Enrichment of effector memory T cells in the CD4 and CD8 T cell compartment during chronic graft versus host disease in children.

BACKGROUND: During allogeneic Hematopoietic stem cell transplantation (HSCT), frequent pathological scenarios include graft versus host disease (GVHD) and viral infections. We hypothesized if exogenous stimulus as alloantigen and viral antigens might impact on central and effector memory T cells in pediatric recipients. PATIENTS AND METHODS: Subjects included 21 pediatric recipients and 20 healthy children (control group). Peripheral blood samples of patients were collected along the first 712 days post-HSCT. T cell phenotyping of naïve, central, and effector memory T cells (TCMs and TEMs, respectively) was conducted using flow cytometry. Viral nucleic acids were detected using real-time PCR. RESULTS: T cell reconstitution was not reached after 1 year post-HSCT. Chronic GVHD was associated with increased numbers of naïve CD4 T cells (p < 0.05) as well as an increase in TEM and TCM cells of the CD4 (p < 0.0001 and p < 0.05, respectively) and CD8 T cell TEM (p < 0.0001). and TCM (p < 0.001) populations too. Moreover, BK and Epstein-Barr viruses were the main viral pathogens detected (<104 copies), which were associated with a decrease in all T cell compartments. CONCLUSION: During chronic GVHD, alloantigen persistence generates TEM cell enrichment among CD4 and CD8 T cells, and viral infections are associated with deficient recovery of T cells after HSCT.

Frequency of respiratory virus-associated infection among children and adolescents from a tertiary-care hospital in Mexico City.

Acute respiratory infections (ARIs) are a major cause of morbidity and mortality among children. The causative pathogens show geographic and seasonal variations. We retrospectively evaluated the frequency and seasonality of respiratory pathogens in children and adolescents (age: 0-19 years) with ARIs treated between January 1, 2021, and March 31, 2022, at a single center in Mexico. Out of 2400 patients, 1,603 were diagnosed with SARS-CoV-2 infection and 797 were diagnosed with other common respiratory pathogens (CRPs). Of the 797 patients, 632 were infected with one CRP and 165 with > 2 CRPs. Deaths occurred only in SARS-CoV-2-infected patients. Rhinovirus/Enterovirus, respiratory syncytial virus B, and parainfluenza virus 3 were the most prevalent in cases with single and multiple infections. CRP showed a high frequency between autumn and winter of 2021, with higher incidence of hospitalization compared to COVID-19. The main comorbidities were immunosuppression, cardiovascular disease (CD), and asthma. The frequency of CRPs showed a downward trend throughout the first half of 2021. CRPs increased in single- and co-infection cases between the fourth and fifth waves of COVID-19, probably due to decreased nonpharmaceutical interventions and changes in diagnostic tests. Age, cyanosis (symptom), and immunosuppression (comorbidity) were found to differentiate between SARS-CoV-2 infection and CRP infection.

Vitamin D levels in the pre- and post-COVID-19 pandemic periods in pediatric patients with chronic kidney disease.

Introduction: Vitamin D (VD) deficiency is common in children with chronic kidney disease (CKD) because of multiple factors. During the coronavirus disease 2019 (COVID-19) pandemic, it increased because of medicine shortage and no enough medical service for patients with non-COVID-19 diseases. Objective: To analyze the effects of the COVID-19 pandemic-related lockdown on the serum levels and status of 25-hydroxyvitamin D3 (25-[OH]D) in children with CKD. Materials and methods: This retrospective study included patients (6-18 years old) who were diagnosed with CKD stage 2-5 and routinely measured for serum VD levels between May 2019 and December 2022. Serum 25-(OH)D levels were measured before, during, and after the pandemic (2019, 2020-2021, and 2022, respectively). The daily dose of cholecalciferol supplementation and the readjustment (if required) were recorded. Results: This study included 171 patients (median age: 12 years). Before the pandemic, the median serum VD level was 25.0 ng/mL (19.3% VD deficiency). Then, VD supplementation was adjusted to 400-1,200 UI daily in 98.8% (n = 169) of patients. During the pandemic, the median VD level decreased to 22.5 ng/mL (43.3% VD deficiency). Hence, the supplementation was readjusted, and after the pandemic, the level was 28.7 ng/mL (18.7% VD deficiency), indicating a statistically significant increase in serum VD levels from the prepandemic period (p = 0.007). Conclusion: Decreased serum VD levels and increased VD deficiency frequency were observed in patients with CKD during the COVID-19 but improved after readjustment of supplementation.

