Comparative Mycobacterium tuberculosis spoligotype distribution in Mexico.

In the present work, we studied the genetic diversity of Mycobacterium tuberculosis clinical isolates from patients according to their gender, age, and geographic location in Mexico. We did not observe any statistically significant differences in regard to age or gender. We found that spoligo international type 53 (SIT53) is more frequent in the northern states and that SIT119 predominates in central Mexico.

Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico.

BACKGROUND: In late March 2009, an outbreak of a respiratory illness later proved to be caused by novel swine-origin influenza A (H1N1) virus (S-OIV) was identified in Mexico. We describe the clinical and epidemiologic characteristics of persons hospitalized for pneumonia at the national tertiary hospital for respiratory illnesses in Mexico City who had laboratory-confirmed S-OIV infection, also known as swine flu. METHODS: We used retrospective medical chart reviews to collect data on the hospitalized patients. S-OIV infection was confirmed in specimens with the use of a real-time reverse-transcriptase-polymerase-chain-reaction assay. RESULTS: From March 24 through April 24, 2009, a total of 18 cases of pneumonia and confirmed S-OIV infection were identified among 98 patients hospitalized for acute respiratory illness at the National Institute of Respiratory Diseases in Mexico City. More than half of the 18 case patients were between 13 and 47 years of age, and only 8 had preexisting medical conditions. For 16 of the 18 patients, this was the first hospitalization for their illness; the other 2 patients were referred from other hospitals. All patients had fever, cough, dyspnea or respiratory distress, increased serum lactate dehydrogenase levels, and bilateral patchy pneumonia. Other common findings were an increased creatine kinase level (in 62% of patients) and lymphopenia (in 61%). Twelve patients required mechanical ventilation, and seven died. Within 7 days after contact with the initial case patients, a mild or moderate influenza-like illness developed in 22 health care workers; they were treated with oseltamivir, and none were hospitalized. CONCLUSIONS: S-OIV infection can cause severe illness, the acute respiratory distress syndrome, and death in previously healthy persons who are young to middle-aged. None of the secondary infections among health care workers were severe.

[Cytochrome P450 and NAT2 polymorphisms and drug metabolism in DOTS]. / Polimorfismos en los genes CYP450 y NAT2 y metabolismo de fármacos para el tratamiento antituberculosis estandarizado.

It has been described an increase of the frequency of Directly Observed Therapy Short-course (DOTS) failure in countries with high rates of mycobacterial drug resistance. This increase could be due to the standardized doses of DOTS results in low or insufficient dosage of drugs in plasma. Several members of cytochrome P450 enzymes superfamily could explain the variations on acetylation velocity and in drug disposition. A population with slow acetylation has a higher risk of toxicity, as that potent inhibition of cytochrome P450 (CYP450) isoforms by isoniazid (CYP2C19 y CYP3A) are dependent of INH plasmatic concentration. This inhibitory effect has been described also for CYP12, CYP2C9 and CYP2E1. INH is metabolized by N-acetyltransferase 2 (NAT2). The wide variability interethnic and intraethnic in acetylation velocity is associated with the polymorphisms of NAT2. Patients with rapid acetylation have plasmatic concentration of INH low or insufficient which induces treatment failure. The study of genotypes of P450 and NAT2 allow us to predict therapeutic and individualized dosages.

Antimicrobial susceptibility patterns of Streptococcus pneumoniae in Mexico.

The susceptibility to 14 beta-lactam and non-beta-lactam antimicrobial agents was evaluated for Streptococcus pneumoniae from patients with community-acquired respiratory infections in a Mexican medical center. Three hundred fifteen pneumococcal isolates obtained from patients between 1995 and 2001 were tested by the broth microdilution test. Fifty-two percent of the isolates were nonsusceptible to penicillin (minimal inhibitory concentration, >0.06 microg/mL). Penicillin-nonsusceptible isolates were more likely to exhibit resistance to cephalosporins, macrolides, ciprofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, and tetracycline when compared to penicillin-susceptible isolates. Ninety-three percent of the penicillin-nonsusceptible isolates were resistant to at least one other class of antimicrobials, in contrast to only 47% of the penicillin-susceptible strains (p < 0.0001). More than 90% of the tested isolates were susceptible to amoxicillin/clavulanate, ceftriaxone, levofloxacin, and gatifloxacin. Reduced susceptibility to penicillin was considered to be a reliable marker for the higher probability of multidrug resistance, thus requiring in vitro tests to guide chemotherapy or the choices of parenteral extended spectrum cephalosporins or newer respiratory quinolones.

Inflammatory profiles in severe pneumonia associated with the pandemic influenza A/H1N1 virus isolated in Mexico City.

