Irvin González-López

Salmonella is a leading cause of foodborne outbreaks worldwide, commonly associated with the consumption of water or food contaminated with feces. This ubiquitous microorganism comprises numerous s...

In large-scale production of corn for feed and food, glyphosate and glufosinate are the most commonly used herbicides for weed control.

Background: Acinetobacter baumannii is a highly concerning pathogen in hospital settings, responsible for severe infections such as ventilator-associated pneumonia, urinary tract infections, and meningitis. Its remarkable genetic plasticity facilitates the rapid acquisition of antibiotic resistance, significantly complicating treatment and increasing mortality rates. As multidrug-resistant (MDR) infections continue to rise, phage therapy emerges as a viable alternative. Methods: This study reports the isolation and characterization of Acinetobacter phage vB_AbaM_A72 from stagnant water in Jalisco, Mexico. Results: Transmission electron microscopy revealed a myovirus-like morphology with an icosahedral head (91.32 ± 0.12 nm) and a contractile tail (123.77 ± 0.19 nm). The phage exhibited high environmental resilience, tolerating temperatures up to 60 °C and pH ranging from 5 to 11. Notably, A72 demonstrated a narrow host range but effectively inhibited the growth of an MDR A. baumannii strain for at least 12 h across different multiplicities of infection. Whole-genome sequencing confirmed the absence of virulence, antibiotic resistance, or lysogeny-associated genes. Comparative genomic analysis identified A72 as the first member of a newly described Obolenskvirus species, sharing only 76.4% similarity with its closest relatives. Conclusions: These findings underscore the importance of fully characterizing novel bacteriophages to expand therapeutic libraries and reinforce the feasibility of phage therapy as a promising approach against MDR A. baumannii infections.

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.

Any means of public transportation (aircraft, ships, and buses) may carry potentially covid19 positive individuals thus, wastewater-based epidemiology (WBE) should be implemented to avoid further spread. The present study focused on tracing the presence of SARS-CoV-2 in wastewater from holding tanks of national and international route buses, as well as the drainage system at the bus station. Testing was performed by the RT-PCR protocol established by the United States Center for Disease Control and Prevention (CDC). SARS-CoV-2 was detected in 8.88% of the wastewater samples from buses and drainage systems (4 of 45). Positives samples were sequenced, and Delta and Omicron were among the variants most prevalent. Our results show that WBE provides a reliable and sensitive tool for spotting the possible presence of COVID-19-positive individuals arriving by bus to a city. Also, the WBE coupled with Whole Genome Sequencing (WGS) may serve as an early warning to trace and display preventative measures upon the introduction of variants of concern.

Farm animals play a crucial role as a primary source of sustenance for human consumption. However continues to be one of the major food-borne pathogens from a public health standpoint. Its persistent global concern surrounding stems from its capability to induce foodborne illnesses. Unraveling the genetic characteristics of this pathogen stands as a pivotal step, shedding light on the intricate biology of and aiming to mitigate its prevalence. Within this context, our study aims to delve into the genomic traits and population structure of Mexican isolates derived from farm animals. We performed next-generation sequencing across 72 genomes. Genomic data was analyzed to determine virulence and antibiotic resistance markers. In addition, a phylogenetic tree and a spanning tree was constructed. The study revealed a diversity of 18 serovars linked to a singular ST, with prominent serovars being Oranienburg, Give, and Saintpaul. Across all isolates, an extensive array of virulence-related genes was identified. Interestingly, 95% of the isolates displayed exclusive resistance to aminoglycosides, while the remaining exhibited multidrug resistance to tetracycline and chloramphenicol. Notably, a substantial prevalence of prophages in the genomes was observed, accounting for 94% and totaling 183 sequences. The serovar Give stood out with the highest number of sequences, featuring Vibrio X29 and Escher RCS47 as the most prevalent phages. This comprehensive analysis provides valuable insights into the intricate world of , paving the way for enhanced understanding and targeted interventions.

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.

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.

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® EcoPlate^TM 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.