Friday, May 15, 2009

The twentieth species of Leptospira

A new species of Leptospira was isolated from soil in Johor, Malaysia by researchers at the Universiti Putra Malaysia. The spirochete was dubbed Leptospira kmetyi to honor Emil Kmety, a Slovak bacteriologist who had made numerous contributions to the understanding of the genus Leptospira. L. kmetyi is the twentieth species of Leptospira to be validly published. The sequence of its 16S rRNA gene places L. kmetyi among the "pathogenic" species of Leptospira, as shown in the phylogenetic tree below (Figure 1 from Slack et al., 2009). (Click on the image for a larger version.) Further studies are needed to prove that L. kmetyi is truly pathogenic.

The tree shows that 19 of the species cluster into four major groupings or "clades" within the genus Leptospira as follows:

Pathogenic
  • L. borgpetersenii
  • L. weilii
  • L. alexanderi
  • L. santarosai
  • L. noguchii
  • L. interrogans
  • L. kirschneri
  • Leptospira genomospecies 1
  • L. kmetyi

Novel
  • L. wolffii

Intermediate
  • L. fainei
  • L. broomii
  • L. inadai

Saprophytic
  • Leptospira genomospecies 3
  • L. biflexa
  • L. wolbachii
  • Leptospira genomospecies 4
  • Leptospira genomospecies 5
  • L. meyeri
The "novel" clade, which currently has L. wolffii as its only member, was first proposed last year in a paper by Slack and colleagues.

The species that was excluded from the phylogenetic analysis is L. licerasiae, which is a recently described member of the intermediate clade (Matthias et al., 2008).

By the way, I have never liked the designation "intermediate" because readers may assume an intermediate pathogenic potential between the pathogenic and saprophytic clades. At least one intermediate member, L. fainei, can cause severe disease, including Weil's syndrome and pulmonary hemorrhage (bleeding of the lungs).

Featured paper

Slack, A.T., Khairani-Bejo, S., Symonds, M.L., Dohnt, M.F., Galloway, R.L., Steigerwalt, A.G., Bahaman, A.R., Craig, S., Harrower, B.J., and Smythe, L.D. (2009). Leptospira kmetyi sp. nov. isolated from an environmental source in Malaysia. International Journal of Systematic and Evolutionary Microbiology 59(4):705-708. DOI: 10.1099/ijs.0.002766-0

Other references

Matthias, M.A., Ricaldi, J.N., Cespedes, M., Diaz, M.M., Galloway, R.L., Saito, M., Steigerwalt, A.G., Patra, K.P., Vidal Ore, C., Gotuzzo, E., Gilman, R.H., Levett, P.N., and Vinetz, J.M. (2008). Human leptospirosis caused by a new, antigenically unique Leptospira associated with a Rattus species reservoir in the Peruvian Amazon. PLOS Neglected Tropical Diseases 2(4):e213. DOI: 10.1371/journal.pntd.0000213

Slack, A.T., Kalambaheti, T., Symonds, M.L., Dohnt, M.F., Galloway, R.L., Steigerwalt, A.G., Chaicumpa, W., Bunyaraksyotin, G., Craig, S., Harrower, B.J., and Smythe, L.D. (2008). Leptospira wolffii sp nov., isolated from a human with suspected leptospirosis in Thailand. International Journal of Systematic and Evolutionary Microbiology 58(10):2305-2308. DOI: 10.1099/ijs.0.64947-0

No comments:

Post a Comment

Post a Comment