AUTHOR=Wei Tian , Zou Chengyun , Qin Jie , Tao Jianmin , Yan Li , Wang Jiangjun , Du Hong , Shen Fang , Zhao Yanqin , Wang Haiying 

TITLE=Emergence of Hypervirulent ST11-K64 Klebsiella pneumoniae Poses a Serious Clinical Threat in Older Patients

JOURNAL=Frontiers in Public Health

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2022.765624

DOI=10.3389/fpubh.2022.765624

ISSN=2296-2565

ABSTRACT=Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) poses severe therapeutic challenge to global public health, and researches on CR-hvKP in elderly patients remain limited. Here, we aimed to investigate the clinical and molecular characteristics and risk factors of CR-hvKP infections in elderly patients. We retrospectively investigated elderly patients with carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in intensive care unit (ICU), between January 2020 and December 2020. The clinical data, and microbiological data including antimicrobial susceptibility testing, phenotype experiment and detection of carbapenemases, string test, virulence genes, capsular serotype-specific (cps) genes and multilocus sequence typing, of the CR-hvKP group defined by the presence of  any one of the virulence genes，including rmpA, rmpA2, iucA, iroN, and peg-344 was compared with those of carbapenem-resistant non-hypervirulent Klebsiella pneumoniae (CR-non-hvKP) strains. Of 80 CRKP strains, 51(63.8%) met the definition of CR-hvKP. The main mechanism of resistance to carbapenems was the presence of the blaKPC-2 gene. Sequence type (ST)11 (81.3%, 65/80) and ST15 (16.3%,13/80) were the most common STs in CRKP strains. The minimum inhibitory concentration (MIC)50 values of CR -hvKP group against the six tested antibiotics (ceftazidime, ceftazidime-avibactam, imipenem-avibactam, tigecycline, levofloxacin, Cefoperazone-Sulbactam) exhibited elevated levels than CR-non-hvKP group. Ceftazidime and imipenem by combining avibactam (4 µg/mL) significantly decreased the MIC90 values more than sixteen-fold than ceftazidime and imipenem alone against KPC-2-producing K. pneumoniae. Cardiovascular disease (odds ratio [OR] = 11.956) and ST11-K64 (OR= 8.385) appeared to be independent variables associated with CR-hvKP infection by multivariate analysis. In conclusion, higher MICs of the last line antibiotic agents (ceftazidime-avibactam, tigecycline) might be a critical consideration in clinical management of older patients where the concentration of these toxic antibiotics matters because of underlying comorbidities. Caution regarding KPC-2-producing ST11-K64 CR-hvKP as being new significant “superbugs” is required as they are widespread, infection control measures should be strengthened to curb further dissemination in nosocomial settings in China.