Using Molecular Methods to Monitor Drug-Resistant Gonorrhea

A recent study has shown that using molecular methods to predict susceptibility testing could serve as a new way to help clinician monitor gonorrhea drug resistance.

Ashima A. Bhatti, RN, from the University of California, Los Angeles (UCLA), and colleagues published the results of their study online ahead of print in the September 2017 issue of Emerging Infectious Diseases, the Centers for Disease Control and Prevention’s (CDC) monthly peer-reviewed public health journal.

In an interview with Contagion®, the study’s corresponding author, Jeffrey D. Klausner, MD, MPH, also from UCLA, emphasized that drug-resistant gonorrhea is an urgent public health threat.

“Increasingly, drug resistance has been reported from more and more countries globally,” he said. “We need to understand the frequency of drug resistance, not only in specimens collected in the CDC surveillance systems, but also in specimens from routine primary care and hospital systems.”

Therefore, Dr. Klausner’s team performed a study to investigate antibiotic resistance in Neisseria gonorrhoeae infections at UCLA Health and to compare these resistance estimates with CDC surveillance estimates.

“We used leftover clinical specimens that tested positive for gonorrhea to monitor for resistance,” explained Dr. Klausner.

The investigators characterized the epidemiology of fluoroquinolone resistance at UCLA Health by using a rapid molecular gyrase A (gyrA) gene assay. This test detects a single-base mutation (Ser91) in the bacterial gene that renders N. gonorrhoeae bacterium resistant to ciprofloxacin, thus, it predicts ciprofloxacin susceptibility.

The study included 110 patients with N. gonorrhoeae infections.

The investigators found a prevalence of 44% for the mutant gyrA genotype among UCLA Health patients infected with N. gonorrhoeae. Dr. Klausner noted that “this was equal to or higher than the prevalence reported in CDC resistance estimates in the general population.”

These findings also suggest that routine leftover clinical specimens may be used to inform public health surveillance efforts, he added.

And because use of rapid molecular resistance tests has been demonstrated in routine clinical laboratories, this suggests that more resistance monitoring can be performed and used to inform local clinical practice, Dr. Klausner indicated. “Hospitals and other laboratories should consider monitoring gonorrhea resistance more routinely,” he said.

Ultimately, if the resistance tests could be performed more quickly and at less cost, the test results could be reported back to the provider at the same time as the original positive test result, said Dr. Klausner. This would make more treatment options available for providers and patients.

Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.