A simple test can identify which patients with gonorrhea can be treated with a single pill rather than a painful injection, researchers report.
This type of testing “is the wave of the future,” Aaron E. Glatt, MD, FACP, FIDSA, FSHEA, Infectious Diseases Society of America expert and spokesperson, told Medscape Medical News.
“This is something that will be very important in many aspects of medicine and specifically in regard to using ciprofloxacin in the treatment of [gonorrhea],” he added.
Glatt, who is also chairman of the Department of Medicine and a hospital epidemiologist at Mount Sinai South Nassau in Oceanside, New York, was not involved with the study.
Jeffrey D. Klausner, MD, MPH, from the Departments of Medicine and Epidemiology at the University of California, Los Angeles, and colleagues report their findings in an article published online August 7 in Clinical Infectious Diseases.
“The new test can be used to predict gonorrhea ciprofloxacin resistance. If the test shows no resistance, the patients and their partners can be safely and effectively treated with a single tablet of ciprofloxacin,” Klausner told Medscape Medical News.
The Centers for Disease Control and Prevention (CDC) had at one time recommended ciprofloxacin as first-line therapy, but that recommendation changed in 2007 when widespread resistance to the drug became apparent.
The CDC “recommended that ciprofloxacin no longer be used in 2007” after its Gonococcal Isolate Surveillance Project found rates of ciprofloxacin resistance “higher than 9%, which was the threshold for not using a drug,” Margaret Hammerschlag, MD, professor of pediatrics and medicine and program director of the Pediatric Infectious Diseases Fellowship Program at State University of New York Downstate Medical Center in New York City told Medscape Medical News.
The CDC currently recommends an intramuscular injection of ceftriaxone 250 mg plus azithromycin 1 g orally. The injection can be painful and may require an additional clinic visit. Also, having an oral treatment would make it easier to treat patients’ sexual partners and to provide treatment in nonclinical settings, the authors note.
Test Detects Key Mutation
The new test picks up a single point mutation in the gyrase A gene (gyrA), which is the primary mechanism behind resistance to ciprofloxacin.
“The quinolones are an excellent choice [for this type of testing] because…the resistance genes are very well defined and the mutations can be looked for molecularly and integrated into this assay,” Hammerschlag said.
For the current study, the researchers screened “all remnant N gonorrhoeae–positive nucleic acid amplification test specimens” from seven US cities for the N gonorrhoeae serine 91 gyrA genotype. Testing was conducted at three clinical microbiology laboratories and used a laboratory-developed polymerase chain reaction test.
Untreated patients with wild-type gyrA N gonorrhoeae infection, as determined on the basis of the screening test, were recruited to the study. During the enrollment visit, patients who agreed to participate provided specimens from the infected anatomic site (rectal, throat, and genital swabs) for gonococcal culture and repeat testing for the genetic mutation.
Of 232 patients screened, 211 participants aged 18 years or older had untreated urogenital or rectal N gonorrhoeae infection, no contraindications to ciprofloxacin, and agreed to abstain from sexual intercourse or use condoms while engaging in any sexual contact until they completed the test-of-cure visit.
Of the study participants, 106 individuals had 117 wild-type gyrA serine 91 N gonorrhoeae culture–positive infections at individual anatomic sites; 73 infections were rectal, 30 were urethral or cervical, and 14 were pharyngeal.
Partipants were treated with a single dose of ciprofloxacin 500 mg by mouth (observed in the clinic) and returned in 5 to 10 days for a test-of-cure visit.
In the per-protocol population, all patients with gyrA serine 91 wild-type N gonorrhoeae experienced microbiologic cure “regardless of the anatomic site of infection.”
Factors that led to exclusion from the analysis after enrollment included lack of a baseline culture-positive wild-type N gonorrhoeae infection at any anatomic site (n = 95), failure to meet other inclusion criteria (n = 6), lack of a determinate culture result at the time of follow-up (n = 2), and receiving a medication that was contraindicated or a systemic antibiotic before the test-of-cure assessment (n = 1).
Failure to complete the test-of-cure visit according to the protocol resulted in nine patients being excluded from the study: seven who ended the study before the test, and two who completed the visit but did so outside the test-of-cure visit window of 5 to 10 days.
Important Tool for Antibiotic Stewardship
“We’re in a crisis with antibiotics, and we’re running out of options for certain infections, and one of them is gonorrhea,” Hammerschlag said. He noted that this test could be an important tool for antibiotic stewardship.
Glatt agreed. “This would be another tool in places that see a lot of [gonorrhea] for them to be routinely doing in helping them to diagnose which patients can get cipro rather than having to be treated with something that’s broader and has more difficulties in giving it, is more expensive, and might involve either an [intramuscular] injection or an [intravenous infusion],” he explained.
“This would allow usage of an excellent drug that’s a single dose to treat both the patient and their partner,” he said.
Klausner said the test “is becoming available at commercial laboratories and [is] available outside of the United States in Europe and Australia.”
“Turnaround time depends on the laboratory and how they use the test. It can be the same turnaround time as the original gonorrhea test result if the gyrA test is combined with the gonorrhea test. Many test manufacturers are working now to integrate the gyrA test into the gonorrhea test so both results are available at the same time,” he explained.
Study limitations include “the modest sample size,” which resulted in estimates of efficacy at specific anatomic sites that were “less precise,” the authors write.
Glatt said the test might not be appropriate in areas where there is a high level of resistance, but “in the general routine setting where you’re expecting 75% to 95% sensitivity…this would be a great test to have.”
Klausner has received advisory board fees and nonfinancial support from Cepheid; consulting fees from BioFire, Shield Bio, and SpeedX; and research study support from Hologic, Gilead, AbbVie, SpeedX, and Visby Medical outside the submitted work. Taylor has received grants from GlaxoSmithKline and AstraZeneca/Entasis outside the submitted work. Bristow has received speaker’s bureau fees from Cepheid Inc outside the submitted work. The remaining authors, Glatt, and Hammerschlag have disclosed no relevant financial relationships.
Clin Inf Dis. Published online August 7, 2020. Abstract
Troy Brown is an award-winning Medscape contributor with a special interest in infectious diseases, women’s health, and pediatrics.