One week of doxycycline is an effective treatment for asymptomatic rectal Chlamydia trachomatis infection A Elgalib, A Skingsley, O Dosekun, S Alexander, CYW Tong, JA White. Ali Elgalib Consultant in GUM/HIV Background Rectal CT infection is the most prevalent bacterial STI in MSM (4-11%). It is usually asymptomatic Rectal LGV is seen commonly in London MSM but almost all is symptomatic infection [1]. STIs increase risk for HIV acquisition and transmission. Re-infection with rectal CT or GC is associated with increased risk of HIV seroconversion [2]. 1.Ward et al, STI 2009 Jun 2.Bernstein et al, JAIDS 2009 Nov
Background The BASHH guidelines recommend doxycycline 100 mg bid for 7 days or azithromycin 1g stat for the treatment of uncomplicated CT infections, including rectal. Evidence is robust for genital infections but scant for rectal CT. Steedman et al [1] reported that 87% (59/68) of asymptomatic rectal CT was cleared with single-dose azithromycin 1g po. 1.Steedman et al, Int J STD AIDS 2009 Jan Objective To determine the efficacy of a 7-day doxycycline regimen for treatment of asymptomatic rectal CT infection.
Methods Routine screening for rectal CT since 2005 using NAAT. BD ProbeTec SDA 2005-2008 GenProbe Aptima Combo2 2008-2010 All MSM with asymptomatic rectal CT offered doxycycline 100mg bid for 7 days and invited for a TOC 4 weeks after the completion of treatment. Case note review of asymptomatic rectal CT cases between Sep 06-Sep 09. Results 766 cases of rectal CT were diagnosed in study period. 487 (64%) were asymptomatic infections. 293 TOC were performed 41 of which were excluded due to missing data or development of anorectal symptoms after testing. 252 TOC in 241 MSM were analysed.
Patient characteristics n=252 Characteristic N (%) Median age, years (IQR) 31 (26-38) Ethnicity n=241 White 165 (68%) Black 18 (8%) Other 30 (12%) Unknown 30 (12%) Known HIV positive 49 (19%) Past history of STI 158 (63%) Receptive anal intercourse 211 (83%) Reason for attendance (%) n=252 29% 8% 7% 56% Asymptomatic screening Genital symptoms General symptoms Contact of CT
Concurrent STI diagnoses (%) n=252 20 16 % 15 12 10 5 6 2 5 3 0 Urethral GC Throat GC Rectal GC Urethral CT New Syphilis New HIV Treatment details n=252 7-day doxycycline regimen 100mg twice daily 191 (76%) Doxycycline for 14 days 35 (14%) Azithromycin 1 g 26 (10%)
TOC results Median time post-treatment for TOC was 45 days (IQR 34-88). 70 (28%) negative tests were performed 4 weeks after treatment. Out of 252 TOC, 11 were positive (4%). TOC results Of the 11 positive TOC: 4/11 had been treated with azithromycin 1g. 6/11 had taken doxycycline for one week. One patient was treated with 3 weeks of doxycycline: He re-attended 57 days post-treatment as a contact of CT (TOC positive). He was retreated with doxycycline for 1 week (TOC was negative).
Characteristics of MSM with treatment failure Characteristic Azithromycin Doxycycline treatment failure N=4 Treatment failure N=6 Past history of STIs 1 1 Known HIV positive 1 1 New HIV infection 0 3 New bacterial STI at time of TOC 0 4 LGV typing for positive samples 0 3 (all LGV-negative) at TOC TOC median time, days (range) 36 (23-328) 257 (34-438) Re-treatment with 7-day 2 5 doxycycline regimen Negative subsequent TOC 2/2 3/3 Summary Most (64%, 487/766) of MSM with rectal CT infection had no anorectal symptoms. The majority (84%, 212/252) of asymptomatic rectal CT infections occurred without concurrent genital CT.
Summary After exclusion of likely re-infection and noncompliant cases, a 7-day doxycycline course achieved clearance of CT in 99.5% (185/186). Azithromycin 1g cleared 85% (22/26) of rectal CT infection. Summary Routine TOC following compliance with a 7-day course of doxycycline is not necessary in the absence of anorectal symptoms. We advocate doxycycline as first line therapy for rectal CT and advise TOC if azithromycin is used. A randomised trial of anti-chlamydial treatment for rectal infection is warranted.
Acknowledgement Clinical and laboratory staff at GSTT Laboratory staff at STBRL in Colindale Co-authors