BackgroundIntegrons play important role in the spread and maintenance of antimicrobial resistance among strains of Escherichia coli (E. coli) and other species of Enterobacteriaceae. This study investigated the prevalence of class 1 and 2 integrons among E. coli strains isolated from aquaculture water of fish fields in Iran.MethodsOne hundred and fifty water samples from different geographical regions in Chaharmahal Va Bakhtiari province were examined over a 2 months period. Isolation was through culture and biochemical tests. Integrons were identified through polymerase chain reaction (PCR) using oligonucleotide primers specific for class 1 and 2 integrons. Antimicrobial susceptibility testing was carried out using disc diffusion methods.ResultsEighteen percent of the water samples were positive for E. coli. All the strains were multi-drug resistant; 100% to ciprofloxacin, chloramphenicol, gentamycin, ampicillin and tetracycline and least resistant to imipenem (7.2%). Ten (50%) of the most resistant strains were positive for class 1 (40%) and class 2 (10%).ConclusionsEscherichia coli in aquaculture in Iran carried integrons class 1 and 2 which could be of public health concern since they could play a role in the spread and maintenance of antimicrobial resistance among bacterial population in the region and should be constantly monitored.Electronic supplementary materialThe online version of this article (doi:10.1186/s12941-015-0096-y) contains supplementary material, which is available to authorized users.

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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.

This study was conducted to isolate generic extended-spectrum cephalosporin (ESC)-resistant and extended-spectrum β-lactamase (ESBL)-producing enterobacteria from horses in Nigeria, and to determine the antibacterial resistance profile. Rectal swabs were collected from 155, systematic randomly selected, apparently-healthy horses. Isolation of ESC-resistant enterobacteria was done using Mac Conkey agar with ceftazidime. ESBL production was assessed by combination disc method. Resistance of the isolates was determined using disc diffusion method. Out of 155 samples, 5.2% gave positive growth. From these, 11 ESC-resistant enterobacteria comprising of 36.4% E. coli, 36.4% Salmonella spp. and 27.2% Proteus spp., were obtained. From 11 isolates, 45.5% consisting of all the 4 E. coli and 1 Proteus isolates, were ESBL-producers, these were recovered from 4 (2.6%) out of the 155 horses sampled. Resistance of the E. coli isolates was 25% to aztreonam (AZT), 75% to amoxicillin-clavulanic acid (AMC), gentamicin (GEN), perfloxacin (PEF), and sulphamethoxazoletrimethoprim (SXT-TRI), 50% to ofloxacin (OFL) and 100% to ampicillin (AMP), ceftazidime (CTZ), cefotaxime (CTX), chloramphenicol (CHL), streptomycin (STR), tetracycline (TET), sparfloxacin (SPA), ciprofloxacin (CIP), norfloxacin (NOR) and enrofloxacin (ENR). Resistance of the Salmonella isolates was 50% to PEF and 100% to CTZ, CTX, AMP, AZT, AMC, CHL, GEN, STR, TET, SPA, CIP, OFL, NOR and ENR. Resistance of the Proteus isolates was 25% to AMC, CHL, STR, TET, SPA and NOR, and 100% to CTZ, CTX, AZT and AMP. Resistance of the isolates to more than 3 classes of antibacterial agents tested was 75% for Proteus and 100% for E. coli and Salmonella, respectively. This study showed that horses in Nigeria are potential reservoirs and disseminators of ESC-resistant and ESBL-producing Enterobacteriaceae.

