Presence and Persistence of ESKAPEE Bacteria before and after Hospital Wastewater Treatment.

The metagenomic surveillance of antimicrobial resistance in wastewater has been suggested as a methodological tool to characterize the distribution, status, and trends of antibiotic-resistant bacteria. In this study, a cross-sectional collection of samples of hospital-associated raw and treated wastewater were obtained from February to March 2020. Shotgun metagenomic sequencing and bioinformatic analysis were performed to characterize bacterial abundance and antimicrobial resistance gene analysis. The main bacterial phyla found in all the samples were as follows: Proteobacteria, Bacteroides, Firmicutes, and Actinobacteria. At the species level, ESKAPEE bacteria such as E. coli relative abundance decreased between raw and treated wastewater, but S. aureus, A. baumannii, and P. aeruginosa increased, as did the persistence of K. pneumoniae in both raw and treated wastewater. A total of 172 different ARGs were detected; blaOXA, blaVEB, blaKPC, blaGES, mphE, mef, erm, msrE, AAC(6'), ant(3″), aadS, lnu, PBP-2, dfrA, vanA-G, tet, and sul were found at the highest abundance and persistence. This study demonstrates the ability of ESKAPEE bacteria to survive tertiary treatment processes of hospital wastewater, as well as the persistence of clinically important antimicrobial resistance genes that are spreading in the environment.

Mouse and human immune responses share neutralization epitopes of HAstV-VA1.

Astroviruses are highly divergent and infect a wide variety of animal hosts. In 2009, a genetically divergent human astrovirus (HAstV) strain VA1 was first identified in an outbreak of acute gastroenteritis. This strain has also been associated with fatal central nervous system disease. In this work, we report the isolation of three high-affinity neutralizing monoclonal antibodies (Nt-MAbs) targeting the capsid spike domain of HAstV-VA1. These antibodies (7C8, 2A2, 3D8) were used to select individual HAstV-VA1 mutants resistant to their neutralizing activity and a HAstV-VA1 triple mutant that escapes neutralization from all three Nt-MAbs. Sequencing of the virus genome capsid region revealed escape mutations that map to the surface of the capsid spike domain, define three potentially independent neutralization epitopes, and help delineate four antigenic sites in human astroviruses. Notably, two of the escape mutations were found to be present in the spike sequence of the HAstV-VA1-PS strain isolated from an immunodeficient patient with encephalitis, suggesting that those mutations arose as a result of the immune pressure generated by the patient's immunotherapy. In agreement with this observation, human serum samples exhibiting strong neutralization activity against wild-type HAstV-VA1 had a 2.6-fold reduction in neutralization titer when evaluated against the triple-escape HAstV-VA1 mutant, suggesting that both mouse and human antibody responses target shared neutralization epitopes. The isolated Nt-MAbs reported in this work will help to characterize the functional domains of the virus during cell entry and have the potential for developing a specific antibody therapy for the neurological disease associated with HAstV-VA1. IMPORTANCE: Human astroviruses (HAstVs) have been historically associated with acute gastroenteritis. However, the genetically divergent HAstV-VA1 strain has been associated with central nervous system disease. In this work high-affinity neutralizing monoclonal antibodies directed to HAstV-VA1 were isolated and characterized. The proposed binding sites for these antibodies and for neutralizing antibodies against classical HAstVs suggest that there are at least four neutralization sites on the capsid spike of astroviruses. Our data show that natural infection with human astrovirus VA1 elicits a robust humoral immune response that targets the same antigenic sites recognized by the mouse monoclonal antibodies and strongly suggests the emergence of a variant HAstV-VA1 virus in an immunodeficient patient with prolonged astrovirus infection. The isolated Nt-MAb reported in this work will help to define the functional sites of the virus involved in cell entry and hold promise for developing a specific antibody therapy for the neurological disease associated with HAstV-VA1.

Presence of SARS-CoV-2-specific T cells before vaccination in the Mexican population.

