Characterization of Integrons and Sulfonamide Resistance Genes among Bacteria from Drinking Water Distribution Systems in Southwestern Nigeria.
BACKGROUND
The emergence of antibiotic resistance among pathogenic bacteria in clinical and environmental settings is a global problem. Many antibiotic resistance genes are located on mobile genetic elements such as plasmids and integrons, enabling their transfer among a variety of bacterial species. Water distribution systems may be reservoirs for the spread of antibiotic resistance.


METHODS
Bacteria isolated from raw, treated, and municipal tap water samples from selected water distribution systems in south-western Nigeria were investigated using the point inoculation method with seeded antibiotics, PCR amplification, and sequencing for the determination of bacterial resistance profiles and class 1/2 integrase genes and gene cassettes, respectively.


RESULTS
sul1,sul2, and sul3 were detected in 21.6, 27.8, and 0% of the isolates, respectively (n = 162). Class 1 and class 2 integrons were detected in 21.42 and 3.6% of the isolates, respectively (n = 168). Genes encoding resistance to aminoglycosides (aadA2, aadA1, and aadB), trimethoprim (dfrA15, dfr7, and dfrA1), and sulfonamide (sul1) were detected among bacteria with class 1 integrons, while genes that encodes resistance to strepthothricin (sat2) and trimethoprim (dfrA15) were detected among bacteria with class 2 integrons.


CONCLUSIONS
Bacteria from these water samples are a potential reservoir of multidrug-resistant traits including sul genes and mobile resistance elements, i.e. the integrase gene.
Department of Biological Sciences, Federal University Dutsin-Ma, Dutsin-Ma, Nigeria.
Ayodele T
AT
Adesoji
Adeniyi A
AA
Ogunjobi
Isaac O
IO
Olatoye
D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification; D060766:Drinking Water / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D006801:Humans; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D009549:Nigeria; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013449:Sulfonamides / Q000494:pharmacology*; D014295:Trimethoprim / Q000494:pharmacology
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D060766:Drinking Water; D012336:RNA, Ribosomal, 16S; D013449:Sulfonamides; D014295:Trimethoprim