Gonorrhea treatments offer 2 new options
Results of a trial conducted by the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH) indicate two new antibiotic regimens using existing drugs successfully treated gonorrhea infections in a clinical trial.1 The regiments are injectable gentamicin in combination with oral azithromycin, and oral gemifloxacin in combination with oral azithromycin.
What does this mean for new treatment options in the face of growing antibiotic resistance to the sexually transmitted infection (STI)?
"These new treatment options identified in the trial provide hope in the fight against drug-resistant gonorrhea," states Robert Kirkcaldy, MD, MPH, a CDC medical epidemiologist who led the trial. "They also offer fallback regimens for certain patients, but they do not address the urgent need for additional first-line treatments."
What led researchers to pick these two particular drug combinations for the study? According to Kirkcaldy, previous lab data suggested the drugs held promise; however, they had not been fully evaluated for gonorrhea treatment in a clinical trial. With cases of drug-resistant gonorrhea rising, the number of effective and well-studied gonorrhea treatment options dwindling, and few new treatments in the pipeline emerging, the trial became a public health priority, Kirkcaldy states.
The trial results represent an encouraging development in a discouraging field, says Kirkcaldy. While they move science in the right direction, patients urgently need more oral options with fewer side effects, he states.
What is the next step in research in determining drug options for gonorrhea treatment? According to Kirkcaldy, the CDC is working closely with the National Institutes for Allergy and Infectious Disease at NIH and other research laboratories to identify drugs that look promising in the laboratory and could be potential treatment options for gonorrhea. However, broader action is needed to prevent untreatable gonorrhea from becoming a reality in the United States, he says. Researchers and pharmaceutical companies must jumpstart research to identify or develop new, effective drugs and drug combinations.
"In addition to looking for new treatment options, we must also continue to monitor how existing treatment options are performing," states Kirkcaldy. "Health departments and labs must help the CDC keep a watchful eye on emerging drug resistance, especially through culture testing."
In other efforts, the CDC is also calling on public and private partners to help develop other urgently-needed tools such as improved diagnostics and a gonorrhea vaccine, says Kirkcaldy.
Why the push?
Gonorrhea is one of the most common STIs in the United States. The most recent CDC report estimates about 820,000 new infections each year.2While some men and women might have symptoms such as discharge or burning when urinating, most people infected with gonorrhea do not exhibit symptoms.
Left untreated, gonorrhea can result in serious health problems, particularly for women. They might develop chronic pelvic pain, ectopic pregnancy, and infertility. Gonorrhea infection also increases a person’s risk of contracting and transmitting HIV, states the CDC.
The drugs included in the clinical trial are approved by the Food and Drug Administration and are available in the United States. The study represents the first effort to evaluate them as combination therapy for gonorrhea.
Scientists conducted a non-comparative trial, randomizing patients with urogenital gonorrhea to one of two regimens: 240 mg of gentamicin intramuscularly plus 2 g of azithromycin orally, or 320 mg of gemifloxacin orally plus 2 g of azithromycin orally. The primary outcome was defined as microbiologic cure of urogenital infections (a negative follow-up culture) at 10-17 days post-treatment. All study participants who returned for follow-up and had evaluable follow-up cultures were included in the protocol analysis.
The study, which began in 2010, enrolled 401 men and women ages 15-60 with untreated gonorrhea infection at clinical trial sites in Baltimore, Birmingham, AL, Los Angeles, Pittsburgh, and San Francisco. Researchers report 100% effectiveness of the injectable gentamicin/oral azithromycin combination in curing genital gonorrhea infections and 99.5% effectiveness of the oral gemifloxacin/oral azithromycin combination. Both combinations cured 100% of infections of the throat and rectum, data indicate.
The downside? Many trial participants reported adverse effects, mostly gastrointestinal issues, from the drugs. The most common adverse events in the injectable gentamicin/oral azithromycin arm were mild to moderate nausea (27% of participants), diarrhea (19%), abdominal discomfort/pain, and vomiting (both 7%). In the oral gemifloxacin/oral azithromycin arm, the most common adverse events were nausea (37% [with 8% recorded as moderate-severe]), diarrhea (23%), and abdominal discomfort/pain (11%).1Results of the study were presented in July 2013 at the annual meeting of the International Society for Sexually Transmitted Diseases Research in Vienna, Austria.
Guidance remains same
While the study’s results appear promising, they do not change current gonorrhea treatment guidelines, states the CDC. The agency still recommends only one first-line treatment regimen. That regimen is injectable ceftriaxone, in combination with one of two other oral antibiotics: azithromycin or doxycycline.3 (To be sure you have the most current recommendations, use the free CDC fact sheet at http://1.usa.gov/Xdyz5k.)The CDC says it is taking the findings of the current trial into consideration for inclusion in future treatment guidelines.
"This regimen remains highly effective in treating gonorrhea and causes limited side effects," the agency reported in a released statement. "However, providers may consider using the regimens studied in this trial as alternative options when ceftriaxone cannot be used, such as in the case of a severe allergy."
Having an injectable option, as opposed to one that requires intravenous administration, will make it so much easier for clinics to offer more effective therapies, says Anita Nelson, MD, professor in the Obstetrics and Gynecology Department at the David Geffen School of Medicine at the University of California in Los Angeles. Oral combination therapy is even easier for the patient to take, but requires patient compliance to achieve optimal benefit, she notes.
- Kirkcaldy RD. S.08 — STI/HIV treatment guidelines: Important areas of clinical uncertainty: S08.1 Treatment of gonorrhea in an era of emerging cephalosporin resistance and results of a randomised trial of new potential treatment options. Sex Transm Infect 2013; 89:Suppl 1 A14-A15.
- Centers for Disease Control and Prevention. Incidence, Prevalence, and Cost of Sexually Transmitted Infections in the United States. Fact sheet. Accessed at http://1.usa.gov/YYc2Ir.
- Centers for Disease Control and Prevention (CDC). Update to CDC’s Sexually Transmitted Diseases Treatment Guidelines, 2010: oral cephalosporins no longer a recommended treatment for gonococcal infections. MMWR 2012; 61(31):590-594.