Molecular detection and characterization of Bartonella strains in small rodents

Abstract

To date, 35 species in Bartonella genus have been officially recognized of which more than 15 Bartonella species have been isolated from small rodents. Bartonella infections in rodents and cases of human infections with Bartonella bacteria of rodent origin have been reported worldwide. However, there still is a lack of knowledge on the geographical distribution, genetic diversity and the reservoir hosts for these microorganisms in Baltic countries. This study aimed to investigate the prevalence and genetic diversity of Bartonella spp. in small rodents in Lithuania. A total of 430 spleen samples obtained from wild-living small rodents of seven species were examined for the presence of Bartonella spp. by PCR. Species identification and molecular characterization of bacteria strains were based on sequence analysis of two housekeeping genes (rpoB, groEL) and the intergenic species region. Bartonella DNA was detected in 23.7% (102/430) of small rodents: in 33.2% of Apodemus flavicollis, 23.7% of Micromys minutus, 15.5% of Myodes glareolus, 12.5% of Microtus oeconomus, and in one of two specimens of M. arvalis. Sequence analysis of Bartonella isolates showed that the Bartonella strains circulating among the investigated rodents are heterogenic and belonged to Bartonella grahamii, Bartonella taylorii and Bartonella rochalimae genogroup. Phylogenetic analysis based on each of the targets demonstrated the presence of two different B. grahamii strains in A. flavicollis, M. minutus, M. glareolus, M. arvalis, M. oeconomus, and three B. taylorii strains in A. flavicollis and M. glareolus. Bartonella strain from B. rochalimae genogroup was detected in M. glareolus. This is the first report of the molecular characterization of Bartonella spp. in rodents in Lithuania. The frequent distribution of Bartonella species suggests that they may contribute to unidentified clinical infections. The impact of this bacterium on wildlife and human health needs to be determined.