Haemophilus parainfluenzae infections in children, with the report of a unique case.

Haemophilus parainfluenzae, although a human commensal, is infrequently reported to be pathogenic. A child with a hepatic abscess caused by this organism was studied, and 54 other significant pediatric infections associated with H. parainfluenzae, as reported in the English-language literature, were reviewed. Meningitis and endocarditis were the most frequently reported infections and affected dissimilar populations of patients. Localized abscesses of the brain, skin, joints, and liver also occurred. Risk factors and antecedent illnesses were occasionally identified. The overall mortality rate was 11%, and the combined rates of morbidity and mortality totaled 38%. Difficulty in identifying H. parainfluenzae may have resulted in misdiagnosis of infections caused by this organism in the past. Antibiotic-resistant strains have emerged. Because H. parainfluenzae is ubiquitous and can cause serious disease in otherwise normal patients, it should be considered a pathogen, and its potential for causing pediatric illness should be more fully appreciated.