The immune response to SARS-CoV-2 has been extensively studied following the pandemic outbreak in 2020; however, the presence of specific T cells against SARS-CoV-2 before vaccination has not been evaluated in Mexico. In this study, we estimated the frequency of T CD4+ and T CD8+ cells that exhibit a specific response to S (spike) and N (nucleocapsid) proteins in a Mexican population. We collected 78 peripheral blood samples from unvaccinated subjects, and the presence of antibodies against spike (RBD) and N protein was determined. Peripheral blood mononuclear cells were isolated and stimulated with a pool of S or N protein peptides (Wuhan-Hu-1 strain). IL-1ß, IL-4, IL-6, IL-10, IL-2, IL-8, TNF-α, IFN-γ, and GM-CSF levels were quantified in the supernatant of the activated cells, and the cells were stained to assess the activation and memory phenotypes. Differential activation frequency dependent on serological status was observed in CD4+ cells but not in CD8+ cells. The predominantly activated population was the central memory T CD4+ cells. Only 10% of the population exhibited the same phenotype with respect to the response to nucleocapsid peptides. The cytokine profile differed between the S and N responses. S peptides induced a more proinflammatory response compared with the N peptides. In conclusion, in a Mexican cohort before vaccination, there was a significant response to the S and N SARS-CoV-2 proteins resulting from previous infections with seasonal coronaviruses or previous undetected exposure to SARS-CoV-2.

Multidrug-Resistant Staphylococcus sp. and Enterococcus sp. in Municipal and Hospital Wastewater: A Longitudinal Study.

The objective of the study was to detect multidrug-resistant Staphylococcus sp. and Enterococcus sp. isolates in municipal and hospital wastewater and to determine their elimination or persistence after wastewater treatment. Between August 2021 and September 2022, raw and treated wastewater samples were collected at two hospital and two community wastewater treatment plants (WWTPs). In each season of the year, two treated and two raw wastewater samples were collected in duplicate at each of the WWTPs studied. Screening and presumptive identification of staphylococci and enterococci was performed using chromoagars, and identification was performed with the Matrix Assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-TOF MS®). Antimicrobial susceptibility was performed using VITEK 2® automated system. There were 56 wastewater samples obtained during the study period. A total of 182 Staphylococcus sp. and 248 Enterococcus sp. were identified. The highest frequency of Staphylococcus sp. isolation was in spring and summer (n = 129, 70.8%), and for Enterococcus sp. it was in autumn and winter (n = 143, 57.7%). Sixteen isolates of Staphylococcus sp. and sixty-three of Enterococcus sp. persisted during WWTP treatments. Thirteen species of staphylococci and seven species of enterococci were identified. Thirty-one isolates of Staphylococcus sp. and ninety-four of Enterococcus sp. were multidrug-resistant. Resistance to vancomycin (1.1%), linezolid (2.7%), and daptomycin (8.2%/10.9%%), and a lower susceptibility to tigecycline (2.7%), was observed. This study evidences the presence of Staphylococcus sp. and Enterococcus sp. resistant to antibiotics of last choice of clinical treatment, in community and hospital wastewater and their ability to survive WWTP treatment systems.

Who is getting COVID-19 boosters? A latent class analysis in a nationally representative sample of Mexican adults 60 years and over.

OBJECTIVE: Estimate COVID-19 vaccine booster uptake and identify sociodemographic profiles associated with vaccine booster uptake in Mexican adults aged 60 and older. METHODS: Using data from the 2022 National Health and Nutrition Survey, we estimated COVID-19 booster uptake in Mexican adults 60 and older. We conducted a latent class analysis using sociodemographic characteristics and then estimated group-specific booster prevalence. RESULTS: Adults aged 60 and older with a completed vaccination schedule had 80.3% booster coverage. Two groups showed the lowest coverage: 1) unemployed and informal working men with elementary education with low socioeconomic status (73.8% boosted), and 2) female homekeepers with elementary education or less living in rural areas (77.0% boosted). CONCLUSIONS: Our analysis points to the need to reach out to men and women with elementary education or less who live in rural areas to strengthen booster campaigns in the future.

Barriers, refusal and a hypothetical monetary incentive for Covid-19 vaccination in Mexican adults.

