Microbiology Laboratory, Ordu University Training and Research Hospital, Ordu, 52000, Turkey.
Department of Medical Microbiology, Faculty of Medicine, Recep Tayyip Erdogan University, Rize, Turkey.
Ann Clin Microbiol Antimicrob. 2023 Oct 27;22(1):93. doi: 10.1186/s12941-023-00640-9.
This study aimed to evaluate antibiotic resistance genes and virulence genes and the clonal relationship of the carbapenem-nonsusceptible Klebsiella pneumoniae strains by molecular methods which are isolated from various clinical specimens from patients treated in tertiary care hospital in Turkey.
Identification of 32 carbapenem non-susceptible K. pneumoniae were determined by VITEK-2 (BioMérieux, France) automated system. Thirteen colistin-resistant strains were tested with the broth microdilution method. Various antibiotic resistance genes and virulence genes frequently seen in carbapenem-resistant strains were screened by PCR. Immunochromatographic tests used in the rapid diagnosis of carbapenemases were compared with PCR results. In addition, PFGE, MLST and MALDI-TOF MS methods were used to determine the clonal relationship among these strains.
PCR demonstrated that 31 of the strains carried at least one of the carbapenemase genes. In one strain, the coexistence of bla was shown. The most common resistance genes were determined as bla (84.3%), bla (46.8%), bla (40.6%), bla (40.6%), bla (31.2%), bla (18.8%) respectively. Among the virulence genes; magA (68.7%) was the most common, followed by kpn (59.3%) and K2 (9.3%). Immunochromatographic tests were found to be 100% compatible with PCR results. All colistin-resistant isolates were also found to be resistant by colistin broth microdilution. In PFGE analysis, 25 different genotypes were determined and clustering isolates were collected in 5 different clusters and the clustering rate was 35.4%. In MLST analysis, ST101 type was determined as the most common ST type with a rate of 29%. ST101 is followed by ST16, ST307, ST14, ST147, ST309, ST377, ST395 and ST2096, respectively. The compatibility rate between MALDI-TOF MS and VITEK-2 was found 94.3%, in bacterial identification. In MALDI-TOF MS typing, the maximum similarity between the strains was less than 70% and clustering not shown.
In addition to OXA-48, which is endemic in our country, it has been determined that KPC, which is more common in the world, is becoming increasingly common in our region. ST101 type was determined as the most common type between the strains. To the best of our knowledge, this is the first study that compares these three methods in our country. There may be differences between bacterial identifications made with VITEK-2 and MALDI-TOF MS. In this study, it was observed that MALDI-TOF MS analyses were not compatible with the typing of strains according to PFGE and MLST analysis results.
本研究旨在通过分子方法评估从土耳其三级保健医院治疗的患者的各种临床标本中分离出的耐碳青霉烯类肺炎克雷伯菌的抗生素耐药基因和毒力基因以及克隆关系。
采用 VITEK-2（法国生物梅里埃公司）自动化系统鉴定 32 株耐碳青霉烯类肺炎克雷伯菌。用肉汤微量稀释法检测 13 株多粘菌素耐药株。通过 PCR 筛选经常出现在耐碳青霉烯类肺炎克雷伯菌中的各种抗生素耐药基因和毒力基因。比较了用于快速诊断碳青霉烯酶的免疫色谱试验和 PCR 结果。此外，还使用 PFGE、MLST 和 MALDI-TOF MS 方法来确定这些菌株之间的克隆关系。
PCR 显示 31 株菌至少携带一种碳青霉烯酶基因。在一株菌中同时存在 blaCTX-M-15 和 blaKPC-2 基因。最常见的耐药基因分别为 blaCTX-M-15（84.3%）、blaDHA-1（46.8%）、blaTEM-1（40.6%）、blaCTX-M-14（40.6%）、blaOXA-1（31.2%）和 blaSHV-12（18.8%）。毒力基因中，magA（68.7%）最为常见，其次是 kpn（59.3%）和 K2（9.3%）。免疫色谱试验与 PCR 结果完全一致。所有多粘菌素耐药分离株经多粘菌素肉汤微量稀释法检测均耐药。PFGE 分析确定了 25 种不同的基因型，并将聚类分离株分为 5 个不同的聚类，聚类率为 35.4%。在 MLST 分析中，ST101 型被确定为最常见的 ST 型，占 29%。其次是 ST16、ST307、ST14、ST147、ST309、ST377、ST395 和 ST2096。MALDI-TOF MS 与 VITEK-2 细菌鉴定的符合率为 94.3%。在 MALDI-TOF MS 分型中，菌株之间的最大相似度小于 70%，未显示聚类。
除了在我国流行的 OXA-48 外，世界范围内更为常见的 KPC 也越来越常见。ST101 型被确定为菌株之间最常见的类型。据我们所知，这是在我国首次比较这三种方法的研究。VITEK-2 进行的细菌鉴定可能与 MALDI-TOF MS 之间存在差异。在这项研究中，观察到 MALDI-TOF MS 分析与根据 PFGE 和 MLST 分析结果进行的菌株分型不兼容。
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