Comparative Analysis of Leptospira Strains Isolated from Environmental Soil and Water in the Philippines and Japan

Abstract

There have been few reports on the epidemiological analysis of environmental Leptospira isolates. This is probably because the isolation of leptospires from the environment was usually unsuccessful due to the overgrowth of contaminants and the slow growth of Leptospira. In this study, we collected a total of 88 samples of soil and water from three sites: Metro Manila and Nueva Ecija, Philippines (an area where Leptospira is now endemic), and Fukuoka, Japan (an area where Leptospira was once endemic). We succeeded in isolating Leptospira from 37 samples by using the novel combination of five antimicrobial agents reported in 2011. The frequencies of positive isolation of Leptospira in the Philippines and Japan were 40 and 46%, respectively. For Leptospira-positive samples, five colonies from each sample were isolated and analyzed by pulsed-field gel electrophoresis (PFGE). The isolates from each area showed their respective characteristics in phylogenetic trees based on the PFGE patterns. Some isolates were closely related to each other across borders. Based on 16S rRNA gene-based phylogenetic analysis, four isolates in Fukuoka were identified as a pathogenic species, L. alstonii; however, its virulence had been lost. One isolate from Nueva Ecija was identified as the intermediate pathogenic species Leptospira licerasiae. Most of the isolates from the environment belonged to nonpathogenic Leptospira species. We also investigated the strain variation among the isolates in a puddle over 5 months. We demonstrated, using PFGE analysis, that Leptospira survived in the wet soil on dry days and appeared in the surface water on rainy days. These results showed that the soil could be a reservoir of leptospires in the environment.

Emerging Infectious Disease Implications of Invasive Mammalian Species: The Greater White-Toothed Shrew (Crocidura russula) Is Associated With a Novel Serovar of Pathogenic Leptospira in Ireland

“…The gene sequence for 16S rDNA was extracted from the complete genome and compared to 108 16S rDNA sequences available for Leptospira from the Ribosomal Database project (https://rdp.cme.msu.edu/). Phylogenetic analysis indicated that GWTS isolate #1 clustered among 4 strains of Leptospira recently isolated from soil samples in Fukuoka, Japan (designated as MS267, MS306, MS311, and MS316 respectively[48]), Fig 1 and S1 Fig. These, in turn, cluster most closely with Leptospira genomospecies 1, which has recently been renamed L .…”

“…Prior isolates of L . alstonii are derived from the amphibians Bombina orientalis and Rana nigromaculata , which belong to Neobatrachia species in China, or are derived from soil samples in Japan or Malaysia [48, 55, 59]. Whether L .…”

“…These results are similar to those previously described for soil isolates of L . alstonii in Japan and in which the authors concluded that such results likely reflect attenuation of strains due to continued maintenance under in vitro laboratory conditions[48]. Alternatively, a more appropriate animal model is required; in any case, culture of L .…”

Potentially Pathogenic <i>Leptospira</i> Species Isolated from a Waterfall in Thailand

“…Of these, 5 isolates (5 17, 29 ) were found to be closely related to L. alstonii with 99 to 100 identity, whereas 1 isolate (1 17, 6 ) is closely related to L. kmetyi, with 99 identity. The presence of L. alstonii and L. kmetyi in the environment has been reported in many countries (7)(8)(9)(10). Recently, L. alstonii was isolated from greater white toothed-shrews in Ireland (11) and from an asymptomatic cow in a slaughter house in Brazil (12).…”

Culture and molecular identification of microorganisms from Digital Dermatitis lesions in dairy cattle: Leptospira, an unexpected finding

“…L. fainei was successively cultured from two human patients with Weil's disease and antibody titers have been found in sera from cattle in Australia, France and Indonesia ( Chappel et al, 1996;Petersen et al, 2001). L. wolffii was identified as a potential pathogenic species, detected in infected humans, in sheep sera and dogs urine and can be potentially pathogenic to human and probably animal hosts (Zakeri et al, 2010); and L. licerasiae causes mild disease in humans and has been isolated from peridomestic and wild rodents and marsupials in Peruvian Amazon (Matthias et al, 2008;Ricaldi et al, 2012) and from environmental water (Saito et al, 2013). Krull et al (2015) showed that early BDD lesions had minimal populations of Treponema spp.…”