Infectious Disease · 3 h ago
Gonococcal gyrA variants amplify zoliflodacin resistance associated with gyrB D429N
A laboratory study using an isogenic Neisseria gonorrhoeae panel found that ciprofloxacin resistance-associated gyrA variants modified resistance and fitness effects of gyrB D429N. Combined mutations increased zoliflodacin and ciprofloxacin minimum inhibitory concentrations, supporting surveillance for interacting resistance determinants.
- Combined gyrA and gyrB mutations increased zoliflodacin MICs two- to fourfold.
- gyrB D429N increased ciprofloxacin MICs three- to sixfold.
- Fitness costs varied substantially across gyrA backgrounds.
- Laboratory findings support surveillance, not conclusions about clinical treatment failure.
Researchers investigated whether common ciprofloxacin resistance-associated gyrA variants influence the effects of the zoliflodacin resistance mutation gyrB D429N in Neisseria gonorrhoeae. Using a constructed isogenic bacterial panel, they assessed minimum inhibitory concentrations (MICs) and bacterial fitness across genetic backgrounds. The study addresses potential interactions between resistance determinants affecting two topoisomerase inhibitors; no patient outcomes were reported.
In strains carrying gyrB D429N, zoliflodacin MICs were two- to fourfold higher when ciprofloxacin resistance-associated gyrA alleles were also present. Conversely, gyrB D429N increased ciprofloxacin MICs in these strains three- to sixfold. The fitness cost of gyrB D429N ranged from modest to severe: costs were greatest in gyrA 91F/95G and 91F/95N backgrounds and comparatively minimal in the gyrA 91F/95A background.
These findings indicate that the consequences of a resistance mutation depend on the accompanying genetic background, supporting genomic surveillance for potentially high-risk combinations. However, laboratory MIC shifts and fitness measurements do not establish clinical treatment failure or transmission potential. Only the abstract was available; absolute MICs, panel size and detailed experimental methods were not provided.
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Antimicrobial Agents and Chemotherapy: Fluoroquinolone resistance-conferring gyrA variants alter the fitness cost and potentiate the resistance of the zoliflodacin resistance mutation gyrB D429N in Neisseria gonorrhoeae ↗This is an automated AI-condensed summary that has not yet been reviewed by an editor. Always consult the full item at the original source.