Markovska Rumyana, Marteva-Proevska Yuliya, Velinov Tzvetan, Pavlov Ivan, Kaneva Radka, Boyanova Lyudmila
1Department of Medical Microbiology, Medical Faculty, Medical University of Sofia, Bulgaria.
2Central Laboratory of Clinical Microbiology, Multiprofile Hospital for Active Treatment Alexandrovska, Sofia, Bulgaria.
Acta Microbiol Immunol Hung. 2022 Jun 27;69(3):220-227. doi: 10.1556/030.2022.01746. Print 2022 Sep 16.
The more frequent usage of colistin resulted in an increase of colistin resistance due to lipopolysaccharide modifications. The aim of this study was to reveal the prevalence and mechanisms of colistin resistance among multidrug-resistant Klebsiella pneumoniae isolates collected in Bulgaria. One hundred multidrug resistant K. pneumoniae isolates were collected in a period between 2017 and 2018. Among them, 29 colistin resistant and 8 heteroresistant isolates were observed and further investigated. Clonal relatedness was detected by RAPD and MLST. Сarbapenemases, two component system phoQ/phoP, pmrA/B, and mgrB were investigated by PCR amplification and Sanger sequencing. Among 37 colistin nonsusceptible isolates, we detected 25 NDM-1 producers. The isolates belonged mainly to ST11 (80%), and also to ST147, ST35, ST340, ST219 (1-2 members per clone). Nine colistin resistant isolates showed changes in mgrB. IS903B-like elements truncated mgrB in five isolates. In two isolates, premature stopcodon (Q30stopcodon) was observed and another two isolates did not amplify mgrB, possibly due to bigger deletion or insertion. No isolates showed phoQ/phoP and pmrA/B mutations except for pmrB (four isolates had R256G). All isolates with IS903B insertions belonged to ST11 clone. The mgrB alterations play major role in colistin resistance in K. pneumoniae isolates studied in the current work. We report truncation of mgrB by IS903 like element in colistin resistant NDM-1 producing K. pneumoniae ST11 clone in Bulgaria.
由于脂多糖修饰，多粘菌素使用频率的增加导致了多粘菌素耐药性的上升。本研究的目的是揭示在保加利亚收集的多重耐药肺炎克雷伯菌分离株中多粘菌素耐药性的流行情况及机制。2017年至2018年期间收集了100株多重耐药肺炎克雷伯菌分离株。其中，观察到29株对多粘菌素耐药和8株异质性耐药分离株，并进行了进一步研究。通过RAPD和MLST检测克隆相关性。通过PCR扩增和桑格测序研究碳青霉烯酶、双组分系统phoQ/phoP、pmrA/B和mgrB。在37株对多粘菌素不敏感的分离株中，我们检测到25株产NDM-1的菌株。这些分离株主要属于ST11（80%），也属于ST147、ST35、ST340、ST219（每个克隆1 - 2个成员）。9株对多粘菌素耐药的分离株显示mgrB有变化。IS903B样元件在5株分离株中截断了mgrB。在2株分离株中观察到提前终止密码子（Q30终止密码子），另外2株分离株未扩增出mgrB，可能是由于更大的缺失或插入。除pmrB外（4株有R256G），未观察到分离株有phoQ/phoP和pmrA/B突变。所有有IS903B插入的分离株都属于ST11克隆。在当前研究的肺炎克雷伯菌分离株中，mgrB改变在多粘菌素耐药性中起主要作用。我们报告了在保加利亚产NDM-1的对多粘菌素耐药的肺炎克雷伯菌ST11克隆中，IS903样元件对mgrB的截断。
