Organisms are said to be susceptible to nitrofurantoin if their minimum inhibitory concentration (MIC) is 32 μg/mL or less. nitrofurantoin cannot be used to treat anything other than simple cystitis although the patient information leaflet states it is used to prevent and treat infections of the bladder, kidney and other parts of the urinary tract.significance, but the combination should be avoided. Resistance to nitrofurantoin may be chromosomal or plasmid mediated and involves inhibition of nitrofuran reductase. Nitrofurantoin and its metabolites are excreted mainly by the kidneys. In renal impairment, the concentration achieved in urine may be subtherapeutic. Nitrofurantoin should not be used in patients with a creatinine clearance of 60 mL/min or less. However a retrospective chart review may suggest that nitrofurantoin is not contraindicated in this population.
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