The Clinical Microbiology Laboratory in the Diagnosis of Lower Respiratory Tract Infections

Lower respiratory tract infections (LRTIs) produce between 5 and 10 % of all deaths reported to the CDC via the 122 Cities Mortality Reporting System (5). The clinical laboratory plays a vital role in the diagnosis of these infections but faces numer-ous challenges due to the complexity of LRTIs, including spec-imen quality and diversity; contamination of specimens with oropharyngeal flora; a diverse pathogen population that in-cludes bacteria, viruses, and fungi; and the complex pathophys-iology of respiratory tract infections, especially in special pop-ulations. Five current questions in the clinical microbiology (CM) of LRTI were discussed: 1. What is the real value of the Gram stain of expectorated sputum? 2. What is the value of quantitative culture techniques on bronchoalveolar lavage (BAL) and mini-BAL specimens, en-