First molecular detection of Rickettsia sibirica ssp. sibirica in skin biopsies from patients with north Asian tick typhus

Abstract number: 1733_950

Shpynov S., Fournier P.-E., Granitov M., Arsen'eva I., Rudakov N., Matushchenko A., Tarasevich I., Raoult D.

Objectives: The tick-borne North Asian tick typhus (NATT) caused by Rickettsia sibirica ssp. sibirica (R. sibirica), has been described in Russia in 1935. Currently, active foci of this communicable disease are spread in 18 administrative territories of Siberia and Far East, in the Asiatic part of Russia. Approximately one of half registered cases occur in the Altay region. From 1936 to 2005, more than 64,000 NATT cases have been registered in Russia. However, the diagnosis is mostly based on clinical and serological data, and no direct confirmation is available.

Methods: In Spring 2005, 12 inoculation eschar biopsies were taken from patients with clinically typical NATT in the city of Barnaul, Altay. Rickettsiae were detected using partial amplification of the 5'-end of the ompA gene with the 190–70 and 190–701 primers, and amplification of the gltA gene using the CS1d-CS535r and CS409d-RP1258n primer pairs. PCR reactions were carried out in a PTC-200 thermal cycler (MJ Research, Inc, Watertown, MA). Positive PCR products were sequenced using the d-Rhodamine Terminator Cycle Sequencing Ready Reaction kit (Applied Biosystems, Warrington, UK) and an ABI 3100 PRISM automated sequencer (Applied Biosystems). Obtained sequences were compared to the GenBank database.

Results: Ten of the 12 skin biopsies were positive by PCR amplifying both genes. Inferred sequences were identical and were 100% similar to those of R. sibirica ssp. sibirica (gltA, GenBank accession number U59734; ompA, U43807).

All 10 proven NATT cases were characterised by a mild clinical picture different from that of Far-Eastern rickettsiosis caused by Rickettsia heilongjiangensis in Russian Far East.

Conclusions: We demonstrate for the first time by direct identification of the aetiological agent in skin biopsies the aetiological role of R. sibirica ssp. sibirica in NATT in the Altay territory of Russia. Other tick-borne members of the order Rickettsiales, such as R. heilongjiangensis, R. helvetica, R. slovaca, R. aeschlimannii, and Anaplasma phagocytophilum are distributed in natural NATT foci in the Altay territory as well as in territories free from NATT. Our results highlight the need to pursue molecular identification of tick-borne human infections in different regions of Russia.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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