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 blaVIM-5. WGS revealed the blaVIM-5 in three novel Tn402-like class 1 integron structures containing the cassette arrays aadB|blaVIM-5|blaPSE-1, aadB|blaVIM-5|aadB|blaPSE-1, and blaVIM-5|aadB|tnpA|blaPSE-1|smr2|tnpA, respectively. Strains carrying the aadB|blaVIM-5|blaPSE-1 cassette also carried an identical integron without blaVIM-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 blaVIM-5 in environmental bacteria isolates. This result underscores the role of the Nigerian environment as reservoir of bacteria carrying clinically relevant antibiotic resistance genes.
Highlights
Antibiotic resistance is an increasing global problem with significant impact on human health[1]
Various colonies of bacteria showing resistance to meropenem were isolated on all agar types: Muller Hinton (MH), Eosine Methylene Blue (EMB), and Pseudomonas isolation (PI) agar used for bacteria isolation from all sediment samples analysed
This study reports the occurrence and genetic environment of blaVIM-5 in bacteria isolated from four Nigerian wetlands
Summary
Antibiotic resistance is an increasing global problem with significant impact on human health[1]. Very little is known about the genetic platforms linked to detected carbapenemase genes in Africa[28,29] These are important omissions considering the widespread and uncontrolled use of beta-lactam antibiotics in human clinical therapy and food animal production in Nigeria[30], and the ubiquitous release of untreated wastewater from several point and non-point sources into the aquatic ecosystem as a result of poor sanitation[31]. The results provide further insight into the global epidemiology of this important group of antibiotic resistance genes
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