Major Predominant Serotypes and Virulence Genes and Antibiotic Resistance Characteristics of Klebsiella pneumoniae Clinical Isolates in Middle and East China.

Abstract

Background: Klebsiella pneumoniae is a common opportunistic pathogen. Predominant serotypes, virulence genes, and resistance characteristics of K. pneumoniae isolates from patients in different regions of China require further investigation.

Methods: K. pneumoniae isolates from patients and healthy individuals in middle and east China were identified using an auto-bacterial detector. Major serotypes and virulence genes in the isolates were detected by polymerase chain reaction, while drug resistance of the isolates was determined using broth microdilution assays.

Results: Respiratory K. pneumoniae infection was observed in 70.0% of the patients. Of the K. pneumoniae isolates from patients, 42.3% were hypervirulent K (hvKp) serotypes, of which 30.1% and 37.0% belonged to K1 and K2 serotypes with 78.6-87.8% positive rates of rmpA and rmpA2 virulence genes. The isolates from healthy individuals had fewer hvKp serotypes and rmpA/rmpA2 genes (7.2% and 22.9%/26.5%). Resistance rates (38.6-79.5%) of the isolates from healthy individuals against 14 antibiotics were higher than those from patients (16.4-40.8%). The isolates from patients were sensitive to amikacin (83.6%) and polymyxin-B (93.9%) but presented 20.3% and 26.6% resistance rates to imipenem and meropenem, respectively. The isolates from patients with urinary infections exhibited higher resistances (42.1-52%) to cefoxitin, cefuroxime, ceftriaxone, ciprofloxacin, and levofloxacin than those from patients with respiratory or blood infections (22.4-39.3%). In the isolates from patients, the K47 and K64 serotypes exhibited multiple drug resistance (65-90%) against 14 antibiotics but all the hvKp serotypes displayed much lower antibiotic resistance (1.9-26.0%).

Conclusion: K1/K2 were the major predominant hvKp serotypes with rmpA/rmpA2 virulence genes and carbapenem-resistant K. pneumoniae strains were prevalent in patients from middle and east China. The hvKp serotypes have low antibiotic resistance, but K. pneumoniae isolates from patients with urinary infections resist the cephalosporin/quinolone antibiotics for treatment of bacterial urinary infections. Amikacin and polymyxin-B can be used to treat drug-resistant K. pneumoniae infections.