The immune mechanisms underlying the pathogenesis of severe pneumonia associated with the A/H1N1 virus are not well known. The objective of this study was to determine whether severe A/H1N1-associated pneumonia can be explained by the emergence of particular T-cell subsets and the cytokines/chemokines they produced, as well as distinct responses to infection. T-cell subset distribution and cytokine/chemokine levels in peripheral blood and bronchoalveolar lavage (BAL) were determined in patients with severe A/H1N1 infection, asymptomatic household contacts, and healthy controls. Cytokine and chemokine production was also evaluated after in vitro infection with seasonal H1N1 and pandemic A/H1N1 strains. We found an increase in the frequency of peripheral Th2 and Tc2 cells in A/H1N1 patients. A trend toward increased Tc1 cells was observed in household contacts. Elevated serum levels of IL-6, CXCL8, and CCL2 were found in patients and a similar cytokine/chemokine profile was observed in BAL, in which CCL5 was also increased. Infection assays revealed that both strains induce the production of several cytokines/chemokines at 24 and 72 h, however, IL-6, CCL3, and CXCL8 were strongly up-regulated in 72-h cultures in presence of the A/H1N1 virus. Several inflammatory mediators are up-regulated in peripheral and lung samples from A/H1N1-infected patients who developed severe pneumonia. In addition, the A/H1N1 strain induces higher levels of pro-inflammatory cytokines and chemokines than the seasonal H1N1 strain. These findings suggest that it is possible to identify biomarkers of severe pneumonia and also suggest the therapeutic use of immunomodulatory drugs in patients with severe pneumonia associated with A/H1N1 infection.

Microbiological implications of periurban agriculture and water reuse in Mexico City.

BACKGROUND: Recycled treated or untreated wastewater represents an important health challenge in developing countries due to potential water related microbiological exposure. Our aim was to assess water quality and health implications in a Mexico City periurban agricultural area. METHODOLOGY/PRINCIPAL FINDINGS: A longitudinal study in the Xochimilco wetland area was conducted, and 42 sites were randomly selected from 211, including irrigation water canals and effluents of treatment plants. Sample collection took place during rainy and dry seasons (2000-2001). Microbiological parameters (total coliforms, fecal coliforms, streptococci/enterococci, and bacteria other than Vibrio grown on TCBS), Helicobacter pylori, and physicochemical parameters including trihalomethanes (THM) were determined. Fecal coliforms and fecal streptococci are appropriate indicators of human or animal fecal contamination. Fecal coliform counts surpass Mexican and World Health Organization irrigation water guidelines. Identified microorganisms associated with various pathologies in humans and domestic animals comprise Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp., Enterococcus spp., and Pseudomonas spp; H. pylori was also present in the water. An environmental characteristic of the canal system showed high Total Organic Carbon content and relatively low dissolved oxygen concentration; residual chlorine as a disinfection control is not efficient, but THMs do not represent a problem. During the rainy season, temperature and conductivity were higher; in contrast, pH, dissolved oxygen, ammonia, and residual chlorine were lower. This is related with the continuous load of feces from human and animal sources, and to the aquatic systems, which vary seasonally and exhibit evidence of lower water quality in effluents from treatment plants. CONCLUSIONS/SIGNIFICANCE: There is a need for improvement of wastewater treatment systems, as well as more efficient monitoring, regulation, and enforcement procedures for wastewater disposal into bodies of water.

Implicaciones de los polimorfismos de un solo nucleótido en Mycobacterium tuberculosis y humanos en el manejo clínico de la tuberculosis / Implication of single nucleotide polymorphisms in Mycobacterium tuberculosis and humans in the clinical management of tuberculosis

Se analizan estudios de los polimorfismos genéticos de Mycobacterium tuberculosis asociados a resistencia y transmisión, así como los polimorfismos genéticos en humanos con asociación a gravedad y formas clínicas de la enfermedad y toxicidad hepática al tratamiento antituberculosis, y su utilidad en el estudio de los pacientes con tuberculosis multifarmacorresistente. Los nuevos métodos que ofrece la medicina geómica para la investigación en tuberculosis permiten sugerir nuevos criterios de aplicación inmediata en el manejo clínico de los pacientes con tuberculosis, en la evaluación de la eficacia de la terapéutica y en la prevención de eventos adversos para el paciente. Por ello, es importante evaluar el costo-beneficio de esta herramienta para fortalecer los centros de atención a pacientes con tuberculosis en países en desarrollo donde existen elevadas tasas de la enfermedad.

