Thursday, July 8, 2004.
Syphilis becoming resistant to oral antibiotic: report
Some strains of the bacterium that causes syphilis have developed a mutation that makes them resistant to Zithromax (known generically as azithromycin), doctors warn in this week's New England Journal of Medicine.
"This is important because an increasing number of physicians are using azithromycin for treatment of patients with syphilis and for sexual contacts," Sheila A Lukehart, from Harborview Medical Centre in Seattle said.
The recommended treatment for syphilis is penicillin, to which there is currently no evidence of resistance.
"However, penicillin injections are painful for the patient and physicians have been looking for an alternative treatment that can be taken by mouth. Azithromycin has looked very hopeful in this regard," Dr Lukehart said.
In their report, Dr Lukehart and colleagues describe one syphilis patient, "among several cases that have been recognised," for whom treatment with azithromycin failed.
A specimen from this patient revealed a mutation in one of the microbe's genes and lab tests confirmed that the bug was resistant to azithromycin.
Dr Lukehart's team subsequently found this azithromycin-resistance mutation in 11 per cent to 88 per cent of syphilis samples obtained in four different regions in the United States and Ireland.
"These findings suggest that physicians should be very cautious about using azithromycin for treatment of syphilis until they know whether the strains in their geographical region are sensitive or resistant," Dr Lukehart said.
Two editorialists agree, saying that azithromycin for syphilis "is not recommended unless careful follow-up can be ensured".