antibioticsbooks

Nitrofurans and
Fosfomycin
14
Agents: nitrofurantoin, fosfomycin
With the rise in resistance among common urinary
tract pathogens (primarily E. coli), first among TMP/
SMX and more recently among the fluoroquinolones,
clinicians are left searching for an alternative
to treat their patients with uncomplicated cystitis.
Nitrofurantoin and fosfomycin, although structurally
dissimilar with different mechanisms of action,
are two agents that are otherwise similar and fit
nicely into this niche. They have retained excellent
activity against E. coli (. 90% in most studies)
and also have adequate coverage of other common
community-acquired urinary tract pathogens. Their
utility is limited to infections of the lower urinary
tract, however, because of pharmacokinetic limitations.
Thus, nitrofurantoin and fosfomycin should
not be used for more severe urinary tract infections
such as pyelonephritis and urosepsis.
Mechanism of Action
Fosfomycin inhibits bacterial cell wall synthesis in
a different way from beta-lactams and glycopeptides,
preventing the production of the building
blocks of peptidoglycan. The mechanism of action
of nitrofurantoin is not well-characterized.