目的:本研究的目的是调查头孢他啶-阿维巴坦(CAZ-AVI)的敏感性,碳青霉烯酶基因,耐碳青霉烯类肺炎克雷伯菌(CrKp)分离株的克隆关系。
方法:通过改良的碳青霉烯失活方法(mCIM)确定的碳青霉烯酶产生阳性的总共28个非重复CrKp分离株,包括在研究中。用MALDI-TOFMS(VITEK-MS,BioMerieux,法国)。自动化系统(VITEK-2,bioMerieux)和梯度扩散测试(Etest,bioMerieux)用于确定抗生素敏感性。mCIM是根据CLSI(2021)的建议进行的。CAZ-AVI敏感性使用标准圆盘扩散方法进行。根据EUCAST2022标准评估结果。blaOXA-48,blaNDM,blaKPC,通过多重PCR研究blaIMP和blaVIM基因。分离株之间的克隆关系通过AP-PCR和PFGE方法确定。
结果:在总共28个分离株中,89.3%对CAZ-AVI敏感。在85.7%的分离物中发现了blaOXA-48基因,blaOXA-48+blaNDM基因占10.7%,blaNDM基因占3.6%。blaKPC,未检测到blaIMP和blaVIM基因。通过PFGE方法确定了具有三种不同基因型的三个簇。最大的簇是基因型A(n:24),其次是基因型B(n:3),和基因型C(n:1)。AP-PCR与PFGE高度兼容。基因型A的分离株,大部分来自重症监护病房(ICU),被评估为单克隆传播的爆发菌株。
结论:OXA-48仍然是我国CrKp菌株中检测频率最高的酶。头孢他啶-阿维巴坦的敏感率为89.3%,表明该抗生素对CrKp分离株仍然有效。在我们的研究中发现的未发现的爆发揭示了影响不同病房的医院内交叉污染的严重程度,包括ICU。因此,为了限制CrKp分离株的传播,实施严格的感染控制措施非常重要,和分子监测计划,尤其是在ICU。
OBJECTIVE: The aim of this study was to investigate ceftazidime-avibactam (CAZ-AVI) susceptibility, carbapenemase genes, and clonal relationship in carbapenem-resistant Klebsiella pneumoniae (CrKp) isolates.
METHODS: A total of 28 non-repetitive CrKp isolates with positive carbapenemase production determined by the modified carbapenem inactivation method (mCIM), were included in the study. Identification of the isolates was performed with MALDI-TOF MS (VITEK-MS, bioMerieux, France). The automated system (VITEK-2, bioMerieux) and gradient diffusion test (Etest, bioMerieux) were used to determine antibiotic susceptibility. The mCIM was performed according to CLSI (2021) recommendations. CAZ-AVI susceptibility was carried out using the standard disc diffusion method. Results were evaluated according to EUCAST 2022 criteria. The blaOXA-48, blaNDM, blaKPC, blaIMP and blaVIM genes were investigated by multiplex PCR. The clonal relationship between isolates was determined by both AP-PCR and PFGE methods.
RESULTS: Of the total 28 isolates, 89.3% were susceptible to CAZ-AVI. blaOXA-48 gene was found in 85.7% of the isolates, blaOXA-48+blaNDM gene in 10.7%, and blaNDM gene in 3.6%. blaKPC, blaIMP and blaVIM genes were not detected. Three clusters with three different genotypes were determined by the PFGE method. The largest cluster was Genotype A (n:24), followed by Genotype B (n:3), and Genotype C (n:1). AP-PCR was highly compatible with PFGE. The isolates of Genotype A, mostly from the intensive care unit (ICU), were evaluated as outbreak strains with monoclonal dissemination.
CONCLUSIONS: OXA-48 remains the most frequently detected enzyme in CrKp strains in our country. The ceftazidime-avibactam susceptibility rate of 89.3% indicates that this antibiotic is still effective against CrKp isolates. The unnoticed outbreak detected in our study revealed the severity of intra-hospital cross-contamination affecting different wards, including the ICU. Therefore, in order to limit the spread of CrKp isolates, it is of great importance to implement strict infection control measures, and molecular surveillance programs, especially in the ICU.