Behavior of immunoglobulin G antibodies for SARS-COV-2 in Mexican pediatric patients with comorbidities: a prospective comparative cohort study.

Background: More than two years after the pandemic of COVID-19 caused by the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) there is a great lack of information. The presence of immunoglobulin G (IgG) have been related with disease severity. Patients with comorbidities could develop more severe infection; however, the evaluation of the humoral response in pediatric population are needed especially in patients with comorbidities. Our aim was to describe the behavior of IgG in pediatric patients and to know if there is a difference between patients with comorbidities. Methods: A prospective comparative cohort study was carried out in a single center from June 2020 to January 2021, with a follow-up of 6 months. The study included all the subjects with confirmatory test for SARS-CoV-2 from 1 month to 17 years 11 months, the follow-up of the disease's evolution and measurement of IgG antibodies was collected. We obtained the clinical data, and comorbidities like arterial hypertension, diabetes, obesity, and cancer, the initial symptoms were recorded as well as the evolution regarding the severity of COVID-19 and the need for hospitalization, intensive care unit or mechanical ventilation. The follow up was carried out through medical consultation with an appointment every month that included direct interrogation, examination, and peripheral blood collection for the IgG quantification. The antibodies detection was done through peripheral blood and chemiluminescence microparticle immunoassay. Results: A total of 237 patients with positive polymerase chain reaction (PCR) for SARS-COV-2 were included, of which 147 presented IgG antibodies (62%), 112 (76%) without comorbidity and 35 (24%) with comorbidities, by the sixth month only 2.7% continue with positive antibody measurements. Patients with comorbidities reach higher IgG levels than patients without comorbidities the basal titters were: 5.17 for patients without comorbidities vs. 6.96 for the group with comorbidities (P<0.001). Conclusions: We found an association between the presence of comorbidities and high levels of IgG units in pediatric patients with COVID-19. Additionally, patients with more severe course of the disease have higher levels of IgG and by the third month less than 35% have immunity.

Myosin 1g as a high-risk biomarker in a pediatric patient with lineage switch from acute lymphoblastic leukemia to myeloid phenotype.

BACKGROUND: Myosin 1g (Myo1g) has recently been identified as a potential diagnostic biomarker in childhood acute lymphocytic leukemia (ALL). CASE REPORT: We describe the case of a 1-year-old Mexican female patient. Although initially studied for hepatomegaly, an infectious or genetic etiology was excluded. Liver biopsy showed infiltration by neoplastic B-cell precursors (BCPs), and bone marrow (BM) aspirate showed 14.5% of BCPs. In a joint session of the oncology, hematology, and pathology departments, low-risk (LR) BCP-ALL of hepatic origin with aberrant myeloid markers was diagnosed. Although treatment was initiated, the patient presented early with BM relapse. Modest overexpression of Myo1g was observed from the onset. However, at the end of the steroid window, expression increased significantly and remained elevated during this first relapse to BM. The parents refused hematopoietic stem cell transplantation, but she continued chemotherapy. After a second BM relapse at 5 years of age, the phenotype switched to myeloid. Her parents then opted for palliative care, and the patient died two months later at home. CONCLUSIONS: This case shows the potential use of Myo1g in clinical practice as a high-risk indicator. Myo1g monitoring may reveal a high risk and relapse trend, even when typical parameter values are not altered: Myo1g could be used to classify patients from low to high risk from diagnosis, allowing patients to promptly receive the best treatment and potentially modifying prognosis and survival.

