Water sampling using modified Moore swab (MMS): the effects of sampling replicates and different media on the frequency and diversity of <i>Salmonella</i> serovars

<i>Salmonella enterica</i> is a significant foodborne pathogen frequently associated with produce contamination through irrigation with untreated surface water. This study investigated the effects of sampling replication and selective media on <i>S. enterica</i> serovar recovery and diversity in surface waters across Paraíba State, Brazil. Water samples (<i>n</i> = 200) were collected from 10 reservoirs using modified Moore swabs (MMSs), with three replicates per sampling site, yielding 600 samples. The prevalence of <i>S. enterica</i> was 53.5% in individual samples, increasing to 68.5% when combining results from triplicate samples. Statistical analyses demonstrated that triplicate sampling significantly enhanced both recovery rates and serovar diversity compared with single samples (<i>P</i> < 0.05). Alpha diversity metrics revealed a 39% increase in serovar richness when using triplicate versus single samples. The parallel use of multiple enrichment broths and selective agars proved essential for maximum serovar detection, as certain serovars were recovered exclusively under specific culture conditions. While triplicate sampling provided optimal detection sensitivity, duplicate sampling emerged as a cost-effective alternative, maintaining sufficient statistical power. These findings demonstrate the effectiveness of MMS combined with replicate sampling for comprehensive <i>S. enterica</i> surveillance in surface waters, with implications for water quality monitoring programs and public health risk assessment.IMPORTANCE<i>Salmonella</i> contamination in irrigation water poses a major threat to food safety, as contaminated produce can cause widespread foodborne illness outbreaks affecting thousands of people. Current water monitoring methods often miss these hazardous bacteria, creating blind spots in our food safety systems. This research addresses a critical gap by demonstrating that taking multiple water samples from the same location, rather than just single samples, improves our ability to detect <i>Salmonella</i> contamination. The study shows that collecting three samples instead of one increases the detection rate from 54% to 69% and reveals nearly 40% more serovars. This enhanced detection capability is crucial for protecting public health, as it provides more accurate information about the occurrence of <i>Salmonella</i> in natural surface waters. Lastly, our findings provide practical guidance for improving surveillance programs worldwide, offering a cost-effective approach that significantly strengthens our defense against <i>Salmonella</i> contamination in the food supply chain.