Edible Fish as a Source of Klebsiella pneumoniae: Incidence, Virulence, Biofilm Formation, Antimicrobial Resistance and Control Strategies.

BACKGROUND: Fish sold in retail markets are prone to contamination with pathogenic bacteria. Investigations on occurrence of Klebsiella pneumoniae, its characterization in seafood are essential for the protection of consumer health. OBJECTIVE: The present study investigated the incidence of K. pneumoniae in fish and characterized their virulence profile, biofilm-forming ability, antimicrobial resistance and their control using water-soluble chitosan and postbiotics. METHODS: In total, 144 fish and processing water samples from fish retail markets of Visakhapatnam, India were screened for presence of K. pneumoniae using MacConkey agar and amplifying khe gene. Virulence characterization (entB, mrkD, kfu, allS, rmpA, ybtS, iutA) antibiotic susceptibility test (disc diffusion assay against 28 antibiotics) biofilm-forming ability and anti-K. pneumoniae activity of water-soluble chitosan (microtiter plate assay) were studied. RESULTS: Eleven fish samples showed presence of K. pneumoniae. All the isolates possessed entB gene, however, 91% of the isolates carried mrkD and kfu genes. Antibiogram studies showed that all isolates were multidrug resistant (MDR), and their Multiple Antibiotic Resistance (MAR) index ranged from 0.19 to 0.39. Resistance genes detected in K. pneumoniae were bla SHV (91%), bla TEM (27%), sul1(18%), tetA (9%), tetD (9%), and catA2 (9%). Majority of K. pneumoniae isolates were moderate biofilm formers (63.6%) and the biofilm-forming ability was potentiated by supplementation with lactose (100%) followed by fructose (90.9%) and ribose (90.9%) sugars. Water-soluble chitosan (1%) showed effective control of all K. pneumoniae. CONCLUSION: The present study showed majority of the K. pneumoniae isolates from seafood were found to be virulent, multidrug-resistant, ESBL producers, and moderate biofilm formers indicating potential health risk to fish consumers. Water-soluble chitosan showed a significant inhibitory effect on growth of all K. pneumoniae isolates. HIGHLIGHTS: The detection of virulent and MDR K. pneumoniae in edible fish meat, albeit at a low level, poses a significant threat to consumers.