INTRODUCCIÓN: Recientemente se ha identificado a miosina 1g (Myo1g) como un potencial biomarcador de diagnóstico en la leucemia linfoblástica aguda (LLA) infantil. CASO CLÍNICO: Se describe el caso de una paciente mexicana de 1 año de edad. Aunque inicialmente se estudió por hepatomegalia, se descartó una etiología infecciosa o genética. La biopsia hepática mostró infiltración por precursores de células B neoplásicas (PCB) y un aspirado de médula ósea (MO) mostró 14.5% de PCB. En una sesión conjunta de los departamentos de oncología, hematología y patología, se diagnosticó PCB-LLA de bajo riesgo de origen hepático con marcadores mieloides aberrantes. Aunque se inició tratamiento, la paciente presentó tempranamente recaída de MO. Se observó una modesta sobreexpresión de Myo1g. Sin embargo, al final de la ventana de esteroides, la expresión aumentó considerablemente y permaneció elevada durante esta primera recaída a MO. El trasplante de células madre hematopoyéticas fue rechazado por los padres, pero se continuó con la quimioterapia. Tras una segunda recaída de MO a los 5 años, el fenotipo cambió a mieloide. Sus padres optaron entonces por cuidados paliativos y la paciente falleció dos meses después en su domicilio. CONCLUSIONES: Este caso muestra el potencial uso de Myo1g como indicador de alto riesgo en la práctica clínica. El seguimiento de Myo1g puede revelar una tendencia de alto riesgo y recaídas, incluso cuando los valores de los parámetros rutinarios son aparentemente normales; Myo1g podría utilizarse para clasificar a los pacientes de bajo a alto riesgo desde el diagnóstico, lo que permitiría que los pacientes reciban el mejor tratamiento de manera oportuna, modificando potencialmente el pronóstico y la supervivencia.

Myosin 1g as a high-risk biomarker in a pediatric patient with lineage switch from acute lymphoblastic leukemia to myeloid phenotype / Miosina 1g como un marcador de alto riesgo en una paciente pediátrica con cambio de linaje de leucemia linfoblástica aguda a fenotipo mieloide

Abstract Background: Myosin 1g (Myo1g) has recently been identified as a potential diagnostic biomarker in childhood acute lymphocytic leukemia (ALL). Case report: We describe the case of a 1-year-old Mexican female patient. Although initially studied for hepatomegaly, an infectious or genetic etiology was excluded. Liver biopsy showed infiltration by neoplastic B-cell precursors (BCPs), and bone marrow (BM) aspirate showed 14.5% of BCPs. In a joint session of the oncology, hematology, and pathology departments, low-risk (LR) BCP-ALL of hepatic origin with aberrant myeloid markers was diagnosed. Although treatment was initiated, the patient presented early with BM relapse. Modest overexpression of Myo1g was observed from the onset. However, at the end of the steroid window, expression increased significantly and remained elevated during this first relapse to BM. The parents refused hematopoietic stem cell transplantation, but she continued chemotherapy. After a second BM relapse at 5 years of age, the phenotype switched to myeloid. Her parents then opted for palliative care, and the patient died two months later at home. Conclusions: This case shows the potential use of Myo1g in clinical practice as a high-risk indicator. Myo1g monitoring may reveal a high risk and relapse trend, even when typical parameter values are not altered: Myo1g could be used to classify patients from low to high risk from diagnosis, allowing patients to promptly receive the best treatment and potentially modifying prognosis and survival.

Resumen Introducción: Recientemente se ha identificado a miosina 1g (Myo1g) como un potencial biomarcador de diagnóstico en la leucemia linfoblástica aguda (LLA) infantil. Caso clínico: Se describe el caso de una paciente mexicana de 1 año de edad. Aunque inicialmente se estudió por hepatomegalia, se descartó una etiología infecciosa o genética. La biopsia hepática mostró infiltración por precursores de células B neoplásicas (PCB) y un aspirado de médula ósea (MO) mostró 14.5% de PCB. En una sesión conjunta de los departamentos de oncología, hematología y patología, se diagnosticó PCB-LLA de bajo riesgo de origen hepático con marcadores mieloides aberrantes. Aunque se inició tratamiento, la paciente presentó tempranamente recaída de MO. Se observó una modesta sobreexpresión de Myo1g. Sin embargo, al final de la ventana de esteroides, la expresión aumentó considerablemente y permaneció elevada durante esta primera recaída a MO. El trasplante de células madre hematopoyéticas fue rechazado por los padres, pero se continuó con la quimioterapia. Tras una segunda recaída de MO a los 5 años, el fenotipo cambió a mieloide. Sus padres optaron entonces por cuidados paliativos y la paciente falleció dos meses después en su domicilio. Conclusiones: Este caso muestra el potencial uso de Myo1g como indicador de alto riesgo en la práctica clínica. El seguimiento de Myo1g puede revelar una tendencia de alto riesgo y recaídas, incluso cuando los valores de los parámetros rutinarios son aparentemente normales; Myo1g podría utilizarse para clasificar a los pacientes de bajo a alto riesgo desde el diagnóstico, lo que permitiría que los pacientes reciban el mejor tratamiento de manera oportuna, modificando potencialmente el pronóstico y la supervivencia.

