C. pneumoniae community-acquired pneumonia (CAP) in mimicking Mycoplasma pneumoniae meningoencephalitis complicated by asthma.

Chlamydophila (Chlamydia) pneumoniae is a common, non-zoonotic cause of community-acquired pneumonia (CAP) in ambulatory young adults. C. pneumoniae clinically presents as a mycoplasma-like illness frequently accompanied by laryngitis. C. pneumoniae CAP may also cause nursing home outbreaks in the elderly. Similar to Mycoplasma pneumoniae in immunocompetent hosts, C. pneumoniae CAP usually manifests as a mild/moderately severe CAP. In contrast with Legionnaire's disease, central nervous system involvement is usually not a feature of C. pneumoniae CAP. M. pneumoniae may rarely present with meningoencephalitis accompanied by high cold agglutinin titers. We present the case of a young man who presented with M. pneumoniae-like illness and was hospitalized for severe CAP that was accompanied by a pertussis-like cough and severe headache. Although his chest x-ray showed a right upper lobe infiltrate, a lumbar puncture was performed to rule out meningitis, but his cerebrospinal fluid profile was unremarkable. Titers for non-zoonotic atypical pneumonia pathogens were negative except for a highly elevated C. pneumoniae immunoglobulin-M titer (1:320). Testing for legionella and pertussis was negative. Q fever and adenoviral titers were also negative. Cold agglutinin titers were repeatedly negative. The patient was successfully treated with moxifloxacin but developed permanent asthma after C. pneumoniae CAP. This case is unusual in several aspects. First, C. pneumoniae usually presents as a mild to moderate CAP, but in this case it was severe. Second, hoarseness was absent, which would have suggested C. pneumoniae. Third, wheezing was an important clue to the diagnosis of C. pneumoniae, which is not a clinical finding with other causes of CAP. Fourth, permanent asthma may follow C. pneumoniae, as well as M. pneumoniae CAP. Fifth, severe headache mimicking M. pneumoniae meningoencephalitis may rarely accompany C. pneumoniae CAP.