PREVALENCE OF POSITIVE SEROLOGY FOR ACUTE CHLAMYDIA-PNEUMONIAE INFECTION IN EMERGENCY DEPARTMENT PATIENTS WITH PERSISTENT COUGH

Objective: To determine the prevalence of acute Chlamydia pneumoniae i nfection in ED patients presenting with a persistent cough. Methods: T his was a case series consisting of a convenience sample of 65 patient s greater than or equal to 18 years of age who presented with a chief complaint of a cough lasting greater than or equal to 2 weeks, Patient s were treated in the ED of an urban university hospital. Patients wit h immunosuppression, lung disease, pneumonia, or a cough lasting great er than or equal to 3 months were excluded. Acute and convalescent ser a were assayed for antibody to C. pneumoniae. Subjects with C. pneumon iae antibody titers showing a fourfold rise in either immunoglobin M ( IgM) or immunoglobin G (IgG) antibody, an IgM titer of greater than or equal to 16, or an IgG titer of greater than or equal to 512 were con sidered to have evidence of acute C. pneumoniae infection. Results: Th irteen (20%; 95% CI, 11% to 32%) of the 65 subjects had serologic evid ence of acute C. pneumoniae infection. Except for an increased rate of fever, clinical signs and symptoms and laboratory studies did not dif ferentiate those who had C. pneumoniae from those who did not have the disease. Patients diagnosed as having Bordetella pertussis or Mycopla sma pneumoniae infection did not have serologic evidence of concurrent C. pneumoniae infection. Conclusions: C. pneumoniae infection appears to be associated with a persistent cough in ED patients. Clinicians s hould consider this organism when evaluating these patients. It is unc lear whether antibiotic therapy is indicated for these patients. If an tibiotics are used, a tetracycline or macrolide antibiotic would be mo st appropriate.