Epidemiological characteristics and molecular biology of carbapenem-resistant Klebsiella pneumoniae / 第二军医大学学报

ABSTRACT

Objective To investigate the distribution, drug resistance and molecular biological characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) in our hospital, so as to provide reference for rational use of antibiotics and prevention and control of nosocomial CRKP infection. Methods Non-repetitive CRKP strains were collected from Jan. to Dec. 2019 in our hospital. VITEK 2 Compact automatic microbial analyzer and Kirby-Bauer test were used for bacterial identification and antimicrobial susceptibility analysis. WHONET 5.6 software was used to analyze CRKP detection rate, sample source and clinical department distribution. Hypermucoviscosity phenotype strains were screened by string test. Carbapenemase resistance genes, capsular serotype and virulence genes were detected by polymerase chain reaction (PCR). Results A total of 532 Klebsiella pneumoniae strains were detected, including 140 (26.3%) CRKP strains. The CRKP strains were mainly isolated from sputum and bronchoalveolar lavage fluid (66 strains, 47.1%), followed by urine (21 strains, 15.0%). The clinical departments of the isolates were mainly cardiovascular surgery intensive care unit (ICU) (47 strains, 33.6%), burn ICU (18 strains, 12.9%) and emergency department (18 strains, 12.9%). The antimicrobial susceptibility test showed that the CRKP strains were susceptible only to tigecycline, with resistance rates being over 50% to other common antibiotics. The resistance rates to the first to fourth generation cephalosporin antibiotics were above 85%, and the resistance rates to carbapenems were up to 100.0%. We also found that out of the 121 CRKP strains, 101 (83.5%) carried Klebsiella pneumoniae carbapenemase 2 (KPC-2) gene, seven (5.8%) with oxacillinase-48 (OXA-48) gene, and two (1.7%) with New Delhi metallo-β-lactmase 1 (NDM-1) gene; while one carried both KPC-2 and NDM-1 genes, and one carried both KPC-2 and OXA-48 genes; and nine carried no target drug-resistance genes. Fifteen (12.4%, 15/121) CRKP strains were positive for string test, with 13 being K64 capsular type and two being K47 capsular type; and 14 strains carried at least one virulence gene. Conclusion The clinical isolation rate of CRKP is high in our hospital, and the CRKP strains (mainly K64 capsular high virulence) are resistant to multiple antibiotics, suggesting that we should further strengthen the monitoring of drug resistance and rational use of antibiotics, so as to prevent the spread and prevalence of drug-resistant and highly virulent strains.