Metabolic plasticity of Salmonella enterica as adaptation strategy in river water.

The survival of Salmonella in subtropical river water depends on genetic and metabolic reorganization for the expression of alternative metabolic pathways in response to starvation, which allows Salmonella to use environmental carbon sources (C-sources). However, knowledge regarding the metabolic plasticity of Salmonella serotypes for C-source utilization when exposed to these conditions remains unclear. The aim of this study was to evaluate the metabolic response and level of environmental C-source consumption by environmental Salmonella (Oranienburg and Saintpaul) and clinical Salmonella (Typhi) serotypes by comparing laboratory growth against exposure to river water conditions. Metabolic characterization was performed using a Biolog® EcoPlateTM containing 31 C-sources. The results obtained under laboratory growth conditions showed that environmental serotypes used 74.1% of the C-sources, whereas the clinical serotype used 45.1%. In contrast, in river water, all strains used up to 96.7% of the C-sources. Salmonella exposure to river water increases its capacity to use environmental C-sources.

Population structure of the Salmonella enterica serotype Oranienburg reveals similar virulence, regardless of isolation years and sources.

Salmonella enterica serotype Oranienburg is a multi-host, ubiquitous, and prevalent Non-typhoidal Salmonella (NTS) in subtropical rivers, particularly in sediments; little studied so far possible the adaptation and establishment of this microorganism based on its genetic content. This study was focused on the first five genomes of S. Oranienburg in sediments through whole-genome sequencing (WGS) and 61 river water genomes isolated in previous studies. Results showed an open pangenome with 5,594 gene clusters (GCs), and the division of their categories showed; 3,303 core genes, 741 persistent genes, 1,282 accessory genes, and 268 unique genes. Additionally, it showed three main subclades within the same serotype and showed a conserved genetic content, suggesting the display of different adaptation strategies to its establishment. Nine genes for antimicrobial resistance were detected: aac (6') - Iy, H-NS, golS, marA, mdsABC, mdtK, and sdiA, and a mutation in the parC gene p. T57S generating a resistance. In addition, virulence genes and pathogenicity islands (SPI's) were analyzed, finding 92 genes and an identity above 80 % in the SPI's 1 to 5, and the centisomes 54 and 63. The environmental strains of S. Oranienburg do not represent a concern as multidrug resistance (MDR) bacterium; however, virulence genes remain a potential health risk. This study contributes to understanding its adaptation to aquatic environments in Mexico.

Genomic Surveillance of SARS-CoV-2 in México: Three Years since Wuhan, China's First Reported Case.

OBJECTIVE: The aim of this work was to analyze the metadata of the SARS-CoV-2 sequences obtained from samples collected in Mexico from 2020 to 2022. MATERIALS AND METHODS: Metadata of SARS-CoV-2 sequences from samples collected in Mexico up to 31 December 2022 was retrieved from GISAID and manually cured for interpretation. RESULTS: As of December 2022, Mexican health authorities and the scientific community have sequenced up to 81,983 SARS-CoV-2 viral genomes deposited in GISAID, representing 1.1% of confirmed cases. The number of sequences obtained per state corresponded to the gross domestic product (GDP) of each state for the first (Mexico City) and the last (Tlaxcala). Approximately 25% of the sequences were obtained from CoViGen-Mex, an interdisciplinary initiative of health and scientific institutions to collect and sequence samples nationwide. The metadata showed a clear dominance of sequences retrieved by women. A similar variant distribution over time was found in Mexico and overseas, with the Omicron variant predominating. Finally, the age group with the highest representation in the sequences was adults aged 21 to 50 years, accounting for more than 50% of the total. CONCLUSIONS: Mexico presents diverse sociodemographic and economic characteristics. The COVID-19 pandemic has been and continues to be a challenge for collaboration across the country and around the world.

Genomic and biological characterization of the novel phages vB_VpaP_AL-1 and vB_VpaS_AL-2 infecting Vibrio parahaemolyticus associated with acute hepatopancreatic necrosis disease (AHPND).

Acute hepatopancreatic necrosis disease (AHPND) is a life-threatening disease to recently stocked shrimp. This disease is mainly caused by Vibrio parahaemolyticus and, to date, it has not been effectively controlled. Bacteriophages are a promising method to control bacterial diseases in aquaculture and multiple phages that infect Asian strains of V. parahaemolyticus have been described. However, few studies have characterized the bacteriophages that infect Latin American strains. Here, two lytic Vibrio phages (vB_VpaP_AL-1 and vB_VpaS_AL-2) were isolated from estuary water in Sinaloa, Mexico. The host ranges were tested using ten AHPND-causing strains isolated from Mexico and phage AL-1 was able to infect two strains while AL-2 infected four. One-step growth curve showed that AL-1 produced 85 PFU/cell and AL-2 produced 68 PFU/cell in 30 and 40 min, respectively. Both phages were able to tolerate temperatures ranging from 20 to 50 °C and pH values ranging from 4 to 10. Phages AL-1 and AL-2 have double-stranded DNA genomes of 42,854 bp and 58,457 bp, respectively. In total, 53 putative ORFs associated with the phage structure, packing, host lysis, DNA metabolism, and additional functions were predicted in the AL-1 genome, while 92 ORFs associated with the same functions as the AL-1 and 1 tRNA were predicted in the AL-2 genome. The lifecycle was classified as virulent for both phages. Morphology, phylogeny, and comparative genomic analyses assigned phage AL-1 as a new member of the genus Maculvirus in the Autographiviridae family, and phage AL-2 as a new member of the Siphoviridae family. These findings suggest that vB_VpaP_AL-1 and vB_VpaS_AL-2 are potential biocontrol agents against AHPND-causing V. parahaemolyticus from Mexico.

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

Salmonella enterica is a leading cause of human gastrointestinal disease worldwide. Given that Salmonella is persistent in aquatic environments, this study examined the prevalence, levels and genotypic diversity of Salmonella isolates recovered from major rivers in an important agricultural region in northwestern Mexico. During a 13-month period, a total of 143 river water samples were collected and subjected to size-exclusion ultrafiltration, followed by enrichment, and selective media for Salmonella isolation and quantitation. The recovered Salmonella isolates were examined by next-generation sequencing for genome characterization. Salmonella prevalence in river water was lower in the winter months (0.65 MPN/100 mL) and significantly higher in the summer months (13.98 MPN/100 mL), and a Poisson regression model indicated a negative effect of pH and salinity and a positive effect of river water temperature (p = 0.00) on Salmonella levels. Molecular subtyping revealed Oranienburg, Anatum and Saintpaul were the most predominant Salmonella serovars. Single nucleotide polymorphism (SNP)-based phylogeny revealed that the detected 27 distinct serovars from river water clustered in two major clades. Multiple nonsynonymous SNPs were detected in stiA, sivH, and ratA, genes required for Salmonella fitness and survival, and these findings identified relevant markers to potentially develop improved methods for characterizing this pathogen.