EVALUATION OF VIRULENCE FACTORS AND ANTIBIOTIC RESISTANCE IN URINARY ISOLATES OF KLEBSIELLA PNEUMONIAE AT MARDAN MEDICAL COMPLEX, MARDAN.

Abstract

Background: Klebsiella pneumoniae is an important uropathogens associated with increasing antimicrobial resistance and a range of virulence-associated characteristics. The coexistence of antimicrobial resistance and virulence determinants may complicate the management of urinary tract infections. This study evaluated antimicrobial susceptibility and selected phenotypic and genotypic virulence characteristics among urinary K. pneumoniae isolates recovered at Mardan Medical Complex, Mardan, Pakistan. Methods: A laboratory-based cross-sectional study was conducted from January 2025 to January 2026 in the Microbiology Laboratory of Mardan Medical Complex. A total of 250 confirmed urinary K. pneumoniae isolates were included using non-probability consecutive sampling. Antimicrobial susceptibility was determined by the Kirby–Bauer disk diffusion method against selected antimicrobial agents. Capsule production was assessed by India ink staining, hypermucoviscosity by the string test, and the virulence-associated rmpA gene was detected by polymerase chain reaction. Associations between virulence characteristics and antimicrobial resistance were assessed using chi-square or Fisher's exact tests. Results: Of the 250 isolates, 146 (58.4%) were recovered from females and 104 (41.6%) from males. The highest antimicrobial resistance was observed against ampicillin (94.8%), followed by cefotaxime (74.0%), ceftazidime (71.2%), ciprofloxacin (68.0%), amoxicillin-clavulanic acid (62.0%), and gentamicin (51.2%). Resistance to imipenem, nitrofurantoin, and fosfomycin was 23.2%, 43.6%, and 26.8%, respectively. Capsule production was detected in 203 (81.2%) isolates, while 91 (36.4%) exhibited a hypermucoviscous phenotype and 78 (31.2%) carried rmpA. Among rmpA-positive isolates, capsule production was significantly more frequent than among rmpA-negative isolates (92.3% vs. 76.2%, p=0.002). Similarly, hypermucoviscosity was significantly associated with rmpA carriage (70.5% vs. 20.9%, p<0.001). Conclusion: Urinary K. pneumoniae isolates demonstrated a substantial burden of antimicrobial resistance together with frequent virulence-associated characteristics, particularly capsule production, hypermucoviscosity, and rmpA carriage. The significant associations of rmpA with capsule production and hypermucoviscosity support a relationship between this gene and capsule-associated phenotypes. Continued local antimicrobial-resistance surveillance and integrated monitoring of virulence characteristics are warranted.