Molecular Characterisation of Biofilm-Forming, Multidrug-Resistant Bacteria from Water Distribution Systems, Choba, Rivers State, Nigeria

Abstract Background This study aimed to molecularly characterize biofilm-forming, multidrug-resistant bacteria isolated from water distribution systems in Choba, Rivers State, Nigeria, using standard microbiological and molecular techniques. Biofilm formation was screened using Congo red agar and tube methods. Twenty-eight bacterial isolates were recovered from water samples obtained from the Abuja campus, and their identities were confirmed through biochemical characterisation. Polymerase Chain Reaction (PCR) was employed to detect selected virulence-associated genes, including type 1 fimbriae (fimH), P fimbriae (papC), afimbrial adhesins (afaCc), and the capsule-associated regulator gene (rmpA). Results Among the isolates Chromobacterium violaceum was the only organism that demonstrated biofilm-forming ability, evidenced by black colouration on Congo red agar and visible ring formation in the tube assay. Antibiotic susceptibility testing revealed that C . violaceum was not resistant to all the antibiotics tested, indicating varying levels of antimicrobial susceptibility. Genomic DNA was extracted from fresh bacterial cultures and used as template for amplification of the target genes. Molecular analysis revealed the presence of papC , afaCc , and rmpA genes in C . violaceum , while the fimH gene encoding type 1 fimbriae was not detected. The detection of these virulence determinants indicates the pathogenic potential of the isolate. Conclusion This study reports the successful isolation, phenotypic characterisation, and molecular identification of Chromobacterium violaceum from a municipal water distribution system, highlighting the public health significance of biofilm-forming and potentially virulent bacteria in treated water supplies and emphasizing the need for continuous monitoring and improved water quality surveillance strategies.