Molecular characterization of hypervirulent phenotype-associated traits among K. pneumoniae in Egypt (RSPM2.6)

Abstract

Background and Aim: Klebsiella pneumoniae is a Gram-negative and an enteric opportunistic bacterial pathogen. It includes classical (cKP) strains which cause hospital-acquired (HA) infections, particularly among immunocompromised patients, and hypervirulent (hvKP) strains that cause invasive community- acquired (CA) infections in immunocompetent individuals. The hvKP strains have been attributed to expression of hypermucoviscous phenotype. Recently, hvKP infections are progressively reported globally not only for CA infections but also for HA infections with increasing morbidity and mortality rates. This project aimed to study the prevalence of hypermucoviscous phenotype among clinical isolates of K. pneumoniae from hospitals in Egypt, and investigate the hypermucoviscosity related factors. Methods: The isolates were identified phenotypically by various biochemical tests and confirmed genotypically using a specific primer set. The hypermucoviscosity phenotype was detected by using string test. Eleven different genes that are potentially associated with the phenotypes of hypermucoviscosity and hypervirulence were investigated by PCR. The biogram antimicrobial susceptibility was evaluated for the isolates against thirteen antimicrobial agents using Kirby-Bauer disc diffusion method. The isolates were tested by ERIC-PCR for fingerprinting. Statistical analysis was conducted using Chi-square. Results: According to string test, hypermucoviscous isolates were 40% of collected isolates. Antimicrobial susceptibility study showed that 26% of hypermucoviscous isolates were MDR while 36% of non- hypermucoviscous isolates were MDR. The PCR assay results for Capsular serotype K2 gene showed that it is harbored by 68% of hypermucoviscous isolates while 7% only by non-hypermucoviscous isolates. Statistically there is no significant difference in all tested attributes between the cKP and hvKP isolates except for K2 gene. Conclusion: The antimicrobial resistance is not corresponded to the hypermucoviscosity phenotype. Resistance to carbapenems is a common feature among K. pneumoniae strains in Egypt. K2 gene is highly related to the hypermucoviscosity phenotype. This study show evidence that the hypermucoviscosity phenotype is not restricted only to the hypervirulent strains and consequently string test is a poor identification method for Hypervirulent variant especially in countries with low prevalence like Egypt.