Is sputum Gram staining useful in the emergency department's management of pneumonia?

Objective: To assess the utility of sputum Gram stains in the management of community-acquired pneumonia (CAP) in the emergency department. Methods: Descriptive, retrospective study of patients with CAP admitted to hospital after evaluation in the emergency department between October 2005 and November 2007. We analyzed patient variables; the Fine index; the results of Gram staining of sputum smears, urine antigen tests, and blood cultures; and the antibiotic therapy initially prescribed. The sensitivity, specificity, and positive and negative predictive values of the Gram stain results were calculated. Results: A total of 608 cases of CAP (mean age, 70.7 years; 64.3% men) were included. Sputum cultures were obtained for 168 patients (27.6%). Gram-negative diplococcal infection was demonstrated in 74 cases, gram-negative coccobacilli in 26, gram-negative stains in 15, gram-positive cocci in clusters or chains in 11, and polymorphonuclear cells with no predominating microorganisms in 42. Streptococcus pneumoniae was isolated in 57 patients and Haemophilus influenza in 19. The sensitivity of a finding of gram-positive diplococci was 47.1% for pneumococcal infection, with a specificity of 94.2%. The sensitivity of a finding of gram-negative coccobacilli was 73% for H. influenzae infection, with a specificity of 95%. Ceftriaxone and levofloxacin were the most frequently assigned treatments in patients with diplococcal and H. influenzae infections, respectively. Conclusions: Gram staining of sputum is of limited value in the emergency department's management of CAP in adult patients. As the results vary according to pathogen, they are of little use in choosing the antibiotic treatment. [Emergencias 2011;23:108-111].