title: Cell aggregation: a mechanism of pathogenic Leptospira to survive in fresh water.
abstract: Transmission of leptospirosis is facilitated by the survival of pathogenic leptospires in moist environments outside their mammalian host. In the present study, the survival mechanisms of Leptospira interrogans serovar Canicola in aqueous conditions and lack of nutrients were investigated. In distilled water, leptospires were able to remain motile for 110 days (pH 7.2). However, when incubated in a semi-solid medium composed of distilled water and 0.5% purified agarose (pH 7.2), they survived 347 days. In this viscous environment, aggregates of live spirochetes were observed. Neither antibiotics (e.g. tetracycline and ampicillin) nor nutrients inhibited leptospiral aggregation. Immunoblot analysis suggested that cells incubated in water down-regulate the expression of LipL31, an inner-membrane protein, but retain expression of other membrane proteins. These studies provide insights into the mechanisms by which pathogenic Leptospira survives for prolonged periods of time in natural aqueous environments, a key stage in the leptospiral lifecycle.
authors.affiliation: Institute of Microbiology, University of San Francisco de Quito, Quito, Ecuador. gabriel@mail.usfq.edu.ec
authors.forename: Gabriel
authors.initials: G
authors.lastname: Trueba
authors.forename: Sonia
authors.initials: S
authors.lastname: Zapata
authors.forename: Kleber
authors.initials: K
authors.lastname: Madrid
authors.forename: Paul
authors.initials: P
authors.lastname: Cullen
authors.forename: David
authors.initials: D
authors.lastname: Haake
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis; D002452:Cell Count; D002633:Chemotaxis / Q000502:physiology*; D004777:Environment; D005618:Fresh Water / Q000382:microbiology*; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D007921:Leptospira interrogans / Q000254:growth & development / Q000472:pathogenicity* / Q000502:physiology*; D007922:Leptospirosis / Q000635:transmission; D011817:Rabbits / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial