Treponema pallidum macrolide resistance in BC
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《加拿大医疗协会学报》
Since mid-1997 British Columbia has experienced an outbreak of syphilis, initially in heterosexuals and more recently among men who have sex with men (MSM). Starting in 1999, primarily in patients presenting to the sexually transmitted diseases clinic at the BC Centre for Disease Control (BCCDC), moist lesions of primary and secondary syphilis were swabbed for polymerase chain reaction (PCR) testing for Treponema pallidum. The PCR method used was polA gene amplification using a CDC protocol.1
When the question of azithromycin resistance arose in 2004, specimens were examined retrospectively for the mutation in the T. pallidum 23sRNA gene in collaboration with investigators from the University of Washington.2
From 2000–2003, 1 of 47 positive PCRs showed resistance in a travel- acquired heterosexual case. In 2004, 4 of 9 positive PCRs showed the resistant gene, all in MSM.
The 23sRNA gene correlated with clinical resistance to azithromycin in Dublin and San Francisco.2
All of the BC patients received penicillin G benzathine or doxycycline; therefore, treatment failure with azithromycin was not tested.
Treatment of choice in BC for early syphilis is one dose of penicillin G benzathine (2.4 MU intramuscularly). Oral doxycycline therapy (100 mg twice daily for 2 weeks) is a second-line treatment, with oral azithromycin therapy (one 2-g dose) as a third-line treatment, especially in noncompliant patients who refuse injections. This sequence is in compliance with the Canadian and US STD treatment guidelines.3,4
In a recent study in Africa, a 2-g oral dose of azithromycin was as effective as a 2.4-MU intramuscular dose of penicillin G benzathine.5 However, in developed countries, because of resistance trends, azithromycin should be reserved as a third-line treatment for early syphilis, and patients thus treated should be followed closely, both serologically and clinically.
REFERENCES
Hsi L, Rodes B, Chen CY, et al. New tests for syphilis: rational design of a PCR method for detection of Treponema pallidum in clinical specimens using unique regions of the DNA polymerase I gene. J Clin Microbiol 2001;39:1941-6.
Lukehart SA, Godornes C, Molini MS, et al. Macrolide resistance in Treponema pallidum in the United States and Ireland. N Engl J Med 2004;351:154-8.
Health Canada. Canadian STD Guidelines. 1998.
US Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines 2002. MMWR Recomm Rep 2002;51(RR-6):1-78.
Riedner G, Rusizoka M, Todd J, et al. Single-dose azithromycin versus penicillin G benzathine for the treatment of early syphilis. N Engl J Med 2005; 353:1236-44.(Muhammad G. Morshed and H)
When the question of azithromycin resistance arose in 2004, specimens were examined retrospectively for the mutation in the T. pallidum 23sRNA gene in collaboration with investigators from the University of Washington.2
From 2000–2003, 1 of 47 positive PCRs showed resistance in a travel- acquired heterosexual case. In 2004, 4 of 9 positive PCRs showed the resistant gene, all in MSM.
The 23sRNA gene correlated with clinical resistance to azithromycin in Dublin and San Francisco.2
All of the BC patients received penicillin G benzathine or doxycycline; therefore, treatment failure with azithromycin was not tested.
Treatment of choice in BC for early syphilis is one dose of penicillin G benzathine (2.4 MU intramuscularly). Oral doxycycline therapy (100 mg twice daily for 2 weeks) is a second-line treatment, with oral azithromycin therapy (one 2-g dose) as a third-line treatment, especially in noncompliant patients who refuse injections. This sequence is in compliance with the Canadian and US STD treatment guidelines.3,4
In a recent study in Africa, a 2-g oral dose of azithromycin was as effective as a 2.4-MU intramuscular dose of penicillin G benzathine.5 However, in developed countries, because of resistance trends, azithromycin should be reserved as a third-line treatment for early syphilis, and patients thus treated should be followed closely, both serologically and clinically.
REFERENCES
Hsi L, Rodes B, Chen CY, et al. New tests for syphilis: rational design of a PCR method for detection of Treponema pallidum in clinical specimens using unique regions of the DNA polymerase I gene. J Clin Microbiol 2001;39:1941-6.
Lukehart SA, Godornes C, Molini MS, et al. Macrolide resistance in Treponema pallidum in the United States and Ireland. N Engl J Med 2004;351:154-8.
Health Canada. Canadian STD Guidelines. 1998.
US Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines 2002. MMWR Recomm Rep 2002;51(RR-6):1-78.
Riedner G, Rusizoka M, Todd J, et al. Single-dose azithromycin versus penicillin G benzathine for the treatment of early syphilis. N Engl J Med 2005; 353:1236-44.(Muhammad G. Morshed and H)