And Then There Was One?

Internal Medicine World Report, August 2007, Volume 0, Issue 0

Single Class of Antibiotics Left to Treat Gonorrhea

By Rebekah McCallister

ATLANTA—Now that the Centers for Disease Control and Prevention (CDC) has removed fluoroquinolones from the list of recommended treatments for gonorrhea, your therapeutic options for this highly common sexually transmitted disease (STD) are limited to a single class of antibiotics: the cephalosporins.

"Gonorrhea has proven to be quite efficient at navigating around the drugs we use to combat it, developing resistance first to penicillin and tetracycline, and most recently to fluoroquinolones," said John M. Douglas Jr, MD, director of the CDC's Division of Sexually Transmitted Diseases Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, at a recent news briefing.

Fluoroquinolone-resistant gonorrhea in the general population increased from <1% of cases in 2001 to 13.3% in the first half of 2006, according to Dr Douglas (Figure).

Widespread fluoroquinolone-resistant gonorrhea among heterosexuals and men who have sex with men (MSM) prompted the new CDC recommendation. New data (MMWR. 2007;56:332-336) show that the proportion of drug-resistant cases among heterosexuals has risen above the recognized threshold of 5% needed to change treatment recommendations, rising to 6.7% in the first half of 2006. The CDC had already recommended that this class of antibiotics no longer be used to treat gonorrhea in MSM when this threshold was crossed in 2003.

The Cephalosporins

Among the cephalosporins, the CDC cites ceftriaxone sodium (Rocephin), available only as an injection, as the preferred treatment for all types of gonorrhea infection (genital, anal, or throat).

For genital and anal gonorrhea, you may consider alternative oral cephalosporins, such as cefixime (Suprax). No alternatives are recommended for pharyngeal infection.

The absence of an oral option for ceftriaxone is a potential drawback, Dr Douglas pointed out. "Clinics that are seeing lots of patients with gonorrhea might find it easy to stock ceftriaxone and have it available for injection," he said. But single-practice offices who are seeing patients with gonorrhea only intermittently, may not be stocking up on this drug for now.

"At this point, we don't have any evidence that there's a shortage. Ceftriaxone is now off patent, so it can be manufactured by both the original manufacturer as well as generic drug manufacturers," Dr Douglas said. "The estimated 700,000 or so gonorrhea cases per year that will be treated only require an estimated 125 mg. So I think that the ultimate impact on the reservoir to treat gonorrhea with single-dose therapy will be not as large as one might fear."

A cause for concern, however, is the lack of additional antibiotic classes to treat gonorrhea. And no new drugs for this STD are in development.

"While we have not seen any additional resistance to cephalosporins to date, any emerging resistance would be a significant public health concern," he said. "Because of the genetic versatility of the organism?increased vigilance in monitoring for resistance to remaining drugs is essential."

Gonorrhea is the second most frequently reported infectious disease in the United States, after chlamydia. In 2005, 339,593 cases were reported nationwide, although experts believe the actual number of cases may be twice that.

Neisseria gonorrhoeae

Figure. Percentage of isolates with intermediate resistance or resistance to ciprofloxin in the United States, 1990-2006*

*Data for 2006 are preliminary (January-June only).

?Demonstrating ciprofloxin minimum inhibitory concentrations (MICs) of 0.125-0.500 μg/mL.

?Demonstrating ciprofloxacin MICs of ≥1.0 μg/mL.

Source: CDC. Update to CDC's sexually transmitted diseases treatment guidelines 2006: fluoroquinolones no longer

recommended for treatment of gonococcal infections. MMWR. 2007;56:332-336.