Department of Microbiology, National Institute of Quality Control in Heath, Fiocruz, Rio de Janeiro, Brazil.
Post-Graduation Program in Health Surveillance, Fiocruz, National Institute of Quality Control in Heath, Rio de Janeiro, Brazil.
Braz J Microbiol. 2020 Jun;51(2):657-664. doi: 10.1007/s42770-020-00252-x. Epub 2020 Mar 16.
Acinetobacter baumannii has been associated with antimicrobial resistance and ability to form biofilms. Furthermore, its adherence to host cells is an important factor to the colonization process. Therefore, this study intended to identify some virulence factors that can explain the success of A. baumannii in causing nosocomial infections. We studied 92 A. baumannii isolates collected from hospitals in Rio de Janeiro, Brazil. Isolates were identified and the susceptibility to antimicrobials was determined. Oxacilinase type β-lactamase encoding genes were amplified by polymerase chain reaction, and genetic diversity was investigated by pulsed-field gel electrophoresis (PFGE). In addition, biofilm formation on polystyrene plates using crystal violet staining was quantified, and adherence to human cell lines was evaluated. Eighty-six isolates were multidrug-resistant, of which 93% were carbapenem-resistant. All isolates had the bla gene and 94% had the bla gene, other searched bla genes were not detected. PFGE typing showed two predominant clones, and biofilm production was observed in 79% of isolates. A. baumannii isolates adhered better to HEp-2 cell compared with A-549 cell. Clones A, B, E, and F showed a significantly increased adherence to HEp-2 compared with adherence to A-549 cell. Our findings revealed that A. baumannii isolates had high frequencies of resistance to antimicrobial agents, ability to form biofilm, and capacity to adhere to HEp-2 cells.
鲍曼不动杆菌与抗菌药物耐药性和形成生物膜的能力有关。此外，其对宿主细胞的黏附是定植过程中的一个重要因素。因此，本研究旨在确定一些毒力因子，以解释鲍曼不动杆菌引起医院感染的成功。我们研究了从巴西里约热内卢的医院收集的 92 株鲍曼不动杆菌分离株。对分离株进行鉴定和药敏试验。通过聚合酶链反应扩增β-内酰胺酶编码基因，通过脉冲场凝胶电泳（PFGE）研究遗传多样性。此外，通过结晶紫染色量化聚苯乙烯板上生物膜的形成，并评估对人细胞系的黏附。86 株分离株为多药耐药株，其中 93%为碳青霉烯耐药株。所有分离株均携带 bla 基因，94%携带 bla 基因，未检测到其他搜索的 bla 基因。PFGE 分型显示了两种主要的克隆，79%的分离株产生生物膜。与 A-549 细胞相比，鲍曼不动杆菌分离株更好地黏附在 HEp-2 细胞上。与黏附在 A-549 细胞相比，克隆 A、B、E 和 F 对 HEp-2 的黏附能力显著增加。我们的研究结果表明，鲍曼不动杆菌分离株对抗菌药物具有较高的耐药率、形成生物膜的能力和黏附 HEp-2 细胞的能力。