OBJECTIVE: To estimate vaccine uptake and assess sociodemographic conditions associated with vaccination barriers and refusal and to explore the effect of a monetary incentive to overcome them. MATERIALS AND METHODS: We used data from adults from the 2021 National Continuous Health and Nutrition Survey conducted during August-October 2021. We evaluated if an hypothetical monetary incentive between 50-650 MXN (~2.5-31 USD) would overcome barriers or refusal. RESULTS: 73.9% were vaccinated with at least one dose, 7.5% refused, 4.8% reported barriers and 13.8% were ineligible at the time of the survey. Refusal and barriers were more frequent in men, older age, lower education and socioeconomic status, unemployed and informal workers. In people with barriers and refusal, the hypothetical incentive increased the acceptance in 57.6% (95%CI 50.7,64.4%) and 17.4% (95%CI 13.2,21.7%) in people with barriers and refusal, respectively. CONCLUSION: Understanding the reasons for barriers and refusal is crucial for future Covid-19 vaccination campaigns or epidemics. A monetary incentive might increase vaccination uptake, although, cost-effectiveness analyses are needed.

Encuesta Nacional de Salud y Nutrición 2023: metodología y avances de la Ensanut Continua 2020-2024.

OBJETIVO: Presentar la metodología de la Encuesta Nacional de Salud y Nutrición 2023 (Ensanut 2023) y describir los procedimientos de inferencia para conjuntar la información colectada por la Ensanut Continua 2020-2024. Material y métodos. La Ensanut 2023 es la cuarta encuesta de la serie Ensanut Continua. Se describe el alcance de la Ensanut 2023 junto con sus procedimientos de muestreo, estimación, medición y organización logística. Además, se discute el procedimiento básico de estimación para analizar la integración de las encuestas Ensanut Continua 2020-2024. RESULTADOS: La Ensanut 2023 obtendrá a nivel nacional al menos 11 720 entrevistas completas de hogar y 13 378 cuestionarios completos de adulto. La unión de las Ensanut Continua 2020-2023 permitirá, en general, estimar a nivel estatal prevalencias p≥5% en adultos, con confiabilidad tolerable según las recomendaciones del Instituto Nacional de Estadística y Geografía. CONCLUSIONES: El análisis de la unión de la Ensanut Continua 2020-2023 permitirá iniciar la generación de estimaciones nacionales y estatales sobre el estado de salud y nutrición de la población mexicana.

Prevalencia de anticuerpos y vacunación contra SARS-CoV-2 en 2022 en México.

OBJETIVO: Describir la prevalencia de anticuerpos contra SARS-CoV-2, vacunación, barreras y rechazo a la vacunación Covid-19 en población mexicana. Material y métodos. Se utilizó información de los integrantes del hogar de uno y más años, incluidos en la Encuesta Nacional de Salud y Nutrición Continua 2022 (Ensanut Continua 2022) realizada de agosto-noviembre. Se estimó la prevalencia de anticuerpos antiproteínas N y S de SARS-CoV-2 en muestras de sangre capilar, dosis reportadas de vacunación a Covid-19 y las razones de barreras y rechazo a la vacunación. RESULTADOS: La prevalencia de anticuerpos anti-N fue de 94.4% y de anti-S 98.1%. La prevalencia de anticuerpos anti-S fue mayor en personas vacunadas con una, dos o tres o más dosis que en no vacunadas. Dentro de la población elegible a vacunación, 20.2% no estaba vacunada, 16.2% tenía una dosis, 30% dos dosis y 33.6% tres dosis o más. El 11.2% de la población elegible rechazó la vacunación, 5.5% reportó una barrera y 3.2% reportó que la vacuna no había llegado a su localidad. Conclusión. La prevalencia de anticuerpos por infección natural y por vacunación Covid-19 es alta en México. Las variaciones de rechazo y barreras a la vacunación entre grupos de edad y regiones deben tomarse en cuenta para intensificar esfuerzos específicos para la vacunación.

The Omicron wave in Mexico: vaccine protection against progression to severe Covid-19 in SARS-CoV-2-infected workers.

