# Genetic Diversity of Aeromonas spp. Isolates from the Paediatric Population in Latvia Based on Multilocus Sequence Typing

## TL;DR

This study explores the genetic diversity of Aeromonas bacteria in Latvian children with gastroenteritis, identifying many new genetic types.

## Contribution

The study reports 25 novel sequence types of Aeromonas isolates from Latvian pediatric patients, establishing a regional baseline for future research.

## Key findings

- MLST analysis identified 25 novel sequence types among 30 Aeromonas isolates from Latvian children.
- Two novel sequence types were found in duplicate, with one case showing an epidemiological link.
- The genetic distribution of Aeromonas in Latvia differs from global datasets, indicating a distinct local population.

## Abstract

Purpose: Aeromonas species are emerging pathogens associated with a range of human infections, particularly gastroenteritis in the paediatric population. However, data on their molecular characteristics in Latvia and the wider Baltic region remain limited. This study aimed to describe the distribution and genetic diversity of Aeromonas isolates from paediatric patients in Latvia using multilocus sequence typing (MLST). Methods: Stool samples were collected from children aged 0–18 years who presented with gastroenteritis at the Children’s Clinical University Hospital between 2020 and 2021. A subset of 30 non-duplicate Aeromonas isolates was randomly selected for molecular characterisation and analysed by MLST. Sequence type data were deposited in the PubMLST.org database. Results: MLST analysis revealed substantial genetic diversity, with 25 novel sequence types (STs) being identified and three isolates matching previously reported STs. Two novel STs were detected in duplicate, with an epidemiological link being confirmed in one case. The local distribution of Aeromonas species and STs differed from global PubMLST datasets, suggesting a distinct local population of Aeromonas strains in Latvian paediatric patients. Conclusions: This study provides the first MLST-based description of paediatric Aeromonas isolates in Latvia and establishes a regional baseline for future comparative and epidemiological research. Although limited by a small sample size, the findings contribute to the molecular characterisation of Aeromonas spp. in the Baltic region and support the value of continued surveillance rather than direct public-health inference at this stage.