Shariff Malini, Chhabra Sunil K, Rahman Mujeeb-Ur
Department of Microbiology, Vallabhbhai Patel Chest Institute, Delhi, India.
Department of Cardio-respiratory Physiology, Vallabhbhai Patel Chest Institute, Delhi, India.
J Med Microbiol. 2017 Oct;66(10):1489-1498. doi: 10.1099/jmm.0.000569. Epub 2017 Sep 12.
Pseudomonas aeruginosa is one of the agents that are commonly implicated in nosocomial infections. However, it is also present as a commensal in various body sites of healthy persons, making the diagnosis of infection by culture difficult. A number of virulence factors expressed by the organism have been implicated in its pathogenicity. We undertook this study to identify the host and organism factors associated with infection.
Pathogenic, colonizing and environmental isolates were tested for apr, lasB, the T3SS effector exoenzymes (exoS, exoT, exoU and exoY) and toxA genes, biofilm production and antimicrobial susceptibility. The isolates were further typed by RAPD.
Eighty-seven isolates from 61 patients, including 11 environmental isolates, were obtained. None of the virulence factors were found to be significantly associated with infection, and nor was the antimicrobial susceptibility. The presence of the exoU gene and infection by MDR strains correlated significantly with the duration of hospital stay. Positivity for exoS and exoU genes was found to be strongly correlated with multi-drug resistance. exoU positivity correlated strongly with fluoroquinolone resistance. Sinks in the ward and intensive care unit were found to be a niche for XDR P. aeruginosa. Eighty-five isolates were typeable using the ERIC2 primer, showing 71 distinct RAPD patterns with >15 % difference in UPGMA-generated dice coefficients.
exoU positivity is associated with severe disease, as evidenced by the longer duration of hospital stay of these patients. However, the presence of virulence factors or multi-drug resistance in the cultured strain should not prompt the administration of anti-pseudomonal chemotherapy.
铜绿假单胞菌是医院感染中常见的病原体之一。然而，它也作为共生菌存在于健康人的各个身体部位，这使得通过培养诊断感染变得困难。该菌表达的多种毒力因子与其致病性有关。我们开展这项研究以确定与感染相关的宿主和病原体因素。
对致病性、定植性和环境分离株进行 apr、lasB、Ⅲ型分泌系统效应外酶（exoS、exoT、exoU 和 exoY）及 toxA 基因检测、生物膜形成检测和药敏试验。分离株进一步通过随机扩增多态性 DNA 分析（RAPD）进行分型。
从 61 名患者中获得了 87 株分离株，包括 11 株环境分离株。未发现任何毒力因子与感染显著相关，药敏结果也无明显关联。exoU 基因的存在及多重耐药菌株感染与住院时间显著相关。发现 exoS 和 exoU 基因阳性与多重耐药密切相关。exoU 阳性与氟喹诺酮耐药密切相关。病房和重症监护病房的水槽被发现是广泛耐药铜绿假单胞菌的一个生态位。85 株分离株可用 ERIC2 引物分型，在基于非加权组平均法（UPGMA）生成的相似系数中显示出 71 种不同的 RAPD 模式，差异>15%。
exoU 阳性与严重疾病相关，这些患者较长的住院时间证明了这一点。然而，培养菌株中存在毒力因子或多重耐药不应促使给予抗假单胞菌化疗。
