Causes of Pneumonia Among Children
To determine if Haemophilus influenzae type b (Hib) and S. pneumoniae could be identified more often from the nasopharynx of patients with pneumonia than from control patients, we obtained nasopharyngeal swab specimens from 96 patients with chest x-ray-confirmed pneumonia and 214 age-matched control patients with diarrhea or dermatitis from the outpatient department at Beijing Children's Hospital.  Pneumonia patients were more likely to be colonized with Hib and S. pneumoniae than control patients, even after the data were adjusted for possible confounding factors such as day-care attendance, the presence of other children in the household, and recent antibiotic use. In China, where blood cultures from pneumonia patients are rarely positive, the results of these nasopharyngeal cultures provide supporting evidence for the role of Hib and S. pneumoniae as causes of childhood pneumonia.

New vaccines for Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae effectively prevent disease caused by these pathogens. However, the relatively high cost of these vaccines inhibits their widespread use in developing countries. Therefore, for most developing countries, surveillance for disease caused by Hib and S. pneumoniae is needed to demonstrate that the investment in these highly effective vaccines is warranted.

Data on the incidence of Hib and pneumococcal disease in China are limited to a few meningitis surveillance studies, which suggest a surprisingly low incidence of confirmed Hib meningitis. In most cases the rate is 5 to 25 times lower than those observed in areas of North America, Europe, Africa, South America, and Oceania where careful surveillance studies have been carried out. However, the apparent low incidence in these studies is difficult to interpret because of concerns that physicians may not routinely perform lumbar punctures on all patients with suspected meningitis, that the laboratory methods may have been inadequate, and that widespread use of oral antibiotics for outpatients may have artificially reduced the yield of cultures. In part because of the uncertainty surrounding the local rate of Hib disease, China has not yet made Hib vaccination a routine infant vaccination. Many authors and organizations have called for further studies of the epidemiology in China, but few data are currently available.

Pneumonia is a leading cause of illness and death among children worldwide. Demonstrating the role of bacterial agents such as H. influenzae and S. pneumoniae in pneumonia, however, is difficult. The most widely accepted method for demonstrating that a bacterial agent causes pneumonia is isolation of the bacterium from cultures of blood or, in some cases, lung aspirates. However, blood cultures are rarely positive in pediatric pneumonia even when microbiologic techniques are optimal, and fastidious organisms such as Hib will not grow unless the appropriate culture medium is used. In China, parents and physicians often resist the collection of blood for cultures, and given the high rate of prior antibiotic use, the yield from these specimens is likely to be low.

Because alternatives are needed to traditional methods of documenting Hib and S. pneumoniae as causes of pneumonia in China, we designed a study to investigate the use of a readily available source of specimens that is likely to be positive more often than a blood culture. We compared the rates of isolation of Hib and S. pneumoniae from nasopharyngeal swabs and blood cultures of patients with radiographically confirmed pneumonia and a group of control patients without pneumonia.