OBJECTIVE: To assess the effectiveness of seven Covid-19 vaccines in preventing disease progression (DP) using data from national private sector workers during the Omicron wave in Mexico from January 2 to March 5, 2022. MATERIALS AND METHODS: This study employed an administrative retrospective cohort design, analyzing DP (hospitalization or death due to respiratory disease) among workers who filed a respiratory short-term disability claim and tested positive for SARS-CoV-2. Risk ratios (RRadj) were estimated using Poisson regression models adjusted for various factors. RESULTS: Vaccinated individuals had a lower risk of hospitalization and death compared with unvaccinated individuals. The overall RRadj for hospitalization and death were 0.36 (95%CI 0.32, 0.41) and 0.24 (0.17, 0.33), respectively. When evaluating vaccines individually, the RRadj for hospitalization were as follows Pfizer BioNTech 0.27 (95%CI 0.22, 0.33), Moderna 0.29 (95%CI 0.15, 0.57), Sinovac 0.32 (95%CI 0.25, 0.41), AstraZeneca 0.39 (95%CI 0.34, 0.46), Sputnik 0.39 (95%CI 0.28, 0.53), CanSino 0.41 (95%CI 0.24, 0.7), and Janssen 0.53 (95%CI 0.39, 0.72). The RRadj for death were as follows: Pfizer BioNTech 0.12 (95%CI 0.07, 0.19), Sputnik 0.15 (95%CI 0.06, 0.38), Sinovac 0.29 (95%CI 0.16, 0.53), AstraZeneca 0.30 (95%CI 0.20, 0.44), CanSino 0.38 (95%CI 0.1, 1.4), and Janssen 0.50 (95%CI 0.26, 0.97). CONCLUSION: Covid-19 vaccines significantly reduced the risk of severe disease during the Omicron wave in Mexico.

SARS-CoV-2 seroprevalence and vaccine coverage from August to November 2021: A nationally representative survey in Mexico.

We aimed to estimate self-reported vaccine coverage and SARS-CoV-2 anti-N and anti-S seroprevalence in Mexico overall and for five vaccine types. We used a nationally representative survey with 7236 dried blood spot samples for adults 18 years and older collected from August to November 2021. Anti-N and anti-S seroprevalence were estimated adjusting for the sensitivity and specificity of the immunoassay test. A multivariate Poisson regression model was used to estimate seroprevalence by vaccine type and by age group adjusting for confounders and test performance. Vaccination coverage was 74%, being higher in women compared to men, high socioeconomic status (SES) compared to low and middle SES, graduates compared to people with high school, and formal workers compared to other employment statuses. Anti-N seroprevalence was 59.2%, compared to 84.1% anti-S seroprevalence. Anti-S seroprevalence was higher for vaccinated than unvaccinated participants. All vaccines were associated with more than 70% anti-S seroprevalence, with the lowest being observed for CoronaVac and Ad5-nCoV. Fully vaccinated participants over 60 years presented a lower seroprevalence (77.6%) compared to younger adults (91.1%), with larger differences for ChAdOx1 and CoronaVac vaccines. Between August and November 2021, three out of four Mexican adults had been vaccinated. Vaccination was associated with a higher positivity to anti-S antibodies. While antibodies do not reflect immunity, our results suggest that booster doses should be offered to people over 60 years of age and to adults who received Ad5-nCoV or CoronaVac as primary vaccination schemes.

Structural and immunological basis of cross-reactivity between dengue and Zika infections: Implications in serosurveillance in endemic regions.

Dengue and Zika are arthropod-borne viral diseases present in more than 100 countries around the world. In the past decade, Zika emerged causing widespread outbreaks in new regions, where dengue has been endemic-epidemic for a long period. The wide and extensive dissemination of the mosquito vectors, Aedes aegypti, and Ae. albopictus, favor the co-existence of both infections in the same regions. Together with an important proportion of asymptomatic infections, similar clinical manifestations, and a short time window for acute infection confirmatory tests, it is difficult to differentially estimate both dengue and Zika incidence and prevalence. DENV and ZIKV flavivirus share high structural similarity, inducing a cross-reactive immune response that leads to false positives in serological tests particularly in secondary infections. This results in overestimation of recent Zika outbreaks seroprevalence in dengue endemic regions. In this review, we address the biological basis underlying DENV and ZIKV structural homology; the structural and cellular basis of immunological cross reactivity; and the resulting difficulties in measuring dengue and Zika seroprevalence. Finally, we offer a perspective about the need for more research to improve serological tests performance.

