| Objective:kdebsiella pneumoniae is the most common clinical gram-negative bacteria. It is widely distributed in nature, and is also in the respiratory and intestinal tract of healthy humans and animals. Infections occurred in the situation of low immunity or the flora imbalance which are caused by long-term using of antibiotics. The types of infection include pneumonia, meningitis, liver abscess, endophthalmitis, urinary tract inflammation, wound infection and septicemia. In recent years, klebsiella pneumoniae is the second most common microorganism isolated from clinical, after Escherichia coli, and is also the potential pathogens which can not be ignored by causing the community-acquired infections and the nosocomial infections.Factors that are implicated in the virulence of K. pneumoniae strains include the capsular serotype, lipopolysaccharide and ironscavenging systems. The abundant polysaccharidic capsule that typically surrounds K. pneumoniae protects against the bactericidal action of serum and impairs phagocytosis, and may be regarded as the most important virulence determinant of K. pneumoniae. Among the82described capsular (K) types of the serotyping scheme, types K1,K2, K4and K5are associated with severe infections in humans.Kl isolates were frequent among Friedlander’s peumonia cases and are prominent among PLA cases, especially those with complications. Serotypes K2and K5were also associated with community-acquired pneumonia. Finally, although their role as a direct cause of ozaena is not fully established, K.pneumoniae subsp. ozaenae isolates from cases of atrophic rhinitis are of serotype K4or more rarely K5. The capsule is an important virulence factor, and some capsular types, particularly K1and K2, but also K54and K57, are associated with a community-acquired invasive pyogenic liver abscess syndrome.Currently studies on the susceptibility of klebsiella pneumoniae, drug resistance and prevalence detection of ESBLs-producing strains were reported in more areas, while it is rare about the capsular serotypes and virulence genes. This study investigated klebsiella pneumoniae serotype distribution and the distribution of virulence genes in China. It is helpful to give a theoretical foundation of the serotype, traceability and reasonable treatment for infections caused by klebsiella pneumoniae.Methods:In this study, the310K.pneumoniae strains were isolated and identified from Chongqing, Shenzhen and Beijing. Genomic DNA was extracted for polymerase chain reaction (PCR) to verify the serotype and the virulence genes. The positive control is NTHU-K2044, which was isolated from an abscess patients in Taiwan and the whole genome sequencing was available. Results:Serotypes K1, K2, K57, K54, K3, K5and K20accounted for14.2%,9.4%,6.5%,4.2%,2.5%and1.9%of the310isolates tested. Compared to the other three serotypes, the serotype K1occurred most frequently in the strains from the respiratory system.11kinds of virulence genes deletions were found. ureA、wabG and fimH have the high detection rates, on the contrary, iroNB has the lowest rate. ureA and wabG also have the highest rates from K. pneumoniae strains in the capsular serotypes. In addition to the K5serotypes, iroNB has the lowest rate.Conclusion:K1serotype is predominant in the310K. pneumoniae strains in relative to the other serotypes tested. Compared to the7serotypes which had been identified above, the other serotypes had a large proportion. Our results suggest the need to further investigate the distribution of the other serotypes. This study investigated klebsiella pneumoniae serotype distribution and the distribution of virulence genes in China, giving a theoretical foundation of the serotype, traceability and reasonable treatment from klebsiella pneumoniae isolates. |
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