title: Etiological Diagnosis of Community-Acquired Pneumonia in Adult Patients: A Prospective Hospital-Based Study in Mashhad, Iran.
abstract: BACKGROUND
  Pneumonia is the third most common cause of death in the world, and mortality is highest for patients who require hospitalization.
  
  
  OBJECTIVE
  This prospective observational study is an etiological survey of community-acquired pneumonia (CAP) over a 12-month period in the Iranian city of Mashhad. To our knowledge, this is one of the first prospective hospital-based studies to comprehensively evaluate the epidemiological, demographical, clinical, and prognostic factors of patients with CAP in Iran.
  
  
  METHODS
  We studied all adult patients (aged ≥ 16 years) with CAP admitted to Imam Reza Hospital, Mashhad, Iran, between February 2013 and January 2014. The etiological diagnosis of CAP was made through conventional culturing and staining of respiratory secretions (i.e. sputum and pleural fluid), standard BACTEC™ Plus Aerobic/F bottles for blood cultures, and the immunochromatographic assays BinaxNOW(®) Streptococcus pneumoniae antigen and BinaxNOW(®) Legionella pneumophila antigen for the detection of S. pneumoniae antigen and L. pneumophila serogroup 1 antigen, respectively.
  
  
  RESULTS
  Among 120 patients with CAP, the most common etiology was S. pneumoniae (24.4%), followed by Mycobacterium tuberculosis (17.5%), S. aureus (6.7%), polymicrobial agents including anaerobes (4.2%), complicated hydatid cyst (2.5%), Influenza A virus (4.2%; including 2 cases of mixed Influenza A-bacterial infection), and Klebsiella pneumoniae, Brucella melitensis, Mucor, and varicella, each in 0.8% of the patients. The diagnosis of pneumonia remained unknown in 49 (40%) patients.
  
  
  CONCLUSIONS
  Tuberculosis was an important cause of CAP in our region. Hence, it should be considered in all patients admitted with a CAP diagnosis.
authors.affiliation: Department of Infectious Diseases, Imam Reza Teaching Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Naderi
authors.affiliation: Department of Infectious Diseases, Imam Reza Teaching Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Fereshte
authors.initials: F
authors.lastname: Sheybani
authors.affiliation: Department of Infectious Diseases, Imam Reza Teaching Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Sarvghad
authors.affiliation: Department of Clinical Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Meshkat
authors.affiliation: Department of Statistics, Faculty of Mathematics, Ferdowsi University, Mashhad, IR Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Jabbari Nooghabi
keywords: Etiology; Pneumonia; Streptococcus pneumonia; Tuberculosis