Diagnosis of bacterial meningitis caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae using a multiplex real-time PCR technique.

Bacterial meningitis is one of the diseases that, despite the introduction of several vaccines, remains a serious public health concern. Streptococcus pneumoniae (Spn), Neisseria meningitidis (Nm), and Haemophilus influenzae (Hi) are responsible for most cases diagnosed in children, adolescents, and adult population. Rapid, sensitive, and specific laboratory assays are critical for effective diagnosis and treatment, particularly in countries like Mexico in which culture positivity rates are very low due to the use of antibiotics prior to sample collection and to delay in transporting samples to the laboratory. The aim of this study was to evaluate the use of real-time polymerase chain reaction (RT-PCR) of cerebrospinal fluid (CSF) as a rapid diagnostic test for bacterial meningitis and compare these results with bacterial culture in three general hospitals in Mexico. During a 5-year period (2014-2018), a total of 512 CSF samples obtained from patients in whom infectious meningitis was suspected as initial clinical diagnosis were tested with RT-PCR with species-specific targets for the three pathogens. For Spn, 5.07% samples were RT-PCR positive; 0.39% for Nm and none for Hi. Only five RT-PCR Spn positive samples had a positive culture. Sensitivity and specificity estimates for RT-PCR are 100% and 95.46%, respectively. DNA amplification methods can provide better sensitive diagnostic tests than the reference standard, which is culture, particularly when antimicrobial treatment is initiated before clinical samples can be obtained.

Metodología de la Encuesta Nacional de Salud y Nutrición 2022 y Planeación y diseño de la Ensanut Continua 2020-2024.

OBJETIVO: Presentar el diseño de la Encuesta Nacional de Salud y Nutrición (Ensanut) 2022 y cuantificar el avance de la Ensanut Continua 2020-2024. Material y métodos. La Ensanut 2022 es la tercera encuesta de la serie de en-cuestas denominada Ensanut Continua 2020-2024. En este documento se describe el alcance de la Ensanut 2022 y sus procedimientos de muestreo, medición y organización logís-tica. Además, se presenta el avance esperado de la Ensanut Continua 2020-2024 al concluir la Ensanut 2022. Resulta-dos. La Ensanut 2022 obtendrá, a nivel nacional, al menos 10 160 entrevistas completas de hogar y 9 441 resultados de seropositividad a SARS-CoV-2. CONCLUSIONES: La Ensanut 2022 estimará la prevalencia de seropositividad a SARS-CoV-2 a nivel nacional y regional y avanzará en la acumulación de información para alcanzar los objetivos de la Ensanut Con-tinua 2020-2024.

Spatiotemporal patterns of dengue and Zika incidence during the 2015-2018 outbreak of Zika in Mexico.

OBJECTIVE: Evaluate spatially and temporally simultaneous presence of clusters of dengue and Zika clinical cases and their relationship with expected dengue transmission risk. MATERIALS AND METHODS: A classification of dengue risk transmission was carried out for whole country, and spatial autocorrelation analyses to identify clusters of confirmed clinical cases of dengue and Zika from 2015 to 2018 was conducted using Moran's Index statistics. RESULTS: Clusters of both diseases were identified in dengue-high risk munici-palities at the beginning of the outbreak, but, at the end of the outbreak, Zika clusters occurred in dengue low-risk mu-nicipalities. CONCLUSION: This study identified Zika clusters in low-risk dengue areas suggesting participation of several factors that favor virus introduction and dissemination, such as differences in entomological and control interventions, and the possibility of cross-immunity in the population.

Antimicrobial Resistance Patterns and Clonal Distribution of E. coli, Enterobacter spp. and Acinetobacter spp. Strains Isolated from Two Hospital Wastewater Plants.

