Surveillance of parasiticLegionellain surface waters by using immunomagnetic separation and amoebae enrichment

Abstract

Free-living amoebae (FLA) are potential reservoirs of Legionella in aquatic environments. However, the parasitic relationship between various Legionella and amoebae remains unclear. In this study, surface water samples were gathered from two rivers for evaluating parasitic Legionella. Warmer water temperature is critical to the existence of Legionella. This result suggests that amoebae may be helpful in maintaining Legionella in natural environments because warmer temperatures could enhance parasitisation of Legionella in amoebae. We next used immunomagnetic separation (IMS) to identify extracellular Legionella and remove most free Legionella before detecting the parasitic ones in selectively enriched amoebae. Legionella pneumophila was detected in all the approaches, confirming that the pathogen is a facultative amoebae parasite. By contrast, two obligate amoebae parasites, Legionella-like amoebal pathogens (LLAPs) 8 and 9, were detected only in enriched amoebae. However, several uncultured Legionella were detected only in the extracellular samples. Because the presence of potential hosts, namely Vermamoeba vermiformis, Acanthamoeba spp. and Naegleria gruberi, was confirmed in the samples that contained intracellular Legionella, uncultured Legionella may survive independently of amoebae. Immunomagnetic separation and amoebae enrichment may have referential value for detecting parasitic Legionella in surface waters.

Acanthamoeba and Dictyostelium as Cellular Models for Legionella Infection

“…In its aquatic habitats L. pneumophila replicates intracellularly in various free-living protozoa, including amoebae such as Acanthamoeba, Vermamoeba (formerly Hartmannella ), Naegleria, Echinamoeba , and Vahlkampfia , as well as in ciliates like Tetrahymena (Fields, 1996 ; Greub and Raoult, 2004 ; Hilbi et al, 2011 ; Hsu et al, 2015 ). From an evolutionary point of view, interactions of L. pneumophila with protozoa shaped the relationship and likely led to adaptive responses, which enable the pathogen to also infect mammalian phagocytes such as human alveolar macrophages (Greub and Raoult, 2004 ; Molmeret et al, 2005 ; Jäger et al, 2014 ).…”

“…A number of studies indicated that L. pneumophila is highly adapted and manages to infect a wide range of protozoan and metazoan hosts (Hilbi et al, 2011 ; Bergmann and Steinert, 2015 ; Hsu et al, 2015 ). This suggests that many protozoan host species and other interaction partners of L. pneumophila in the environment remain to be discovered.…”

Decreasing Pasteurization Treatment Efficiency against Amoeba-Grown Legionella pneumophila—Recognized Public Health Risk Factor

“…Legionellae are gram-negative bacteria commonly found in freshwater ecosystems such as rivers, lakes, ponds, and streams [1,2]. The entry of bacteria into purpose-built water systems and drinking-water distribution systems make a serious health concern.…”

Enhancement of Culture of Legionella longbeachae from Respiratory Samples by Use of Immunomagnetic Separation and Antimicrobial Decontamination

“…Immunomagnetic separation has been successfully adopted for identifying Legionella pneumophila serogroup 1 from tap water and other environmental samples as well as other microorganisms from clinical samples and foods (10)(11)(12)(13)(14)(15). We thought that isolation rates may be improved by eliminating the acid wash step and using decontamination with glycine, vancomycin hydrochloride, polymyxin B sulfate, and cycloheximide (GVPC) together with immunomagnetic separation.…”