Neumonia por Legionella pneumophila. Experiencia en un Hospital Universitario de Buenos Aires / Pneumonia due to Legionella pneumophila. Experience gathered in a University Hospital in Buenos Aires

Legionnaires' disease is a well recognized cause of community acquired pneumonia (CAP) all around the world. In Latin America its incidence remains unknown. This study analyzed a cohort of 9 patients with CAP due to Legionella pneumophila observed from 1997 to 2001, in the Hospital de Clínicas José de San Martin, University of Buenos Aires. Clinical history included recent illnesses, work exposure, physical exam, prior antibiotic use and severity of illness criteria. None of the 9 patients had a history of recent travels, and 4 of them required admission in intensive care unit (ICU). Seven patients had a cigarette smoking history, four of them also had COPD, and one patient had a non-Hodgkin lymphoma. This study confirms the low specificity of clinical and general laboratory criteria to predict this etiology. Legionella isolation is difficult, and serological testing allows retrospective diagnosis but takes several weeks, while urinary antigen test gives a bed-side diagnosis. When Legionella appears in isolated cases, as happens in Argentina, it should be necessary to have a high index of suspicion to successfully arrive at an etiological diagnosis. Legionella pneumophila is a pathogen causing CAP in our area. A surveillance should be established preferably focused on selected populations including severe CAP, immunocompromised hosts and patients with chronic obstructive pulmonary disease.

La enfermedad de los legionarios es una causa de neumonía adquirida en la comunidad (NAC)reconocida en todo el mundo. En Latinoamérica su incidencia es desconocida. En este estudiose analizó a 9 pacientes con NAC por Legionella pneumophila atendidos entre 1997 y 2001 en el Hospital deClínicas José de San Martín de la Universidad de Buenos Aires. Se registraron datos de antecedentes, enfermedad actual, contactos, exposición laboral, examen físico, pruebas de laboratorio y uso previo de antibióticos, y se tomó en cuenta la presencia de criterios de gravedad. Nueve pacientes presentaron diagnóstico de NAC por Legionella, ninguno refirió antecedentes de viajes recientes; cuatro de ellos debieron ser internados en unidades de cuidado intensivo. Siete pacientes tenían antecedentes de tabaquismo, 4 tenían EPOC y un paciente linfoma no-Hodgkin. Nuestra casuística corrobora la baja especificidad de la clínica y estudios complementarios para predecir esta etiología. El aislamiento de Legionella es dificultoso, la seroconversión permite eldiagnóstico retrospectivo y requiere plazos prolongados y el antígeno urinario aporta un diagnóstico inmediato.Cuando la legionelosis aparece en casos aislados, como ocurriría en Argentina, si no se piensa en esta etiologíano se llegará al diagnóstico. Legionella pneumophila es un patógeno de NAC en nuestro medio, debe buscarsemejor, particularmente en pacientes graves, inmunodeprimidos y en fumadores con enfermedad pulmonarobstructiva crónica (EPOC).

Neumonia por Legionella pneumophila. Experiencia en un Hospital Universitario de Buenos Aires / Pneumonia due to Legionella pneumophila. Experience gathered in a University Hospital in Buenos Aires

Legionnaires disease is a well recognized cause of community acquired pneumonia (CAP) all around the world. In Latin America its incidence remains unknown. This study analyzed a cohort of 9 patients with CAP due to Legionella pneumophila observed from 1997 to 2001, in the Hospital de Clínicas José de San Martin, University of Buenos Aires. Clinical history included recent illnesses, work exposure, physical exam, prior antibiotic use and severity of illness criteria. None of the 9 patients had a history of recent travels, and 4 of them required admission in intensive care unit (ICU). Seven patients had a cigarette smoking history, four of them also had COPD, and one patient had a non-Hodgkin lymphoma. This study confirms the low specificity of clinical and general laboratory criteria to predict this etiology. Legionella isolation is difficult, and serological testing allows retrospective diagnosis but takes several weeks, while urinary antigen test gives a bed-side diagnosis. When Legionella appears in isolated cases, as happens in Argentina, it should be necessary to have a high index of suspicion to successfully arrive at an etiological diagnosis. Legionella pneumophila is a pathogen causing CAP in our area. A surveillance should be established preferably focused on selected populations including severe CAP, immunocompromised hosts and patients with chronic obstructive pulmonary disease.(AU)

