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

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 vertical bar bla(VIM-5)vertical bar bla(PSE-1), aadB vertical bar bla(VIM-5)vertical bar aadB vertical bar bla(PSE-1), and bla(VIM-5)vertical bar aadB vertical bar tnpA vertical bar bla(PSE-1)vertical bar smr2 vertical bar tnpA, respectively. Strains carrying the aadB vertical bar bla(VIM-5)vertical bar 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.