Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Sci Rep. 2018 May 8;8(1):7289. doi: 10.1038/s41598-018-25661-9.
The effect of biofilm formation on bacteraemic pneumonia caused by A. baumannii is unknown. We conducted a 4-year multi-center retrospective study to analyze 71 and 202 patients with A. baumannii bacteraemic pneumonia caused by biofilm-forming and non-biofilm-forming isolates, respectively. The clinical features and outcomes of patients were investigated. Biofilm formation was determined by a microtitre plate assay. The antimicrobial susceptibilities of biofilm-associated cells were assessed using the minimum biofilm eradication concentration (MBEC) assay. Whole-genome sequencing was conducted to identify biofilm-associated genes and their promoters. Quantitative reverse transcription polymerase chain reaction was performed to confirm the expression difference of biofilm-associated genes. There was no significant difference in the clinical characteristics or the outcomes between patients infected with biofilm-forming and non-biofilm-forming strains. Compared with non-biofilm-forming isolates, biofilm-forming isolates exhibited lower resistance to most antimicrobials tested, including imipenem, meropenem, ceftazidime, ciprofloxacin and gentamicin; however, the MBEC assay confirmed the increased antibiotic resistance of the biofilm-embedded bacteria. Biofilm-associated genes and their promoters were detected in most isolates, including the non-biofilm-forming strains. Biofilm-forming isolates showed higher levels of expression of the biofilm-associated genes than non-biofilm-forming isolates. The biofilm-forming ability of A. baumannii isolates might not be associated with worse outcomes in patients with bacteraemic pneumonia.
生物膜形成对鲍曼不动杆菌菌血症性肺炎的影响尚不清楚。我们进行了一项为期 4 年的多中心回顾性研究，分析了分别由形成生物膜和非生物膜的鲍曼不动杆菌分离株引起的 71 例和 202 例鲍曼不动杆菌菌血症性肺炎患者。研究了患者的临床特征和结局。通过微量滴定板测定法确定生物膜形成。使用最低生物膜清除浓度 (MBEC) 测定法评估生物膜相关细胞的抗菌药物敏感性。进行全基因组测序以鉴定生物膜相关基因及其启动子。进行定量逆转录聚合酶链反应以确认生物膜相关基因的表达差异。感染形成生物膜和非生物膜的菌株的患者在临床特征或结局方面无显著差异。与非生物膜形成分离株相比，生物膜形成分离株对大多数测试的抗菌药物的耐药性较低，包括亚胺培南、美罗培南、头孢他啶、环丙沙星和庆大霉素；然而，MBEC 测定法证实了生物膜包埋细菌的抗生素耐药性增加。在大多数分离株中检测到生物膜相关基因及其启动子，包括非生物膜形成菌株。生物膜形成分离株的生物膜相关基因表达水平高于非生物膜形成分离株。鲍曼不动杆菌分离株的生物膜形成能力与菌血症性肺炎患者的不良结局无关。