La enfermedad de los legionarios es una causa de neumonía adquirida en la comunidad (NAC)reconocida en todo el mundo. En Latinoamérica su incidencia es desconocida. En este estudiose analizó a 9 pacientes con NAC por Legionella pneumophila atendidos entre 1997 y 2001 en el Hospital deClínicas José de San Martín de la Universidad de Buenos Aires. Se registraron datos de antecedentes, enfermedad actual, contactos, exposición laboral, examen físico, pruebas de laboratorio y uso previo de antibióticos, y se tomó en cuenta la presencia de criterios de gravedad. Nueve pacientes presentaron diagnóstico de NAC por Legionella, ninguno refirió antecedentes de viajes recientes; cuatro de ellos debieron ser internados en unidades de cuidado intensivo. Siete pacientes tenían antecedentes de tabaquismo, 4 tenían EPOC y un paciente linfoma no-Hodgkin. Nuestra casuística corrobora la baja especificidad de la clínica y estudios complementarios para predecir esta etiología. El aislamiento de Legionella es dificultoso, la seroconversión permite eldiagnóstico retrospectivo y requiere plazos prolongados y el antígeno urinario aporta un diagnóstico inmediato.Cuando la legionelosis aparece en casos aislados, como ocurriría en Argentina, si no se piensa en esta etiologíano se llegará al diagnóstico. Legionella pneumophila es un patógeno de NAC en nuestro medio, debe buscarsemejor, particularmente en pacientes graves, inmunodeprimidos y en fumadores con enfermedad pulmonarobstructiva crónica (EPOC).(AU)

Enfermedad de Rendu-Osler-Weber. Fístulas arteriovenosas / Rendu-Osler-Weber syndrome. Pulmonary arteriovenous fistulas. A report of three cases

La telangiectasia hemorrágica heredofamiliar (THH) o síndrome de Rendu-Osler-Weber es un trastorno sistémico infrecuente asociado con malformaciones vasculares pulmonares (MPAV). Aunque el diagnóstico clínico puede fundamentarse en las manifestaciones cutaneomucosas, de vías aéreas altas o en los múltiples episodios de sangrado, la presencia de un compromiso pulmonar suele cursar inaparente y definir el pronóstico. Se presentan tres pacientes con una THH y con MPAV en los que la medición del shunt con O2 al 100 per cent, la ecocardiografía con contraste y la tomografía helicoidal sustentan el enfoque diagnóstico no invasor. En uno de los pacientes, la arteriografía confirmó la sospecha de MPAV única. Recibió emboloterapia quirúrgica con un coil y se obtuvo definida mejoría clínica y funcional (AU)

[Rendu-Osler-Weber syndrome. Pulmonary arteriovenous fistulas. A report of three cases]. / Enfermedad de Rendu-Osler-Weber. Fístulas arteriovenosas.

Hereditary hemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber syndrome, is a rare disorder that is closely linked to the development of pulmonary arteriovenous malformations (PAVM). Diagnosis can be based on clinical signs such as upper respiratory tract changes or recurrent hemorrhagic events. Nevertheless, pulmonary involvement, a prognostic factor, may remain undetected. In the three HTT cases with PAVM we report, the following diagnostic information was obtained non-invasively: shunt fraction measurements (breathing 100% oxygen), echocardiographic contrast studies, and three-dimensional helical computed tomographs. Arteriography demonstrated a single PAVM in one case and the patient underwent successful coil embolization, with clinical and functional improvement.

Yeast AMP pathway genes respond to adenine through regulated synthesis of a metabolic intermediate.

In Saccharomyces cerevisiae, AMP biosynthesis genes (ADE genes) are transcriptionally activated in the absence of extracellular purines by the Bas1p and Bas2p (Pho2p) transcription factors. We now show that expression of the ADE genes is low in mutant strains affected in the first seven steps of the pathway, while it is constitutively derepressed in mutant strains affected in later steps. Combined with epistasy studies, these results show that 5'-phosphoribosyl-4-succinocarboxamide-5-aminoimidazole (SAICAR), an intermediate metabolite of the pathway, is needed for optimal activation of the ADE genes. Two-hybrid studies establish that SAICAR is required to promote interaction between Bas1p and Bas2p in vivo, while in vitro experiments suggest that the effect of SAICAR on Bas1p-Bas2p interaction could be indirect. Importantly, feedback inhibition by ATP of Ade4p, catalyzing the first step of the pathway, appears to regulate SAICAR synthesis in response to adenine availability. Consistently, both ADE4 dominant mutations and overexpression of wild-type ADE4 lead to deregulation of ADE gene expression. We conclude that efficient transcription of yeast AMP biosynthesis genes requires interaction between Bas1p and Bas2p which is promoted in the presence of a metabolic intermediate whose synthesis is controlled by feedback inhibition of Ade4p acting as the purine nucleotide sensor within the cell.