Chronic Comorbidities in Middle Aged Patients Contribute to Ineffective Emergency Hematopoiesis in Covid-19 Fatal Outcomes.

BACKGROUND AND AIMS: Mexico is among the countries with the highest estimated excess mortality rates due to the COVID-19 pandemic, with more than half of reported deaths occurring in adults younger than 65 years old. Although this behavior is presumably influenced by the young demographics and the high prevalence of metabolic diseases, the underlying mechanisms have not been determined. METHODS: The age-stratified case fatality rate (CFR) was estimated in a prospective cohort with 245 hospitalized COVID-19 cases, followed through time, for the period October 2020-September 2021. Cellular and inflammatory parameters were exhaustively investigated in blood samples by laboratory test, multiparametric flow cytometry and multiplex immunoassays. RESULTS: The CFR was 35.51%, with 55.2% of deaths recorded in middle-aged adults. On admission, hematological cell differentiation, physiological stress and inflammation parameters, showed distinctive profiles of potential prognostic value in patients under 65 at 7 days follow-up. Pre-existing metabolic conditions were identified as risk factors of poor outcomes. Chronic kidney disease (CKD), as single comorbidity or in combination with diabetes, had the highest risk for COVID-19 fatality. Of note, fatal outcomes in middle-aged patients were marked from admission by an inflammatory landscape and emergency myeloid hematopoiesis at the expense of functional lymphoid innate cells for antiviral immunosurveillance, including NK and dendritic cell subsets. CONCLUSIONS: Comorbidities increased the development of imbalanced myeloid phenotype, rendering middle-aged individuals unable to effectively control SARS-CoV-2. A predictive signature of high-risk outcomes at day 7 of disease evolution as a tool for their early stratification in vulnerable populations is proposed.

Leukocyte surface expression of the endoplasmic reticulum chaperone GRP78 is increased in severe COVID-19.

Hyperinflammation present in individuals with severe COVID-19 has been associated with an exacerbated cytokine production and hyperactivated immune cells. Endoplasmic reticulum stress leading to the unfolded protein response has been recently reported as an active player in inducing inflammatory responses. Once unfolded protein response is activated, GRP78, an endoplasmic reticulum-resident chaperone, is translocated to the cell surface (sGRP78), where it is considered a cell stress marker; however, its presence has not been evaluated in immune cells during disease. Here we assessed the presence of sGRP78 on different cell subsets in blood samples from severe or convalescent COVID-19 patients. The frequency of CD45+sGRP78+ cells was higher in patients with the disease compared to convalescent patients. The latter showed similar frequencies to healthy controls. In patients with COVID-19, the lymphoid compartment showed the highest presence of sGRP78+ cells versus the myeloid compartment. CCL2, TNF-α, C-reactive protein, and international normalized ratio measurements showed a positive correlation with the frequency of CD45+sGRP78+ cells. Finally, gene expression microarray data showed that activated T and B cells increased the expression of GRP78, and peripheral blood mononuclear cells from healthy donors acquired sGRP78 upon activation with ionomycin and PMA. Thus, our data highlight the association of sGRP78 on immune cells in patients with severe COVID-19.

Presence of antibodies against HLA class I and class II molecules in children before and after allo-HSCT. Alloantibodies before and after HSCT.

A severe complication of allogeneic hematopoietic stem cell transplantation (HSCT) is graft failure (GF). Among others, donor-specific anti-HLA antibodies (DSA) are associated with graft rejection after allogeneic or haploidentical transplantation in adults. Knowledge of DSA and pediatric recipients is limited. Hence, we aimed to generate more information about the presence of DSA (pre- and post-HSCT) and the clinical outcomes (graft rejection and poor function) in children. We identified DSA in 27% of the patients. We observed a higher frequency (50%) of DSA-bearing patients with a benign disease diagnosis than those diagnosed with leukemia (16.66%). We observed graft rejection in one patient (with DSA against two alleles of HLA class I molecules) and poor function in three recipients during the first 30 days after HSCT in the absence of DSA. The presence of donor and nondonor HLA-specific antibodies decreased substantially after transplantation. After the transplant, we identified two patients with DSA specific for HLA class I molecules (independent of clinical relevance), and four recipients showed PGF in the absence of DSA. We were unable to establish any association between the presence of DSA and a clinical outcome: graft failure or prevalence of viral infection.

