Arıcı Neslihan, Tanrıverdi Elif Seren, Çalık Şeyma, Kansak Nilgün, Adaleti Rıza, Otlu Barış, Aksaray Sebahat
University of Health Sciences, Haydarpasa Numune Research and Training Hospital, Medical Microbiology, Istanbul, Turkey.
Inonu University, Medical Faculty, Department of Medical Microbiology, Malatya, Turkey.
Indian J Med Microbiol. 2023 Nov-Dec;46:100431. doi: 10.1016/j.ijmmb.2023.100431. Epub 2023 Jul 27.
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.
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 bla, bla, bla, bla and bla genes were investigated by multiplex PCR. The clonal relationship between isolates was determined by both AP-PCR and PFGE methods.
Of the total 28 isolates, 89.3% were susceptible to CAZ-AVI. bla gene was found in 85.7% of the isolates, bla+bla gene in 10.7%, and bla gene in 3.6%. bla, bla and bla 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.
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.
本研究旨在调查耐碳青霉烯类肺炎克雷伯菌（CrKp）分离株对头孢他啶-阿维巴坦（CAZ-AVI）的敏感性、碳青霉烯酶基因及克隆关系。
本研究纳入了28株经改良碳青霉烯灭活法（mCIM）检测碳青霉烯酶产生呈阳性的非重复CrKp分离株。采用基质辅助激光解吸电离飞行时间质谱（VITEK-MS，法国生物梅里埃公司）对分离株进行鉴定。使用自动化系统（VITEK-2，生物梅里埃公司）和梯度扩散试验（Etest，生物梅里埃公司）测定抗生素敏感性。mCIM按照美国临床和实验室标准协会（CLSI，2021年）的建议进行。采用标准纸片扩散法检测CAZ-AVI敏感性。结果根据欧洲药敏试验委员会（EUCAST，2022年）标准进行评估。通过多重聚合酶链反应（PCR）检测bla、bla、bla、bla和bla基因。采用任意引物聚合酶链反应（AP-PCR）和脉冲场凝胶电泳（PFGE）方法确定分离株之间的克隆关系。
在28株分离株中，89.3%对CAZ-AVI敏感。85.7%的分离株中检测到bla基因，10.7%的分离株中检测到bla+bla基因，3.6%的分离株中检测到bla基因。未检测到bla、bla和bla基因。通过PFGE方法确定了具有三种不同基因型的三个聚类。最大的聚类是基因型A（n = 24），其次是基因型B（n = 3）和基因型C（n = 1）。AP-PCR与PFGE高度一致。基因型A的分离株大多来自重症监护病房（ICU），被评估为单克隆传播的暴发菌株。
OXA-48仍然是我国CrKp菌株中最常检测到的酶。89.3%的头孢他啶-阿维巴坦敏感性率表明该抗生素对CrKp分离株仍然有效。我们研究中发现的未被注意到的暴发揭示了影响包括ICU在内的不同病房的医院内交叉污染的严重性。因此，为了限制CrKp分离株的传播，实施严格的感染控制措施和分子监测计划非常重要，尤其是在ICU。
