Gonorrhea Treatment Quickly Losing Effectiveness in Isolates in Hawaii

Gonorrhea may soon become untreatable with current antibiotics, according to Jonathan Mermin, MD, MPH, director of the National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP) of the Centers for Disease Control and Prevention (CDC).

The first known case cluster in the United States of genetically related isolates with high-level azithromycin resistance and decreased ceftriaxone susceptibility to Neisseria gonorrhoeae (NG) was detected this spring by Hawaii's laboratory surveillance system for gonococcal susceptibility, according to research presented on September 22 at the 2016 CDC STD Prevention Conference in Atlanta, Georgia.

“Our last line of defense against gonorrhea is weakening,” Dr. Mermin, who was not a study author, said in a press release. “If resistance continues to increase and spread, current treatment will ultimately fail and 800,000 Americans a year will be at risk for untreatable gonorrhea.”

"Reduced antimicrobial susceptibility starts in Hawaii and California and moves east. This is probably due to sources in Asia," said lead study author Alan Katz, MD, MPH, professor and associate director of the Office of Public Health sciences at the University of Hawaii, and member of the Hawaii State Board of Health, who presented their findings in a talk on September 22.

In 2011, Hawaii reported the first NG isolate in the United States that had high-level azithromycin resistance. Since 2014, the prevalence of reduced azithromycin susceptibility in the United States has increased, but the strains have been highly susceptible to cephalosporins.

Dr. Katz and his colleagues reported on the first cluster of cases to show decreased susceptibility to both azithromycin and ceftriaxone in isolates they collected from seven patients in Honolulu who had no known epidemiological commonality.

The researchers collected isolates over the course of about three weeks in the Hawaii Department of Health’s (HDOH) STD clinic and two private practice settings, and tested antimicrobial susceptibility by E-test at HDOH’s State Laboratory Division. Azithromycin minimum inhibitory concentrations (MICs) of greater than 256 µg/ml were considered to have high-level resistance; ceftriaxone MICs of 0.125 µg/ml or higher were considered to have reduced susceptibility. The researchers interviewed the patients, and they interviewed, tested, and treated their partners whenever possible.

Isolates were recovered from six males and one female. All of the patients had dysuria and penile vaginal discharge. None of the patients reported recent travel, antibiotic use, or partners in common, and no male patients reported same-sex contact. All isolates showed high-level azithromycin resistance; all were β-lactamase positive; and five showed decreased ceftriaxone susceptibility.

Preliminary pulsed-field gel electrophoresis patterns were similar. All of the patients were given 250 mg ceftriaxone and 1 g azithromycin. Of the six patients who followed up at the STD clinic, all had negative cultures and nucleic acid amplification tests (NAATs); and the one patient who refused follow-up testing reported post-treatment symptom resolution.

"This cluster of genetically related isolates with both decreased ceftriaxone susceptibility and high-level azithromycin resistance in case-patients without known epidemiological commonality is disconcerting," the authors wrote in their abstract.

In a press briefing on September 21, Dr. Mermin advised health officials to respond to the growing threat of gonorrhea by making sure that they’re fully implementing the CDC’s STD treatment guidelines:

• Health care workers should talk with patients about their risk for gonorrhea and screen all appropriate patients for gonorrhea and other STDs
• Doctors should treat gonorrhea cases with ceftriaxone and azithromycin, which still work, and monitor for treatment failure
• With CDC support, state and local health departments should continue to strengthen systems for detecting and responding to drug-resistant gonorrhea
• Pharmaceutical companies, researchers, and other partners should cooperate to develop better diagnostic tests

Lorraine L. Janeczko, MPH, is a medical science writer who creates news, continuing medical education and feature content in a wide range of specialties for clinicians, researchers and other readers. She has completed a Master of Public Health degree through the Department of Epidemiology of the Johns Hopkins Bloomberg School of Public Health and a Dana Postdoctoral Fellowship in Preventive Public Health Ophthalmology from the Wilmer Eye Institute, the Johns Hopkins University School of Medicine and the Bloomberg School.

SOURCES:

• 2016 CDC STD Prevention Conference Program p78
• Abstract
• Audio recording and slides from Dr. Katz's talk
• Printed transcript of phone press briefing

Study Presented:

Alan Katz, MD, MPH, professor and associate director of the Office of Public Health sciences, University of Hawaii, Honolulu, Cluster of Neisseria Gonorrhoaea Isolates with High-Level Azithromycin Resistance and Decreased Ceftriaxone Susceptibility