TreatmentUpdate82 - Vol. 9, No. 8 - pp. 4; October 1997
Sean Hosein

In the late 1980s reports appeared of cases of syphilis in HIV-infected people that did not respond to standard treatment. Indeed, in some cases, the microbe that causes syphilis, T. pallidum, had been found in the fluid surrounding the brain even after treatment with penicillin. Some doctors think that T. pallidum has become resistant to standard anti-syphilis therapy. Others think that like many illnesses seen in AIDS, HIV infection has made syphilis more difficult to treat. To investigate the effectiveness of standard anti-syphilis therapy, researchers conducted a study comparing its effect against "enhanced therapy". They found that standard therapy "appears adequate for most patients [with early syphilis], " although treatment didn't work in 20% of people.

Study details

Doctors recruited 541 subjects with syphilis, 101 of whom also had HIV infection. About 25% of the HIV+ subjects had primary syphilis, 50% had secondary syphilis and the rest early latent syphilis. Most HIV-infected subjects were male and 50% were at least 30 years old. Doctors randomly assigned people to receive either :

* standard therapy as recommended by the Centers for Disease Control (USA): 2.4 million units of intramuscular penicillin G benzathine or,

* standard therapy and enhanced therapy: 2g amoxicillin/day and probenecid 500 mg three times daily, both for 10 days.

Results

Follow up -- two weeks after treatment, 84% of subjects returned for monitoring. Six months later that figure had fallen to 61% and one year later it was 52%.

Sores

About 1/3 of subjects had sores at the start of the study. Sores in HIV-infected subjects took slightly longer to heal (16.5 days) than in non-HIV-infected subjects (13 days).

Treatment failure

In about 25% of cases, blood tests revealed that syphilis had cleared within 3 months of treatment. Subjects with primary and secondary syphilis who also had HIV were more likely to have their treatment fail than non-HIV-infected subjects. Treatment failure was not linked to the type of regimen subjects received.

HIV-infected subjects with early latent syphilis were less likely to have their therapy fail than non-HIV-infected subjects with the same type of syphilis. This is quite interesting given that people with HIV are supposed to have weakened immune systems.

The type of treatment received did not appear to affect recovery from syphilis. Generally, HIV-infected subjects recovered as well as non-HIV-infected subjects. That therapy didn't work in 20% of people is troubling and does raise questions about the effectiveness of the current treatment regimens. Perhaps other antibiotics -- such as ceftriaxone -- need to be studied to see if their use is associated with lower failure rates.

REFERENCES:

1. Rolfs RT, Joesoef MR, Hendershot EF, et al. A ramdomized trial of enhanced therapy for early syphilis in patients with and without human immunodeficiency virus infection. New England Journal of Medicine 1997;337:307-314.

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