azaguanine and Leptospirosis

The greater white-toothed shrew (Crocidura russula) is an invasive mammalian species that was first recorded in Ireland in 2007. It currently occupies an area of approximately 7,600 km2 on the island. C. russula is normally distributed in Northern Africa and Western Europe, and was previously absent from the British Isles. Whilst invasive species can have dramatic and rapid impacts on faunal and floral communities, they may also be carriers of pathogens facilitating disease transmission in potentially naive populations. Pathogenic leptospires are endemic in Ireland and a significant cause of human and animal disease. From 18 trapped C. russula, 3 isolates of Leptospira were cultured. However, typing of these isolates by standard serological reference methods was negative, and suggested an, as yet, unidentified serovar. Sequence analysis of 16S ribosomal RNA and secY indicated that these novel isolates belong to Leptospira alstonii, a unique pathogenic species of which only 7 isolates have been described to date. Earlier isolations were limited geographically to China, Japan and Malaysia, and this leptospiral species had not previously been cultured from mammals. Restriction enzyme analysis (REA) further confirms the novelty of these strains since no similar patterns were observed with a reference database of leptospires. As with other pathogenic Leptospira species, these isolates contain lipL32 and do not grow in the presence of 8-azagunaine; however no evidence of disease was apparent after experimental infection of hamsters. These isolates are genetically related to L. alstonii but have a novel REA pattern; they represent a new serovar which we designate as serovar Room22. This study demonstrates that invasive mammalian species act as bridge vectors of novel zoonotic pathogens such as Leptospira.

Topics: Animals; Azaguanine; Bacterial Outer Membrane Proteins; Bacterial Typing Techniques; China; Communicable Diseases, Emerging; Cricetinae; Disease Vectors; Humans; Introduced Species; Ireland; Japan; Leptospira; Leptospirosis; Lipoproteins; Malaysia; Polymerase Chain Reaction; Prohibitins; RNA, Ribosomal, 16S; Serogroup; Shrews; Zoonoses

Topics: Amides; Animals; Azaguanine; Azoles; Colistin; Cricetinae; Cycloserine; Dihydrostreptomycin Sulfate; Leptospira interrogans serovar canicola; Leptospirosis; Mercaptopurine; Polyamines; Propylamines; Rodent Diseases; Selenium; Thiouracil

Johnson, Russell C. (University of Minnesota, Minneapolis), and Palmer Rogers. Differentiation of pathogenic and saprophytic leptospires with 8-azaguanine. J. Bacteriol. 88:1618-1623. 1964.-The use of the purine analogue, 8-azaguanine, as a differential agent for the separation of pathogenic and saprophytic leptospires was investigated. Growth of strains of the saprophyte Leptospira biflexa was almost insensitive to the bacteriostatic action of 8-azaguanine at concentrations varying from 25 to 600 mug/ml; these saprophytic leptospires were serially transferred five times in media containing 225 mug without any change in growth rate or cell yield. In contrast, decreased growth rate and cell yield of the pathogenic serotypes were observed with 25 to 50 mug/ml of 8-azaguanine. Complete inhibition of growth occurred at concentrations of 100 mug/ml and above. A medium containing 225 mug/ml of 8-azaguanine was successfully used to differentiate 20 serotypes of pathogenic leptospires and 10 saprophytic strains. L. andaman CH11, L. semarang Veldrat S1 73, and L. andaman Correa, were classified with the L. biflexa strains on the basis of their growth response to 8-azaguanine.

Topics: Antimetabolites; Azaguanine; Fluorouracil; Leptospira; Leptospira interrogans serovar icterohaemorrhagiae; Leptospirosis; Pharmacology; Research