Nontuberculous Mycobacteria Prevalence in Bats' Guano from Caves and Attics of Buildings Studied by Culture and qPCR Examinations.

A total of 281 guano samples were collected from caves (N = 181) in eight European countries (Bulgaria, Czech Republic, France, Hungary, Italy, Romania, Slovakia and Slovenia) and attics in the Czech R. (N = 100). The correlation of detection of mycobacteria between Ziehl-Neelsen (ZN) microscopy and culture examination and qPCR was strong. ZN microscopy was positive in guano from caves (58.6%) more than double than positivity in guano from attics (21.0%; p < 0.01). From 89 mycobacterial isolates (73 isolates from cave guano and 16 isolates from attics' guano), 68 (76.4%) isolates of 19 sp., ssp. and complex were identified as members of three Groups (M. fortuitum, M.chelonae, and M. mucogenicum) and four complexes (M. avium, M. terrae, M.vaccae, and M.smegmatis). A total of 20 isolates (22.5%) belonged to risk group 1 (environmental saprophytes), 48 isolates (53.9%) belonged to risk group 2 (potential pathogens), and none of the isolates belonged to risk group 3 (obligatory pathogens). When comparing bat guano collected from caves and attics, differences (p < 0.01; Mann-Whitney test) were observed for the electrical conductivity, total carbon, total organic, and total inorganic carbon. No difference (p > 0.05; Mann-Whitney test) was found for pH and oxidation-reduction potential parameters.

Bat population recoveries give insight into clustering strategies during hibernation.

BACKGROUND: Behaviour during hibernation contributes to energy conservation in winter. Hibernating bats select roosts with respect to physiological and environmental stressors, available local microclimate and species-specific requirements. RESULTS: We found that, in the period between 1977 and 2018, hibernating Myotis myotis and Rhinolophus hipposideros bats showed exponential population growth. The growth rates, corrected for local winter seasonal severity and winter duration, were equal to 10 and 13%, respectively. While R. hipposideros only utilised the thermally stable and, at survey time, warmer corridors in the hibernaculum, an increasing proportion of M. myotis roosted in the thermally stable corridors as their abundance increased. About 14% of all hibernating M. myotis displayed solitary roosting, irrespective of other covariates. Those bats that clustered together formed progressively larger clusters with increasing abundance, particularly in cold corridors. We found no statistically significant relationship for clustering behaviour or cluster size with winter severity or winter duration. CONCLUSIONS: Abundance of hibernating bats is increasing in Central Europe. As the number of M. myotis bats increases, thermally unstable corridors become saturated with large clusters and the animals begin to roost deeper underground.