Empyema: the use of broad range 16S rDNA PCR for pathogen detection.

BACKGROUND: An increase in the incidence of thoracic empyema in children has been reported. The causative pathogen is often unknown as pleural fluid is frequently sterile at the time of culture. The role of unusual organisms is unclear.

AIMS: (1) To compare the detection of organisms in pleural fluid from children with empyema using a molecular technique (16S rDNA polymerase chain reaction (PCR)) and bacterial culture. (2) To compare the concordance of organisms identified using the two techniques and the influence of prior antibiotic treatment on positive detection rate.

METHODS: Pleural fluid from children admitted with empyema between January 2000 and February 2002 was cultured and additionally analysed using broad range 16S rDNA PCR.

RESULTS: Pleural fluid was cultured from 32 patients, aged 1 month-16 years. Median duration of previous antibiotic therapy was 8 days (range 1-42 days). Six samples were culture positive and 22 were PCR positive. A causal organism was detected by PCR alone, after considering results from the local hospital, in 14 patients. There was complete concordance in organisms cultured and detected by PCR. Additional organisms detected by PCR were predominantly S pneumoniae, S pyogenes, and anaerobes.

CONCLUSIONS: Analysis of pleural fluid by broad range 16S rDNA PCR in addition to culture, increases organism identification in empyema.