Etiología de las infecciones respiratorias bajas agudas en lactantes hospitalizados.

Abstract

Studies on the etiology of lower respiratory infectionsAs a contribution to knowledge about the etiology of lower respiratory tract infections (LRI) in infants, 235 patients aged one year or less admitted to a children's hospital at northern metropolitan area of Santiago, Chile along years 1987 throughout 1989 with radiologically confirmed diagnosis were studied. Infants were eligible only if their symptoms lasted for not more than five days and their hospital stay was less than two days. Controls consisted on 74 healthy infants. A search for presumtive etiology was done by means of usual bacteriological procedures {pharyngeal swabs and blood cultures), plus latex test for type b Haemophitus influanzae (Hib) and Streptococcus pneumoniae (SP* in concentrated urine specimens; indirect inmunofluorescence (IF) for specific Chlamydia tracbomatis <CT) IgM; serological tests, isolation and IF in pharyngeal aspirates for sinctitial respiratory virus (SRV), influenza, parainfluenzae and adenoviruses were also used. Evidence of viral infection was detected from 135/235 (57.5%) of cases and 21/74 (28.3%) controls, SRV being the most common. From 18/119 and 2/ 119 studied patients Hib and SP antigens were respectivelly detected, but urinary antigens were also present in 6/24 controls, raising questions about this test's specificity. IF titers of 1:32 or higher for CT were found in 5/80 patients, all younger than 5 months. It was possible to perform the wole set of available methods in 80 patients, in 70% of which some evidence of a known etiologic agent was found, Serology alone gave etiological clues in only 30% of these cases and usual microbiological cultures of throat swabs and blood from none of them. No combinations of age, fever, respiratory rate, apnea, bronchial obstructive syndrome, white blood cell counts over 15,000 or of band forms over 500 per cu mm, erithrocyte sedimentation rates, reactive C protein and x-ray findings allowed differential diagnosis between presumptive bacterial or viral etiology, except in one case of an infant presenting with pleural efussion and positive antigenuria for Hib. (Key words: respiratory tract infections, lower respiratory infections, etiology.) Las infecciones respiratorias agudas (IRA)El reducido numero de estudios etiologicos constituyen una de las principals causas de con-completes de IRAB en lactantes, incluso en paisulta en los servicios de salud y, ciertamente, ses desarrollados, se debe a la dificultad en la las infecciones respiratorias agudas del tracto obtencion de muestras de expectoration reprerespiratorio bajo (IRAB), bronquiolitis y bron-sentativas. coneumom'a, son una causa importante de muerEs conocido el hecho de que los datos ch'nite en niffos menores de un aflo, especialmente en cos, de laboratorio y radiologkos, son elementos los paises en desarrollo 1 " 3 .imprecisos para definir la etiologia bacteriana o Los estudios efectuados en paises en desarro-viral de las IRAB. Los estudios bacteriologicos llo han demostrado que las bacterias son los clasicos tienen ...

Programa de prevención y control de las enfermedades respiratorias agudas de la infancia en Santiago, Chile

“…En Chile, las enfermedades respiratorias agudas del lactante son causadas principalmente por virus y en menor proporción por bacterias (8,(14)(15)(16)(17)(18). El estado de la inmunidad celular y humoral en los primeros meses de la vida, los requerimientos de oxígeno relativamente altos, la inmadurez de las vías respiratorias y la mayor fatigabilidad de la musculatura respiratoria (19,20) hacen que el lactante sea muy susceptible a infecciones respiratorias que pueden evolucionar hacia la gravedad en poco tiempo, dando lugar a una obstrucción bronquial o bronconeumonía.…”

Infección extra e intrahospitalaria por virus sincicial respiratorio en lactantes

“…La posibilidad de realizar un diagnostico etio16gico rapido ha aumentado al disponer de te*cnicas de inmunofluorescencia 5 por lo que su hallazgo podria implicar un rol patogenico 5 -14 . La mayoria de las infecciones por VRS son de caracter leve, pero algunas comprometen el tracto respiratorio inferior, produciendo bronconeumom'as o bronquiolitis que requicrcn hospitalizacion; ademas, el VRS causa frecuentemente infecciones nosocomiales 7 .…”