Physiological and potentially pathogenic microbial flora in bats

The study of bats has a significant interest from a systematic, zoogeographic, ecological and physiological point of view, but their possible role as potential carriers of pathogenic bacteria is little explored and very little research has been carried out on the European continent. The aim of this study is to investigate the culturable aerobic enteric, conjunctival and oral bacterial flora of bats living in southern Italy to determine the physiological bacterial microflora and to investigate the possible occurrence of pathogenic bacteria. Five hundred and sixty-seven samples were collected from 189 individuals of 4 species of bats (Myotis myotis, Myotis capaccinii, Miniopterus schreibersii and Rhinolophus hipposideros). The sampling was carried out in six areas of the territory of Sicily and Calabria (southern Italy). All samples were examined for Gram negative bacteria; conjunctival and oral swabs were also submitted to bacteriological examination for Gram positive bacteria. Four hundred thirteen Gram negative strains were isolated. Of these, 377 belonged to 17 different genera of the Enterobacteriaceae Group and 30 to 5 other Families. One hundred eighty three Gram positive strains were isolated. Of these, 73 belonged to Staphylococcaceae Family, 72 to Bacillaceae Family and 36 to 4 other Families. To the best of our knowledge, this is the first time that some of these genera have been isolated from bats. The results confirmed that bats play an important role in the ecology and circulation of potentially pathogenic bacteria not only for wild species but also for domestic animals and for humans.

Greater Mouse-Eared Bats (Myotis myotis) Hibernating in the Nietoperek Bat Reserve (Poland) as a Vector of Airborne Culturable Fungi

Bats can contribute to an increase of aeromycota in underground ecosystems and might be a vector/reservoir of microorganisms; however, there is no information about the number and species composition of fungi around hibernating bats. One of the most common species in Europe with direct human contact is the greater mouse-eared bat (Myotis myotis). The goal of our research was the first report of the airborne fungi present in the close vicinity of hibernating M. myotis in the Nietoperek bat reserve (Western Poland) by the use of culture-based techniques and genetic and phenotypic identifications. Aerobiological investigations of mycobiota under hibernating bats were performed on two culture media (PDA and YPG) and at two incubation temperatures (7 and 24 ± 0.5 °C). Overall, we detected 32 fungal species from three phyla (Ascomycota, Basidiomycota, and Zygomycota) and 12 genera. The application of YPG medium and the higher incubation temperature showed higher numbers of isolated fungal species and CFU. Penicillium spp. were dominant in the study, with spores found outside the underground hibernation site from 51.9% to 86.3% and from 56.7% to 100% inside the bat reserve. Penicillium chrysogenum was the most frequently isolated species, then Absidia glauca, Aspergillus fumigatus, A. tubingensis, Mortierella polycephala, Naganishia diffluens, and Rhodotorula mucilaginosa. Temperature, relative humidity, and the abundance of bats correlated positively with the concentration of airborne fungal propagules, between fungal species diversity, and the concentration of aeromycota, but the number of fungal species did not positively correlate with the number of bats. The air in the underground site was more contaminated by fungi than the air outside; however, the concentration of aeromycota does not pose a threat for human health. Nevertheless, hibernating bats contribute to an increase in the aeromycota and as a vector/reservoir of microscopic fungi, including those that may cause allergies and infections in mammals, and should be monitored.

Long-term population trends of the lesser horseshoe bat Rhinolophus hipposideros and the greater mouse-eared bat Myotis myotis in Poland

Bats are particularly susceptible to environmental changes because of their low reproductive rate, longevity, and high metabolic rates, which lead to relatively high food requirements. Thus, bat populations take a relatively long time to recover from increased mortality rates, and monitoring schemes should cover long time periods. In this work we analyzed the population trajectories of two bat species, Rhinolophus hipposideros and Myotis myotis, the most numerous in five caves in southern Poland, which are known as important bat hibernacula on a continental scale. Data were collected by regular counts in 1985–2001, depending on the particular cave; in addition, previous data on the number of hibernating bats in these caves, available since 1951, were taken from existing publications. We analyzed time-series data using average locality indices and TRIM methods, and both produced similar results. Generally, the populations of the two studied bat species showed recent increasing trends, especially visible as an effect of recovery after years of decline. The situation recorded in southern Poland is very similar to that described in other places in Europe, where recoveries of bat populations have also been observed in the last decades. Although it is difficult to present results from formal analyses, because of the lack of good data, at least some factors—less exposure to contaminants (pesticides, heavy metals), improving food availability due to climate change, and a lower predation rate (including human pressure), both in the breeding season and during wintering—positively affected both species.

