The efficiency of routine endotracheal aspirate cultures compared to bronchoalveolar lavage cultures in ventilator-associated pneumonia diagnosis

Abstract

Objective: Ventilator.associated pneumonia (VAP) is the most common nosocomial infection in  intensive Care Units (ICUs) and its mortality rate varies from 24% to 50%. The most important factor in decreasing the mortality is administering adequate antibiotics as early as possible. In this study, we investigate the efficiency of routine endotracheal aspirate (EA) cultures to identify the etiology of VAP earlier.
Materials and Methods: Fifty-nine patients who were accepted to our ICU with acute cerebrovascular disease with mechanical ventilation (MV) requirement were chosen for this study over a 12.month period. The patients intubated in our ICU were included in the study to exclude prior colonization. Upon ICU  admission, the patientfs; age, sex, comorbidities, diagnosis, acute physiology and chronic health  evaluation II score, and sequential organ failure assessment (SOFA) score were recorded. When bronchoalveolar lavage (BAL) was performed, the SOFA score, temperature, leukocyte count, C-reactive protein levels, PaO₂/FiO₂ ratio, PCO₂, clinical pulmonary infection score value, length of MV, and  presence of antimicrobiological treatments were recorded. Routine microbiological analysis was  performed by EA (pre.VAP EA) twice weekly in all patients until the endotracheal tube was removed. When VAP was suspected, fiberoptic bronchoscopy examination with BAL was performed. A diagnosis of VAP was established when the BAL quantitative culture grew at least one microorganism at a concentration .104 cfu/mL.
Results: VAP was diagnosed in 41 (69%) of the 59 patients based on BAL culture results. Among 41 positive BAL cultures, pre.VAP EA identified the same microorganism with the same antibiotics resistance pattern in 23 (56%) patients. Regarding only late.onset VAP, pre.VAP EA identified the same microorganisms found by BAL culture in 17 (63%) of the 27 cases. Among 18 BAL culture negative patients, 7 (39%) patients had negative prior pre.VAP EA culture results. Acinetobacter baumannii was the most frequently isolated microorganism from BAL cultures (n = 21, 51%). The diagnostic value of pre.VAP EA results in predicting A. baumannii VAP documented with the following values (sensitivity: 62%; specificity: 95%, positive predictive value: 87%, negative predictive value: 82%).
Conclusion: VAP patients should be treated with international guidelines, but if pre.VAP EA cultures identify multidrug resistant pathogens, the initial antibiotic therapy should cover these microorganisms. Thus, quantitative EA cultures are a useful noninvasive diagnostic tool in critically ill patients suspected of having pneumonia especially in the case of VAP.

Key words: Appropriate antibiotics, bronchoalveolar lavage, routine endotracheal aspirate cultures, ventilator.associated pneumonia