1.High level quinolone resistance and the mechanisms of resistance in carbapenem-resistant Klebsiella pneumoniae
Aimaiti ALIMIRE ; Zhewei SUN ; Qingqing XU ; Xiaogang XU ; Minggui WANG
Chinese Journal of Infection and Chemotherapy 2024;24(3):326-331
Objective To examine the quinolone resistance and mechanisms of resistance,including prevalence of transferable mechanisms of quinolone resistance(TMQR)genes in carbapenem-resistant Klebsiella pneumoniae(CRKP).Methods Antimicrobial susceptibility was tested for CRKP isolated from 7 hospitals in China during 2019 by broth microdilution method.Genome sequencing analysis was performed on Illumina HiseqX sequencing platform.The virulence genes,multilocus sequence typing(MLST),chromosome quinolone resistance-determining region(QRDR)variation,and prevalence of TMQR genes in CRKP were analyzed.Results Overall,98.4%and 99.2%of the 481 CRKP strains were non-susceptible to levofloxacin and ciprofloxacin,respectively.ST11(77.8%)and ST15(15.8%)were the dominant clones.Among the 303 CRKP strains carrying virulence gene(CV-CRKP),ST11 type and ST15 type strains accounted for 92.1%and 5.0%,respectively,while ST11 and ST15 type strains accounted for 53.4%and 34.3%in the 178 CRKP strains without the virulence gene(non-CV-CRKP).All of the ST11 and ST 15 type strains were resistant to quinolones associated with gyrA and parC mutation.All of the quinolone-sensitive strains were not ST11 type or not ST15 type.TMQR analysis showed that qnrS1(61.1%,294 strains),qnrB4(10.0%,48 strains)and aac(6)-Ib-cr(18.7%,90 strains)were most prevalent in CRKPs,while qnrB1(4 strains),qnrB2(2 strains),qnrD1(2 strains)and qnrB6(1 strain)were infrequently identified in CRKPs.Specifically,qnrB4 was mainly identified in high-level levofloxacin-resistant strains(MIC≥8 mg/L),while aac(6)-Ib-cr was found mainly in ciprofloxacin-resistant strains(MIC>8 mg/L).Conclusions Clinical CRKPs were highly resistant to quinolone.The rate of QRDR variation were high in quinolone resistant CRKP strains,with high TMQR gene carriage.

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