Intracellular multiplication ofLegionella pneumophila in amoebae isolated from hospital hot water tanks

The novel Legionella pneumophila type II secretion substrate NttC contributes to infection of amoebae Hartmannella vermiformis and Willaertia magna

“…That T2S is required for infection of four out of four amoebae tested suggests that T2S contributes to infection of many, if not all, amoebal hosts and is thus very important for Legionella survival in the environment. Further work along these lines would involve infection of E. exudans and V. jugosa, the two remaining types of amoeba that are known to coexist with and be permissive for L. pneumophila (Fields et al, 1989;Rowbotham, 1986). Yet, the host range of L. pneumophila is remarkably broad.…”

“…Indeed, aside from three studies that documented the intracellular growth of L. pneumophila in Echinamoeba exudans, Vahlkampfia jugosa and Willaertia magna (Dey et al, 2009;Fields et al, 1989;Rowbotham, 1986), very little is known about how L. pneumophila grows in its other known hosts. Hence, we incorporated L. pneumophila infection of W. magna into our analysis.…”

Fish-isolated strains of Hartmannella vermiformis Page, 1967: morphology, phylogeny and molecular diagnosis of the species in tissue lesions

“…Contrary to Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris and Sappinia diploidea known as primary agents of human diseases, opinion is divided on the pathogenicity of Hartmannella species (Aitken et al 1996, Inoue et al 1998, De Jonckheere and Brown 1998, 1999, Kinnear 2003. The data collected on a variety of bacterial endocytobionts in Hartmannella vermiformis Page, 1967, and the recognition of its special role in the propagation of Legionnaires' disease, provide evidence that these amoebae are more important as hosts of true or potential pathogens of humans than as primary agents of human diseases (Fields et al 1989, Kuchta et al 1993, Brieland et al 1996, Fields 1996, Horn et al 2000. Scarce data available on Hartmannella infections in animals including fish point to a similar situation (Kadlec 1978, Bomhard et al 2002, Telford and Bursey 2003, Dyková and Lom 2004.…”

Amoeba-Related Health Risk in Drinking Water Systems: Could Monitoring of Amoebae Be a Complementary Approach to Current Quality Control Strategies?

“…Although further research regarding bacteriaamoeba interactions is necessary, the current knowledge for all bacteria present in the CCL [7,13,23,26,30,41,49] indicates that amoebae could play a key role in bacterial resistance to disinfection, and survival and spread in drinking water systems. Additionally, bacteria-amoeba interactions suggest that, after a contamination episode, the presence of fecal-related pathogens, such as C. jejuni, E. coli O157:H7, H. pylori, S. enterica and S. sonnei, could not be detected using only conventional fecal indicators, as some enteric bacterial pathogens may survive within a moebae and still be present at lower concentrations.…”

“…Fourteen species of amoebae and two species of ciliated protozoa have been identified as potential natural environmental hosts for L. pneumophila [39,40]. Numerous studies have identified amobae as a growth-supporting factor for L. pneumophila [41][42][43][44]. However, some authors have questioned these facts and suggested the bacterial consortium within the biofilm as the nutrient supplier to enable extracellular Legionellae growth [45].…”