Last Effective Treatment Option for Gonorrhea at Risk of Failing

A number of gonorrhea isolates in the United States are showing decreased susceptibility to the Centers for Disease Control and Prevention’s (CDC) recommended dual therapy of 250 mg ceftriaxone and 1 g azithromycin, according to a joint investigation by the Hawaii State Department of Public Health and CDC. The findings were presented at the 2016 STD Prevention Conference in Atlanta, Georgia.¹

Alan Katz, MD, MPH, from the University of Hawaii, Honolulu and a member of Hawaii’s State Board of Health, noted during a press briefing at the conference that from April 21 to May 10, 2016, 8 gonococcal isolates from 7 patients demonstrated very high level of minimum inhibitory concentrations (MICs) to azithromycin and elevated MICs to ceftriaxone.

“The Hawaii cluster is concerning, as all 8 isolates demonstrated high levels of azithromycin resistance, resistance to penicillin, tetracycline, and ciprofloxacin, and 5 of the 8 demonstrated reduced susceptibility to ceftriaxone by agar dilution testing, and the isolates were genetically related,” Dr Katz said during the press briefing.

All patients were successfully treated with CDC’s recommended dual therapy of ceftriaxone and azithromycin but the findings suggest that if resistance continues to increase, the last effective treatment option for gonorrhea could eventually fail.

During the press briefing, Stephanie N. Taylor, MD, from Louisiana State University in Baton Rouge, Louisiana, presented the findings from a phase 2 randomized control trial (ClinicalTrials.gov Identifier: NCT02257918) of a potential study drug, ETX0914 in the treatment of gonorrhea.

Patients (N=179) were randomly assigned to receive either 2 g or 3 g of ETX0914 orally or 500 mg of ceftriaxone by intramuscular injection. “The primary end point was eradication of the organism that was measured by negative cultures for gonorrhea at the test of cure visit.”

The findings are very promising. “In the per protocol population, 98% of the participants converted their cultures from positive to negative by the test of cure,” said Dr Taylor.  What is most exciting about ETX0914 is that this antibiotic has a different mechanism of action by which it kills the organism.

In light of the reports in Hawaii, Gail Bolan, MD, CDC’s director of the division of sexually transmitted disease prevention, has urged health care providers to adhere to CDC’s treatment recommendation for gonorrhea (combination ceftriaxone and azithromycin) and report any treatment failures to local health officials and CDC.

“Because drug-resistant gonorrhea is one of the key national threats identified in the Federal Government’s National Action Plan for combating antibiotic-resistant bacteria, CDC is implementing targeted efforts against the threat of untreatable gonorrhea specifically. These include introducing new laboratory tests to more rapidly detect gonorrhea strains and with decreased susceptibility…helping state and local health departments build rapid epidemiologic response capacity for outbreaks,” Dr Bolan concluded.

Reference

1.  New Warning Signs that Gonorrhea Treatment May be Losing Effectiveness [press release]. Atlanta, GA: Center for Disease Control and Prevention; September 22, 2016.