Comparison of PCR, culture & serological tests for the diagnosis of Mycoplasma pneumoniae in community-acquired lower respiratory tract infections in children.

BACKGROUND & OBJECTIVE: Mycoplasma pneumoniae is known to be a major cause of lower respiratory tract infections in children. A specific diagnosis is important to institute the appropriate treatment. Information on diagnostic methods used for M. pneumoniae in Indian paediatric population is scarce. The study was thus conducted to compare polymerase chain reaction (PCR), culture and serology for the diagnosis of M. pneumoniae in community-acquired lower respiratory tract infections in children.

METHODS: Seventy five children aged 6 months to 12 yr with signs of community-acquired lower respiratory tract infections were selected for the study. Culture of nasopharyngeal aspirates was done. The serum samples were analyzed for the detection of IgM and IgG antibodies to M. pneumoniae. A 543 base pairs (bp) region of P1 gene of M. pneumoniae was selected for amplification in PCR assay applied to nasopharyngeal aspirates.

RESULTS: M. pneumoniae was isolated in culture from 4 (5.33%) children. Serological evidence of M. pneumoniae infection was observed in 16(21.3%) children. All culture positive patients were also positive by serology. Overall, PCR for M. pneumoniae was positive in 13 (17.3%) patients. All four culture positive patients were also positive by PCR. In 11 out of 13 (84.62%) PCR positive patients, serological evidence was there. Culture and/or serology and/or PCR positive results diagnosed M. pneumoniae infection in 18 (24%) of 75 patients.

INTERPRETATION & CONCLUSION: A combination of culture, serology and PCR may provide diagnostic information on the aetiology of M. pneumoniae community-acquired lower respiratory tract infections in paediatric population.