Bianchi A, Tesauro M, Consonni M, Galli M G
Dipartimento di Sanità Pubblica, Microbiologia e Virologia, Università degli Studi di Milano, Milano.
Ann Ig. 2009 Sep-Oct;21(5):517-22.
Various techniques have been developed in recent years for the molecular typing of microorganisms. Remains particularly difficult to isolate clinical strains for the low availability of cases and even more problematic matching clinical / environmental strains. We investigated 13 strains of Legionella pneumophila of clinical and environmental origin, isolated in 3 Health Facilities in Milan (2003-2006), using three molecular typing methods: Pulse-Field Gel Electrophoresis, Amplified Fragment Length Polymorphism and Sequence-Based Typing. PFGE and AFLP showed the correlation between a clinical case with only one of the environmental isolates taken from the places frequented by the patient, demonstrating with certainty the nosocomial origin of the case and identifying the source of infection in the shower water (Clin. 1 and Env. 1N). Two clinical samples from patients admitted to different wards presented an identical profile, which suggests that the nosocomial origin assumed an epidemic form, even without having isolated the environmental strain due to the absence of samples drawn during the period under consideration (Clin. 2 and 3). Finally, the comparison between the isolated environmental strains demonstrated a heterogeneous presence of strains, not correlated to each other although they belong to the same serum-group, having profiles that are clearly different regarding number and position of bands (Env. 2 and 4). The profile 2,10,18,10,1,1 had never been isolated and typed previously in Europe. The SBT has proved a better technique for reproducibility and interpretation of results than PFGE and AFLP To complete studies on SBT method, now considered gold standard, is currently being the EWGLI 5th Proficiency Panel, in which we are actively involved with the genotyping of five strains according to the latest version of the protocol (4.1).
近年来已开发出多种用于微生物分子分型的技术。由于病例来源有限，分离临床菌株仍然特别困难，而匹配临床/环境菌株则更是问题重重。我们使用三种分子分型方法：脉冲场凝胶电泳（PFGE）、扩增片段长度多态性（AFLP）和基于序列的分型（SBT），对在米兰的3家医疗机构中分离出的13株临床和环境来源的嗜肺军团菌菌株进行了研究（2003 - 2006年）。PFGE和AFLP显示，在仅从患者常去场所采集的一株环境分离株与一个临床病例之间存在相关性，从而确定无疑地证明了该病例的医院感染来源，并确定淋浴水为感染源（临床1株和环境1N株）。来自不同病房的两名患者的临床样本呈现出相同的图谱，这表明医院感染源呈现出流行形式，尽管由于在所考虑期间没有采集样本，未分离出环境菌株（临床2株和3株）。最后，对分离出的环境菌株进行比较表明，尽管它们属于同一血清群，但菌株存在异质性，彼此之间没有相关性，其图谱在条带数量和位置方面明显不同（环境2株和4株）。2,10,18,10,1,1这种图谱以前在欧洲从未被分离和分型过。与PFGE和AFLP相比，SBT已被证明是一种在结果重现性和解释方面更好的技术。为了完成对目前被视为金标准的SBT方法的研究，目前正在进行EWGLI第5次能力验证小组的工作，我们正按照最新版方案（4.1）积极参与其中5株菌株的基因分型。