The evaluation of liver dysfunction and oxidative stress due to urban environmental pollution in Mexican population related to Madin Dam, State of Mexico: a pilot study.

One of the most important causes of disease and premature death in the world is environmental pollution. The presence of pollutants in both water and air contributes to the deterioration of the health of human populations. The Mexico City Metropolitan Area is one of the most populous and affected by air pollution worldwide; in addition, in recent years there has been a growing demand for water, so urban reservoirs such as the Madin dam are vital to meet the demand. However, this reservoir is highly polluted due to the urban settlements around it. Therefore, the aim of the present study was to evaluate oxidative stress in clinically healthy subjects by means of the degree of lipoperoxidation, as well as the modification of serum enzyme levels, such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase associated with air and drinking water pollutants from three zones of the Mexico City Metropolitan Area, two of them related to Madin Dam. This descriptive cross-sectional study was conducted between March 2019 and September 2021 in 142 healthy participants (age range 18-65 years). Healthy subjects were confirmed by their medical history. The results showed that chronic exposure to air (SO2) and water pollutants (Al and Fe) was significantly associated with elevated levels of lipoperoxidation. There was evidence that contamination from the Madín dam can generate oxidative stress and affect the health status of people who receive water from this reservoir or who consume fish that inhabit it.

Effects of Carbonated Beverage Consumption on Oral pH and Bacterial Proliferation in Adolescents: A Randomized Crossover Clinical Trial.

Sugary soft drinks modify salivary pH and favor bacterial proliferation and are associated with the development of caries. Information on the effects of consuming carbonated drinks without sucrose is limited. Methods: In this crossover clinical trial, salivary and dental biofilm pH were determined at 0, 5, 10, 15, 30, 45, and 60 min after the participants (n = 18) ingested a soft drink with sucrose, a soft drink with aspartame/acesulfame K, carbonated water, and plain water on different days. Dental biofilm cultures were conducted at 0- and 120-min. Results: Salivary pH decreased significantly after ingestion of the sucrose-containing soft drink when compared with the other types of beverages (median difference, -0.3--0.4, p ≤ 0.05), and the greatest difference was found with mineral water. A greater bacterial proliferation (Colony Forming Units [CFU]) was observed after ingestion of the drink with sucrose (↑310 × 103 CFU, p ≤ 0.01), followed by the drink with aspartame/acesulfame K (↑160 × 103 CFU, p ≤ 0.01) and carbonated water (↑60 × 103 CFU, p ≤ 0.05). No significant changes in bacterial proliferation were observed after the consumption of natural water. Conclusions: Ingestion of sucrose-containing soft drinks favors the acidification of salivary pH and the bacterial proliferation of dental biofilm. Although to a lesser extent, soft drinks containing aspartame/acesulfame K also favor bacterial proliferation.

Clinical Characteristics of Coronavirus Disease (COVID-19) in Mexican Children and Adolescents.

BACKGROUND: We analyzed the demographic, clinical, and diagnostic data of children and adolescents in Mexico, from the first case of coronavirus disease (COVID-19) to 28 February 2022. METHODS: Using the open databases of the Ministry of Health and a tertiary pediatric hospital, we obtained demographic and clinical data from the beginning of the COVID-19 pandemic until 28 February 2022. In addition, quantitative reverse-transcription polymerase chain reaction outputs were used to determine the viral load, and structural protein-based serology was performed to evaluate IgG antibody levels. RESULTS: Of the total 437,832 children and adolescents with COVID-19, 1187 died. Of these patients, 1349 were admitted to the Hospital Infantil de Mexico Federico Gómez, and 11 died. Obesity, asthma, and immunosuppression were the main comorbidities, and fever, cough, and headache were the main symptoms. In this population, many patients have a low viral load and IgG antibody levels. CONCLUSION: During the first 2 years of the COVID-19 pandemic in Mexico, children and adolescents had low incidence and mortality. They are a heterogeneous population, but many patients had comorbidities such as obesity, asthma, and immunosuppression; symptoms such as fever, cough, and headache; and low viral load and IgG antibodies.

