The Usefulness of Quantitative Culture of Bronchoalveolar Lavage Fluid in the Diagnosis of Bacterial Pneumonia

Hahn, Tae Ho; Jang, Myoung Kuk; Kim, Seong Gyun; Lee, Ja Young; Lee, Jae Myung; Kim, Dong Kyu; Choi, Jeong Eun; Mo, Eun Kyung; Park, Myung Jae; Lee, Myung Goo; Hyun, In Gyu; Jung, Ki Suck

Abstract

BACKGROUND: The aim of this study is to evaluate the usefulness of quantitative culture of bronchoalveolar lavage(BAL) fluid for the diagnosis of bacterial pneumonia and identification of causative agents.
METHODS
Study group consisted of 30 episodes in 28 patients, enrolled from January 1995 through June 1996. Inclusion criteria were 1) presence of respiratory symptoms such as cough, sputum or dyspnea 2) increased peripheral blood leukocyte count(> or =11,000/mm3) 3) Fever(> or =38.3 degrees C) 4) purulent sputum 5) new or progressive infiltrate on chest radiography. For the diagnosis of pneumonia and its causative agents, sputum smear and culture, blood culture and BAL fluid studies were performed. BAL fluid studies included differential count of white blood cell, BAL fluid smear and culture, detection of elastin fibers and presence of intracellular organisms(ICO). Quantitative culture of BAL fluid was considered positive if colony-forming units was more than 1.0 x 104/ml. Positive criteria for ICO was presence of microorganism in more than five per 100 of phagocytes. RESULT: Recruited were 22 males and 6 females. The mean age was 57.5+/-13.5 years(range 25-84). Of 30 episodes underwent BAL fluid studies, 19 cases were diagnosed to be bacterial pneumonia. S. aureus(7 cases) was the most common causative agent and was followed by P. aeruginosa(4), E. cloacae(2), A. baumanii(1), H. influenzae(1) and -hemolytic Streptococcus(1). Sensitivity of quantitative culture of BAL fluid for the diagnosis of bacterial pneumonia was 68.4% and its specificity was 63.6%. Elastin fibers were detected in 5 cases(31%) and ICO over 5% in 3 cases(15.7%). When criteria of quantitative culture of BAL fluid, detection of ICO and elastin fibers were applied together, diagnostic rate of pneumonia was 84.2%(16/19). CONCLUSON: Quantitative culture of BAL fluid was more sensive and specific compared to sputum and blood culture for the diagnosis of bacterial pneumonia. It was suggested that detection of ICO and elastic fibers in BAL fluid could raise the diagnostic rate of bacterial pneumonia.