Dutch investigators have found evidence supporting the recommended 21 days of doxycycline treatment for the sexually transmitted infection lymphogranuloma venereum (LGV). In an article published the online edition of Clinical Infectious Diseases they report that the genetic material of LGV was still detectable in rectal swabs up to 16 days after treatment for the infection was initiated. However, they find no evidence to support treating LGV for up to 42 days should symptoms of the infection persist, noting such symptoms are likely to be the result of inflammation rather than the persistence of the infection.
LGV is an ulcerative, sexually transmitted infection caused by a strain of chlamyida. It spreads beyond the musocal linings causing inflammation and the destruction of tissue.
Since 2003 outbreaks of LGV have been reported amongst gay men in several European and north American cities. Most of the infections have been anorectal involving symptoms such as proctitis, anal cramps, pain, bloody discharge and constipation. Many of the cases of LGV have been seen in HIV-positive men.
The non-LGV strain of chlamydia causes only mild symptoms and can be successfully treated with either a seven-day course of the antibiotic doxycycline or a single dose of the antibiotic azithromycin.
Because of its invasive nature, a longer course of treatment for LGV is necessary, and treatment normally involves a 21-day course of doxycycline (100mg twice daily).
The recommendation for longer duration of treatment for LGV is partly based upon the findings of a meta-analysis published in 2007 (McLean et al). However, the best duration of treatment for LGV and other chlamydia infections has not been studied and treatment recommendations are based upon clinical experience only.
Investigators at the Netherlands therefore designed a study involving men who were receiving antibiotic treatment for anorectal infection with either LGV or non-LGV strains of chlamydia. In accordance with guidelines, men with LGV infection received 21 days of treatment with doxycycline and men with non-LGV strains of chlamydia were treated with doxycycline for seven days.
Anal swabs were taken from the men before and after the completion of treatment. These swabs were examined for the presence of chlamydia’s DNA and RNA.
The study involved 20 men with LGV proctitis and 26 men with non-LGV proctitis.
All 20 patients with LGV procititis had chlamydia DNA present at baseline. This was still detectable in five patients after a week of treatment and in four patients after two weeks of doxycycline treatment. None of the men had chlamydia’s DNA detectable after completing 21 days of treatment or 21 days after that.
The researchers found that chlamydia’s RNA was present in four patients after one week of treatment and in one individual over two weeks after starting treatment (day 16).
Doxycycline treatment lead to rapid clearance of clamydia’s genetic material in men with non-LGV strains of the infection and its DNA was undetectable after seven days of treatment.
However, six men with LGV still had abnormalities in their rectal mucus membranes after successfully completing their 21 day course of doxycycline therapy. Five of these individuals therefore received an additional 21 days of treatment with the drug.
“We showed the persistence of chlamydia RNA in patients with LGV proctitis for up to 16 days during doxycycline treatment”, write the investigators, concluding that this supports “the necessity of prolonged antichlamydial treatment regimens for LGV proctitis.”
Some doctors advise that treatment for LGV should be extended to 42 days should symptoms persist. However, the investigators note that they found “no association between delayed microbial cure and persisting mucosal abnormalities.” They suggest that the persistence of symptoms after the completion of 21 days of antibiotic therapy is likely to be due to the inflammation that the infection can cause. They doubt that prolonging antibiotic treatment will have a beneficial effect on such inflammation and instead suggest that “anti-inflammatory approaches, such as corticosteroid therapy” may be beneficial.
de Vries, J.C. et al, Delayed microbial cure of lymphogranuloma venereum proctitis with doxycycline treatment. Clin Infect Dis 48 (online edition), 2009.