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Current recommendations for treating Neisseria gonorrhoeae infection involve the use of a cephalosporin plus either azithromycin or doxycycline. In May 2011, the CDC reported the isolation of azithromycin-resistant gonococci from five male patients at a sexually transmitted disease (STD) clinic in California (JW Infect Dis Jun 8 2011). Now, using data from the Gonococcal Isolate Surveillance Project, the CDC has described trends in cephalosporin susceptibility among N. gonorrhoeae isolates in the U.S. from 2000 to 2010. This project involves testing isolates from men attending publicly funded STD clinics and each year includes about 4% of reported gonorrhea cases among men nationwide.
During the study period, the proportion of isolates with elevated minimum inhibitory concentrations (MICs) to the two most commonly used antigonococcal cephalosporins increased, indicating decreased susceptibility to these drugs. Overall, the proportion of isolates with cefixime MICs ≥0.25 µg/mL rose from 0.2% to 1.4% (P<0.001), and the proportion with ceftriaxone MICs ≥0.125 µg/mL went from 0.1% to 0.3% (P=0.047). Significant increases were seen only in isolates from men who have sex with men (MSM).
Centers for Disease Control and Prevention (CDC). Cephalosporin susceptibility among Neisseria gonorrhoeae isolates — United States, 2000–2010. MMWR Morb Mortal Wkly Rep 2011 Jul 8; 60:873.
Ohnishi M et al. The new superbug Neisseria gonorrhoeae makes gonorrhoea untreatable? — First high-level ceftriaxone resistance worldwide and public health importance. 19th Biennial Conference of the International Society for Sexually Transmitted Diseases Research, Quebec City, Canada, July 2011. Abstract O3-S4.01. (http://dx.doi.org/10.1136/sextrans-2011-050109.121)
Comment
Over the last 40 years, the gonococcus has shown a remarkable ability to develop resistance to each new antimicrobial agent used against it. Although the overall proportion of isolates resistant to cephalosporins is still small, the negative portent of this new finding is large. As if to highlight the warning, researchers in Japan just reported the first N. gonorrhoeae strain that is highly resistant to ceftriaxone. They noted that we may have entered the “era of untreatable gonorrhea.”
The CDC urges confirmation of treatment success, especially in MSM in the western U.S., by having patients return for testing (preferably with culture) 1 week after treatment. Patients with cefixime treatment failure should be retreated with 250 mg of ceftriaxone intramuscularly and 2 g of azithromycin orally. In cases involving ceftriaxone treatment failure, an infectious diseases expert and the CDC should be consulted. All isolates with decreased cefixime or ceftriaxone susceptibility should be reported to local or state health departments and, ultimately, to the CDC (gipsinfo@cdc.gov).