# Exploring Antimicrobial Resistance in Bacteria from Fecal Samples of Insectivorous Bats: A Preliminary Study

## TL;DR

This study found that insectivorous bats in Sicily carry many antibiotic-resistant bacteria, raising concerns about public health and the need for further research.

## Contribution

The study provides new insights into the role of Sicilian insectivorous bats as reservoirs of multidrug-resistant bacteria.

## Key findings

- 84.5% of bacterial isolates from Sicilian bats were multidrug-resistant.
- Gram-negative bacteria like Escherichia coli showed high resistance to colistin, amoxicillin, and ampicillin.
- Bats may serve as significant reservoirs and vectors of antibiotic-resistant bacteria.

## Abstract

This study investigated the presence of pathogenic bacteria and antibiotic-resistant bacteria in bat populations from southern Italy. Rectal swabs and guano samples were collected from four natural sites located in the provinces of Catania, Siracusa, and Ragusa, in Sicily. A total of 213 bacterial isolates, predominantly Gram-negative species such as Escherichia coli, Citrobacter freundii, and Morganella morganii, were obtained from 132 samples. Antibiotic susceptibility testing revealed high levels of resistance to multiple antibiotics, particularly colistin, amoxicillin, and ampicillin. Notably, 84.5% of the isolates were classified as multidrug-resistant. These findings suggest that Sicilian bats may serve as significant reservoirs and potential vectors of antibiotic-resistant bacteria, highlighting the need for further research to assess the implications for public health and biodiversity conservation.

Bats (order Chiroptera) are increasingly recognized as important reservoirs and potential vectors of pathogenic and antimicrobial-resistant bacteria (ARB), with potential implications for human, animal, and environmental health. This study aimed to assess the presence and antimicrobial resistance profiles of bacterial isolates from bat populations in Sicily, an area for which data are currently limited. A total of 132 samples (120 rectal swabs and 12 guano samples) were collected at four sites in the provinces of Catania, Siracusa, and Ragusa. Bacteriological analysis yielded 213 isolates, including 161 Gram-negative and 52 Gram-positive strains, representing 55 different species. Among Gram-negative isolates, Escherichia coli, Citrobacter freundii, and Morganella morganii were most frequently detected, while Bacillus licheniformis and Staphylococcus xylosus were predominant among Gram-positive bacteria. Antimicrobial susceptibility testing revealed high resistance rates to colistin, amoxicillin, and ampicillin in Gram-negative strains, and to oxacillin, ceftazidime, and lincomycin in Gram-positive strains. Notably, 84.5% of isolates exhibited multidrug resistance. These findings highlight the potential role of bats as reservoirs of ARB and underline the importance of ongoing monitoring within a One Health framework to mitigate risks to public and animal health.