title: Validation of sputum Gram stain for treatment of community-acquired pneumonia and healthcare-associated pneumonia: a prospective observational study.
abstract: BACKGROUND
  The usefulness of sputum Gram stain in patients with community-acquired pneumonia (CAP) is controversial. There has been no study to evaluate the diagnostic value of this method in patients with healthcare-associated pneumonia (HCAP). The purpose of this study was to evaluate the usefulness of sputum Gram stain in etiological diagnosis and pathogen-targeted antibiotic treatment of CAP and HCAP.
  
  
  METHODS
  We conducted a prospective observational study on hospitalized patients with pneumonia admitted to our hospital from August 2010 to July 2012. Before administering antibiotics on admission, Gram stain was performed and examined by trained physicians immediately after sputum samples were obtained. We analyzed the quality of sputum samples and the diagnostic performance of Gram stain. We also compared pathogen-targeted antibiotic treatment guided by sputum Gram stain with empirical treatment.
  
  
  RESULTS
  Of 670 patients with pneumonia, 328 were CAP and 342 were HCAP. Sputum samples were obtained from 591 patients, of these 478 samples were good quality. The sensitivity and specificity of sputum Gram stain were 62.5% and 91.5% for Streptococcus pneumoniae, 60.9% and 95.1% for Haemophilus influenzae, 68.2% and 96.1% for Moraxella catarrhalis, 39.5% and 98.2% for Klebsiella pneumoniae, 22.2% and 99.8% for Pseudomonas aeruginosa, 9.1% and 100% for Staphylococcus aureus. The diagnostic yield decreased in patients who had received antibiotics or patients with suspected aspiration pneumonia. Pathogen-targeted treatment provided similar efficacy with a decrease in adverse events compared to empirical treatment.
  
  
  CONCLUSIONS
  Sputum Gram stain is highly specific for the etiologic diagnosis and useful in guiding pathogen-targeted antibiotic treatment of CAP and HCAP.
authors.affiliation: Department of Respiratory Medicine, Okinawa Chubu Hospital, 281 Miyazato, Uruma, Okinawa, Japan. fukuyama.hajime.55@gmail.com.
authors.forename: Hajime
authors.initials: H
authors.lastname: Fukuyama
authors.forename: Shin
authors.initials: S
authors.lastname: Yamashiro
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kinjo
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tamaki
authors.forename: Tomoo
authors.initials: T
authors.lastname: Kishaba
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D004396:Coloring Agents / Q000737:chemistry; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000188:drug therapy; D003428:Cross Infection; D005260:Female; D005840:Gentian Violet / Q000737:chemistry; D006192:Haemophilus Infections / Q000175:diagnosis* / Q000188:drug therapy; D006801:Humans; D007710:Klebsiella Infections / Q000175:diagnosis* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D045828:Moraxellaceae Infections / Q000175:diagnosis* / Q000188:drug therapy; D010619:Phenazines / Q000737:chemistry; D011018:Pneumonia, Pneumococcal / Q000175:diagnosis* / Q000188:drug therapy; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology*; D013194:Staining and Labeling
chemical_list: D000900:Anti-Bacterial Agents; D004396:Coloring Agents; C035863:Gram's stain; D010619:Phenazines; D005840:Gentian Violet