We review studies of Mycobacterium tuberculosis genetic polymorphisms associated to resistance and transmission; also, the genetic polymorphisms associated to severity and clinical presentation of human tuberculosis (TB) and hepatic toxicity associated to antituberculosis treatment. We discuss its usefulness in studies of patients with multidrug resistant TB. The new methods of genomic medicine suggest new criteria for immediate application in TB management, the evaluation of treatment efficacy and the prevention of patient complications. It is important to appraise cost-benefit of this tool to improve TB medical care centers from developing countries with high rates of TB.

Tuberculosis drogorresistente: Algunas consideraciones clínicas / Drug-resistant tuberculosis: clinical considerations

Introducción. La tuberculosis es uno de los mayores problemas de salud a nivel mundial, pues una tercera parte de la población está infectada por Mycobacterium tuberculosis, y es considerada como causa importante de muerte. Investigaciones sobre nuevos métodos de diagnóstico y nuevas alternativas de tratamiento son realizadas a nivel mundial. Diagnóstico. Se utilizan dos métodos para determinar la presencia de drogorresistencia, el método de las proporciones y el método de concentraciones absolutas, este último se utiliza en países en vías de desarrollo. Tipos de resistencia. Se conocen dos tipos de resistencia del Mycobacterium a los antituberculosos, la primaria y la secundaria, esta diferencia es debida a la exposición previa de las micobacterias a los diferentes antituberculosos. Es posible encontrar resistencia cruzada entre algunos fármacos. Causas de resistencia. La resistencia es ocasionada por los tratamientos inadecuados o por poca cooperación de los pacientes. Clasificación. Se clasifica con base al número de antituberculosos a los que hay resistencia, en monorresistencia, multidrogorresistencia y "otras resistencias". Mutantes. En toda población bacilar se encuentran normalmente micobacterias mutantes, es decir presentan resistencia a los diferentes antituberculosos. La selección de estas micobacterias por deficiencias en los tratamientos lleva a los pacientes con tuberculosis a la drogorresistencia para cada antituberculoso. Conductas a seguir. Generalmente las medidas que favorecen el éxito de un tratamiento son aquellas que evitan la drogorresistencia, por lo que el garantizar un tratamiento adecuado disminuimos la frecuencia de tuberculosis drogorresistente

Salmonella gastroenteritis outbreak among workers from a tertiary care hospital in Mexico City

Objetivo. Descubrir un brote de gastroenteritis por Salmonella enteritidis ocurrido en julio de 1994, entre los empleados del Instituto Nacional de la Nutrición Salvador Zubirán (INNSZ), de la Ciudad de México. Métodos. Se elaboró historia clínica y se incluyeron al estudio los empleados que desarrollan diarrea o fiebre asociada a síntomas gastrointestinales, los cuales iniciaron el 14 de julio, y simultáneamente se estudiaron 50 controles (empleados sanos). A todos se les aplicó un cuestionario y se tomó una muestra de heces para coprocultivo, también se obtuvo muestra de otras 80 personas asintomáticas, incluyeron trabajadores de la cocina. Resultados. Se encontró que 97 empleados que regularmente comían en el hospital fueron afectados por el brote, y 67 de ellos (69 por ciento) pudieron ser evaluados. La mayoría de los empleados afectados fueron enfermeras (34 por ciento) y personal de vigilancia (27 por ciento) los síntomas más comunes fueron: dolor abdominal (97 por ciento), diarrea (95 por ciento), nausea (91 por ciento) y fiebre (89 por ciento). Los cultivos de los alimentos sospechosos fueron todos negativos, pero en los cultivos de heces 10/70 casos fueron positivos para Salmonella enteritidis, contra 0/130 de los controles. Los 10 aislamientos de Salmonella enteritidis resultaron idénticos tanto para serotipificación como por reacción rápida de poliomerasa en cadena DNA (RAPD). Los cultivos de todos los empleados de la cocina fueron negativos para S. enteritidis. El desayuno del 14 de julio se asoció con el desarrollo de gastroenteritis (91 por ciento casos Vs 52 por ciento controles, p < 0.001), y particularmente con un platillo compuesto por carne capeada con huevo (torta de carne) (90 por ciento casos Vs 50 por ciento controles, p < 0.0001). Conclusiones. Este brote fue causado probablemente por huevo contaminado con Salmonella, debido a que nincuno de los trabajadores de la cocina fue identificado como portador asintomático, y que la receta del platillo (torta de carne) involucró un cocimiento insuficiente. Las recomendaciones para mejorar los procedimientos que se siguen en la preparación de los alimentos, debe de añadirse a las reglas habituales para disminuir la frecuencia de brotes de enfermedades relacionadas a alimentos en hospitales