Department of Molecular Microbiology and National Medicines Institute, Warsaw, Poland.
Department of Epidemiology and Clinical Microbiology, National Medicines Institute, Warsaw, Poland.
Microb Drug Resist. 2021 Mar;27(3):291-300. doi: 10.1089/mdr.2019.0504. Epub 2020 Jul 8.
The objective of this study was to characterize Polish penicillin-resistant, ampicillin-susceptible (PRASEF), increasingly reported to the National Reference Centre for Susceptibility Testing, Poland, to elucidate the path of emergence of such strains. A total of 136 isolates were examined by antimicrobial susceptibility testing and for the β-lactamase production (cefinase test). The clonality of isolates was established by multilocus sequence typing (MLST) and the penicillin-binding protein gene was sequenced to search for putative mutation(s). The presence of pheromone-responsive plasmids was investigated by clumping test and PCR detection of plasmid-specific genes. All Polish PRASEF were multidrug resistant and β-lactamase-negative. MLST assigned isolates mostly to high-risk enterococcal clonal complexes (HIRECCs) 6 (57.4%) and 87 (30.1%), in addition to to CC88 (12.5%). The sequencing of revealed mutations upstream of a putative promoter region and amino acid alterations in PBP4, affecting 24 positions and resulting in 30 variants. While production of aggregation substance was observed for 17.6% of isolates, genes of pheromone plasmids were much more commonly detected. However, no conjugal transfer of penicillin resistance was observed. Penicillin resistance in emerges mostly in HiRECCs due to PBP4 overproduction and/or mutations. The acquisition of penicillin resistance by HiRECCs may represent the next step in the evolution of as human nosocomial pathogen.
本研究的目的是对波兰青霉素耐药、氨苄西林敏感（PRASEF）进行特征描述，这些菌株越来越多地被报道至波兰国家药敏检测参考中心，以阐明这些菌株出现的途径。对总共 136 株分离株进行了抗生素敏感性检测和β-内酰胺酶产生（头孢菌素酶试验）。通过多位点序列分型（MLST）确定分离株的克隆性，并对青霉素结合蛋白基因进行测序以寻找可能的突变。通过凝聚试验和质粒特异性基因的 PCR 检测来研究类菌毛反应质粒的存在。所有波兰 PRASEF 均为多药耐药且β-内酰胺酶阴性。MLST 将分离株主要分配至高风险肠球菌克隆复合体（HIRECCs）6（57.4%）和 87（30.1%），此外还有 CC88（12.5%）。发现基因序列的上游存在一个假定启动子区域的突变和 PBP4 中的氨基酸改变，影响 24 个位置并导致 30 种变体。虽然观察到 17.6%的分离株产生聚集物质，但更常见的是检测到类菌毛质粒基因。然而，没有观察到青霉素耐药性的接合转移。HIRECCs 中青霉素耐药的出现主要是由于 PBP4 的过度产生和/或突变。HIRECCs 获得青霉素耐药性可能代表作为人类医院病原体的肠球菌进化的下一步。
