Drug susceptibility and molecular epidemiology of Klebsiella pneumoniae bloodstream infection in ICU patients in Shanghai, China

Background: Bloodstream infections (BSIs) are always associated with increased cost, prolonged hospitalization and higher mortality, especially for patients in intensive care units (ICUs). Klebsiella pneumoniae is recognized as the major cause of bacteremia around the world and resistant to most clinically significant antibiotics. This retrospective study focused on drug susceptibility and molecular epidemiology of K. pneumoniae isolated from ICU patients with BSI in Shanghai, China. Methods: Consecutive K. pneumoniae isolates were collected from ICU patients with bacteremia in Shanghai from January 2016 to December 2019. Antibiotic susceptibility testing and primary screening test for extended-spectrum β-lactamase (ESBL) and carbapenemase production were conducted by broth microdilution method. Polymerase chain reaction (PCR) was performed to detect antimicrobial resistance genes and to confirm carbapenemase production. We also conducted multilocus sequence typing (MLST), of which the result was analyzed by GoeBURST. Results: A total of 78 K. pneumoniae isolates were enrolled. K. pneumoniae isolated from ICU bloodstream infections (ICU-BSIs) were highly resistant to almost all clinically common antibiotics, except for colistin (11.5%) and tigecycline (23.0%). ESBL-producing and carbapenemase-producing K. pneumoniae accounted for 74.4% and 71.7%, respectively. The most frequently found genotype in ESBL producers was bla CTX−M−14 (44/58, 75.9%), followed by bla CTX−M−15 (15/58, 25.9%) and bla CTX−M−55 (8/58, 13.8%). KPC is the only enzyme generated by carbapenemase producers and all KPC enzymes were encoded by bla KPC−2 . The most principal ST was ST11 (50/78, 64.1%), followed by ST15 (7/78, 9.0%) and ST23 (3/78, 3.8%). Two newfound sequence types were identified in our study. Conclusions: This study is the first to demonstrate the antibiotic resistance phenotype and molecular epidemiology of K. pneumoniae isolated from ICU patients with bloodstream infections in Shanghai. It is noteworthy that ICU-BSI K. pneumoniae is characteristic of high resistance rate. According to the consequence of resistance gene detection and MLST analysis, the prevalence of KPC-2 enzyme may result from nosocomial clonal dissemination of ST11 K. pneumoniae .