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As the human population grows, an increase in food trade is needed. This elevates the risk of epidemiological outbreaks. One of the prevalent pathogens associated with food production in Mexico has been Salmonella Oranienburg. Effective surveillance systems require microbial genetic knowledge. The objective of this work is to describe the genetic composition of Mexican S. Oranienburg genomes. For that, 53 strains from different environmental sources were isolated and sequenced. Additionally, 109 S. Oranienburg genomes were downloaded. Bioinformatic analyses were used to explore the clonal complex and genomic relatedness. A major clonal group formed by ST23 was identified comprising four STs. 202 SNPs were found the maximum difference among isolates. Virulence genes for host invasion and colonization as rpoS, fimbria type 1, and, T3SS were found common for all isolates. This study suggests that Mexican S. Oranienburg strains are potential pathogens circulating continuously in the region between host and non-host environments. [ABSTRACT FROM AUTHOR]

Introduction: Salmonella is a major foodborne pathogen widely distributed in the environment. Surface water, soil, and sediments may confer a protective effect on Salmonella against non-host conditions., Methodology: This study focused on determining the prevalence of Salmonella spp. in river sediments from Sinaloa central region by the Most Probable Number (MPN) technique and determining the antimicrobial resistance profile by Kirby-Bauer assay., Results: Results showed the prevalence of Salmonella from 37.5 to 62.5% of the samples, oscillating from 0.322 to 20 MPN/4g, with August being the month with the highest levels. In silico geno-serotyping reveals the presence of Salmonella serotypes Typhi, Javiana, Ohio, Montevideo, Oranienburg, Pomona, Agona, Livingstone, Weltevreden, Anatum, and Minnesota. The most prevalent serotypes in river sediments were Pomona, Montevideo, and Oranienburg. Almost all isolates showed resistance to erythromycin, rifampin, and penicillin., Conclusions: This study reveals the prevalence and distribution of Salmonella enterica in river sediments, which may represent a potential niche for establishment and survival in the environment and become a potential contamination source., Competing Interests: No Conflict of Interest is declared, (Copyright (c) 2024 José Andrés Medrano-Félix, Juan Carlos Guerra-Rodríguez, Vianey Araceli Verdugo Arredondo, Berenice González-Torres, Lennin Isaac Garrido-Palazuelos, Irvin González-López, Nohelia Castro-del Campo, Osvaldo López-Cuevas, Cristóbal Chaidez Quiroz.)

The Yucatan Peninsula of Mexico hosts a karst aquifer system that is the only source of freshwater for the area; however, it is vulnerable to human-mediated contamination. Pepper mild mottle virus (PMMoV) is one of the most abundant RNA viruses associated with human feces, making it a viable indicator for tracking fecal pollution in aquatic environments, including groundwater. In this study, groundwater samples collected from a karst aquifer from fresh and brackish water locations were analyzed for fecal indicator bacteria, somatic and male F+ specific coliphages, and PMMoV during the rainy and dry seasons. Total coliform bacteria were detected at all sites, whereas Escherichia coli were found at relatively low levels <40 MPN/100 ml. The highest average concentrations of somatic and male F+ specific coliphages were 920 and 330 plaque forming units per 100 ml, respectively, detected in freshwater during the rainy season. PMMoV RNA was detected in 85% of the samples with gene sequences sharing 99-100% of nucleotide identity with PMMoV sequences available in GenBank. Quantification of PMMoV genome copies (GC) by quantitative real-time PCR indicated concentrations ranging from 1.7 × 10 1 to 1.0 × 10 4 GC/L, with the highest number of GC detected during the rainy season. No significant correlation was observed between PMMoV occurrence by season or water type (p > 0.05). Physicochemical and indicator bacteria were not correlated with PMMoV concentrations. The abundance and prevalence of PMMoV in the karst aquifer may reflect its environmental persistence and its potential as a fecal indicator in this karst aquifer system.

Cryptosporidium and Giardia are gastrointestinal disease-causing organisms transmitted by the fecal-oral route, zoonotic and prevalent in all socioeconomic segments with greater emphasis in rural communities. The goal of this study was to assess the risk of cryptosporidiosis and giardiasis of Potam dwellers consuming drinking water from communal well water. To achieve the goal, quantitative microbial risk assessment (QMRA) was carried out as follows: (a) identification of Cryptosporidium oocysts and Giardia cysts in well water samples by information collection rule method, (b) assessment of exposure to healthy Potam residents, (c) dose-response modelling, and (d) risk characterization using an exponential model. All well water samples tested were positive for Cryptosporidium and Giardia. The QMRA results indicate a mean of annual risks of 99:100 (0.99) for cryptosporidiosis and 1:1 (1.0) for giardiasis. The outcome of the present study may drive decision-makers to establish an educational and treatment program to reduce the incidence of parasite-borne intestinal infection in the Potam community, and to conduct risk analysis programs in other similar rural communities in Mexico.