To the Editor: I appreciated the excellent review of chlamydia and gonorrhea infections provided by Dr. Yonke and colleagues.¹ Doxycycline is now the preferred treatment for chlamydia, with azithromycin as an alternative.²

The authors are correct that this change was partially based on increasing rates of macrolide resistance. However, it is important that family physicians know that there are additional reasons for the recommendation change, which can help them adequately counsel patients and ensure appropriate follow-up.

Doxycycline is a more effective treatment for rectal chlamydia than azithromycin. In a study of rectal chlamydia in men who have sex with men, 100% of patients treated with doxycycline achieved microbiologic cure vs. 74% of those treated with azithromycin.³ In another study, 95.5% of women with rectal chlamydia treated with doxycycline achieved a microbiologic cure, compared with 78.5% of women treated with azithromycin.⁴ This difference is significant because many women with urogenital chlamydia may have a concurrent rectal infection. One recent review found that 33% to 83% of women with urogenital chlamydia also had a rectal infection, regardless of reported receptive anal intercourse.⁵ Patients may receive insufficient treatment for chlamydia if treated with azithromycin alone.

Editor's Note: This letter was sent to the authors of “Chlamydial and Gonococcal Infections: Screening, Diagnosis, and Treatment,” who declined to reply.