There is considerable interest in bringing back single-dose IM gentamicin (Garamycin) for the treatment of gonorrhea. A systematic review of five studies (Syst Rev. 2014 Sep 19;3:104. doi: 10.1186/2046-4053-3-104) reported cure rates that were mostly in the 90% range, but “not quite high enough to say you’d want to go to gentamicin as your front-line therapy,” in Dr. Duncan’s opinion.
Dr. Workowski noted that the National Institutes of Health is interested in trying to resurrect cefixime (Suprax) for gonorrhea after the CDC guidelines demoted it several years ago. An ongoing clinical trial is examining the impact of increasing the dose and duration of therapy.
Public health officials are also interested in spectinomycin, an antibiotic not currently available in the United States, which has achieved high cure rates as single-dose therapy in several foreign studies.
Dr. Duncan noted that a randomized trial of gentamicin plus azithromycin or gemifloxacin (Factive) plus azithromycin reported cure rates of 100% and 99.5%, respectively (Clin Infect Dis. 2014 Oct 15;59(8):1083-91). He found the study less than convincing, however: “These strains were almost all susceptibile to azithromycin, so you can’t actually say that gentamicin or gemifloxacin added a lot,” he said.
A number of researchers are working on rapid tests for susceptibility of a particular gonococcal strain so physicians could choose an effective antimicrobial for an individual patient right from the start.
“These are all in the developmental phase. It’s going to be difficult, because there are so many different mechanisms for resistance,” he said.
Similarly, vaccine development in the gonococcal field is a great challenge. The microorganism’s multiple mechanisms of immune evasion make it tough to identify correlates of protection, Dr. Duncan continued.
“Epidemiologic studies suggest there is not efficient development of natural immunity. Folks who get gonorrhea and then come back with reinfection often have the exact same strain,” he noted.
Dr. Duncan’s research is funded by the National Institutes of Health and the Burroughs Wellcome Fund. He reported having no financial conflicts of interest.