AUTHOR=Li Shirong , Shen Siquan , Ding Li , Han Renru , Guo Yan , Yin Dandan , Guan Ming , Hu Fupin 

TITLE=First Report of blaCTX–M–167, blaSHV–1, and blaTEM–1B Carrying Klebsiella pneumonia Showing High-Level Resistance to Carbapenems

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.916304

DOI=10.3389/fmicb.2022.916304

ISSN=1664-302X

ABSTRACT=<p>The prevalence of carbapenem-resistant <italic>Klebsiella pneumoniae</italic> is increasing. Although carbapenemase production is the main resistance mechanism of <italic>K. pneumonia</italic> to carbapenems, there are still some reports of non-carbapenemase-producing <italic>K.pneumoniae</italic> showing high-level resistance to carbapenems. In this study, we had also isolated a carbapenemase-negative carbapenem-resistant <italic>K. pneumoniae</italic> L204 from a patient with an asymptomatic urinary tract infection. Species identification was performed using MALDI-TOF MS, and carbapenemase-encoding genes were detected using both NG-test carba-5 and whole-genome sequencing. Antimicrobial susceptibility testing was performed by the broth microdilution method according to CLSI guidance. The results of antimicrobial susceptibility testing indicated that <italic>K. pneumoniae</italic> L204 was resistant to meropenem (MIC = 16 mg/L) and imipenem (MIC = 4 mg/L), but susceptible to ceftazidime-avibactam (MIC = 8 mg/L). Through whole-genome sequencing, several resistance genes had been identified, including <italic>bla</italic><sub>TEM–1B</sub>, <italic>bla</italic><sub>CTX–M–167</sub>, <italic>bla</italic><sub>SHV–1</sub>, <italic>aac(6’)-1b-cr</italic>, <italic>qnrS</italic>, <italic>aadA16</italic>, <italic>tet(A)</italic>, <italic>fosA</italic>, <italic>sul1</italic>, and <italic>mph(A)</italic>. The efflux pump inhibition testing showed that the efflux pump was not involved in the resistance mechanism to carbapenems. The result of the conjugation experiment indicated that the plasmid with <italic>bla</italic><sub>CTX–M–167</sub> and <italic>bla</italic><sub>SHV–1</sub> was transferrable. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that <italic>K. pneumoniae</italic> L204 only contained outer membrane porin OmpK35.</p>