First insights into the genetic diversity of Mycobacterium tuberculosis isolates from HIV-infected Mexican patients and mutations causing multidrug resistance.

BACKGROUND: The prevalence of infections with Mycobacterium tuberculosis (MTb) and nontuberculous mycobacteria (NTM) species in HIV-infected patients in Mexico is unknown. The aims of this study were to determine the frequency of MTb and NTM species in HIV-infected patients from Mexico City, to evaluate the genotypic diversity of the Mycobacterium tuberculosis complex strains, to determine their drug resistance profiles by colorimetric microplate Alamar Blue assay (MABA), and finally, to detect mutations present in katG, rpoB and inhA genes, resulting in isoniazid (INH) and rifampin (RIF) resistance. RESULTS: Of the 67 mycobacterial strains isolated, 48 were identified as MTb, 9 as M. bovis, 9 as M. avium and 1 as M. intracellulare. IS6110-RFLP of 48 MTb strains showed 27 profiles. Spoligotyping of the 48 MTb strains yielded 21 patterns, and 9 M. bovis strains produced 7 patterns. Eleven new spoligotypes patterns were found. A total of 40 patterns were produced from the 48 MTb strains when MIRU-VNTR was performed. Nineteen (39.6%) MTb strains were resistant to one or more drugs. One (2.1%) multidrug-resistant (MDR) strain was identified. A novel mutation was identified in a RIF-resistant strain, GAG --> TCG (Glu --> Ser) at codon 469 of rpoB gene. CONCLUSIONS: This is the first molecular analysis of mycobacteria isolated from HIV-infected patients in Mexico, which describe the prevalence of different mycobacterial species in this population. A high genetic diversity of MTb strains was identified. New spoligotypes and MIRU-VNTR patterns as well as a novel mutation associated to RIF-resistance were found. This information will facilitate the tracking of different mycobacterial species in HIV-infected individuals, and monitoring the spread of these microorganisms, leading to more appropriate measures for tuberculosis control.

Increased number of cytotoxic CD3+ CD28- gammadelta T cells in peripheral blood of patients with cutaneous malignant melanoma.

BACKGROUND: A rise of CD3+ TCRgammadelta+ CD28- T cells has previously been observed after an in vitro long-lasting activation or even during viral infection. OBJECTIVE: The aim of this study was to investigate the expression of CD28 on lymphocytes bearing CD3/TCRgammadelta receptors in cancer, i.e. cutaneous melanoma. METHODS: TCRgammadelta lymphocytes were analysed in 41 Caucasian melanoma patients and 39 healthy individuals by flow cytometry. Patients were stratified according to the American Joint Committee on Cancer (AJCC) clinical stage. RESULTS: The number of circulating CD3+ TCRgammadelta+ T cells was significantly increased in both AJCC stages I-II and AJCC stage III patients compared with healthy individuals. This increase was mediated by an accumulation of the CD3+ TCRgammadelta+ CD28- T-cell subset, which expressed a high amount of perforin both in normal individuals and melanoma patients. CONCLUSION: This work shows, for the first time, a rise of the cytotoxic CD3+ TCRgammadelta+ CD28- T-cell population in melanoma patients, which may be important in anticancer surveillance.

Frecuencia de micosis en pacientes inmunosuprimidos de un hospital regional de la Ciudad de México / Frequency of mycoses in immunosuppressed patients in a regional hospital in Mexico City

OBJETIVO: Aislar e identificar hongos en diferentes especímenes de pacientes inmunocomprometidos, atendidos en un hospital de la Ciudad de México, y determinar su asociación con micosis. MATERIAL Y MÉTODOS: Se realizó un estudio de tipo observacional transversal en pacientes del Hospital Regional General Ignacio Zaragoza, de junio de 1999 a mayo de 2000. De 108 pacientes se procesaron 268 especímenes para estudio micológico que incluyó examen directo, frotis, cultivos y microcultivos en medios específicos además de pruebas bioquímicas. La mayoría de pacientes tenía diagnóstico clínico de tuberculosis pulmonar y de síndrome de inmunodeficiencia adquirida. RESULTADOS: Se obtuvieron 183 aislamientos de levaduras y 66 de hongos filamentosos. Se diagnosticaron 45 micosis que en su mayoría correspondieron a candidosis pulmonar (32 casos). Las especies de Candida más frecuentes asociadas a patología fueron Candida albicans y C parapsilosis. Se obtuvieron cinco aislamientos de Cryptococcus neoformans variedad neoformans, uno de C albidus, tres de Histoplasma capsulatum y uno de Geotrichum candidum, asociados a infección micótica. CONCLUSIONES: El 41.6 por ciento de los pacientes estudiados presentaron una micosis asociada principalmente a síndrome de inmunodeficiencia adquirida y a tuberculosis pulmonar.

OBJECTIVE: To isolate and identify the fungi in specimens collected from immunocompromised patients seen in Mexico City hospital, and to assess their association with mycosis. MATERIAL AND METHODS: A total of 268 specimens from 108 patients were processed for mycological study, including direct examination, smears, cultures, and microcultures in specific media, in addition to biochemical tests. Most of the patients had been diagnosed with pulmonary tuberculosis and Acquired Immunodeficiency Syndrome (AIDS). RESULTS: One hundred and eighty-three yeasts and 66 mycelial fungi were isolated. Forty-five mycoses were diagnosed; the most frequent mycosis was pulmonary candidosis (32 cases). Candida albicans and C parapsilosis were the predominant species associated with mycotic infection. Five Cryptococcus neoformans var. neoformans, one C albidus, three Histoplasma capsulatum and one Geotrichum candidum isolats were associated with mycosis. CONCLUSIONS: Of the studied patients, 41.6 percent showed a mycotic infection, principally associated with AIDS and pulmonary tuberculosis.

[Frequency of mycosis in immunosuppressed patients at a regional hospital of Mexico City]. / Frecuencia de micosis en pacientes inmunosuprimidos de un hospital regional de la Ciudad de México.

OBJECTIVE: To isolate and identify the fungi in specimens collected from immunocompromised patients seen in Mexico City hospital, and to assess their association with mycosis. MATERIAL AND METHODS: A total of 268 specimens from 108 patients were processed for mycological study, including direct examination, smears, cultures, and microcultures in specific media, in addition to biochemical tests. Most of the patients had been diagnosed with pulmonary tuberculosis and Acquired Immunodeficiency Syndrome (AIDS). RESULTS: One hundred and eighty-three yeasts and 66 mycelial fungi were isolated. Forty-five mycoses were diagnosed; the most frequent mycosis was pulmonary candidosis (32 cases). Candida albicans and C parapsilosis were the predominant species associated with mycotic infection. Five Cryptococcus neoformans var. neoformans, one C albidus, three Histoplasma capsulatum and one Geotrichum candidum isolates were associated with mycosis. CONCLUSIONS: Of the studied patients, 41.6% showed a mycotic infection, principally associated with AIDS and pulmonary tuberculosis. The English version of this paper is available at:http://www.insp.mx/salud/index.html.