UTILITY OF GRAMS STAIN AND EFFICACY OF QUANTITATIVE CULTURES FOR POSTTRAUMATIC PNEUMONIA - A PROSPECTIVE-STUDY

Objective This prospective trial examined the efficacy of using bronch oal-veolar lavage (BAL) for the diagnosis of pneumonia (PN) end the ut ility of Gram's stain (GS) for dictating empiric therapy. Summary Back ground Data Posttraumatic nosocomial PN remains a significant cause of morbidity and mortality. However, its diagnosis is elusive, especiall y in multiply injured patients. The systemic inflammatory response syn drome of fever, leukocytosis, and a hyperdynamic state is common in tr auma patients, especially patients with pulmonary contusion. Bronchosc opy with BAL with quantitative cultures of the lavage effluent may dis tinguish between PN and systemic inflammatory response syndrome, and G S of the ravage effluent may guide empiric therapy before quantitative culture results. Methods Mechanically ventilated trauma patients with a clinical diagnosis of PN (fever, leukocytosis, purulent sputum, and new or changing infiltrate on chest radiograph) underwent bronchoscop y with BAL. Effluent was sent for GS and quantitative cultures. The di agnostic threshold for PN was greater than or equal to 10(5) colony-fo rming units (CFU)/mL, and antibiotics were continued. Antibiotics were stopped for <10(5) CFU/mL and the diagnosis of systemic inflammatory response syndrome was made. Causative organisms for PN were compared t o GS. Results Over a 2-year period, 232 patients underwent 443 broncho s-copies with BAL (71 % men, 29% women; mean age, 41). The mean injury severity score was 30. Sixty percent of the patients had pulmonary co ntusion, and 59% were cigarette smokers. The overall incidence of PN w as 39% and was no different regardless of the number of BALs a patient had. The false-negative rate of BAL was 7%. GS identified gram-positi ve organisms in 80% of patients with gram-positive PN and 40% of patie nts with gram-negative PN. GS Identified gramnegative organisms in 52% of patients with gram-positive PN and 77% with gram-negative PN. The duration of the intensive care unit stay relative to the timing of BAL was beneficial for guiding empiric therapy. BAL in week 1 primarily i dentified Haemophilus influenzae and gram-positive organisms; Acinetob acter sp. and Pseudomonas sp. were more common after week 1. Conclusio ns Bronchoscopy with BAL is an effective method to diagnose PN and avo ids prolonged, unnecessary antibiotic therapy... Empiric therapy shoul d be adjusted to the duration of the intensive care unit stay because the causative bacteria flora changes over time. GS of BAL effluent cor relates poorly with quantitative cultures and is not reliable for dict ating empiric therapy.