Virulence Factor Analysis and Biofilm Formation Capacity of Klebsiella pneumoniae from Bovine Mastitis in South East Nigeria

This study analyses virulence factors and biofilm formation capacity of Klebsiella pneumoniae isolated from bovine mastitis cases in South East Nigeria, encompassing Anambra, Enugu, Imo, Abia, and Ebonyi States. K. pneumoniae is an increasingly important environmental mastitis pathogen in Nigerian dairy cattle and its virulence properties influence therapeutic outcome and intramammary persistence. Using a cross-sectional laboratory design, milk samples were collected from 300 clinical and subclinical mastitis quarters from 80 dairy farms across the five South East states. K. pneumoniae was isolated by standard bacteriological methods and confirmed by VITEK 2 identification. Virulence factors including capsular serotype (K1-K6), presence of magA, rmpA, ureA, fimH, and kfu genes were detected by PCR. Biofilm formation was quantified using the crystal violet microtitre plate method. Antibiotic susceptibility testing was performed by disc diffusion and MIC determination. The study fills a gap in virulence characterisation of bovine K. pneumoniae in the South East zone. Findings revealed K. pneumoniae isolation from 22 percent of mastitis samples. Hypervirulent strains (carrying magA and rmpA) constituted 18 percent of isolates. Biofilm-positive strains were detected in 71 percent of isolates, providing a mechanistic explanation for treatment failure in chronic mastitis. Multidrug resistance was detected in 48 percent of isolates. The study recommends biofilm-targeted treatment protocols and environmental management to reduce K. pneumoniae mastitis in South East Nigeria dairy herds. Keywords: Klebsiella pneumoniae, mastitis, virulence factors, biofilm, South East Nigeria.