Doxycycline may be better choice for rectal chlamydia infection

Last Updated: 2015-02-19

By Will Boggs MD

NEW YORK (Reuters Health) - Seven days of doxycycline may be better than a single dose of azithromycin for treating rectal chlamydia infection, according to a systematic review and meta-analysis of eight observational studies.

"We undertook the meta-analysis because there were and continue to be discussions about 'treatment failure' following the use of single-dose azithromycin for both urogenital and anorectal chlamydia infections," Fabian Yuh Shiong Kong, from the University of Melbourne, Australia, told Reuters Health by email.

"We were not surprised by the results of a lower efficacy for azithromycin for the treatment of rectal chlamydia; however, we were concerned about the lack of quality epidemiological evidence for the treatment of rectal infections," he added.

U.S. guidelines recommend treatment of rectal chlamydia with a single 1-g dose of azithromycin or seven days (100 mg twice daily) doxycycline, whereas both European and Australian guidelines favor treatment with seven days of doxycycline.

But, Kong said, "There haven't been any randomized controlled trials investigating treatment for rectal chlamydia."

Kong's team reviewed all studies reporting microbial cure among individuals aged 15 years or older using 1 g of azithromycin as a single dose or 100 mg doxycycline twice daily for seven days for the treatment of rectal chlamydia.

The pooled efficacy was 82.9% for azithromycin and 99.6% for doxycycline, with a nonsignificant 19.9% difference in favor of doxycycline (p=0.101).

As none of the studies included randomized controlled trials, treatment was not randomly allocated and physician's prescribing preferences were unknown, so confounding factors cannot be ruled out, according to the February 11 Journal of Antimicrobial Chemotherapy online report.

"It remains uncertain if doxycycline is indeed more efficacious than azithromycin," Kong said. "Local consensus/guidelines should be followed, based on the best available, robust, evidence and what physicians are seeing in practice."

"Aside from azithromycin's advantages in pregnancy (where doxycycline is contraindicated past 18 weeks of pregnancy), azithromycin as a single dose treatment, has better compliance compared with a week-long doxycycline regimen," Kong explained. "So azithromycin is better suited where we are likely to suspect that patient compliance could be low, such as, for example, in resource-limited settings, such as in developing countries or remote settings where access to healthcare and medicines remain a challenge, for the treatment of casual contacts, and where populations are transient or are targeted in outreach program."

Kong noted that "taking less than five days of doxycycline rather than the full seven-day dose has been shown to be associated with a nine-fold increase in microbiological failure at follow up. This study also found that 28% of men were non-adherent with their doxycycline (based on self-report). So it's not as simple as just swapping to doxycycline, as non-compliance can also result in 'treatment failure' - something you were trying to overcome in the first place."

The real test would be a randomized controlled trial, which is exactly what Kong and his team have planned.

Dr. William M. Geisler, from the University of Alabama at Birmingham's Division of Infectious Diseases, told Reuters Health by email, "I don't put much stock in these studies to date because they are not randomized clinical trials (RCTs), and if you read the studies, most have limitations. I think the meta-analysis does raise the concern that there might be a difference in the efficacy of the two treatments for rectal chlamydia, but the available evidence is not sufficient for there to be a change in prescribing practice at this time; rather it just argues why we need an RCT on rectal chlamydia treatment."

The authors report no disclosures.

SOURCE: http://bit.ly/1z3ygbI

J Antimicrob Chemother 2015.