# P-815. A Randomized Trial of Doxycycline vs. Trimethoprim Sulfamethoxazole (TMP-SMX) for Uncomplicated Skin and Skin Structure Infections (SSSIs)

## TL;DR

This study compared doxycycline and TMP-SMX for treating skin infections and found both drugs equally effective and safe.

## Contribution

The study provides new evidence on the efficacy and safety of doxycycline compared to TMP-SMX for outpatient treatment of uncomplicated skin infections.

## Key findings

- Doxycycline and TMP-SMX showed similar cure rates at 48-72 hours (66% vs. 64%).
- Both drugs had comparable clinical responses at the end of treatment (78% vs. 77%).
- Adverse events like nausea and diarrhea were similar between the two groups.

## Abstract

In the U.S., there are > 8 million visits for SSSIs annually, the vast majority of which are managed in the outpatient setting. However, safety and efficacy of doxycycline in comparison to other oral antibiotics for suppurative uncomplicated SSSIs (uSSSIs) remains unclear.

We performed a double-blind, randomized controlled clinical trial of adults and children > 8 years of age with suppurative uSSSIs managed in the outpatient setting at 3 sites, two in California and one in Missouri. All participants were required to have adequate source control of uSSSI and were randomized to doxycycline 100 mg po or 1 double strength (DS) tablet of TMP-SMX twice daily. Doses of study medication were modified for children < 40 kg. Primary outcome was early clinical response (ECR) at 48-72 hours in the intent to treat population. Secondary outcomes included clinical response at end of treatment (EOT), clinical response at one month (1M) and adverse effects.

Among the 269 participants, 248 (92%) were adults and 21 (8%) were children; 132 (50%) were Hispanic, 93 (35%) African American, 33 (12%) white, 5 (2%) Asian, 1 (0.4%) Am. Indian/Alaskan Native, and 4 (1%) were other race/ethnicity. At the primary endpoint, ECR, cure rate was not significantly different between the two groups with a clinical response in 89/134 (66%) in the doxycycline arm in vs. 86/135 (64%) in the TMP-SMX arm (p=0.64). At the EOT visit, response was seen in 104 (78%) in the doxycycline arm and 104 (77%) in the TMP-SMX arm (p=0.91). Finally, at the 1M visit, clinical response was seen in 101 (75%) in the doxycycline arm in and 95 (70%) in the TMP-SMX arm (p=0.59). Adverse events were similar in the two groups with nausea (15 (11%) in the doxycycline arm vs. 10 (7%) in the TMP-SMX), headache (10 (7%) vs. 12 (9%)) and diarrhea (12 (9%) vs. 8 (6%)) being the most common. (Table)

In our multi-center randomized trial of outpatient treatment of suppurative uSSSI performed in a diverse population, we found no significant differences in clinical response between doxycycline and TMP-SMX. Safety and tolerability were also similar between groups. For adults and children with suppurative uSSSIs undergoing source control, doxycycline appears to be a safe and efficacious alternative to TMP/SMX.

Loren G. Miller, MD MPH, Armata: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|Paratek: Grant/Research Support Gregory J. Moran, MD, FACEP, AbVacc: Grant/Research Support Mark Munekata, MD,MPH, Intuitive Surgical: Stocks/Bonds (Public Company)