Singh T, Coogan M M
Department of Immunology and Microbiology, National Institute for Occupational Health, P.O. Box 4788, Johannesburg 2000, South Africa.
J Hosp Infect. 2005 Nov;61(3):257-62. doi: 10.1016/j.jhin.2005.05.001. Epub 2005 Aug 15.
Legionella released into the air during treatment are a potential source of infection. Water stagnation in dental unit waterlines (DUWLs) creates biofilms and promotes the proliferation of these micro-organisms. This study investigated the presence of amoeba infected with legionella, L. pneumophila and other pathogenic Legionella species in a dental teaching hospital. Water samples were collected in the morning and afternoon from 99 dental units and 16 taps connected to the municipal water supply. Samples were plated on selective media and tested for legionella using the direct immunofluorescent antibody technique and the latex agglutination test. Legionella were found in 33% of the DUWLs and in 47% of the mains taps supplying these units. Legionella-laden amoebae occurred in one mains tap sample and in 20% of DUWLs in a clinic of the teaching hospital. L. micdadei was the predominant species isolated from this clinic. L. pneumophila serogroups 2-14 predominated in the mains water, whereas L. pneumophila serogroup 1 was found in approximately half of the contaminated DUWLs and mains taps irrespective of the time of sampling. Pathogenic Legionella species seeded by municipal water into DUWLs is a potential source of legionella infection for both dental personnel and patients during prolonged dental treatment. This problem is compounded by the presence of legionella-laden amoebae which may contain levels of organism well within the infective dose. The interaction of legionella with amoebae is an important ecological factor that may significantly increase the risk of legionellosis, and thus should be given further consideration in the refinement of risk assessment models.
治疗过程中释放到空气中的军团菌是潜在的感染源。牙科设备水管（DUWLs）中的水停滞会形成生物膜并促进这些微生物的繁殖。本研究调查了一家牙科教学医院中感染军团菌、嗜肺军团菌和其他致病性军团菌的变形虫的存在情况。上午和下午从99个牙科设备和16个连接到市政供水的水龙头采集水样。将样本接种在选择性培养基上，并使用直接免疫荧光抗体技术和乳胶凝集试验检测军团菌。在33%的DUWLs和为这些设备供水的47%的主水龙头中发现了军团菌。在教学医院一个诊所的一个主水龙头样本和20%的DUWLs中发现了携带军团菌的变形虫。米克戴德军团菌是从该诊所分离出的主要菌种。嗜肺军团菌血清型2 - 14在主水中占主导地位，而嗜肺军团菌血清型1在大约一半受污染的DUWLs和主水龙头中被发现，与采样时间无关。市政供水引入DUWLs中的致病性军团菌种是牙科治疗时间延长期间牙科工作人员和患者军团菌感染的潜在来源。携带军团菌的变形虫的存在使这个问题更加复杂，因为它们可能含有处于感染剂量范围内的生物体水平。军团菌与变形虫的相互作用是一个重要的生态因素，可能会显著增加军团菌病的风险，因此在完善风险评估模型时应进一步考虑。
