Etiological analysis and epidemiological comparison among adult CAP and NHCAP patients in Okinawa, Japan

J Infect Chemother. 2017 Jul;23(7):452-458. doi: 10.1016/j.jiac.2017.03.018. Epub 2017 Apr 18.


Background: Etiological epidemiology and diagnosis are important issues for CAP and NHCAP. Despite the availability of effective therapies, significant morbidity and mortality ensues.

Methods: We retrospectively analyzed the etiology of 200 pneumonia patients at the University of the Ryukyus Hospital. Patients were categorized into CAP (n = 97) or NHCAP (n = 103), according to the Japanese Respiratory Society guidelines. Diagnoses were made using clinical tests including, Gram stain, bacterial culture, serum and urinary tests.

Results: Pathogens were detected in 71% of patients, and identified as the source of infection in 52% (104/200). The majority of patients suffered from Streptococcus pneumoniae (32/200), Haemophilus influenzae (22/200), and Moraxella catarrhalis (16/200). Gram stain guided pathogen-oriented therapy decisions for 38 of 96 patients with unknown pathogens. Atypical pathogens were only diagnosed in CAP patients (n = 5). Severity of pneumonia was related to male sex (p = 0.006), and preexisting conditions, such as chronic heart failure (p < 0.001) and COPD (p < 0.001). Risk factors associated with increased length of stay included chronic heart failure, chronic renal failure, other pulmonary diseases and diabetes. Mortality for NHCAP patients was associated with lung cancer and bronchiectasis. CAP patients were more frequently admitted during winter months, while NHCAP patients were admitted during all other seasons. Seasonal patterns for individual pathogens could not be determined.

Conclusion: Gram staining remains useful to guiding diagnostics. Pathogens affecting CAP and NHCAP patients were not significantly different; as such, attention should be focused on the management of underlying conditions. Clinical outcomes were not affected by guideline discordant therapy.

Keywords: Community-acquired pneumonia; Epidemiology; Etiology; Gram staining; Nursing and healthcare-associated pneumonia.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Community-Acquired Infections / epidemiology*
  • Community-Acquired Infections / microbiology
  • Cross Infection / epidemiology*
  • Cross Infection / microbiology
  • Female
  • Haemophilus influenzae
  • Hospitalization
  • Humans
  • Japan / epidemiology
  • Male
  • Middle Aged
  • Pneumonia, Bacterial / epidemiology*
  • Pneumonia, Bacterial / microbiology
  • Retrospective Studies
  • Risk Factors
  • Streptococcus pneumoniae