Antibiotic Resistance Profile and Resistance Determination of Bacteria Isolated from Water in Southern Benin

Background: The environment plays an important role in the dissemination of multidrug resistant bacteria, especially through the aquatic ecosystem, including hospital effluents, rivers, but also spring water and drinking water. This study aims to determine selected antimicrobial resistance genes in some aquatic matrices in southern Benin.

Methods: Collected water samples were filtered through a membrane 0.22 µm thick. After filtration, the membrane was deposited on Muëller Hinton agar. Then the colonies resulting from this subculture were subjected to a microbiological examination by the conventional method. The antibiotic sensitivity test was carried out by the Kirby Bauer method according to the recommendations of the French Society of Microbiology. Resistance genes were looked for by PCR.

Results: Of the 222 water samples collected, 265 bacterial strains were isolated, the majority of which were strains of Coagulase Negative Staphylococcus (CNS) with 37.74% (n = 100), followed by strains of Klebsiella pneumoniae (21.89%; n = 58), Escherichia coli (10.57%; n = 28). All isolated gram-negative bacilli strains are multidrug resistant with resistance of all strains to amoxicillin, ampicillin and amoxicillin + clavulanic acid. Of the 15 resistance genes searched in the genome of Gram-negative bacilli strains, 8 were detected, namely the TEM, SHV, CTX-M15, VIM, NDM, SUL1, SUL2 and AADA genes. Resistance of CNS strains to amoxicillin, oxacillin and cefoxitin was observed. The meca gene was detected in all CNS strains. The vanA and VanB genes were only detected in strains isolated from drinking water in sachets collected from producers and street sellers.

Conclusion: These results show the dissemination of resistance genes in Benin and once again confirms the urgency of a global fight against antimicrobial resistance.