Pneumonias com e sem ventilação mecânica em neonatos críticos internados em uma UTI neonatal de um hospital universitário brasileiro : aspectos clínicos, radiológicos e microbiológicos

Abstract

Although pneumonia is considered serious and frequent in NICU, there are few studies, mainly about those associated to mechanical ventilation. The aim of the study was epidemiological, considering the evaluation of pneumonia associated or not to mechanical ventilation diagnosed by clinical, radiological and microbiological in critically neonates hospitalized in a NICU. We conducted a case-control study including 305 newborns admitted to the NICU in the period of August 2008 to September 2009. Totally, 143 (46.9%) neonates submitted to mechanical ventilation and 129 (42.2%) submitted over than 48 hours. The clinical and radiological diagnosis of VAPs were according to NHSN, including microbiological criteria for endotracheal aspirates, which was considered positive culture when ≥ 106 CFU / ml. The identification of microorganisms was performed by phenotypic tests and antimicrobial susceptibility in vitro was defined by diffusion technique gel. In total, 10 (6.9%) cases of pneumonia was detect, five (50%) in infants without mechanical ventilation and remaining (50%) of VAPs. Neonates were divided in four distinct groups concerning to diagnosis of pneumonia: no mechanical ventilation, VAPs, false-positive and colonized neonates. Five (3.4%) neonates with pneumonia without mechanical ventilation and five (3.4%) with VAP, were classified in the first and second group, respectively. Third group included seven (10%) neonates with positive cultures (≥ 106 CFU / ml), considered as false positives, therefore did not present both clinical and radiographic signs of VAP, and finally, fourth group, with nineteen (27.1%) neonates with positive cultures under 106 CFU / ml were classified as colonized. In the study, five neonates with pneumonia without mechanical ventilation, risk factors statistically significant by univariate analysis were: use of antibiotics and pulmonary or heart comorbidities, but they were not confirmed in the logistic regression analysis. While in those newborns (five) with VAP, no risk factors was significant, OR values for the use of antibiotics and the presence of pulmonary comorbidities and / or heart rate were high (above 2.4) . In total, in newborns with VAP, false-positive and colonized, the following pathogens were isolated: S. epidermidis (19), S. aureus (6) Enterobacter aerogenes (2), Klebsiella pneumoniae (1), Bordetella parapertussis (1), Flavobacterium sp. (1), Sphingobacterium sp. (1) and Candida sp. (1). Among the isolates (32) only one (16.6%) of S. aureus act if it was MRSA, while about half of S. epidermidis presented multidrug resistance, among Gram-negative rods, only one (16.6%) sample (Bordetella parapertussis) was multiresistant. Accuracy in the diagnosis of VAps in critically neonates is extremely necessary, but it still dependent on microbiological and epidemiological investigations.