Prevalence and diversity of Bartonella species in small rodents from coastal and continental areas

Abstract

Worldwide, Bartonella infections are known to inflict a wide range of mammals and, within rodents alone, more than 20 Bartonella species have been detected. There is, however, a lack of studies on the presence of Bartonella spp. in rodents in the Baltic region. We analysed 580 individuals belonging to eight small rodent species trapped in coastal and continental areas of Lithuania during 2015-2016. The presence of Bartonella DNA was examined by real-time PCR targeting the ssrA gene. The molecular characterization of the bacteria strains was based on sequence analysis of two housekeeping genes (rpoB, groEL) and the intergenic spacer region (ITS). For the rodents overall, the prevalence of Bartonella spp. was 54.8%, while the prevalence figures for each of the individual species were 8.3% in M. musculus, 15.8% in A. agrarius, 33.3% in M. arvalis, 42.4% in M. glareolus, 53.4% in M. oeconomus, 57.5% in M. minutus, 79.6% in A. flavicollis to 80% in M. agrestis. Sequence analysis revealed that the Bartonella strains belonged to the B. grahamii, B. taylorii, B. rochalimae, B. tribocorum, B. coopersplainsensis and B. doshiae genogroups. The highest Bartonella infection rates and the highest species diversity were both detected in rodents captured in the coastal area. To our knowledge, these are the first reports of the presence of B. coopersplainsensis, B. doshiae and B. tribocorum in Lithuania.

Figure 1

Maximum-likelihood phylogenetic tree for the partial rpoB gene of Bartonella spp. The phylogenetic tree was created using the Tamura-Nei model and bootstrap analysis of 1000 replicates. Identification source (rodent host) is given after the code of sample. Sequences MH547313, MH547314 and MH547315 are representative of three other samples sequenced in this study (all derived from A. flavicollis); Sequence MH547320 is representative of one other sample derived from M. glareolus; Sequence MH547321 is representative of two other samples (all derived from M. agrestis); Sequence MH547327 is representative of other sample from M. glareolus; Sequence MH547329 is representative of other sample from M. minutus; Sequence MH547328 are representative of two other samples sequenced in this study (all derived from M. glareolus). Samples sequenced in the present study are marked. Abbreviations: A. fla – Apodemus flavicollis; M. min – Micromys minutus; M. gla – Myodes glareolus; A. agr – Apodemus agrarius; M. mus – Mus musculus; M. oec. – Microtus oeconomus; M. agr – Microtus agrestis.

Figure 2

Maximum-likelihood phylogenetic tree for the partial ITS region of Bartonella spp. The phylogenetic tree was created using the Tamura-Nei model and bootstrap analysis of 1000 replicates. Identification source (rodent host) is given after the code of sample. Sequence MH547346 is representative of three other samples sequenced in this study (all derived from M. minutus); Sequence MH547348 is representative of one other sample derived from A. flavicollis; Samples sequenced in the present study are marked. Abbreviations: A. fla – Apodemus flavicollis; M. min – Micromys minutus; M. gla – Myodes glareolus; A. agr – Apodemus agrarius; M. mus – Mus musculus; M. oec. – Microtus oeconomus; M. agr – Microtus agrestis.

Figure 3

Maximum-likelihood phylogenetic tree for the partial groEL gene of Bartonella spp. The phylogenetic tree was created using the Tamura-Nei model and bootstrap analysis of 1000 replicates. Identification source (rodent host) is given after the code of sample. Samples sequenced in the present study are marked. Sequence MH547353 is representative of other sample from M. minutus. Abbreviations: M. min – Micromys minutus; M. gla – Myodes glareolus; A. agr – Apodemus agrarius; M. arv – Microtus arvalis; M. agr – Microtus agrestis.

Figure 4

Small rodent trapping sites on the Curonian Spit (sites 1–5), the Nemunas River Delta (sites 6–7) and continental (sites 8–12) areas of Lithuania, 2015–2016.