Abstract
Bartonella infections are widespread and highly prevalent in rodents. Several rodent-associated Bartonella species have been related to human diseases. Recently, Bartonella species was reported as the etiology of a human case in the country of Georgia (Caucasus). However, information on Bartonella in rodents in Georgia is absent. Rodent hearts were collected from Georgia to investigate the presence and diversity of Bartonella species. Bartonella bacteria were cultured from 37.2% (16/43) of rodents examined, while Bartonella DNA was detected in 41.2% (28/68) of rodents by polymerase chain reaction targeting citrate synthase (gltA) gene. Sequences of gltA showed that rodents in this region harbored multiple Bartonella strains, including Bartonella elizabethae, Bartonella tribocorum, Bartonella grahamii, and an unknown genogroup. The first three Bartonella species, known to be rat-associated and human cases linked, were commonly observed in wood mice (Apodemus [Sylvaemus] uralensis) (5/8 positive with B. elizabethae and B. tribocorum) and social voles (Microtus socialis) (4/6 positive with B. grahamii and B. elizabethae) in this study. The frequent distribution of these Bartonella species suggests that they may contribute to unidentified clinical infections. The unknown genogroup was observed in 24 Bartonella isolates and/or DNA extracts from heart tissues, all of which were obtained from Libyan jirds (Meriones libycus). Further characterization of the bacterial cultures based on sequence analysis of four additional genes (ftsZ, nuoG, rpoB, and ssrA) supported that the jird-associated Bartonella strains comprise a distinct monophyletic clade. The impact of this bacterium on wildlife and human health needs to be determined.
Highlights
Bacteria of the genus Bartonella are small, fastidious, and slow-growing Gram-negative aerobic rods
Phylogenetic analysis based on each of the targets demonstrated that the two variants were grouped together and comprised a distinct monophyletic clade with divergences of at least 7%, 7%, 5%, and 4% from all described Bartonella species or genotypes by ftsZ, nicotinamide adenine dinucleotide dehydrogenase gamma-subunit (nuoG), RNA polymerase beta subunit (rpoB), and ssrA, respectively. These results suggested that the strains isolated from L. jirds are unique and likely represent a novel Bartonella species according to the definition of bacterial species.[31]
Comparative analyses of partial sequences of gltA gene that has been shown to be reliable for distinguishing between closely related Bartonella genotypes[26,32] showed that rodents in Georgia harbor multiple Bartonella species, including B. elizabethae, B. tribocorum, B. grahamii, and a presumably novel species that is associated with L. jirds
Summary
Bacteria of the genus Bartonella are small, fastidious, and slow-growing Gram-negative aerobic rods. They parasitize erythrocytes and endothelial cells of a wide range of mammals[1] and are usually host specific at different taxonomical levels.[2,3,4,5] Currently, there are around 30 recognized species and/or subspecies within the genus that have been described from different vertebrate reservoirs. B. elizabethae and B. tribocorum are specific to Rattus rats,[3,14,19] whereas B. washoensis is specific to squirrels of family Sciuridae.[12] These findings indicated the potential role of rodents as reservoirs for Bartonella species that could be pathogenic to humans.
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