Nitrofurantoin is an effective and therefore often the first-line choice for cystitis. A 2010 update of the guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis (Clin Infect Dis. 2011;52:e103-e120) recommends against the use of nitrofurantoin when the diagnosis of cystitis is uncertain vis-à-vis pyelonephritis, because it does not achieve adequate renal tissue levels. According to the guideline, “such uncertainly may exist in the setting of cystitis symptoms accompanied by subjective fever that is not verified at the time of examination, a prolonged duration of cystitis symptoms (typically greater than 5-7 days), or vague flank pain or tenderness which is not otherwise explained”.
In such cases, a urine culture and susceptibility test should always be done and choice of antibiotic should be based on the culture and antibiotic sensitivity testing. Local community resistance prevalence, availability, cost, patient allergy and compliance history are other factors that may influence the choice of antibiotic in these patients.