Efficacy and safety of vitamin D supplementation in hospitalized COVID-19 pediatric patients: A randomized controlled trial.

Background: Some studies suggested that adequate levels of vitamin D (VD) decrease the risk of severe COVID-19. Information about the effectiveness of VD supplementation in children is scarce. Objective: To assess the efficacy and safety of VD supplementation compared to the standard of care in hospitalized children with COVID-19. Patients and methods: An open-label randomized controlled single-blind clinical trial was carried out. We included patients from 1 month to 17 years, with moderate COVID-19, who required hospitalization and supplemental oxygen. They were randomized into two groups: the VD group, which received doses of 1,000 (children < 1 year) or 2,000 IU/day (from 1 to 17 years) and the group without VD (control). The outcome variables were the progression of oxygen requirement, the development of complications, and death. Statistical analysis: For comparison between groups, we used the chi-squared test or Fisher's exact test and the Mann-Whitney U test. Absolute risk reduction (ARR) and the number needed to treat (NNT) were calculated. p ≤ 0.05 was considered statistically significant. Results: From 24 March 2020 to 31 March 2021, 87 patients were eligible to participate in the trial; 45 patients were randomized: 20 to the VD group and 25 to the control group. There was no difference in general characteristics at baseline, including serum VD levels (median 13.8 ng/ml in the VD group and 11.4 ng/ml in the control group). Outcomes: 2/20 (10%) in the VD group vs. 9/25 (36%) in the control group progressed to a superior ventilation modality (p = 0.10); one patient in the VD group died (5%) compared to 6 (24%) patients in the control group (p = 0.23). ARR was 26% (95% CI 8.8 to 60.2%) and NNT was 3 (2 to 11) for progression and ARR was 19% (95% CI -3.9 to 42.8%) and NNT was 6 (2 to 26) for death. None of the patients receiving VD had adverse effects. The trial was stopped for ethical reasons; since after receiving the results of the basal VD values, none of the patients had normal levels. Conclusion: In this trial, VD supplementation in pediatric patients seems to decrease the risk of COVID-19 progression and death. More studies are needed to confirm these findings. Clinical Trial Registration: This protocol was registered on ClinicalTrials.gov with the registration number NCT04502667.

Clinical features and severe acute respiratory syndrome-coronavirus-2 structural protein-based serology of Mexican children and adolescents with coronavirus disease 2019.

Severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 infection in children and adolescents primarily causes mild or asymptomatic coronavirus disease 2019 (COVID-19), and severe illness is mainly associated with comorbidities. However, the worldwide prevalence of COVID-19 in this population is only 1%-2%. In Mexico, the prevalence of COVID-19 in children has increased to 10%. As serology-based studies are scarce, we analyzed the clinical features and serological response (SARS-CoV-2 structural proteins) of children and adolescents who visited the Hospital Infantil de México Federico Gómez (October 2020-March 2021). The majority were 9-year-old children without comorbidities who were treated as outpatients and had mild-to-moderate illness. Children aged 6-10 years and adolescents aged 11-15 years had the maximum number of symptoms, including those with obesity. Nevertheless, children with comorbidities such as immunosuppression, leukemia, and obesity exhibited the lowest antibody response, whereas those aged 1-5 years with heart disease had the highest levels of antibodies. The SARS-CoV-2 spike receptor-binding domain-localized peptides and M and E proteins had the best antibody response. In conclusion, Mexican children and adolescents with COVID-19 represent a heterogeneous population, and comorbidities play an important role in the antibody response against SARS-CoV-2 infection.

New Variants of Pseudomonas aeruginosa High-Risk Clone ST233 Associated with an Outbreak in a Mexican Paediatric Hospital.

