Laboratory of Microbiology and Virology, Vita-Salute San Raffaele University, Milan, Italy
Laboratory of Microbiology and Virology, IRCCS San Raffaele Scientific Institute, Milan, Italy
New Microbiol. 2022 Jul;45(3):199-209.
The spread of multidrug-resistant (MDR) K. pneumoniae carbapenemase-producing bacteria (KPC) is one of the most serious threats to global public health. Due to the limited antibiotic options, colis- tin often represents a therapeutic choice. In this study, we performed Whole-Genome Sequencing (WGS) by Illumina and Nanopore platforms on four colistin-resistant K. pneumoniae isolates (CoRKp) to explore the resistance profile and the mutations involved in colistin resistance. Mapping reads with reference sequence of the most com- mon genes involved in colistin resistance did not show the presence of mobile colistin resistance (mcr) genes in all CoRKp. Complete or partial deletions of mgrB gene were observed in three out of four CoRKp, while in one CoRKp the mutation V24G on phoQ was identified. Complementation assay with proper wild type genes restored colistin susceptibility, validating the role of the amino acid substitution V24G and, as already described in the literature, confirming the key role of mgrB alterations in colistin resistance. In conclusion, this study allowed the identification of the novel mutation on phoQ gene involved in colistin resistance phenotype.
耐多药（MDR）肺炎克雷伯菌碳青霉烯酶产生菌（KPC）的传播是对全球公共卫生的最严重威胁之一。由于抗生素选择有限，黏菌素通常是一种治疗选择。在这项研究中，我们通过 Illumina 和 Nanopore 平台对四个黏菌素耐药肺炎克雷伯菌分离株（CoRKp）进行了全基因组测序（WGS），以探讨其耐药谱和与黏菌素耐药相关的突变。将读序列与最常见的参与黏菌素耐药的基因参考序列进行映射，并未在所有 CoRKp 中发现可移动黏菌素耐药（mcr）基因。在四个 CoRKp 中有三个观察到 mgrB 基因的完全或部分缺失，而在一个 CoRKp 中鉴定出 phoQ 上的 V24G 突变。用适当的野生型基因进行互补试验恢复了黏菌素敏感性，验证了氨基酸取代 V24G 的作用，并且正如文献中所述，证实了 mgrB 改变在黏菌素耐药中的关键作用。总之，本研究鉴定了与黏菌素耐药表型相关的 phoQ 基因的新突变。
