Antibiotic resistance and resistance genes in Escherichia coli from poultry farms, southwest Nigeria

Introduction: This study investigated the mechanisms of resistance in 36 E. coli isolated from waste, litter, soil and water samples collected from poultry farms in Southwestern Nigeria. Methodology: Minimum inhibitory concentration (MIC) distributions of the isolates were determined using the methods of the Clinical and Laboratory Standard Institute and resistance genes detected by PCR. Results: A total of 30 isolates (94%) showed resistance to more than one antimicrobial. Percentage resistance was: tetracycline 81%, sulphamethoxazole 67%, streptomycin 56%, trimethoprim 47 %, ciprofloxacin 42%, ampicillin 36%, spectinomycin 28%, nalidixic acid 25%, chloramphenicol 22%, neomycin 14%, gentamicin 8%, amoxicillin-clavulanate, ceftiofur, cefotaxime, colistin, florfenicol and apramycin 0%. Resistance genes found among the isolates include bla-TEM (85%), sul2 (67%), sul3 (17%), aadA (65%), strA (70%), strB (61%), catA1 (25%), cmlA1 (13%), tetA (21%) and tetB (17%). Class 1 and 2 integrons were found in five (14%) and six (17%) isolates, respectively, while one isolate was positive for both classes of integrons. Seven out of eight isolates with resistance to ciprofloxacin and MIC ≤ 32 mg/L to nalidixic acid contained qnrS genes. Conclusions: Our findings provided additional evidence that the poultry production environment in Nigeria represents an important reservoir of antibiotic resistance genes such as qnrS that may spread from livestock production farms to human populations via manure and water.</jats:p

Detection of the carbapenemase gene blaVIM-5 in members of the Pseudomonas putida group isolated from polluted Nigerian wetlands

Abstract There are increasing concerns about possible dissemination of clinically relevant antibiotic resistance genes, including genes encoding for carbapenemases in the environment. However, little is known about environmental distribution of antibiotic resistance in Africa. In this study, four polluted urban wetlands in Nigeria were investigated as potential reservoirs of carbapenem-resistant bacteria (CRB). CRB were isolated from the wetlands, characterized by Blue-Carba test, MIC determinations and whole genome sequencing (WGS). Nine of 65 bacterial isolates identified as members of the Pseudomonas putida group (P. plecoglossicida and P. guariconensis, respectively) harboured the metallo-beta-lactamase gene bla VIM-5. WGS revealed the bla VIM-5 in three novel Tn402-like class 1 integron structures containing the cassette arrays aadB|bla VIM-5|bla PSE-1, aadB|bla VIM-5|aadB|bla PSE-1, and bla VIM-5|aadB|tnpA|bla PSE-1|smr2|tnpA, respectively. Strains carrying the aadB|bla VIM-5|bla PSE-1 cassette also carried an identical integron without bla VIM-5. In addition, the strains harboured another Tn402-like class 1 integron carrying bcr2, several multidrug resistance efflux pumps, and at least one of ampC, aph(3”)-lb, aph(6)-ld, tetB, tetC, tetG, floR, and macAB. This is the first report of a carbapenemase gene in bacteria from environmental sources in Nigeria and the first report of bla VIM-5 in environmental bacteria isolates. This result underscores the role of the Nigerian environment as reservoir of bacteria carrying clinically relevant antibiotic resistance genes

Metal-resistance encoding gene-fingerprints in some bacteria isolated from wastewaters of selected printeries in Ibadan, South-western Nigeria

Several studies have reported the occurrence of metal-resistant bacteria and their genes in different wastewater, but there is a dearth of information on wastewater generated from printing operations as a probable source. This study aimed at fingerprinting metal-resistance encoding genes in bacteria recovered from wastewaters of selected printeries in Ibadan, Nigeria. Wastewaters from 10 selected printeries in Ibadan were collected monthly for 12 months. The metal composition of wastewater was determined using Atomic Absorption Spectrophotometry. Metal-resistant bacteria were isolated on metal-supplemented nutrient medium, and characterized using 16S rRNA gene sequencing. Metal-resistance genes were detected using specific primers and the presence of plasmids was determined using alkaline-lysis method. Forty metal-resistant bacteria belonging to six genera; Bacillus, Klebsiella, Pseudomonas, Citrobacter, Providencia and Proteus were identified. cusCBA, encoding resistance to copper and silver was detected in nine bacteria, while pbrA (encoding lead resistance) was detected in seven Pseudomonas aeruginosa isolates. chrA, encoding resistance to chromate ions, was detected in Proteus mirabilis PW3a and two isolates of Pseudomonas aeruginosa, while chrB was detected in Providencia vermicola PWAP3 and Proteus mirabilis PW4c. Bacillus stratosphericus PW1b possessed the copper-resistance genes, pcoA and pcoR. Thirty-six bacteria (90%) of the total bacteria possessed plasmids larger than 10 Kb in size. In conclusion, wastewater generated from printing operations could be a potential source of metal-resistant bacteria and their genes