Salmonella enterica Serovar Diversity, Distribution, and Prevalence in Public-Access Waters from a Central California Coastal Leafy Green-Growing Region from 2011 to 2016

Abstract

Prevalence and serovar diversity of Salmonella enterica was measured during a five-year survey of surface waters in a 500 mi^2 agricultural region of the Central California Coast. Rivers, streams, lakes, and ponds were sampled bimonthly resulting in 2,979 samples. Overall prevalence was 56.4% with higher levels detected in Spring than in Fall. Small, but significant, differences in prevalence were detected based on sample locations. Detection of Salmonella was correlated positively with both significant rain events and, in some environments, levels of generic Escherichia coli . Analysis of 1,936 isolates revealed significant serovar diversity, with 91 different serovars detected. The most common isolated serovars were S. enterica subsp. enterica serovars I 6,8:d:- (406 isolates, 21.0%, and potentially monophasic Salmonella Muenchen), Give (334 isolates, 17.3%), Muenchen (158 isolates, 8.2%), Typhimurium (227 isolates, 11.7%), Oranienburg (106 isolates, 5.5%), and Montevideo (78 isolates, 4%). Sixteen of the 24 most common serovars detected in the region are among the serovars reported to cause the most human salmonellosis in the United States. Some of the serovars were associated with location and seasonal bias. Analysis of Xba I Pulsed Field Gel Electrophoresis (PFGE) patterns of strains of serovars Typhimurium, Oranienburg, and Montevideo showed significant intra-serovar diversity. PFGE pulsotypes were identified in the region for multiple years of the survey, indicating persistence or regular re-introduction to the region. Importance Non-typhoidal Salmonella is the among the leading causes of bacterial foodborne illness and increasing numbers of outbreaks and recalls are due to contaminated produce. High prevalence and 91 different serovars were detected in this leafy green growing region. Seventeen serovars that cause most of the human salmonellosis in the United States were detected, with 16 of those serovars detected in multiple locations and multiple years of the 5-year survey. Understanding the widespread prevalence and diversity of Salmonella in the region will assist in promoting food safety practices and intervention methods for growers and regulators.

Prevalence and Genomic Diversity of Salmonella enterica Recovered from River Water in a Major Agricultural Region in Northwestern Mexico

“…Further quantitative analysis determined a Simpson's diversity index with combined values higher that 0.92, revealing that a high diversity of serovars was found in this survey. The diversity identified in this agricultural region in Mexico is significantly higher than that reported for other major agricultural regions for fresh produce in the United States, which have an overall index of 0.89 [65]. Although the clinically associated serovar Typhimurium was recovered at low levels during the sampling period in the Culiacan Valley, S. Oranienburg, S. Anatum, S. Saintpaul, and S. Pomona were commonly identified.…”

Salmonella serovars associated with human salmonellosis in Brazil (2011-2020)

“…Outbreaks caused by S. Infantis have been associated with pet food and treats, and the main animal reservoirs of serovar Infants are poultry and swine. It is a common serovar in a number of countries and recognizes as invasive serovar specially for children (Gorski et al, 2022). Table 1 details the top 10 serovars of each year in the analysed period.…”

Comparison of Phenotype Nutritional Profiles and Phosphate Metabolism Genes in Four Serovars of Salmonella enterica from Water Sources

“…The strains used in this study are listed in Table 1 . Most of the strains were isolated in our laboratory as part of a large surface-water survey [ 10 ]. Strains were chosen based on the serovar, and strains within serovars were of different Pulsed Field Gel Electrophoresis (PFGE) pulsotypes isolated at different times and from different locations.…”

“…Strains were chosen based on the serovar, and strains within serovars were of different Pulsed Field Gel Electrophoresis (PFGE) pulsotypes isolated at different times and from different locations. Serovar identity was previously determined using sero-agglutination [ 10 ]. Because S. Kentucky strains were not well represented in that survey, additional S. Kentucky strains from the strain collection in the Produce Safety and Microbiology research unit were added.…”

“…A recent outbreak of salmonellosis in France associated with dried pork sausages was traced back to two different serovars, Bovismorbificans and monophasic Typhimurium [ 8 ]. Similarly, several surveys of surface water report the isolation of multiple serovars of Salmonella from the same sample [ 9 , 10 ].…”