Prevalence of Virulence Genes and Biofilm-Forming Ability Among Multidrug-Resistant Klebsiella pneumoniae Isolates from Intensive Care Unit Patients

Background: Multidrug-resistant Klebsiella pneumoniae is an important cause of healthcare-associated infection, and its persistence is enhanced by biofilm formation and virulence-associated genes. This study investigated antimicrobial susceptibility, biofilm-forming ability, and the prevalence of mrkA and luxS among clinical K. pneumoniae isolates recovered in Mosul, Iraq. Methods: Ten non-duplicate isolates were obtained from Al-Salam Teaching Hospital, Al-Jumhuriya Teaching Hospital, and the Specialized Burn Center. Isolates were identified phenotypically and confirmed using the VITEK 2 system and 16S rRNA PCR. Antimicrobial susceptibility was assessed by the Kirby-Bauer disc diffusion method. Biofilm formation was quantified using the crystal-violet microtiter plate assay. Endpoint PCR was used to detect mrkA, which encodes the major subunit of type 3 fimbriae, and luxS, which is involved in autoinducer-2 quorum sensing. Results: Burn swabs accounted for 50% of isolates, wound swabs for 30%, and sputum and urine for 10% each. All isolates were resistant to the ten antimicrobial agents tested. The 16S rRNA target was detected in all isolates. mrkA was present in 10/10 isolates (100%), whereas luxS was detected in 4/10 isolates (40%). All isolates were classified as moderate biofilm producers. Conclusion: The isolates showed extensive antimicrobial resistance together with a high prevalence of mrkA and consistent biofilm formation. The lower frequency of luxS suggested that quorum-sensing capacity varied among isolates. These findings support continued surveillance of resistant K. pneumoniae and virulence-associated traits in hospital settings.