Evaluating the Aquatic Environment as a Reservoir for Salmonella: A Comparative Analysis with Clinical Strains

Aquatic environments are potential reservoirs for the persistence and spread of pathogenic bacteria. This study investigated the prevalence of <i>Salmonella</i> spp. in stream environments and their relationship with clinical isolates in Republic of Korea. A total of 4582 water samples were collected from 94 streams. We identified these isolates using MALDI-TOF MS and the Kauffmann-White scheme. Polymerase chain reaction and sequencing were performed to identify the resistance genes. Whole genome sequencing analysis and pulsed-field gel electrophoresis (PFGE) were performed to investigate genetic relatedness. In total, 110 <i>Salmonella</i> isolates showing 23 serotypes were isolated from the streams. <i>S.</i> Typhimurium (20.9%) was the most common, followed by <i>S.</i> Livingstone (17.3%), <i>S.</i> Infantis (10.9%), <i>S.</i> Othmarschen (6.4%), <i>S.</i> I. 4,[5],12:i:- (5.5%), and <i>S.</i> Thompson (5.5%). PFGE patterns of eight serotypes were identical or closely related to the stream and clinical strains. The sequence types of <i>S.</i> Mbandaka and <i>S.</i> Livingstone isolates from streams were identical to those of the clinical specimens as ST413 and ST543, respectively. <i>Salmonella</i> strains are highly prevalent in streams and are closely related to the isolates obtained from patients. Therefore, the continuous monitoring of stream environments is required to control the spread of <i>Salmonella</i>.