Legionella pneumophila: un patógeno emergente en Argentina / Legionella pneumophila: an emerging pathogen in Argentina

La enfermedad del Legionario es causada por bacterias pertenecientes al género Legionella, siendo la especie pneumophila el principal agente etiológico de esta patología. Esta bacteria se describió por primera vez en 1977 como causa de un brote de neumonía grave registrado en 1976 en un centro de convenciones en los Estados Unidos de América. La enfermedad se presenta como una neumonía atípica, responsable del 1 al 15 % de los casos de neumonías adquiridas en la comunidad (NAC), del 5 al 10% de neumonías del adulto y del 1% en menores de 15 años. Los miembros de la familia Legionellaceae son bacilos aeróbicos gramnegativos que crecen lentamente y se encuentran ampliamente distribuidos en cuerpos de agua. La forma más común de transmisión de Legionella spp es la inhalación de aerosoles contaminados generados a partir de fuentes de agua artificiales. Se asocian con la aparición de brotes esporádicos y epidémicos en la comunidad y en infecciones nosocomiales. Las especies pertenecientes al género Legionella se consideran patógenos emergentes transmitidos por el agua. El objetivo de este trabajo es realizar una revisión sobre las manifestaciones y presentaciones clínicas de la infección causada por L. pneumophila, en virtud de que es considerado mundialmente un patógeno emergente y por existir evidencias de su presencia en sistemas de almacenamiento de agua tratada en la región nordeste de la República Argentina, razón primordial para alertar y actualizar conocimientos al respecto

Legionnaires' disease is caused by bacteria belonging to the genus Legionella, being the pneumophila specie the main etiological agent of this pathology. This bacterium was first described in 1977 as the cause of a severe pneumonia outbreak in 1976 at a convention center in the United States of America. The disease presents as an atypical pneumonia, responsible for 1% to 15% of cases of community-acquired pneumonia (CAP), 5% to 10% of pneumonia in adults and 1% in children under 15 years of age. Members of the Legionellaceae family are aerobic, gram-negative rods that grow slowly and are widely distributed in water bodies. The most common way of transmission of Legionella spp is the inhalation of contaminated aerosols generated from artificial water sources. They are associated with the appearance of sporadic and epidemic outbreaks in the community and in nosocomial infections. Species belonging to the genus Legionella are considered emerging waterborne pathogens.The aim of this work is to carry out a review on the manifestations and clinical presentations of the infection caused by L. pneumophila, due to that it is considered an emerging pathogen worldwide and because there is evidence of its presence in storage systems of treated water in the Northeast region of the Argentine Republic, primary reason to alert and update knowledge in this regard.

Evolution of legionnaires' disease in an urban hospital - abstract

Ongoing epidemiological surveillance for nosocomial Legionnaires' Disease (LD) was initiated after control of an initial outbreak involving eight cases at a Nova Scotia Hospital in 1984. All cases of nosocomial pneumonia were screened for LD, and water samples were cultured for Legionella at intervals. No clinical cases of LD were identified until April, 1987, although there were occasional positive cultures from water samples in different areas of the hospital. Subsequently, six to seven cases have been identified over each 12-month period with no more than two cases in any month. The mean age of patients was 67.7 years (range 54 - 83) with a male to female ratio 2.5:1. The mean time of onset of pneumonia after admission was 19.9 days (range 8 - 27) with diagnosis being made in most cases by sputum culture. Risk factors included smoking, immunosuppressive therapy and admission to a specific wing of the hospital. Water samples from the specific wing of the hospital were persistently positive at high levels until certain plumbing revisions were instituted. In contrast to the initial outbreak, these cases represent an endemic level of nosocomial LD related to a specific area of the hospital. Ongoing surveillance is required for detection and control (AU)

Potable water as a cause of sporadic cases of community-acquired legionnaires' disease.

BACKGROUND: The environmental sources of sporadic, community-acquired legionnaires' disease are largely unknown, and culturing of water sources after identification of a case is currently not recommended. We conducted a prospective study of sporadic cases of community-acquired legionnaires' disease to determine whether the environmental reservoirs could be identified. METHODS: We cultured samples of potable water obtained from sources to which each of 20 patients with culture-confirmed, community-acquired legionnaires' disease had been exposed during the two weeks before the onset of symptoms. Monoclonal-antibody subtyping and restriction-endonuclease analysis were performed on the legionella isolates recovered from both the patients and the associated environmental cultures. RESULTS: For 8 of the 20 patients, isolates of Legionella pneumophila with identical subtypes were identified in cultures from both the patient and the potable water to which the patient had been exposed. The environmental reservoirs linked to the infections were the water supplies of two private residences, two nursing homes, two hospital outpatient clinics, and an industrial plant. CONCLUSIONS: Potable-water supplies that harbor L. pneumophila are an important source of community-acquired legionnaires' disease. Future studies should include attempts to identify the environmental sources of this infection.