Recent multidrug resistance in Pseudomonas aeruginosa has favoured the adaptation and dissemination of worldwide high-risk strains. In June 2018, 15 P. aeruginosa strains isolated from patients and a contaminated multi-dose meropenem vial were characterized to assess their association to an outbreak in a Mexican paediatric hospital. The strains were characterized by antibiotic susceptibility profiling, virulence factors' production, and biofilm formation. The clonal relationship among isolates was determined with pulse-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) sequencing. Repressor genes for the MexAB-OprM efflux pump were sequenced for haplotype identification. Of the strains, 60% were profiled as extensively drug-resistant (XDR), 33% as multidrug-resistant (MDR), and 6.6% were classified as sensitive (S). All strains presented intermediate resistance to colistin, and 80% were sensitive to aztreonam. Pyoverdine was the most produced virulence factor. The PFGE technique was performed for the identification of the outbreak, revealing eight strains with the same electrophoretic pattern. ST235 and ten new sequence types (STs) were identified, all closely related to ST233. ST3241 predominated in 26.66% of the strains. Twenty-five synonymous and seventeen nonsynonymous substitutions were identified in the regulatory genes of the MexAB-OprM efflux pump, and nalC was the most variable gene. Six different haplotypes were identified. Strains from the outbreak were metallo-ß-lactamases and phylogenetically related to the high-risk clone ST233.

Herpesvirus Screening in Childhood Hematopoietic Transplant Reveals High Systemic Inflammation in Episodes of Multiple Viral Detection and an EBV Association with Elevated IL-1ß, IL-8 and Graft-Versus-Host Disease.

Infections remain a major cause of morbidity and mortality among hematopoietic stem cell transplant (HSCT) recipients. Unlike Epstein-Barr Virus (EBV) and Human Cytomegalovirus (HCMV), Human Herpesvirus (HHV) 6, HHV7 and HHV8 are not routinely monitored in many centers, especially in the pediatric population of low-medium income countries. We screened EBV, HCMV, HHV6, HHV7 and HHV8 in 412 leukocytes-plasma paired samples from 40 pediatric patients assisted in a tertiary hospital in Mexico. Thirty-two underwent allo-HSCT, whereas eight received auto-HSCT. Overall viral detection frequencies in allo- and auto-HSCT were: EBV = 43.7% and 30.0%, HCMV = 5.0% and 6.7%, HHV6 = 7.9% and 20.0% and HHV7 = 9.7% and 23.3%. HHV8 was not detected in any sample. Interestingly, HHV6 and HHV7 were more frequent in auto-HSCT, and HHV6 was observed in all episodes of multiple detection in auto-HSCT patients. We found EBV DNA in plasma samples, whereas HCMV, HHV6 and HHV7 DNA were predominantly observed in leukocytes, indicative of their expansion in cellular compartments. We also found that IL-1ß, IL-2, IL-6 and IL-8 were significantly increased in episodes in which multiple viruses were simultaneously detected, and samples positive for EBV DNA and graft-versus-host disease had a further increase of IL-1ß and IL-8. In conclusion, the EBV, HCMV, HHV6 and HHV7 burdens were frequently detected in allo- and auto-HSCT, and their presence associated with systemic inflammation.

Usefulness of High-Resolution Computed Tomography in Early Diagnosis of Patients with Suspected COVID-19.

BACKGROUND: Diagnosis of coronavirus disease 2019 (COVID-19) is mainly based on molecular testing. General population studies have shown that chest Computed Tomography (CT) can also be useful. OBJECTIVE: The study aims to examine the usefulness of high-resolution chest CT for early diagnosis of patients with suspected COVID-19. DESIGN AND SETTING: This is a cross-sectional study from May 1, 2020, to August 31, 2021, at the COVID Hospital, Mexico City. METHODS: This study examined the clinical, high-resolution chest CT imaging, and laboratory data of 160 patients who were suspected to have COVID-19. Patients with positive Reverse Transcription- Polymerase Chain Reaction (RT-PCR) testing and those with negative RT-PCR testing but clinical data compatible with COVID-19 and positive antibody testing were considered to have COVID-19 (positive). Sensitivity and specificity of CT for diagnosis of COVID-19 were calculated. p < 0.05 was considered significant. RESULTS: Median age of 160 study patients was 58 years. The proportion of patients with groundglass pattern was significantly higher in patients with COVID-19 than in those without COVID (65.1% versus 0%; P = 0.005). COVID-19 was ruled out in sixteen (11.1%). Only four of the 132 patients diagnosed with COVID-19 (3.0%) did not show CT alterations (p < 0.001). Sensitivity and specificity of CT for COVID-19 diagnosis were 96.7% and 42.8%, respectively. CONCLUSIONS: Chest CT can identify patients with COVID-19, as characteristic disease patterns are observed on CT in the early disease stage.

