Purpose: Limited data suggest that tetracycline or erythromycin is the antibiotic of choice for treating Chlamydia pneumoniae infection, but they are not always effective or well tolerated. Because the fluoroquinolone ofloxacin is effective for Chlamydia trachomatis infections, we investigated its role in treating C. pneumoniae infections.
Patients and methods: Eighty-seven patients were enrolled in a randomized trial of antibiotic therapy for acute lower respiratory tract infections. The patients were randomly assigned to oral treatment with either ofloxacin (400 mg twice a day) or erythromycin (400 mg four times a day) for 10 days. Frozen acute and convalescent serologic specimens were tested for TWAR antibody by microimmunofluorescence. Susceptibility testing of C. pneumoniae to ofloxacin was also performed.
Results: Four patients who received ofloxacin were retrospectively identified as having C. pneumoniae pneumonia (two) or bronchitis (two). Within 2 weeks of starting ofloxacin therapy, all were cured or markedly improved. The minimum inhibitory concentrations of ofloxacin for three previously isolated clinical strains of C. pneumoniae were determined to be 1.0 to 2.0 micrograms/mL, well within the achievable serum levels (3 to 5 micrograms/mL) with ofloxacin therapy.
Conclusion: Ofloxacin may be an effective alternative antibiotic treatment for C. pneumoniae respiratory infections.