Prevalencia de Bartonella henselae en donantes de sangre y riesgo de transmisión sanguínea en Chile / Prevalence of Bartonella henselae in blood donors and risk of blood transmission in Chile

Resumen Introducción: Bartonella henselae es el agente causal de la enfermedad del arañazo del gato en personas inmunocompetentes y de la angiomatosis bacilar y peliosis hepatis en inmunocomprometidos. En Chile la prevalencia de anticuerpos contra B. henselae en niños y adolescentes sanos es de 13,3%, en personas con riesgo ocupacional 60,5% y en gatos 85,6%. No existen datos publicados respecto de la seroprevalencia en donantes de sangre en nuestro país, por lo que determinar si B. henselae se encuentra presente en la sangre de los donantes al momento de la donación es muy importante, ya que este microorganismo puede sobrevivir hasta 35 días en los eritrocitos almacenados en banco de sangre a 4 °C. Objetivo: Determinar la prevalencia de B. henselae en donantes de sangre. Metodología: Se analizaron 140 muestras de sangre de donantes, para detectar la presencia de B. henselae, utilizando la técnica de la reacción de polimerasa en cadena (RPC). Resultados: Se obtuvo 13,6% de los donantes de sangre con RPC positiva para la B. henselae. La secuencia de los fragmentos amplificados presentó una identidad por sobre 98% con respecto a secuencias de B. henselae de referencia. Conclusión: El riesgo de transmisión sanguínea debiera ser considerado en un país con alta seroprevalencia de infección por B. henselae.

Background: Bartonella henselae is the causal agent of cat scratch disease in immunocompetent persons and bacterial angiomatosis in immunocompromised patients. In Chile, the prevalence of antibodies against B. henselae in healthy children and adolescents is 13.3%, in persons with occupational risk 60.5%, and in cats 85.6%. There are no published data regarding the seroprevalence in blood donors in our country, so determining if B. henselae is present in the blood of donors at the time of donation is very important, since this microorganism can survive up to 35 days in the red blood cells stored in a blood bank at 4 °C. Objective: To determine the prevalence of B. henselae in blood donors. Methodology: 140 donor blood samples were analyzed to detect the presence of B. henselae, using the polymerase chain reaction technique. Results: 13.6% of the blood donors with positive polymerase chain reaction for B. henselae were obtained. The sequence of the amplified fragments showed an identity of over 98% with respect to B. henselae reference sequences. Conclusion: The risk of blood transmission is due to a country with high B. henselae infection.

Measurement of psychosocial health in medical students: Validation of the Jefferson Medical College's Questionnaire in Mexico

