Abstract

Multidrug resistant (MDR) bacteria are of global concern due to the rapid horizontal transfer of resistance genes within microbial populations and with challenges in quick treatment interventions. This study investigated virulence factors, antibiotic sensitivity of bacteria isolated from a sand mining (dredging) site of Ox-Bow Lake, in Yenagoa, Bayelsa State, Nigeria. Multidrug resistant (MDR) isolates were further investigated by molecular studies to determine the presence or antibiotic resistance genes, toxigenic genes and virulence genes. Bacteria previously isolated from the sand mining site which were; Klebsiella pneumonia, Klebsiella oxytoca, Vibrio cholerae, Chromobacterium violaceum, Staphylococcus aureus, Staphylococcus cohnii, Kluyvera ascorbata, Bacillus tequilensis, Enterobacter aerogenes, Bacillus myoides, Yersinia intermedia, Citrobacter koseri, Salmonella typhi, and Bacillus cereus were employed for this study. Results revealed that all the isolates possess multiple virulence traits and widespread antibiotic resistance. Several isolates exhibited multidrug resistance (MDR) to fluoroquinolones, β-lactams, and other antibiotic classes. Notably, Klebsiella pneumoniae, Klebsiella oxytoca, Vibrio cholerae, Chromobacterium violaceum, Salmonella typhi, and Bacillus cereus showed resistance to multiple antibiotics, while species, such as Kluyvera ascorbata and Enterobacter aerogenes, retained susceptibility to aminoglycosides. Molecular analysis revealed presence of blaCTX-M resistance gene in Klebsiella pneumoniae strain DSM 30/04 and Chromobacterium violaceum strain JCM 1249, and presence of qnrA resistance gene in Staphylococcus aureus Subsp. aureus strain MRSA 252. The stx1 toxigenic gene was present in Klebsiella oxytoca strain ATCC 13182 and Klebsiella pneumoniae strain DSM 30/04, while Staphylococcus aureus strain ATCC12600 and Staphylococcus aureus Subsp. aureus strain MRSA 252 possess the entFM toxigenic gene. Klebsiella oxytoca strain ATCC 13182 possess both fimH and spvC virulence genes while Staphylococcus aureus strain ATCC12600 and Staphylococcus aureus Subsp. aureus strain MRSA 252 possess the spvC virulence genes. This study demonstrates that Ox-Bow Lake harbors multidrug-resistant, virulent and toxigenic bacteria, representing a potential source of public health hazards through water use, seafood consumption, and direct human contact. These findings emphasize the importance of sustained environmental monitoring, effective waste management, and strengthened antibiotic stewardship to reduce the risks associated with antimicrobial resistance in aquatic ecosystems.