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

Abstract

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