What to do about multidrug-resistant gonorrhea

Gonorrhea, caused by the bacterium, Neisseria gonorrhoeae, continues to be a major US public health problem in terms of its prevalence as well as the lack of effective treatments available.

Multidrug-resistant gonorrhea is a growing problem that the Centers for Disease Control and Prevention (CDC) has based on the evidence that cephalosporin resistance may be emerging in the United States, according to the February 15, 2013, Morbidity and Mortality Weekly Report (MMWR).

“Gonorrhea is the second most commonly reported notifiable infection in the United States; >300,000 cases were reported in 2011,” according the CDC Grand Rounds. “In the United States, health inequities persist; the incidence of reported gonorrhea among blacks is 17 times the rate among whites, likely because of structural socioeconomic factors.”

Ongoing surveillance of gonococcal antimicrobial resistance has been undertaken by the CDC since 1986, with the introduction of the Gonococcal Isolate Surveillance Project (GISP). This system monitors gonococcal antimicrobial susceptibility from urethal N gonorrhoeae isolates that have been collected from men at STD clinics. These results help to form gonorrhea treatment recommendations before a major public health problem develops, according to the MMWR article.

“Cefiximine minimum inhibitory concentrations (MICs) recently increased, suggesting that the effectiveness of cefixime might be threatened,” the authors said. “The percentage of isolates with elevated cefixime MICs (≥0.25 µg/mL) increased from 0.1% in 2006 to 1.4% in 2011.”

The populations with higher increases in isolates were seen from men in the western United States and from men who have sex with men, which is the place where the fluoroquinolone-resistant N gonorrhoeae was first seen.

In 2011, approximately 12% of the isolates could no longer be treated with penicillin, about 23% could not be treated with tetracycline, and 13% were resistant to fluoroquinolones. With the development of cephalosporin resistance to the bacterium, treatment of gonorrhea has become much more complicated.

CDC currently recommends treatment of gonorrhea at any anatomic site with a single dose of 250 mg intramuscular ceftriaxone, which should then be followed with either one single dose of 1 g of azithromycin or 100 mg of doxycycline orally twice daily for 7 days. CDC also offers 2 alternative treatments for urogenital and rectal gonorrhea:

1) cefixime 400 mg as single oral dose and either azithromycin 1 g as a single oral dose or the doxycycline regimen above.

2) If the patient is allergic to cephalosporins, a single oral dose of azithromycin 2 g can be taken. Patients must return in a week to be tested for a cure, the authors noted.

At the moment, only 1 new antimicrobial is being tested in a clinical study for the treatment of gonorrhea. The National Institutes of Health has provided funding for more than 130 research grants on gonorrhea, including research to identify other targets for antimicrobial development. Unfortunately, a vaccine has not yet been developed, but research on this is in the works. ■