Virulence genes, efflux pumps, and molecular typing of Klebsiella pneumoniae isolates from North Iran.

Resistant and virulent strains of Klebsiella pneumoniae (K. pneumoniae) are rapidly disseminated among both hospitalized patients and communities, therefore, the identification of the genes responsible for virulence and resistance, along with the clonal relatedness of these strains, could be beneficial in the management of the dissemination of these strains among patients. The aim of the present study was to assess antibiotic susceptibility, virulence and resistance genes, as well as the genetic relatedness of K. pneumoniae strains isolated from patients admitted to four hospitals in Mazandaran, Iran. A total of 95 K. pneumoniae were gathered from hospitalized patients. All isolates were confirmed using biochemical and conventional microbiological methods, followed by the assessment of susceptibility patterns through disk diffusion and the detection of resistance and virulence genes using conventional PCR. The genetic diversity of clinical isolates was determined using the Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) technique. The resistance frequencies varied, with the highest being for ampicillin/sulbactam (95.8%) and the lowest for fosfomycin (3.2%). Only one strain displayed a non-MDR profile against all antibiotics tested. Virulence-associated genes were detected, such as mrkD (90.5%), fimH (80%), entB (92.6%), iutA (25.3%), and ybtS (68.4%). Genes associated with efflux pumps and outer membrane porins included acrAB (98.9%), tolC (95.8%), mdtK (83.2%), ompK35 (95.8%), and ompK36 (92.6%). Based on ERIC-PCR patterns with a 90% similarity, the isolates were categorized into 17 distinct clusters. While the majority of isolates had a same profile and were grouped in the predominant pattern, 11 isolates were identified as singletons. Our study indicates that the prevalence of MDR K. pneumoniae carrying virulence genes and exhibiting close relatedness underscores the urgent need for effective strategies to control and prevent infections caused by K. pneumoniae.