Epidemiology and etiology of pneumonia in children in Hong Kong.

The epidemiologic and etiologic features of cases of pneumonia among 1,740 children admitted to a teaching hospital in Hong Kong over a 3-year period were studied. Of the patients, 23% were < 1 year old and 69% were < 5 years old. The incidence of pneumonia requiring admission to the hospital was 6.4 episodes per 1,000 children per year for those < 5 years of age. The overall case fatality rate was 0.15% among patients who did not have severe underlying disease before contracting pneumonia. A bacterial etiology was confirmed by blood culture for only 2% of patients. However, culture of sputum or nasopharyngeal aspirates yielded predominant or pure growth of one bacterial agent in 17% of cases. Haemophilus influenzae was the bacterial agent most frequently isolated from nasopharyngeal aspirates or sputum, followed by Streptococcus pneumoniae and Staphylococcus aureus. Of the H. influenzae isolates, 38% were resistant to ampicillin. A viral etiology was proven in 9.1% of cases, and evidence of mycoplasmal infection was found in 3.8% of cases. Respiratory syncytial virus was the most frequently identified viral agent, followed by adenovirus and influenza A virus.