Tetracycline Resistant Vibrio Species with tet Genes in Soil Samples from Two Dumpsites in Port-Harcourt, South-South, Nigeria

Abstract

With consistent evolutions in the menace of antimicrobial-resistance, there is an ongoing need to continuously grow in 
understanding the developmental strategies of drug resistant pathogens and possible reservoirs of the resistance determinants. 
Resistance against tetracycline, a first line anti-cholera drug choice has been reported. With acquisition of resistance in Vibrio
thought to be associated with exchange of extrachromosomal genetic material from closely related species, this study therefore 
explores the potential role of environmental Vibrio species from Rivers State, Nigeria as reservoirs of tetracycline -resistance 
genes. Soil samples were collected from two dumpsites in Rivers State, Nigeria and processed for the isolation and identification 
of Vibrio sp according to standard protocols. Identified Vibrio isolates were then screened for the presence of four tetracycline -
resistance determinants (tet A, tet B, tet G and tet M) following DNA extraction by boiling. A total of 29.2% of isolates (14/48) 
possessed at least one of the four tet genes assayed for. For specific occurrence, tet B was the most occurring of the four (14.6%) 
and tet G the least occurring (2.1%). Both dumpsites had a similar level of occurrence of the tet genes (26.9% and 31.8%), but 
there was a higher representation (54.5%) of tet genes in isolates obtained from the subsoil than the surface (7.7%). Results 
indicate a potential role of these environmental Vibrio sp. as reservoirs of tetracycline -resistance genes. The presence of the tet 
M gene associated with a conjugative transposon adds more risk to this potential. More studies are needed to proffer a better
understanding of the risks and relationships present.