Virulence Factors, Capsular Serotypes and Antimicrobial Resistance of Hypervirulent Klebsiella pneumoniae and Classical Klebsiella pneumoniae in Southeast Iran

Abstract

Background: The present study was conducted to investigate the distribution of virulence factors, capsular serotypes and antibiotic resistance properties of classical Klebsiella pneumoniae (cKP) and hypermucoviscous/hypervirulent Klebsiella pneumoniae (hvKP) isolated from different clinical specimens in Kerman, south-east of Iran.

Materials and methods: A total of 146 K. pneumoniae isolates were obtained from different clinical specimens. HvKP isolates were identified using the string test. Genes of capsular serotypes K1, K2, K5, K20, K54 and K57 and virulence-associated genes, rmpA, kfu, fimH, mrkD, allS, iutA, magA, entB and ybtS were evaluated by PCR. Antimicrobial susceptibility was also determined using the disc diffusion method.

Results: Out of 146 K. pneumoniae isolates, 22 (15.1 %) were hvKP. More than half of the hvKP isolates, 13 (59.1%), belonged to non-K1, K2, K5, K20, K54, K57 serotypes. Out of 22 hvKP isolates, 3 and 3 had K1 and K2 serotypes respectively. Among all isolates, entB 140 (95.9%) and mrkD 138 (94.5%) were the most common virulence genes. RmpA, iutA and kfu were associated with hvKP isolates (P-value <0.05). However, no significant difference was found in fimH, allS, mrkD, entB and ybtS genes between hvKP and cKP strains. HvKP exhibited significantly lower resistance rates to all antimicrobial agents than cKP, except to trimethoprim-sulphamethoxazole and ampicillin (P-value <0.05).

Conclusion: The frequency of hvKP was low, but overall, the prevalence of virulence-related genes was higher in hvKP than cKP. HvKP was not related to specific serotypes. Furthermore, hvKP isolates were more susceptible to antimicrobial agents compared to cKP isolates.

Keywords: Antibiotic resistance; Capsular serotypes; Klebsiella pneumonia; Virulence factors.