Treating Chlamydial Infections in Reactive Arthritis May Promise a Cure

Zeidler H, Hudson AP. New insights into Chlamydia and arthritis. Promise of a cure?Ann Rheum Dis. 2013 Dec 2. doi: 10.1136/annrheumdis-2013-204110. [Epub ahead of print]

Common Chlamydial infections, both the sexually-transmitted disease and the respiratory form, are the most frequent cause of reactive arthritis (ReA), and effective antibiotic treatments raise the possibility of a cure for ReA, say US and German researchers.

Chlamydia trachomatis (C. trachomatis) and the non-STD Chlamydia pneumoniae (C. pneumoniae) bacteria infect and persist in joints of ReA patients and some with spondyloarthritis (SpA) -- causing up to 16% of undifferentiated oligoarthritis, the researchers report.

C. trachomatis can be cured by the antibacterials azithromycin or doxycycline, while tetracyclines or erythromycin can cure C. pneumoniae,  but monotherapy has not been shown to eradicate the bacterium from joints.

However, placebo-controlled studies have found a 6-month course of combination antibiotic therapy -- with rifampicin (300 mg/day) plus doxycycline (200 mg/day) or plus azithromycin (500 mg/day followed by 5 days of 2–500 mg once/week -- effective both in eliminating both bacteria from joints and in improving arthritis.

Rifampicin/doxycycline induced a response in 63% of patients and remission in 20%, while 22% of patients given rifampicin/azithromycin had a response compared to placebo, but no remission.

C. trachomatis is the most common STD in the US and Europe, with an estimated 2.86 million cases reported to the CDC annually, but many people are asymptomatic and are not tested. The actual prevalence of C. pneumoniae is unknown.

The current study found evidence of C. trachomatis infection in 30% of ReA cases and a history of the STD in 42% of cases of SpA.

The researchers say their report suggests antibiotics as a possible cure for SpA, and stress the importance for rheumatologists of being alert for Chlamydia-related SpA.