BACKGROUND There are few data on paediatric community acquired pneumonia (PCAP) in the UK.

AIMS To investigate the aetiology and most useful diagnostic tests for PCAP in the north east of England.

RESULTS A pathogen was isolated from 60% (81/136) of cases, and considered a definite or probable cause of their pneumonia in 51% (70/136). Fifty (37%) had a virus implicated (65% respiratory syncytial virus) and 19 (14%) a bacterium (7% group A streptococcus, 4% Streptococcus pneumoniae), with one mixed infection. Of a subgroup (51 patients) in whom serum antipneumolysin antibody testing was performed, 6% had evidence of pneumococcal infection, and all were under 2 years old. The best diagnostic yield was from paired serology (34%, 31/87), followed by viral immunofluorescence (33%, 32/98).

CONCLUSION Viral infection accounted for 71% of the cases diagnosed. Group A streptococcus was the most common bacterial infective agent, with a low incidence of bothMycoplasma pneumoniae andS pneumoniae. Pneumococcal pneumonia was the most common bacterial cause of pneumonia in children under 2 years but not in older children. Inflammatory markers and chestx ray features did not differentiate viral from bacterial pneumonia; serology and viral immunofluorescence were the most useful diagnostic tests.