Teresa Estrada-Garcia

Background: Enterohemorrhagic Escherichia coli (EHEC) is a considerable public health concern associated with several foodborne outbreaks of bloody diarrhea (BD) and the potentially lethal hemolytic uremic syndrome (HUS), the pathophysiology of which is attributable to the Shiga toxin (Stx) produced by this bacterium. In most patients, supportive treatment will be sufficient; however, in some cases, antibiotic treatment may be necessary. Most antibiotics are not recommended for EHEC infection treatment, particularly those that kill the bacteria, since this triggers the release of Stx in the body, inducing or worsening HUS. Azithromycin, which prevents the release of Stx and is a weaker inducer of the SOS system, has been successfully used to reduce EHEC shedding. It is necessary to identify compounds that eliminate EHEC without inducing Stx release. The use of natural compounds such as curcumin (CUR), a polyphenol derived from turmeric, has been highlighted as an alternative bactericidal treatment approach. Objective: The objective of this study was to establish the effect of CUR and its interactions with selected antibiotics on resistant EHEC O157/H7/EDL933. Methods: Bacterial cultures were exposed to CUR at three different concentrations (110, 220, and 330 µg/mL) and 1.2% DMSO, and the antimicrobial activity of CUR was assessed by measuring the optical density at 600 nm (OD600). The synergy of CUR and the antibiotics was determined with the FIC method. RT-PCR was performed to determine the expression levels of the bla_CTX-M-15, catA1, acrAB-tolC stx2A, and stx2B genes. Results: Our data indicate that CUR did not affect the growth of EHEC, but when combined with the antibiotics, it acted as a bacterial resistance breaker. Synergistic combinations of CUR and cefotaxime or chloramphenicol significantly reduced colony counts. Conclusions: Our findings support the potential of CUR as a sensitizer or in combination therapy against EHEC.

Enterotoxigenic Escherichia coli (ETEC) produces two types of enterotoxins, LTs and STs, as well as several colonization factors (CFs), including CS21, CS3 fimbriae, and flagellar structures. This study investigated how these structures contribute to ETEC colonization and the immune response in HT-29 and HuTu-80 intestinal cells. ETEC strains with single, double, and triple mutations in the lngA, cstH, and fliC genes were generated and confirmed using PCR and Western blotting. The colonization of HT-29 and HuTu-80 intestinal cells by the ETEC E9034A strain, which was fully sequenced using a hybrid approach involving both Illumina and Oxford Nanopore technologies, was used to generate the mutant and recombinant proteins. The colonization and adherence of E9034A and its mutants were assessed through colony-forming unit (CFU) counts. Cytokine levels were assessed using flow cytometry and analyzed via FlowJo 7.6.1. Quantitative analysis revealed that the absence of the lngA, cstH, and fliC genes significantly (p < 0.01) reduced ETEC adherence to HT-29 and HutU-80 cells. In addition, only ETEC strains expressing the FliC protein induced IL-8 secretion. These findings suggest that LngA, CstH, and FliC in ETEC E9034A enhance adherence to intestinal cells and trigger the release of IL-8.

Background: Obesity-linked insulin resistance (IR) is an important risk factor for metabolic diseases, and anthropometric indices are commonly used for risk assessment. Aim: The study aimed to assess possible differences between women and men in the predictive value and association of nine obesity indices with IR, as assessed by HOMA-IR, in a nondiabetic adult population. Methods: The cross-sectional study included individuals recruited from a hospital in Mexico City. Indices evaluated were waist circumference (WC), hip circumference (HC), body mass index (BMI), waist-to-hip ratio, waist-to-height ratio, visceral adiposity index, body adiposity index (BAI), relative fat mass (RFM), and conicity index (CI). Fasting plasma glucose and insulin were measured to calculate HOMA-IR. Correlation analysis was performed between obesity indices and HOMA-IR. Receiver operating characteristics curve analyses were performed to determine predictive accuracy and cut-off values of obesity indices for IR. A binary logistic regression (BLR) analysis with OR calculation was performed to determine the strength of association with HOMA-IR. Results: We included 378 individuals (59% females, mean age 46.38 ±12.25 years). The highest Pearson coefficient value was observed for BMI among women, while among men, the highest values were found for BMI and BAI. WC among women, and BAI and RFM among men showed the highest sensitivity, while the highest specificity was observed for WHR among women and WC among men with respect to insulin prediction. In the adjusted BLR model, BMI, WC, and WHR among women and WC and RFM and BAI among men were independently associated with IR, showing the highest odds ratio (OR). Conclusion: In Mexican adults, WC, WHR, RFM and BAI could be complementary tools for BMI in screening for IR.

