Available fosfomycin MICs and zone diameter breakpoints according to the latest EUCAST and CLSI criteriaa

CriteriabOrganism(s) and delivery routeMIC (mg/liter) Zone diameter (mm)
EUCAST Enterobacteriaceae
    Intravenous≤32 >32NR NR
    Oralc ≤32 >32NR NR
Pseudomonas spp.
    OralNR NRNR NR
Staphylococcus spp.
    Intravenous≤32 >32e
    OralNR NRNR NR
CLSIf E. coli g ≤64128≥256≥1613–15≤12
E. faecalis h ≤64128≥256≥1613–15≤12
  • a S, susceptible, I, intermediate, R, resistant; NR, not reported.

  • b EUCAST criteria are from version 5.0, 2015 (; CLSI criteria are from 2015 (48).

  • c For uncomplicated urinary tract infections.

  • d Epidemiological cutoff for wild-type isolates, ≤128 mg/liter.

  • e —, MICs are recommended.

  • f Pseudomonas spp., Acinetobacter spp., B. cepacia complex, S. maltophilia, S. saprophyticus, and S. capitis are considered to have intrinsic resistance, defined as inherent or innate (not acquired) antimicrobial resistance, which is reflected in wild-type antimicrobial patterns of all or almost all representatives of a species. Intrinsic resistance is so common that susceptibility testing is unnecessary.

  • g Testing and reporting only for E. coli urinary isolates.

  • h Testing and reporting only for E. faecalis urinary isolates.