More research may be needed comparing antibiotic regimens to treat Chlamydia trachomatis in men and nonpregnant women in order to understand which antibiotic is superior, according to a review recently published in Cochrane Database of Systematic Reviews.

C trachomatis is one of the most common sexually transmitted genital infections in the world. In women, C trachomatis is generally asymptomatic but can produce infertility and chronic pelvic pain; in men, C trachomatis is usually symptomatic. Current clinical practice guidelines for C trachomatis infections do not give specific recommendations regarding first-line antibiotic therapy. Clinical guidelines recommend the following antibiotic regimens: azithromycin (single 1 g dose), doxycycline (100 mg twice daily for 7 days), tetracycline (500 mg 4 times daily for 7 days), erythromycin (500 mg 4 times daily for 7 days), ofloxacin (200 to 400 mg 2 times daily for 7 days), or levofloxacin (500 mg once daily for 7 days). Of these regimens, evidence has suggested that azithromycin and doxycycline may be the most effective. Therefore, this review assessed the efficacy and safety of antibiotic treatment for C trachomatis genital infection in men and non-pregnant women.

Electronic databases (CENTRAL, MEDLINE, EMBASE, and LILACS) were searched from inception to June 2018 for studies that included sexually-active men and nonpregnant women with symptomatic or asymptomatic genital C trachomatis infection diagnosed by any of the following diagnostic tests: cell culture for C trachomatis, antigen-based detection methods, immunofluorescence test, enzyme immunoassay or nucleic acid amplification test. A total of 14 studies were included that were mainly performed in clinics for sexually transmitted diseases were included. These studies included a total of 2715 participants (average age, 27 years; 79.08% men). For the meta-analysis, only studies with head-to-head comparisons were included. The primary outcomes were microbiologic failure and adverse events; the secondary outcomes were clinical failure, antimicrobial resistance, and reinfection. Results were organized on the basis of antibiotic comparisons, for example, macrolides (azithromycin) vs tetracyclines (doxycycline) and tetracyclines (doxycycline) vs quinolones (ofloxacin).

The azithromycin vs doxycycline comparison showed that the risk for microbiologic failure was higher in men who took azithromycin (relative risk [RR] 2.45), but the clinical failure results were uncertain. In women, microbiologic failure was uncertain (RR 1.71), but there were no studies that assessed clinical failure or adverse events in women. However, azithromycin may have fewer adverse events in both men and women (RR 0.83).

The doxycyline vs ofloxacin comparison showed that in men treated for C trachomatis, the effect on microbiologic failure and clinical failure were both uncertain (RR 8.53 and 0.85, respectively). The effect on microbiologic failure in women and in both men and women was not estimable. Further, the effect of adverse events in both men and women was uncertain (RR 1.02). The most frequently reported adverse effect was gastrointestinal in nature and not serious.

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The included studies used poor methodology, which may have led to their results being biased by favoring one drug over another. Overall, the study authors concluded that, “Based on the fact that women suffer mainly asymptomatic infections, and in order to test the effectiveness and safety of the current recommendations (azithromycin, doxycycline, and ofloxacin), for C trachomatis infection, especially in low and middle income countries, future [randomized clinical trials] should be designed and conducted to include a large enough sample size of women, and with low risk of bias.”

Reference

Páez-Canro C, Alzate JP, González LM, Romero-Rubio JA, Lethaby A, Gaitán HG. Antibiotics for treating urogenital Chlamydia trachomatis infection in men and nonpregnant women (Review) [published online January 25, 2019]. Cochrane Database of Systematic Reviews. doi:10.1002/14651858.CD010871.pub2