Background: India has the largest burden of childhood community acquired pneumonia (CAP), but lacks well-designed studies reporting microbial etiology. The Community Acquired Pneumonia Etiology Study (CAPES) was undertaken for this knowledge gap.
Methods & Materials: Children (1-144 mo) with CAP < 7 days diagnosed by WHO IMNCI criteria, were enrolled through community and hospital-based surveillance during April 2011 to December 2014. All underwent blood and nasopharyngeal aspirate (NPA) bacterial culture. Multiplex Viral PCR in NPA was performed retrospectively in 40% cases representative of the whole cohort.
Results: A total of 4045 children were enrolled; 13.1% had very severe pneumonia, 54.3% severe pneumonia and 32.6% non-severe pneumonia. Blood culture yielded pathogens in 2.0%; Gram negative bacilli predominated (Klebsiella pneumoniae 12, Pseudomonas aeruginosa 6, Acinetobacter baumannii 6, Salmonella typhi 3, others 4), followed by S. aureus (22), S. pneumoniae (12), H. influenzae 5, and others (one each of 11 organisms). NPA culture yielded potential pathogens in 15.0% cases: S. pneumoniae (522), H. influenzae (51), S. aureus (27), Pseudomonas aeruginosa (4) and others (5). Blood and NPA cultures were discordant in most cases. Multiplex PCR in 1731 (42.8%) cases revealed viruses in 805 (46.5%): RSV (423), Rhinovirus (143), parainfluenza virus (65), human metapneumovirus (47), coronavirus (24), influenza virus (19), others (33) and combinations (51). Attributing etiology based on bacteremia or NPA viruses associated with pneumonia (RSV, PIV, HMPV or Influenza) confirmed etiology in 636 (15.7%) cases. Inclusion of NPA bacteria in those negative for bacteremia or pathogenic viruses, yielded etiology in another 423 (10.5%) cases. Inclusion of non-pneumonia viruses in the remainder provided potential etiology in an additional 196 (4.5%) cases. Overall, etiology was bacterial in 505 (12.5%), viral in 750 (18.5%) and indeterminate in the remainder. There were no obvious differences in etiology pattern with respect to age groups, pneumonia severity, symptoms, duration of symptoms, and presence of risk factors. However, those with wheezing were more likely to have viruses (especially RSV). Demographic parameters and clinical symptoms also did not differ among the different pathogens.
Conclusion: RSV, Gram negative bacteria, and Staphylococcus aureus are the dominant pathogens in childhood CAP in India.