Approach
Clinically, community-acquired pneumonia due to Chlamydia pneumoniae cannot be differentiated from pneumonia due to other organisms, especially Mycoplasma pneumoniae.
History
Disease history is nonspecific. Patients may have 1 to 2 weeks of fever and cough, and may complain of pleuritic chest pain, headache, and sore throat.[11] Shortness of breath may also be evident with an effusion.
Physical examination
Patients are usually febrile and may be tachypneic. Auscultation of the chest may reveal rales and wheezing. Findings consistent with pleural effusions may also be present (e.g., dullness to percussion, decreased air entry, reduced chest expansion, and decreased tactile fremitus), although uncommon.[11]
Investigations
Chest x-ray and WBC with differential should be done in all patients with suspected chest infection on clinical evaluation. Both are nonspecific in the diagnosis of C pneumoniae, but are useful in confirming pneumonia.
Identification of the organism in respiratory specimens (nasopharyngeal swabs or aspirates, sputum and pleural fluid) by culture or validated PCR is diagnostic. However, culture is not readily available. Serology correlates poorly with identification of the organism.
There are two FDA-approved commercially available nucleic acid amplification (NAA) based respiratory panels that detect 14 viruses and three bacterial targets including C pneumoniae, Mycoplasma, pneumoniae and Bordetella pertussis. They have FDA approval for use with nasopharyngeal swab samples only. The NAA based panels combine nucleic acid extraction, nested PCR, detection, and data analysis in a single-use cassette. However, data on their performance for detection of C pneumoniae in clinical settings are limited. Most of the published studies have been limited to respiratory viruses or have had very few patients with C pneumoniae infection. [2]
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