The objective of this study was to determine the presence and persistence of antimicrobial-resistant enterobacteria and their clonal distribution in hospital wastewater. A descriptive cross-sectional study was carried out in wastewater from two Mexico City tertiary level hospitals. In February and March of 2020, eight wastewater samples were collected and 26 isolates of enterobacteria were recovered, 19 (73.1%) isolates were identified as E. coli, 5 (19.2%) as Acinetobacter spp. and 2 (7.7%) as Enterobacter spp. Antimicrobial susceptibility profiles were performed using the VITEK 2® automated system and bacterial identification was performed by the Matrix-Assisted Laser Desorption/Ionization-Time of Flight mass spectrometry (MALDI-TOF MS®). ESBL genes were detected by polymerase chain reaction (PCR) and clonal distributions of isolates were determined by pulsed-field gel electrophoresis (PFGE). E. coli susceptibility to different classes of antimicrobials was analyzed and resistance was mainly detected as ESBLs and fluoroquinolones. One E. coli strain was resistant to doripenem, ertapenem, imipenem and meropenem. The analysis by PCR showed the presence of specific ß-lactamases resistance genes (blaKPC, blaCTX-M). The PFGE separated the E. coli isolates into 19 different patterns (A-R). PFGE results of Acinetobacter spp. showed the presence of a majority clone A. Surveillance of antimicrobial resistance through hospital wastewater is an important tool for early detection of clonal clusters of clinically important bacteria with potential for dissemination.

Antimicrobial resistance: One Health approach.

In this research, a review of antimicrobial resistance (AMR) is conducted as part of the One Health approach. A review of publications, which included "antimicrobial resistance" and "One Health," was conducted. Among the global health problems, AMR is the one that most clearly illustrates the One Health approach. AMR is a critical global problem affecting humans, the environment, and animals. This is related to each of these three components due to the irresponsible and excessive use of antimicrobials in various sectors (agriculture, livestock, and human medicine). Improper management of antimicrobials, inadequate control of infections, agricultural debris, pollutants in the environment, and migration of people and animals infected with resistant bacteria facilitate the spread of resistance. The study aimed to analyze the problem of AMR from a health perspective to analyze the different actors involved in One Health.

Surveillance of Antimicrobial Resistance in Hospital Wastewater: Identification of Carbapenemase-Producing Klebsiella spp.

The objective of this study was to investigate the presence and persistence of carbapenemase-producing Klebsiella spp. isolated from wastewater and treated wastewater from two tertiary hospitals in Mexico. We conducted a descriptive cross-sectional study in two hospital wastewater treatment plants, which were sampled in February 2020. We obtained 30 Klebsiella spp. isolates. Bacterial identification was carried out by the Matrix-Assisted Laser Desorption/Ionization-Time of Flight mass spectrometry (MALDI-TOF MS®) and antimicrobial susceptibility profiles were performed using the VITEK2® automated system. The presence of carbapenem resistance genes (CRGs) in Klebsiella spp. isolates was confirmed by PCR. Molecular typing was determined by pulsed-field gel electrophoresis (PFGE). High rates of Klebsiella spp. resistance to cephalosporins and carbapenems (80%) were observed in isolates from treated wastewater from both hospitals. The molecular screening by PCR showed the presence of blaKPC and blaOXA-48-like genes. The PFGE pattern separated the Klebsiella isolates into 19 patterns (A-R) with three subtypes (C1, D1, and I1). Microbiological surveillance and identification of resistance genes of clinically important pathogens in hospital wastewater can be a general screening method for early determination of under-detected antimicrobial resistance profiles in hospitals and early warning of outbreaks and difficult-to-treat infections.

Nationally representative SARS-CoV-2 antibody prevalence estimates after the first epidemic wave in Mexico.

