The Isolation of Aeromonas Species and Other Common Enteric Bacterial Pathogens from Patients with Gastroenteritis in an Australian Population.

Aeromonas species are emerging human enteric pathogens. However, systematic analysis of Aeromonas species infection in human gastroenteritis in comparison with other enteric bacterial pathogens in the Australian population is lacking. Here we analysed the isolation of Aeromonas species and other bacterial pathogens in five consecutive years (2015-2019) from 375,842 stool samples of patients with gastroenteritis in a large Australian diagnostic laboratory and identified a subset (48 isolates) of Aeromonas isolates to species level, using multilocus phylogenetic analysis. Aeromonas species were the third most common bacterial pathogens, following Campylobacter and Salmonella species. Aeromonas infection rate was significantly correlated with increasing age (p < 0.001). Aeromonas species were more often isolated in warm seasons and in males than females (p < 0.001). Five Aeromonas species were identified. Most of the infections were from three species, namely Aeromonas veronii (52%), Aeromonas caviae (27%) and Aeromonas hydrophila (12.5%). The majority of patients with Aeromonas species infection did not have a documented overseas travel history. The findings from this study support the importance of Aeromonas species in human gastroenteritis and suggest that the sources of Aeromonas infection in Australian patients should be further investigated.