Cystitis vs pyelonephritis: same bug, different drug?
Nitrofurantoin is built for the bladder — it concentrates in urine and never makes it to kidney tissue.
Select any card for the reasoning, what to watch for and an exam tip.
vs
Cystitis
Lower UTI — the bladder and urethra, bathed in urine
Pyelonephritis
Upper UTI — the kidney tissue itself, and beyond
Key takeaway
Match the drug to where the infection lives: nitrofurantoin or trimethoprim for cystitis, where urine does the delivering; cefalexin — or IV ceftriaxone, cefuroxime or gentamicin — for pyelonephritis, where the drug must reach kidney tissue and blood. Nitrofurantoin can’t do both.
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