Introduction Mycoplasma pneumoniae is a common cause of pneumonia. Incidence ranges from 0.5 to 5.0 per 1000 population or up to 20% of all pneumonias, and generally declines with age, being rare in adults over 50. Classically epidemics occur in 4 to 7-year cycles. Usual features are insidious onset “viral”-type symptoms, including fever, headache, dyspnoea and dry cough, together with a variety of extra pulmonary manifestations. Diagnosis is often missed because of the atypical and unusual presentation.
Methods and Results We examined electronic records of patients during 2010 diagnosed with M pneumoniae by an elevated specific IgM immunoassay method. There were 35 cases. Of those, 20 required acute admission to our hospital (18 adults and two children). In adults, common presenting features were fever, cough, headaches, lethargy and myalgia. Major presenting features, however, were meningitis/encephalitis in two patients, Stevens-Johnson syndrome in 1, confusion in 1, and haemoptysis in 1. In six adults (33%), the diagnosis was not made during hospital admission, and symptoms were erroneously attributed to presumptive diagnoses of viral meningitis, acute viral illness, dyspnoea of unknown cause, asthma/pericarditis, and an acute drug reaction. We compared length of admission in patients diagnosed early on in admission to those misdiagnosed or diagnosed late; early diagnosis of M pneumoniae using this method was associated with significantly shorter lengths of stay.
Conclusion and Discussion An appreciation of common presenting clinical features of Mycoplasma is important in ensuring the diagnosis is made promptly and not missed. The advantage of an IgM based assay is the detection of early/acute illness rather than convalescent disease (as in the case of parallel assays of acute and convalescent samples), having the potential to change management, refine antibiotics where appropriate and also to potentiate early discharge.