Open Access Research

Multispacer typing of Rickettsia isolates from humans and ticks in Tunisia revealing new genotypes

Abir Znazen1*, Fatma Khrouf2, Nihel Elleuch1, Dorra Lahiani3, Chakib Marrekchi3, Youmna M’Ghirbi2, Mounir Ben Jemaa3, Ali Bouattour2 and Adnene Hammami1

Author Affiliations

1 Laboratory of Microbiology, Research Laboratory “MPH”, Habib Bourguiba University Hospital of Sfax, Sfax, Tunisia

2 Laboratory of entomology, Pasteur Institute, Tunis, Tunisia

3 Infectious diseases department, Hedi Chaker University Hospital of Sfax, Sfax, Tunisia

For all author emails, please log on.

Parasites & Vectors 2013, 6:367  doi:10.1186/1756-3305-6-367

Published: 31 December 2013

Abstract

Background

Rickettsioses are important remerging vector born infections. In Tunisia, many species have been described in humans and vectors. Genotyping is important for tracking pathogen movement between hosts and vectors. In this study, we characterized Rickettsia species detected in patients and vectors using multispacer typing (MST), proposed by Founier et al. and based on three intergenic spacers (dksA-xerC, rmpE- tRNAfMet, mppA-pruC) sequencing.

Methods

Our study included 25 patients hospitalized during 2009. Ticks and fleas were collected in the vicinity of confirmed cases. Serology was performed on serum samples by microimmunofluorescence using Rickettsia conorii and Rickettsia typhi antigens. To detect and identify Rickettsia species, PCR targeting ompA, ompB and gltA genes followed by sequencing was performed on 18 obtained skin biopsies and on all collected vectors. Rickettsia positive samples were further characterized using primers targeting three intergenic spacers (dksA-xerC, rmpE- tRNAfMet and mppA-purC).

Results

A rickettsial infection was confirmed in 15 cases (60%). Serology was positive in 13 cases (52%). PCR detected Rickettsia DNA in four biopsies (16%) allowing the identification of R. conorii subsp israelensis in three cases and R. conorii subsp conorii in one case. Among 380 collected ticks, nine presented positive PCR (2.4%) allowing the identification of six R. conorii subsp israelensis, two R. massiliae and one R. conorii subsp conorii. Among 322 collected fleas, only one was positive for R. felis. R. conorii subsp israelensis strains detected in humans and vectors clustered together and showed a new MST genotype. Similarly, R. conorii subsp conorii strains detected in a skin biopsy and a tick were genetically related and presented a new MST genotype.

Conclusions

New Rickettsia spotted fever strain genotypes were found in Tunisia. Isolates detected in humans and vectors were genetically homogenous despite location differences in their original isolation suggesting epidemiologic circulation of these strains.

Keywords:
Rickettsia; Multispacer typing; Intergenic spacers; Vectors; Spotted fever rickettsioses; Tunisia