Prevalence and Antibiogram of Generic Extended-Spectrum β-Lactam-Resistant Enterobacteria in Healthy Pigs

Abstract

This study was conducted to isolate generic extended-spectrum β-lactam (ESBL)-resistant enterobacteria from pigs reared in Enugu State Southeast, Nigeria and determine the antibacterial resistance profile of the isolates. Rectal swabs were collected from 190, randomly selected, apparently healthy pigs. Isolation of ESBL-resistant enterobacteria was done using Mac Conkey agar supplemented with 2 µg/ml of cefotaxime. Phenotypic characterization of the isolates to generic level was done following standard biochemical methods. Phenotypic resistance of the isolates to antibacterial agents was determined using the disc diffusion method. Out of 46 ESBL-resistant enterobacterial isolates, 4 (8.7%) were Escherichia coli, 11 (23.9%) were Salmonella species, while 31 (67.4%) were Klebsiella species. Resistance of the Salmonella isolates was 45.5% to ciprofloxacin, 36.4% to ofloxacin and levofloxacin, 9.1% to norfloxacin, amikacin and gentamicin, 27.3% to streptomycin, 72.7% to chloramphenicol and 90.9% to tetracycline. Resistance of the Klebsiella isolates was 93.5% to ampicillin, 12.9% to ciprofloxacin, 19.4% to ofloxacin and levofloxacin, 9.7% to norfloxacin and streptomycin, 64.5% to chloramphenicol and 38.7% to tetracycline. Resistance of the E. coli isolates was 100% to gentamicin, 75% to ampicillin and streptomycin, 50% to ciprofloxacin, norfloxacin, chloramphenicol and tetracycline, and 25% to ofloxacin, levofloxacin and amikacin. All the isolates were resistant to ceftriaxone, cefotaxime, ceftazidime, cefepime, cefpodoxime, amoxicillin/clavulanic acid and aztreonam. Resistance of the isolates to more than 3 classes of antibacterial agents tested was 54.8% for Klebsiella, 90.9% for Salmonella and 100% for E. coli, respectively. This study has shown that pigs reared in Enugu State Southeast, Nigeria, are colonized by ESBL-resistant Enterobactericeae and are potential reservoirs and disseminators of these organisms.

Prevalence and Antibiogram of Generic Enterococci in Ready-to-Slaughter Beef Cattle

“…1. Prevalence of generic enterococci in healthy beef cattle high cost) in the Nigeria (Eze et al, 2013;Ugwu et al, 2015b). The 1.3% ciprofloxacin resistance in this study is lower when compared with 9.5, 8, and 24.1% ciprofloxacin resistance reported among faecal enterococcal isolates from cattle in USA (Anderson et al, 2008) and Lithuania (Ruzauskas et al, 2009), and food animals in Tunisia (Klibi et al, 2014) respectively.…”

“…Differences in application of these drugs in treatment of infections in the study areas may account for the variation in their resistance. In Nigeria, streptomycin is often combined with penicillin to exert broad-spectrum effect in treatment of food-producing animals (Ugwu et al, 2015b). The high LLAR observed in this study may be a cause for concern because of compromise (if aminoglycosides resistance genes are acquired) that would occur during treatment of enteroccocal infection in humans and animals in the study area (Donabedian et al, 2003).…”

“…The isolates may also have exerted resistance to the ampicillin by changing their cell wall permeability, expressing active efflux pump, gene mutation and/or altered penicillin binding protein (PBP) receptors, a well-known intrinsic (natural) βlactam resistance mechanism in enterococci (Livermore and Brown, 2001;Kak and Chow, 2002;Kristich et al, 2014;Li et al, 2014;Urmunova, 2015). The high ampicillin resistance may be a result of selective pressure due to inappropriate use of β-lactams (probably because they are cheap) in Nigeria (Chah and Nweze, 2001;Ugwu et al, 2015b). High rate (94%) of resistance to amoxicillin/clavulanic acid (a β-lactamβ-lactamase inhibitor) in this study suggested that the isolates produced AmpC β-lactamases (cephalosporinases), the major mediators of resistance to β-lactam-β-lactamase inhibitors (Ben Sallem et al, 2012).…”

“…There is increasing numbers of reports on isolation of antimicrobial-resistant enterococci from food-producing animals in the last decennium (Anderson et al, 2008). Determination of antibiogram of enterococcal isolates from food-producing animals is essential for monitoring the spread of resistance in food-borne bacteria (Jackson et al, 2010;Ugwu et al, 2015b). This helps in evaluation of trends and identification of mitigation strategies including empirical treatment of infections associated with the organisms (Ugwu et al, 2015b).…”

“…Determination of antibiogram of enterococcal isolates from food-producing animals is essential for monitoring the spread of resistance in food-borne bacteria (Jackson et al, 2010;Ugwu et al, 2015b). This helps in evaluation of trends and identification of mitigation strategies including empirical treatment of infections associated with the organisms (Ugwu et al, 2015b). Surveillance studies to screen food-producing animals as potential reservoirs and disseminators of antimicrobial-resistant enterococci have been conducted in America (Hershberger et al, 2005;Anderson et al, 2008), and some countries in Asia (Stobberingh et al, 1999;Seo et al, 2005;Shin et al, 2006;Han et al, 2011;Li et al, 2014), Europe (Aarestrup et al, 2000;Kaszanyitzky et al, 2007;Kempf et al, 2008;Brtkova et al, 2010;Kasimoglu-Dogru et al, 2010;Trembley et al, 2011) and Africa (Klibi et al, 2014;Iweribor et al, 2015) Unfortunately, there is paucity of information on occurrence of antimicrobial-resistant enterococci in foodproducing animals in Nigeria.…”