2025 Southeastern Residency Conference

Title: Doxycycline Versus Azithromycin for Chlamydia Treatment in the Emergency Department 

Authors: Paakhee Shah, Dora Hall, Sarah Cullen 

Background/Purpose: 
Chlamydia is a sexually transmitted infection with a high rate of incidence, and most commonly affects those 24 years old and younger. It can often present asymptomatically, so it is important to test and treat patients routinely. Untreated chlamydia infection can cause complications such as pelvic inflammatory disease, ectopic pregnancy, and infertility. Before the 2021 Sexually Transmitted Infections (STI) Treatment Guidelines were released by the Centers for Disease Control and Prevention (CDC), the treatment of choice for chlamydia infection was a one-time oral dose of azithromycin 1 gram. With its continued use, Chlamydia trachomatis has developed resistance to azithromycin, especially in patients with rectal infection. The 2021 CDC STI Treatment Guideline recommends using doxycycline 100 mg orally twice daily for 7 days, which is highly efficacious in urogenital, rectal, and oropharyngeal infections. Azithromycin should still be used as an alternative in pregnant patients, in patients where nonadherence is a high concern, or patients with an allergy to doxycycline. 
A previous evaluation of prescribing according to the CDC Guidelines at Emory Decatur Hospital (EDH) and Emory Hillandale Hospital (EHH) showed that 66% of patients received doxycycline and azithromycin double coverage inappropriately. As a result of the evaluation, an order panel was developed to prompt providers to prescribe doxycycline over azithromycin, unless indicated otherwise. This study's purpose was to determine if the increased use of doxycycline reduces treatment failure incidence and contributes to better patient outcomes.  

Methods: 
This single-center, retrospective cohort study aimed to evaluate the impact of the updated CDC guidelines and hospital order panel on re-infection rates and treatment failure. Outcomes compared two cohorts: cohort one included 224 patients who were treated for Chlamydia infection in the emergency department with only doxycycline and cohort two included 40 patients who were treated for Chlamydia infection in the emergency department with only azithromycin. The primary outcome was treatment failure or re-infection rates, defined as having a subsequent positive NAAT test three to four weeks after initial diagnosis. Secondary outcomes included order panel and CDC guideline adherence and prescribing patterns of doxycycline versus azithromycin.  

Results: 
The incidence of treatment failure in the doxycyline group was 0.9% (n=2) and 5% in the azithromycin group (n=2) (OR 5.8, 95% CI [0.8-42.7], p-value 0.11) with a power of 0.3. For secondary endpoint of appropriate antibiotic use following the placement of the order panel, 88.3% of patients received the appropriate antibiotic selection, 9.1% of patients received azithromycin inappropriately, and 2.7% of patients had a treatment duration of longer than 7 days. Of the 173 patients that were screened to determine the secondary endpoint incidence of double coverage following placement of the order panel, 1.7% of patients received double coverage (n=3).  

Conclusion: 
The study was not adequately powered to identify a statistically significant difference in re-infection or treatment failure between doxycycline and azithromycin, but more patients who received azithromycin experienced re-infection/treatment failure compared to doxycycline. Antibiotic selection for treatment of Chlamydia infection should continue to be based on 2021 CDC STI Guideline recommendations with doxycycline as the agent of choice. Creation of the order panel was beneficial in minimizing double coverage and allowed for better treatment administration.