By NewsDesk  @bactiman63

Last year, the Southern Nevada Health District (SNHD) in Las Vegas reported on a gonorrhea case with reduced susceptibility to ceftriaxone and cefixime.

Neisseria
Image/CDC

Today, the Southern Nevada Public Health Laboratory reported in the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report (MMWR) more details on the case.

According to the Notes from the Field, the male urethral gonococcal isolate demonstrated reduced susceptibility to cefixime (minimum inhibitory concentration [MIC] = 2.0 μg/mL) and ceftriaxone (MIC = 1.0 μg/mL) but susceptible to azithromycin (MIC = 0.25 μg/mL). Molecular testing by CDC in the United States revealed the emerging mosaic penA60 allele, first identified in Japan in 2016, which confers reduced susceptibility to cephalosporins and increases the risk for treatment failure.

This is the first identified case of a Neisseria gonorrhoeae isolate harboring the mosaic penA60 allele reported in the United States.

The patient was empirically treated with the recommended regimen of ceftriaxone (250 mg) given intramuscularly plus azithromycin (1 g) administered orally. He reported at the end of November 2019 that his symptoms had resolved, and further testing returned negative results.

The report states:

To identify other cases of N. gonorrhoeae with the penA60 allele in the southern Nevada area, in December 2019, SNHD provided CDC with all N. gonorrhoeae NAAT-positive specimens from all SNHD clinics (257 remnant NAATs collected during September 2019–November 2019). Culture-independent molecular testing for the mosaic penA60 allele of the remnant NAATs identified no additional isolates with the mosaic penA60 allele. Approximately 5,500 gonococcal isolates were submitted for testing nationwide as part of GISP during January 2019–December 2019. No other isolates had MICs as high as those for the isolate in the Nevada case (2.0 μg/mL for cefixime and 1.0 μg/mL for ceftriaxone). An advisory was sent to state and local jurisdictions in early 2020; the investigation was stopped in February 2020 because no other isolates of concern had been identified.

To date, continued spread of this isolate has not been seen in southern Nevada or GISP. Despite the susceptibility patterns identified in this case, no treatment failures in the United States using the current recommended regimen of ceftriaxone and azithromycin have been reported.

In addition to Japan, the penA60 allele has been identified in China, Canada, Denmark, Australia, France, and the United Kingdom.