QUANTITATION OF MICROORGANISMS IN LOWER RESPIRATORY TRACT SECRETIONS

The usefulness of lower respiratory tract secretions culture in guiding microbiological diagnosis of pneumonia is controversial. Dueto the inevitable oropharyngeal bacterial contamination that occurs in the collection of all respiratory secretion samples,quantitative culture techniques are always needed to differentiate oropharyngeal contaminants present at low concentration fromhigher-concentration infecting organisms. A number of 783 patients from Dr. Soetomo hospital Surabaya on 2012 with pneumoniawere studied. Before administering antibiotic therapy, lower respiratory tract secretion was collected and processed according tostandard protocols. Quantitation of sputum from patients with pneumonia revealed that probable pathogens were present inpopulation of ≥ 107 organisms/ml. The threshold for positive culture defining pneumonia was 104 cfu/ml for bronchoalveolar lavage(BAL) and 105 cfu/ml for endotracheal aspirate (EA). There were 384 gram-positive cocci, and 307 gram-negative bacilli.Quantitation of microorganisms in lower respiratory tract secretion yielded a causative organism in 691 (88%) of the 783 samples.In conclusion, lower respiratory tract secretions with quantitative culture can be helpful for the diagnosis of bacterial pneumonia.(FMI 2013;49 109-111)