This study was conducted to isolate generic extended-spectrum β-lactam-resistant enterobacteria from household dogs in Nigeria, and to determine the antibacterial resistance profile of the isolates. Rectal swabs were collected from 100, randomly selected, apparently healthy household dogs. Isolation of ESBL-resistant enterobacteria was done using Mac Conkey agar supplemented with 4 µg/ml of ceftazidime. 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 27 ESBL-resistant enterobacterial isolates, 40.7% were Escherichia coli, 37% were Klebsiella species, 18.5% were Salmonella species, while 3.7% was Proteus species. Resistance of the E. coli isolates was 81.8% to ampicillin, 27.2% to streptomycin, 54.5% to ciprofloxacin and tetracycline, 45.4% to enrofloxacin, 90.9% to sulphamethoxazole/trimethoprim, 9.1% to amoxicillin/clavulanic acid and 0% resistant to gentamicin. Resistance of the Klebsiella isolates was 80% to ampicillin, 20% to streptomycin and amoxicillin/clavulanic acid, 30% to ciprofloxacin and enrofloxacin, 60% to tetracycline, 90% to sulphamethoxazole/trimethoprim and 10% to gentamicin. Resistance of the Salmonella isolates was 100% to sulphamethoxazole/trimethoprim, 80% to gentamicin and ampicillin, 60% to streptomycin and tetracycline, 20% to amoxicillin/clavulanic acid, and 0% to ciprofloxacin and enrofloxacin. The Proteus isolate was resistant to streptomycin and gentamycin. All the isolates were resistant to ceftazidime and cefotaxime. Resistance of the isolates to more than 3 classes of antibacterial agents tested was 81.8% for E. coli, 70% for Klebsiella and 100% for Salmonella, respectively. This study has shown that household dogs in Nigeria, are colonized by ESBL-resistant Enterobacteriaceae and are potential reservoirs and disseminators of these organisms.

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.

This study was conducted to isolate and detect methicillin-resistant staphylococci (MRS) in healthy broilers in Nsukka Southeast, Nigeria and determine the antibiogram of the isolates. Cloacal and skin swabs were collected from each of 101 randomly sampled broilers meant for slaughter. The samples were processed for isolation and identification of methicillin-resistant Staphylococcus species, following standard methods. Confirmation of methicillin-resistance by the isolates was done using penicillin binding protein 2a (PBP2a) kit. Phenotypic resistance of the isolates to antimicrobial agents was determined using disc diffusion method. Out of 202 samples processed, 200 (99.01%) yielded positive growth of staphylococci on oxacillin-supplemented oxacillin-resistance staphylococcal agar base (ORSAB). A total of 200 methicillin-resistant staphylococcal isolates were obtained. Of these, 91 (45.5%) were identified as methicillin-resistant coagulase-positive Staphylococcus (MRCoPS), while 109 (54.5%) were identified as methicillin-resistant coagulase-negative Staphylococcus species (MRCoNS). Out of the 91 MRCoPS, 53 (58.2%) were identified as methicillin-resistant Staphylococcus aureus (MRSA). Resistance of the isolates was 99.5% to erythromycin and chloramphenicol, 100% to oxacillin, 76.5% to gentamicin, 96.5% to clindamycin, 92.5% to ciprofloxacin, 99% to sulphamethoxazole/trimethoprim and tetracycline, and 98.5% to streptomycin and cefoxitin. All the isolates were multidrug resistant. This study has shown that healthy broilers reared and slaughtered in Nsukka Southeast, Nigeria harbour multidrugresistant MRS and thus serve as their reservoirs.

This study was conducted to isolate and detect methicillin-resistant staphylococci (MRS) in healthy broilers in Nsukka Southeast, Nigeria and determine the antibiogram of the isolates. Cloacal and skin swabs were collected from each of 101 randomly sampled broilers meant for slaughter. The samples were processed for isolation and identification of methicillin-resistant Staphylococcus species, following standard methods. Confirmation of methicillin-resistance by the isolates was done using penicillin binding protein 2a (PBP2a) kit. Phenotypic resistance of the isolates to antimicrobial agents was determined using disc diffusion method. Out of 202 samples processed, 200 (99.01%) yielded positive growth of staphylococci on oxacillin-supplemented oxacillin-resistance staphylococcal agar base (ORSAB). A total of 200 methicillin-resistant staphylococcal isolates were obtained. Of these, 91 (45.5%) were identified as methicillin-resistant coagulase-positive Staphylococcus (MRCoPS), while 109 (54.5%) were identified as methicillin-resistant coagulase-negative Staphylococcus species (MRCoNS). Out of the 91 MRCoPS, 53 (58.2%) were identified as methicillin-resistant Staphylococcus aureus (MRSA). Resistance of the isolates was 99.5% to erythromycin and chloramphenicol, 100% to oxacillin, 76.5% to gentamicin, 96.5% to clindamycin, 92.5% to ciprofloxacin, 99% to sulphamethoxazole/trimethoprim and tetracycline, and 98.5% to streptomycin and cefoxitin. All the isolates were multidrug resistant. This study has shown that healthy broilers reared and slaughtered in Nsukka Southeast, Nigeria harbour multidrug-resistant MRS and thus serve as their reservoirs.