PHENOTYPIC AND GENOTYPIC CHARACTERISTICS OF BACTERIAL ISOLATES FROM URINE SAMPLES AND THEIR SUSCEPTIBILITY PATTERNS TO SOME SELECTED ANTIBIOTICS.

Abstract Urinary tract infections (UTIs) remain a significant global health concern, with increasing reports of multidrug-resistant (MDR) uropathogens complicating treatment efforts. This study investigated the phenotypic and genotypic characteristics of bacterial isolates from urine samples and assessed their susceptibility to selected antibiotics. A total of 50 midstream urine samples were collected from individuals presenting with symptoms of UTI in Agbor, Delta State, Nigeria. Samples were cultured on MacConkey and CLED agar, and isolates were identified using morphological and biochemical techniques. Antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method following Clinical and Laboratory Standards Institute (CLSI) guidelines. Genotypic analysis involved DNA extraction and 16S rRNA gene amplification by PCR, followed by sequencing and phylogenetic analysis. Five bacterial species were identified: Staphylococcus aureus (38%), Escherichia coli (28%), Klebsiella spp. (16%), Proteus spp. (10%), and Staphylococcus saprophyticus (8%). S. aureus was the predominant isolate. Antibiotic susceptibility testing revealed high resistance to ampicillin and cotrimoxazole, while ciprofloxacin and nitrofurantoin showed the highest effectiveness across most isolates. Genotypic sequencing of a representative S. aureus isolate (SL2) confirmed its identity with 99% similarity to reference strain CFSAN082783. The comparison of phenotypic and genotypic results highlighted the enhanced accuracy of molecular identification. The study concluded that integrating genotypic techniques with conventional methods improves diagnostic reliability and supports rational antibiotic selection. The findings underscore the urgent need for regular surveillance, antibiotic stewardship, and molecular resistance profiling in the management of UTIs.