A comparison of IgM anti-P1 immunoblotting and a polymerase chain reaction assay for the diagnosis of acute Mycoplasma pneumoniae respiratory infection in children

A rapid IgM immunoblotting serological test was compared to a polymerase chain reaction (PCR) assay of respiratory specimens for the diagnosis of acute Mycoplasma pneumoniae infection. Among 112 paired specimens, the frequency of a positive diagnosis by any method was 7.1%. Both IgM serology and PCR were positive for only two out of eight infected patients. PCR positive, IgM negative patients (4) were ill for an insufficient period to allow the IgM response to be demonstrable (⩽7 days). PCR negative, IgM positive patients (2) were likely to have had negative amplification assays because of the nature of the respiratory specimens. Nasopharyngeal washings uncommonly inhibited PCR amplification. Both rapid serological and genetic amplification assays have a role, together or alone, in the diagnosis of M. pneumoniae infection and paradigms for cost-effective utilization will be required.