Seroprevalence of Toscana Virus and Sandfly Fever Sicilian Virus in European Bat Colonies Measured Using a Neutralization Test

Toscana phlebovirus (TOSV) and Sicilian phlebovirus (SFSV) are endemic in the Mediterranean area where they are transmitted to humans by infected sandflies. Vertebrates of several species have been postulated to act as reservoirs of these viruses, but convincing evidence is still awaited. Among them, bats have been suggested, however documented evidence is lacking. Here we tested a total of 329 bats belonging to eight species collected from twelve localities in southern Spain for the presence of neutralizing antibodies specific to TOSV and SFSV. Positive sera were detected in Schreiber’s long-fingered bat (Miniopterus schreibersii), mouse-eared Myotis (Myotis myotis), European free-tailed bat (Tadarida teniotis), and common serotine (Eptesicus serotinus) with the latter showing the highest prevalence rates for SFSV (22.6%) and TOSV (10%). There was no difference between females and males. Results suggest that bats are not likely to play a major role in the natural cycle of these two sandfly-borne phleboviruses. However, large breeding colonies of bats can be used as sentinels for surveillance of the presence of such viruses in a given locality. In addition, capture–recapture studies should be initiated in order to understand better the dynamics of TOSV and SFSV in bat populations.

Occurrence of a forest-dwelling bat, northern myotis (Myotis septentrionalis), within Canada’s largest conurbation

While some species thrive in urban areas, many are absent from such environments. Those that are successful often have high behavioural flexibility that allows them to exploit new niches in a human-modified landscape. Northern myotis (Myotis septentrionalis) is an endangered bat species rarely identified in urban areas, though it is unclear whether this is due to absence or difficulties in surveying. We investigated the ecology of a population of northern myotis within Canada’s largest conurbation, including reproductive status, roosting preference, and movements. Using capture surveys, we confirmed the presence of reproductive females and healthy juveniles over two seasons. Using radio telemetry and acoustic surveys, we identified a cluster of tree roosts in the centre of the forest, and foraging areas concentrated around waterways within the bounds of the forest. These observations suggest the roosting and movement ecology of this population is similar to that observed for this species in rural environments, despite the urban surroundings. Our results suggest that northern myotis is not a synurbic species but can occur within urbanized environments when suitable habitat is available. We suggest that large forest patches with mature, interior forest cover are likely to be an important resource for northern myotis, and they will be vulnerable to the loss or fragmentation of these features in rapidly urbanizing landscapes. These findings are highly relevant to the ecology and preservation of northern myotis and present a case for greater consideration of this species in urban forests.

Extremely high mortality of newborn juveniles in the nursery colony of Myotis myotis at Žihobce, SW Bohemia, Czech Republic (Chiroptera: Vespertilionidae)

In 2020, an extremely high mortality of juveniles was recorded in a nursery colony of Myotis myotis at Žihobce (Klatovy Dist.), reaching 50.6% of the potential growth. Most juveniles died within two weeks of age (67.4%). The cause of this phenomenon is not known. The results of chemical analyses carried out in five dead juveniles showed neither the presence of heavy metals nor pesticides in the bodies. The dissection of cadavers revealed a good nutrition state. In all dissected individuals, intestinal inflammation was recorded. Most juveniles in the colony were significantly parasitised. In the period of parturition, it was cold and very rainy for several days, the mortality thus may have been caused by chilling of the juveniles. The effort of females to nurse even the dying juveniles which fell down from the colony was observed. The mortality of juveniles was checked in further 28 control colonies in different parts of the Czech Republic in 2020. At eight sites, making up 27.6% of all studied sites, the mortality of 10.1–20.0% was recorded. At the remaining twenty sites (69% of the studied sites), the mortality reached 0–10%. High mortality of juveniles of M. myotis (18.7–39.2%) was also recorded at Vyšší Brod (Český Krumlov Dist.) in the years 1988–1991. In that case, the probable cause was the application of Lastanox (tributyltin oxide), a toxic chemical used for timber treatment in the colony roost.