Background: The incidence and causative organisms associated with complicated parapneumonic effusions in children with community-acquired pneumonia are likely to have changed during the past several years.
Methods: Data regarding clinical and laboratory features were abstracted retrospectively from medical records of 76 subjects with complicated parapneumonic effusions at a tertiary children's hospital from 1996 through 2001. Incidence rates per 10 000 hospital discharges and per 1000 patients with nonviral pneumonia were calculated.
Results: Etiologic organisms were Streptococcus pneumoniae (31 subjects), Staphylococcus aureus (7), Streptococcus pyogenes (5), Abiotrophia sp. (1) and no culture-confirmed agent (32). The annual incidence of complicated parapneumonic effusions per 10 000 discharges progressively increased from 4.5 in 1996 to 25.0 in 1999 (P = 0.0001), then declined to 10.1 in 2001 (P = 0.03). Similarly the incidence per 1000 cases of nonviral pneumonia increased from 2.9 in 1996 to 11.0 in 1999 (P = 0.003) and then declined to 4.8 in 2001 (P = 0.053). Whereas S. pneumoniae was the leading confirmed etiology in each year, the proportion of cases caused by Staphylococcus aureus increased from 6% in 1996 to 2000 (all of which were methicillin-susceptible) to 30% in 2001 (all methicillin-resistant; P = 0.04).
Conclusions: The incidence of complicated parapneumonic effusions in children with community-acquired pneumonia increased from 1996 to 1999 and then declined concomitant with the introduction of the pneumococcal conjugate vaccine. Although cases caused by S. pneumoniae have decreased, community onset methicillin-resistant Staphylococcus aureus has emerged as a cause of pneumonia with complicated effusions in children.