Prospective study of the usefulness of sputum gram stain in the initial approach to community-acquired pneumonia requiring hospitalization

From February 1995 through May 1997, we prospectively studied 533 patients with community-acquired pneumonia requiring hospitalization in order to ass ess the current usefulness of sputum Gram stain in guiding the etiologic di agnosis and initial antibiotic therapy when applied routinely. Sputum sampl es of good quality were obtained in 210 (39%) patients, 175 of whom showed a predominant morphotype. Sensitivity and specificity of Gram stain for the diagnosis of pneumococcal pneumonia were 57% and 97%, respectively; the co rresponding values for Haemophilus influenzae pneumonia were 82% and 99%. P atients with a predominant morphotype were more frequently treated with mon otherapy than were patients without a demonstrative sputum sample (89% vs. 75%; P<.001), Analysis of our data shows that a good-quality sputum sample can be obtained from a substantial number of patients with community-acquir ed pneumonia. Gram stain was highly specific for the diagnosis of pneumococ cal and H. influenzae pneumonia and may be useful in guiding pathogen-orien ted antimicrobial therapy.