-owned, small-scale farms (SSFs) (1-50 sows) and (ii) that farmers working at the MSFs were more prone to attain antibiotic resistant bacteria than farmers working at SSFs. The study was conducted in North-Eastern Thailand, comprising fecal Escherichia coli isolates from pigs, farmers working with the pigs (contact humans) and persons living in the same household as the farmer (non-contact humans) at 51 MSFs and 113 SSFs. Samples from all farms were also screened for methicillin-resistant staphylococcus aureus (MRSA), which was not detected in pig samples, but was found in one human sample. Susceptibility was tested by disc-diffusion for seven antibiotics commonly used in the study area. Resistance in pig isolates from MSFs were more frequent for chloramphenicol which (P < 0.001), trimethoprim/sulfamethoxazole (P < 0.001) and gentamicin (P < 0.05) compared with isolates from SSFs, whereas the opposite was true for tetracycline (P < 0.01). Resistance in the human isolates was lower than those in the isolates from pigs for tetracycline, trimethoprim/sulfamethoxazole and chloramphenicol (P < 0.001). The frequency of resistance in the contact human samples from SSFs and MSFs did not differ. There was no difference between isolates from contact and non-contact humans for any of the tested antibiotics. Multidrug resistance in isolates from pigs was 26%, significantly higher (P < 0.01) than the 13% from humans. The data indicate that (i) resistance to antibiotics, including those critical and highly important for human medicine, were more common in fecal E. coli from pigs at the MSFs than at the SSFs, whereas (ii) the resistance in fecal E. coli from pig farmers seemed not to be influenced by the level of intensification of the farm they were working at.

Project description:Escherichia coli often carries linked antimicrobial resistance genes on transmissible genetic elements. Through coselection, antimicrobial use may select for unrelated but linked resistance or virulence genes. This study used unconditional statistical associations to investigate the relationships between antimicrobial resistance phenotypes and antimicrobial resistance genes in 151 E. coli isolates from healthy pigs. Phenotypic resistance to each drug was significantly associated with phenotypic resistance to at least one other drug, and every association found that the probability of observing the outcome resistance was increased by the presence of the predictor resistance. With one exception, each statistical association that was identified between a pair of resistance genes had a corresponding significant association identified between the phenotypes mediated by those genes. This suggests that associations between resistance phenotypes might predict coselection. If this hypothesis is confirmed, evaluation of the associations between resistance phenotypes could improve our knowledge of coselection dynamics and provide a cost-effective way to evaluate existing data until large-scale genotypic data collection becomes feasible. This could enable policy makers and users of antimicrobials to consider coselection in antimicrobial use decisions. This study also considered the unconditional relationships between resistance and virulence genes in E. coli from healthy pigs (aidA-1, eae, elt, estA, estB, fedA1, stx1, and stx2). Positive statistical associations would suggest that antimicrobial use may select for virulence in bacteria that may contaminate food or cause diarrhea in pigs. Fortunately, the odds of detecting a virulence gene were rarely increased by the presence of an antimicrobial resistance gene. This suggests that on-farm antimicrobial use did not select for the examined virulence factors in E. coli carried by this population of healthy pigs.

Dataset Information

Dynamics of quinolone resistance in fecal Escherichia coli of finishing pigs after ciprofloxacin administration.

Publications

Dynamics of quinolone resistance in fecal Escherichia coli of finishing pigs after ciprofloxacin administration.

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