Thomas Vincent, Herrera-Rimann Katia, Blanc Dominique S, Greub Gilbert
Center for Research on Intracellular Bacteria, Institute of Microbiology, CHUV Hospital, Bugnon 46, 1011 Lausanne, Switzerland.
Appl Environ Microbiol. 2006 Apr;72(4):2428-38. doi: 10.1128/AEM.72.4.2428-2438.2006.
Free-living amoebae (FLA) are ubiquitous organisms that have been isolated from various domestic water systems, such as cooling towers and hospital water networks. In addition to their own pathogenicity, FLA can also act as Trojan horses and be naturally infected with amoeba-resisting bacteria (ARB) that may be involved in human infections, such as pneumonia. We investigated the biodiversity of bacteria and their amoebal hosts in a hospital water network. Using amoebal enrichment on nonnutrient agar, we isolated 15 protist strains from 200 (7.5%) samples. One thermotolerant Hartmannella vermiformis isolate harbored both Legionella pneumophila and Bradyrhizobium japonicum. By using amoebal coculture with axenic Acanthamoeba castellanii as the cellular background, we recovered at least one ARB from 45.5% of the samples. Four new ARB isolates were recovered by culture, and one of these isolates was widely present in the water network. Alphaproteobacteria (such as Rhodoplanes, Methylobacterium, Bradyrhizobium, Afipia, and Bosea) were recovered from 30.5% of the samples, mycobacteria (Mycobacterium gordonae, Mycobacterium kansasii, and Mycobacterium xenopi) were recovered from 20.5% of the samples, and Gammaproteobacteria (Legionella) were recovered from 5.5% of the samples. No Chlamydia or Chlamydia-like organisms were recovered by amoebal coculture or detected by PCR. The observed strong association between the presence of amoebae and the presence of Legionella (P < 0.001) and mycobacteria (P = 0.009) further suggests that FLA are a reservoir for these ARB and underlines the importance of considering amoebae when water control measures are designed.
自由生活阿米巴（FLA）是普遍存在的生物体，已从各种生活用水系统中分离出来，如冷却塔和医院供水网络。除了自身的致病性外，FLA还可充当“特洛伊木马”，自然感染可能与人类感染（如肺炎）有关的抗阿米巴细菌（ARB）。我们调查了医院供水网络中细菌及其阿米巴宿主的生物多样性。通过在无营养琼脂上进行阿米巴富集，我们从200个样本（7.5%）中分离出15株原生生物菌株。一株耐热的蠕虫状哈特曼氏阿米巴分离株同时携带嗜肺军团菌和日本慢生根瘤菌。通过以无菌的卡氏棘阿米巴作为细胞背景进行阿米巴共培养，我们从45.5%的样本中至少回收了一种ARB。通过培养获得了4株新的ARB分离株，其中一株分离株在供水网络中广泛存在。从30.5%的样本中分离出了α变形菌（如红游动菌属、甲基杆菌属、慢生根瘤菌属、阿菲波菌属和博斯氏菌属），从20.5%的样本中分离出了分枝杆菌（戈登分枝杆菌、堪萨斯分枝杆菌和偶发分枝杆菌），从5.5%的样本中分离出了γ变形菌（军团菌属）。通过阿米巴共培养未回收衣原体或衣原体样生物体，也未通过PCR检测到。观察到的阿米巴的存在与军团菌（P < 0.001）和分枝杆菌（P = 0.009）的存在之间的强关联进一步表明，FLA是这些ARB的储存库，并强调了在设计水控制措施时考虑阿米巴的重要性。
