Molecular screening for blood pathogens in synanthropic Pipistrellus bats in Spain reveals novel and human-related hemoplasmas

Urbanization profoundly alters natural habitats, creating environments where adaptable species such as bats thrive. In developed countries, cities may act as hotspots for pathogen transmission from bats to humans, yet urban bat pathogens remain understudied in Europe. This study examined vector-borne and zoonotic bacteria and protozoa in soprano (Pipistrellus pygmaeus, PPY) and Kuhl’s pipistrelles (Pipistrellus kuhlii, PKU) inhabiting Zaragoza, Spain. A total of 213 bats (143 urban, 70 rural; including 7 recaptures) were live-trapped between 2022 and 2024, and blood samples were collected. Initial screening of 77 individuals for Anaplasmataceae, Bartonella, Borrelia, hemotropic Mycoplasma (hemoplasmas), and Leishmania revealed hemoplasmas as the only haemopathogens present. Sequencing of a 330-bp 16S rRNA fragment confirmed infection, which was subsequently assessed in the full sample. Overall, ten bats (4.69 %) tested positive: eight PPY (two rural, six urban) and two PKU (one rural, one urban). Two hemoplasma genotypes were identified. The first, detected in both species across habitats, showed similarity to sequences from bats in Germany and Chile. The second, found in PPY from both environments, clustered closely with the human hemolytic pathogen Candidatus Mycoplasma haematohominis. Extended 16S rRNA (∼ 1400 bp) and 23S rRNA (∼ 1100 bp) sequences were obtained only for the first genotype, which phylogenetic analyses indicated represents a novel species. Since both samples had 99.8–100 % sequence identity across markers, we propose naming it Candidatus Mycoplasma haematopipistrellus sp. nov. Despite the low pathogen diversity observed, results highlight bats as potential ecological bridges for hemoplasma transmission between rural and urban environments.