One week of doxycycline is an effective treatment for asymptomatic rectal Chlamydia trachomatis infection

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1 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

2 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.

3 Methods Routine screening for rectal CT since 2005 using NAAT. BD ProbeTec SDA GenProbe Aptima Combo 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.

4 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

5 Concurrent STI diagnoses (%) n= % 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%)

6 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).

7 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.

8 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.

9 Acknowledgement Clinical and laboratory staff at GSTT Laboratory staff at STBRL in Colindale Co-authors