Antimicrobial activities of lefamulin against all Neisseria gonorrhoeae isolates and isolate subgroups and susceptibility of all isolates to antimicrobials currently or previously recommended for treatment of gonorrhea

Antimicrobial and isolate group (no.)MIC (μg/ml)aSusceptibility (%)b
    All isolates (251)0.004–20.2510.5NDeNDND
    Contemporary consecutive isolates (100)f0.004–
    Selected resistant isolates (117)0.016–20.510.5NDNDND
    Azithromycin-resistant isolates (123)0.016–20.510.5NDNDND
    Azithromycin-susceptible isolates (128)0.004–
    Reference strains (34)0.016–20.510.5NDNDND
Ceftriaxone (251)<0.002–40.0080.0640.00497.2ND2.8
Cefixime (251)<0.016–80.0160.125<0.01691.2ND8.8
Azithromycin (251)0.016–>2560.5161640.610.449.0
Spectinomycin (251)4–1,02416161698.0ND2.0
Ciprofloxacin (251)<0.002–>320.25>32≥3248.60.051.4
Ampicillin (251)0.016–>2560.580.12537.847.414.7
Tetracycline (251)0.125–128216225.923.151.0
  • a MIC was determined using the agar dilution technique for lefamulin and the Etest for the additional antimicrobials. Only whole MIC dilutions are reported.

  • b S, susceptible; I, intermediately susceptible; R, resistant. The EUCAST breakpoints ( were applied for all antimicrobials.

  • c MIC at which 50% of the isolates tested were inhibited.

  • d MIC at which 90% of the isolates tested were inhibited.

  • e Not determined due to lack of interpretative criteria.

  • f Consecutive clinical Swedish gonococcal isolates obtained in 2016.