Phenotypic Characterization of Biofilm Formation and Efflux Pump Activity in Multidrug-Resistant Klebsiella pneumoniae

Abstract

Klebsiella pneumoniae is a significant pathogen responsible for a wide array of nosocomial and community-acquired infections. This bacterium often targets patients with indwelling medical devices, such as urinary catheters, by forming biofilms. The formation of biofilms has facilitated the acquisition of antibiotic resistance in K. pneumoniae strains. Efflux pumps further contribute to this resistance by exporting commonly used antibiotics from the bacterial cells to the extracellular environment. Together, biofilm formation and efflux pump activity have accelerated the spread of this multidrug-resistant (MDR) pathogen. An organism is classified as multidrug-resistant when it exhibits resistance to two or more antibiotics. This study investigated the antibiotic resistance profiles of K. pneumoniae isolates, along with their biofilm-forming capabilities and efflux pump activities. Sixteen isolates were obtained from the Department of Microbiology, University of Lagos, Lagos State. Confirmation of K. pneumoniae was conducted through culture, microscopy, and biochemical assays. Antibiotic susceptibility was tested against six commonly used antibiotics, alongside phenotypic screening for efflux pump activity and biofilm formation using the ethidium bromide cartwheel method and Congo red agar method, respectively. The results indicated that all isolates were multidrug-resistant, exhibiting high resistance to ofloxacin (75%), cephalexin (56.25%), and ampicillin (50%). Four isolates demonstrated biofilm-forming ability, while only two isolates exhibited efflux pump activity. These findings suggest that biofilm formation and efflux pump activity are critical virulence factors in K. pneumoniae.