The greater the psychosocial health, the greater is the well-being and the capacity for adaptation and overcoming problems and common life frustrations in family, relationships, and work. Medical students and practicing physicians, in comparison with the general population and that of other professions, are exposed to academic and professional stress and therefore are vulnerable to psychosocial health problems and certain specific dysfunctions that may compromise their physical, mental, and social health. In the field of psychosocial research in medical education, the key issue is to find relevant and psychometrically sound measures. The Jefferson Medical College's Psychosocial Questionnaire contains abridged versions of nine personality tests, as well as questions about respondents' relationships with parents in the first five years of life and with classmates in the early schooling. The scales in the questionnaire have shown satisfactory internal consistency reliability and construct validity through factor analysis. To our knowledge, in Mexico, there is not a specific questionnaire that measures psychosocial profile in a non-clinical population such as medical students. The present study adapted and translated the questionnaire from English to Spanish in order to evaluate its validity and reliability in Mexican medical students, to further learn its predictive validity of academic performance. In this study, we compared the factor structure in Mexico to the results obtained in the United States research. Implications for predicting academic and clinical performance of medical students and physicians were discussed. Study participants consisted of 3,603 matriculates at the Escuela de Medicina de la Universidad Autónoma de Nuevo León (Mexico). Psychosocial measures included Loneliness, Test anxiety, General anxiety, Self-esteem, Extroversion, External locus of control, Neuroticism, Depression, Stressful life events, Perceptions of early relationships with mother and father, Peer relationships and Perception of health, used by researchers at Jefferson Medical College in the United States. The items were translated into Spanish and back translated from Spanish to English, following the guidelines for adaptation of instruments for psychological evaluation. The questionnaire was administered in the third month after admission of the students to the Medicine School in the students' usual classrooms, on a schedule and day set aside for it according to the school's administration program. They were assured of the strict confidentiality of the test scores and of the individual data. Dimensionality of 40 items of the eight brief psychosocial scales was assessed with factor analysis using the principal components extraction method and orthogonal rotation; the Depression Scale was not included in the factorial analysis because it was not shortened for the present study. Correlation coefficients and internal consistencies were calculated for all the scales. Unidimensionality and construct validity were confirmed for measures of Loneliness, Test anxiety, General anxiety, Self-esteem, and Extroversion. The pattern and direction of the scale correlations with external criterion measures supported the concurrent validity of some of the measures. Also, the magnitude and direction of the inter-scale correlations supported the convergent and discriminant validities with the exception of the External locus of control and Neuroticism scales. The results supported the psychometric properties of the scales useful for providing information for medical educators and mental health professionals in early detection of psychosocial problems. It is important to mention that in spite of frequent talk about the importance of health among college students, few schools of Medicine in Mexico and in Latin America actually promote empirical research and support detect problems and develop solutions once they are identified. The mental health professionals should be responsible for sharing their understanding. They are capable of helping faculty for optimizing mental health through allocation of educational and remedial resources when designing academic programs in agreement with necessities of their students.

Como la literatura consigna, los estudiantes y profesionales de la Medicina en comparación con la población general y de otras carreras conforman una población que resulta vulnerable frente a los trastornos de salud psicosocial. En la investigación psicosocial de la educación médica un punto clave corresponde a la identificación de medidas relevantes con cualidades psicométricas. En el presente trabajo se analiza la validez y confiabilidad de un conjunto de escalas psicosociales aplicadas a 3.603 alumnos de la Facultad de Medicina de la Universidad Autónoma de Nuevo León (México). Las escalas administradas fueron: Soledad, Ansiedad ante los exámenes, Ansiedad general, Autoestima, Extroversión, Locus de control externo, Neuroticismo, Depresión, Eventos estresantes en la vida, Percepción de relaciones tempranas con los padres y amigos y Percepción de estado de salud general. Estas escalas fueron propuestas por investigadores de la Escuela de Medicina de Jefferson (Estados Unidos). Se confirmó la unidimensionalidad y la validez de constructo de las mediciones de Soledad, Ansiedad ante los exámenes, Ansiedad general, Autoestima y Extroversión. Así también, la magnitud y dirección de las correlaciones interescalas apoyaron la validez convergente y discriminante, con excepción de Locus de control externo y Neuroticismo. Los resultados confirman las propiedades psicométricas de las escalas, las cuales son útiles para proveer información a los educadores médicos y a profesionales de la salud mental en la detección temprana de problemas psicosociales quienes en conjunto pueden coadyuvar en la optimización de la salud mental de los estudiantes de escuelas de Medicina a través de programas académicos acordes a sus necesidades.

Un nuevo procedimiento para el aislamiento de DNA de mycobacterium tuberculosis / A new procedure for mycobacterium tuberculosis DNA isolation

Se describe un procedimiento para el aislamiento de DNA cromosomal de Mycobacterium tuberculosis. La digestión simultánea con lisozima y lipasa pancreática, seguida de lisis celular con dodecil sulfato de sodio (SDS), extracciones con fenol-cloroformo y precipitación con acetato de sodio y etanol, permiten recuperar DNA cromosomal adecuado para análisis con enzimas de restricción, estudios de hibridización de DNA, experimentos de DNA recombinante y reacciones de amplificación génica(PCR)