Tracing COVID-19 Source of Infection Among Health Personnel in a Pediatric Hospital.

Health personnel (HP) have been universally recognized as especially susceptible to COVID-19. In Mexico, our home country, HP has one of the highest death rates from the disease. From the beginning of the SARS-CoV-2 pandemic, an office for initial attention for HP and a call center were established at a COVID-19 national reference pediatric hospital, aimed at early detection of COVID-19 cases and stopping local transmission. The detection and call center implementation and operation, and tracing methodology are described here. A total of 1,042 HP were evaluated, with 221 positive cases identified (7.7% of all HP currently working and 26% of the HP tested). Community contagion was most prevalent (46%), followed by other HP (27%), household (14%), and hospitalized patients (13%). Clusters and contact network analysis are discussed. This is one of the first reports that address the details of the implementation process of contact tracing in a pediatric hospital from the perspective of a hybrid hospital with COVID-19 and non-COVID-19 areas.

Efficacy and Safety of Vitamin D Supplementation to Prevent COVID-19 in Frontline Healthcare Workers. A Randomized Clinical Trial.

BACKGROUND: Associations between vitamin D (VD) deficiency and the risk of SARS-CoV-2 infection have been documented in cross-sectional population studies. Intervention studies in patients with moderate to severe COVID-19 have failed to consistently document a beneficial effect. OBJECTIVE: To determine the efficacy and safety of VD-supplementation in the prevention of SARS-CoV-2 infection in highly exposed individuals. METHODS: A double-blind, parallel, randomized trial was conducted. Frontline healthcare workers from four hospitals in Mexico City, who tested negative for SARS-CoV-2 infection, were enrolled between July 15 and December 30, 2020. Participants were randomly assigned to receive 4,000 IU VD (VDG) or placebo (PG) daily for 30 d. RT-PCR tests were taken at baseline and repeated if COVID-19 manifestations appeared during follow-up. Serum 25-hydroxyvitamin D3 and antibody tests were measured at baseline and at day 45. Per-protocol and intention-to-treat analysis were conducted. RESULTS: Of 321 recruited subjects, 94 VDG and 98 PG completed follow-up. SARS-CoV-2 infection rate was lower in VDG than in PG (6.4 vs. 24.5%, p <0.001). The risk of acquiring SARS-CoV-2 infection was lower in the VDG than in the PG (RR: 0.23; 95% CI: 0.09-0.55) and was associated with an increment in serum levels of 25-hydroxyvitamin D3 (RR: 0.87; 95% CI: 0.82-0.93), independently of VD deficiency. No significant adverse events were identified. CONCLUSIONS: Our results suggest that VD-supplementation in highly exposed individuals prevents SARS-CoV-2 infection without serious AEs and regardless of VD status.

Cell surface expression of GRP78 and CXCR4 is associated with childhood high-risk acute lymphoblastic leukemia at diagnostics.

Acute lymphocytic leukemia is the most common type of cancer in pediatric individuals. Glucose regulated protein (GRP78) is an endoplasmic reticulum chaperone that facilitates the folding and assembly of proteins and regulates the unfolded protein response pathway. GRP78 has a role in survival of cancer and metastasis and cell-surface associated GRP78 (sGRP78) is expressed on cancer cells but not in normal cells. Here, we explored the presence of sGRP78 in pediatric B-ALL at diagnosis and investigated the correlation with bona fide markers of leukemia. By using a combination of flow cytometry and high multidimensional analysis, we found a distinctive cluster containing high levels of sGRP78, CD10, CD19, and CXCR4 in bone marrow samples obtained from High-risk leukemia patients, which was absent in the compartment of Standard-risk leukemia. We confirmed that sGRP78+CXCR4+ blood-derived cells were more frequent in High-risk leukemia patients. Finally, we analyzed the dissemination capacity of sGRP78 leukemia cells in a model of xenotransplantation. sGRP78+ cells emigrated to the bone marrow and lymph nodes, maintaining the expression of CXCR4. Testing the presence of sGRP78 and CXCR4 together with conventional markers may help to achieve a better categorization of High and Standard-risk pediatric leukemia at diagnosis.