Virulence and Antimicrobial Resistance Pattern of Aeromonas spp. Colonizing European Pond Turtles Emys orbicularis and Their Natural Environment. First Study from Poland

SIMPLE SUMMARY: Aeromonas species are Gram-negative facultative anaerobic bacteria with a wide distribution in nature. The genus comprises bacteria which can cause different types of diseases in many warm- and cold-blooded animals. Moreover, exposure to these bacteria can cause gastroenteritis or localized skin infections in humans. In the current study, Aeromonas species were identified in samples from water sources and European pond turtles (Emys orbicularis) from Eastern Poland. Our results revealed a high prevalence of Aeromonas isolates (43.2%) in the turtles and 66.7% in the water samples. All isolates were resistant to ampicillin, 62% to sulfamethoxazole, 40.5% to erythromycin, and 40.5% to colistin. Eight strains were intermediately resistant to meropenem. Additionally, most Aeromonas isolates (from 90.5% to 45.2%) were found to possess the following virulence genes: fla, aer, hlyA, act, ela, alt, and ast. This report indicated that European pond turtles were colonized by Aeromonas spp. While acting as reservoirs for these pathogens, they may play an important role in the etiology of Aeromonas-associated animal infections. Moreover, the undesirable properties of water quality caused by the presence of drug-resistant aeromonads could exert a negative impact on human health. ABSTRACT: The aim of the study was to isolate and identify species belonging to the Aeromonas genus and evaluate the antimicrobial resistance and virulence patterns of isolates colonizing European pond turtles (Emys orbicularis) from natural environment of Eastern Poland. In total, 74 turtles and 15 samples of water from their natural environment were examined. More than 40 strains were isolated and identified: A. bestiarum (n = 1), A. hydrophila (n = 13), A. allosaccharophila (n = 2), A. salmonicida (n = 3), and A. veronii (n = 23). The highest incidence of resistance was noted for ampicillin (100%) and sulfamethoxazole (62.0%), followed by erythromycin and colistin (both 40.5%). Moreover, eight strains were intermediately resistant to meropenem (19%). Most Aeromonas isolates were found to possess more than one virulence gene among fla, aer, hlyA, act, ela, alt, and ast. We showed that the population of free-living European pond turtles was highly colonized by Aeromonas spp. Such strains may be an infectious agent not only for the population of turtles but also for other species of animals inhabiting their natural environment. Moreover, the undesirable properties of water quality caused by the presence of drug-resistant aeromonads could have a negative impact on human health.