Seroprevalence surveys provide estimates of the extent of SARS-CoV-2 infections in the population, regardless of disease severity and test availability. In Mexico in 2020, COVID-19 cases reached a maximum in July and December. We aimed to estimate the national and regional seroprevalence of SARS-CoV-2 antibodies across demographic and socioeconomic groups in Mexico after the first wave, from August to November 2020. We used nationally representative survey data including 9,640 blood samples. Seroprevalence was estimated by socioeconomic and demographic characteristics, adjusting by the sensitivity and specificity of the immunoassay test. The national seroprevalence of SARS-CoV-2 antibodies was 24.9% (95%CI 22.2, 26.7), being lower for adults 60 years and older. We found higher seroprevalence among urban and metropolitan areas, low socioeconomic status, low education and workers. Among seropositive people, 67.3% were asymptomatic. Social distancing, lockdown measures and vaccination programs need to consider that vulnerable groups are more exposed to the virus and unable to comply with lockdown measures.

SARS-CoV-2 infection fatality rate after the first epidemic wave in Mexico.

BACKGROUND: Estimates of SARS-CoV-2 infection fatality rates (IFRs) in developing countries remain poorly characterized. Mexico has one of the highest reported COVID-19 case-fatality rates worldwide, although available estimates do not consider serologic assessment of prior exposure nor all SARS-CoV-2-related deaths. We aimed to estimate sex- and age-specific IFRs for SARS-CoV-2 in Mexico. METHODS: The total number of people in Mexico with evidence of prior SARS-CoV-2 infection was derived from National Survey of Health and Nutrition-COVID-19 (ENSANUT 2020 Covid-19)-a nationally representative serosurvey conducted from August to November 2020. COVID-19 mortality data matched to ENSANUT's dates were retrieved from the death-certificate registry, which captures the majority of COVID-19 deaths in Mexico, and from the national surveillance system, which covers the subset of COVID-19 deaths that were identified by the health system and were confirmed through a positive polymerase chain reaction test. We analysed differences in IFRs by urbanization and region. RESULTS: The national SARS-CoV-2 IFR was 0.47% (95% CI 0.44, 0.50) using death certificates and 0.30% (95% CI 0.28, 0.33) using surveillance-based deaths. The IFR increased with age, being close to zero at age <30 years, but increasing to 1% at ages 50-59 years in men and 60-69 years in women, and being the highest at ≥80 years for men (5.88%) and women (6.23%). Across Mexico's nine regions, Mexico City (0.99%) had the highest and the Peninsula (0.26%) the lowest certificate-based IFRs. Metropolitan areas had higher certificate-based IFR (0.63%) than rural areas (0.17%). CONCLUSION: After the first wave of the COVID-19 pandemic, the overall IFR in Mexico was comparable with those of European countries. The IFR in Mexico increased with age and was higher in men than in women. The variations in IFRs across regions and places of residence within the country suggest that structural factors related to population characteristics, pandemic containment and healthcare capabilities could have influenced lethality at the local level.

Molecular and Genomic Insights of mcr-1-Producing Escherichia coli Isolates from Piglets.

The use of colistin in food-producing animals favors the emergence and spread of colistin-resistant strains. Here, we investigated the occurrence and molecular mechanisms of colistin resistance among E. coli isolates from a Mexican piglet farm. A collection of 175 cephalosporin-resistant colonies from swine fecal samples were recovered. The colistin resistance phenotype was identified by rapid polymyxin test and the mcr-type genes were screened by PCR. We assessed the colistin-resistant strains by antimicrobial susceptibility test, pulse-field gel electrophoresis, plasmid profile, and mating experiments. Whole-Genome Sequencing data was used to explore the resistome, virulome, and mobilome of colistin-resistant strains. A total of four colistin-resistant E. coli were identified from the cefotaxime-resistant colonies. All harbored the plasmid-borne mcr-1 gene, which was located on conjugative 170-kb IncHI-2 plasmid co-carrying ESBLs genes. Thus, high antimicrobial resistance rates were observed for several antibiotic families. In the RC2-007 strain, the mcr-1 gene was located as part of a prophage carried on non-conjugative 100-kb-plasmid, which upon being transformed into K. variicola strain increased the polymyxin resistance 2-fold. The genomic analysis showed a broad resistome and virulome. Our findings suggest that colistin resistance followed independent acquisition pathways as clonal and non-genetically related mcr-1-harboring strains were identified. These E. coli isolates represent a reservoir of antibiotic resistance and virulence genes in animals for human consumption which could be potentially propagated into other interfaces.