Introduction: Patients with Human Hyper IgM syndromes (HIGM) developed pulmonary and gastrointestinal infections since infancy and most patients have mutations in the CD40 ligand (CD40L) gene. Most HIGM patients compared to healthy subjects have higher/similar IgM and lower IgG, and IgA serum concentrations but gut antibody concentrations are unknown. CD40L on activated T-cells interacts with CD40 on B-cells, essential for the formation of germinal centres (GCs) inside secondary lymphoid organs (SLOs), where high-affinity antibodies, long-lived antibody-secreting plasma cells, and memory B-cells, are produced. C57BL6-CD40 ligand deficient mice (C57BL6-cd40l^−/−), are a model of HIGM, because serum immunoglobulin concentrations parallel levels observed in HIGM patients and have higher faecal IgA concentrations. In mice, TGFβ and other cytokines induce IgA production.Aims: To compare and evaluate B-cell populations and IgA-producing plasma cells in peritoneal lavage, non-gut-associated SLOs, spleen/inguinal lymph nodes (ILN), and gut-associated SLOs, mesenteric lymph nodes (MLN)/Peyer´s patches (PP) of unimmunised C57BL6-cd40l^−/− and C57BL6-wild-type (WT) mice.Material and methods: Peritoneal lavages, spleens, ILN, MLN, and PP from 8-10 weeks old C57BL6-cd40l^−/− and WT mice, were obtained. Organ cryosections were analysed by immunofluorescence and B-cell populations and IgA-positive plasma cell suspensions by flow cytometry.Results: In unimmunised WT mice, GCs were only observed in the gut-associated SLOs, but GCs were absent in all C57BL6-cd40l^−/− SLOs. PP and MLN of C57BL6-cd40l^−/− mice exhibited a significantly higher number of IgA-producing cells than WT mice. In the spleen and ILN of C57BL6-cd40l^−/− mice IgA-producing cells significantly decreased, while IgM-positive plasma cells increased. C57BL6-cd40l^−/− B-1 cells were more abundant in all analysed SLOs, whereas in WT mice most B-1 cells were contained within the peritoneal cavity. C57BL6-cd40l^−/− B-cells in MLN expressed a higher TGFβ receptor-1 than WT mice. Mouse strains small intestine microvilli (MV), have a similar frequency of IgA-positive cells.Discussion: Together our results confirm the role of PP and MLN as gut inductive sites, whose characteristic features are to initiate an IgA preferential immune response production in these anatomical sites even in the absence of GCs. IgA antibodies play a pivotal role in neutralising, eliminating, and regulating potential pathogens and microorganisms in the gut.

Introduction: Diarrhoeal illness is the second cause of morbidity/mortality among children from less-developed regions worldwide. Nonetheless, there is scarce information regarding their gut microbiome. Aim: Microbiome characterization, with an emphasis on the virome, of children’s stools with diarrhoea, by a commercial microbiome array. Methodology: Nucleic acids extraction, optimised for viral identification, of stool samples from 20 Mexican children with diarrhoea (10 children < 2 and 10 ≥ 2-years-old), collected 16 years ago and kept at -70 °C, were analysed for the presence of viruses, bacteria, archaea, protozoa, and fungi species sequences. Results: Only viral and bacterial species sequences were identified among children’s stools. Most stool samples harboured species belonging to the bacteriophages (95%), anellovirus (60%), diarrhoeagenic viruses (40%), and non-human pathogens viruses (45% avian virus and 40% plant viruses) groups. Among the children's stools, virome inter-individual species composition was observed, even in presence of illness. The < 2-years-old children group has significantly higher viral richness (p = 0.01), conferred mainly by bacteriophages and diarrheagenic-viruses (p = 0.01) species, in comparison with the ≥ 2-years-old group. Conclusions: The virome of stools of children with diarrhoea revealed inter-individual viral species composition. Similarly, to the few virome studies in healthy young children, the bacteriophages group was the most abundant. A significantly higher viral richness, conferred by bacteriophages and diarrheagenic-viral species, was observed among < 2-years-old children in comparison with older children. Stools preserved at -70 °C for long term can successfully be used for microbiome studies.

Fresh cheeses and cream are important garnishes of traditional Mexican food, often purchased at street or itinerant open markets or tianguis. However, there is scarce information regarding the microbiological quality of cheeses and cream sold in tianguis. For 2 years, three dairy stalls from three tianguis in Mexico City were visited once each season, trading practices were registered, and 96 dairy products were purchased. In total 72 fresh pasteurized cheeses that were hand-cut to order (24 Panela, 24 Canasto, and 24 Doble Crema) and 24 unpasteurized Crema de Rancho samples were collected. All dairy products remained without refrigeration for 8 h. Based on the National Guidelines limits, 87.5% of cheeses and 8% of Crema de Rancho samples were of low microbiological quality, and 1 sample of each type of cheese and 3 samples of Crema de Rancho exceeded the guidelines limits for Staphylococcus aureus. All dairy products were negative for Salmonella, Listeria monocytogenes, and all diarrheagenic Escherichia coli pathotypes, including Shiga toxin–producing E. coli. Among the 96 dairy samples, the prevalence of uropathogenic E. coli (UPEC) and of mycobacteria strains were determined because food items contaminated with these strains have been associated with urinary tract infections and mycobacteriosis, respectively. UPEC strains were isolated from 43% of cut-to-order cheeses and 29% of Crema de Rancho samples. Nontuberculous mycobacteria (NTM) strains were identified in 12.5% of Doble Crema cheese samples and 21% of Crema de Rancho samples. From the eight NTM-positive samples, 10 strains were identified (3 strains of Mycolicibacterium fortuitum, 2 of Mycobacteroides abscessus, 2 of Mycobacteroides chelonae, 2 of Mycolicibacterium porcinum, and 1 of Mycolicibacterium rhodesiae). All produced biofilms, and 70% had sliding motility (both virulence traits). Trading practices of cut-to-order pasteurized cheeses and unpasteurized Crema de Rancho in tianguis increase the risk of microbiological contamination of these products, including with human pathogens, and their consumption may cause human illness.HIGHLIGHTSThe microbiological quality of cut-to-order cheeses and cream was assessed.The presence of foodborne pathogens in cheeses and cream was evaluated.Most cheese samples had low microbiological quality.Some cheese and cream samples harbored S. aureus and uropathogenic E. coli strains.NTM with virulence traits were identified in some dairy products.