Background Implementation of sputum Gram stain in the initial assessment of community-acquired pneumonia (CAP) patients is still controversial. We performed a systematic review and meta-analysis to investigate the usefulness of sputum Gram stain for defining the etiologic diagnosis of CAP in adult patients. Methods We systematically searched the Medline, Embase, Science Direct, Scopus and LILACS databases for full-text articles. Relevant studies were reviewed by at least three investigators who extracted the data, pooled them using a random effects model, and carried out quality assessment. For each bacterium ( Streptococcus pneumoniae , Haemophilus influenzae , Staphylococcus aureus , and Gram-negative bacilli), pooled sensitivity, specificity, positive and negative likelihood ratios were reported. Results After a review of 3539 abstracts, 20 articles were included in the present meta-analysis. The studies included yielded 5619 patients with CAP. Pooled sensitivity and pooled specificity of sputum Gram stain were 0.59 (95% CI, 0.56–0.62) and 0.87 (95% CI, 0.86–0.89) respectively for S. pneumoniae , 0.78 (95% CI, 0.72–0.84) and 0.96 (95% CI, 0.94–0.97) for H. influenzae , 0.72 (95% CI, 0.53–0.87) and 0.97 (95% CI, 0.95–0.99) for S. aureus , and 0.64 (95% CI, 0.49–0.77) and 0.99 (95% CI, 0.97–0.99) for Gram-negative bacilli. Conclusion Sputum Gram stain test is sensitive and highly specific for identifying the main causative pathogens in adult patients with CAP. Trial registration This study has been registered at PROSPERO International prospective register of systematic reviews under registration no. CRD42015015337 . Electronic supplementary material The online version of this article (10.1186/s12879-019-4048-6) contains supplementary material, which is available to authorized users.

Summary Objective The aim of this study was to appraise the methodological quality of published clinical practice guidelines (CPGs) of community‐acquired pneumonia (CAP) using AGREE II instrument for further enhancing the CAP CPG development. Methods We performed a systematic review of published CPGs on CAP from January 2007 to May 2019. All reviewers independently assessed each CPG using the AGREE II instrument. A standardised score was calculated for each of the six domains. Results Our search strategy identified 4125 citations but just 18 met our inclusion criteria. Agreement among reviewers was very good: 0.98. The domains that scored better were: “scope and purpose” and “clarity and presentation”. Those that scored worse were “editorial independence”, and “applicability”. According to the AGREE II evaluation for each Guideline, the NICE, IDSA, BTS, SWAB, Korea, Consensur II, Colombian and Peruvian CPGs were the only recommended with no further modifications. In addition, ERS and SEPAR CPGs were recommended with modifications, with lower scores regarding the editorial independence and applicability. Conclusion In conclusion, published CPGs for CAP management vary in quality with a need to improve the methodological and applicability rigour. This could be achieved following the standards for guidelines development and a better emphasis on how to apply CPGs recommendations in clinical practice.