Urinary tract disease often requires longer treatment
than other body sites, possibly due to the location
of bacteria within the bladder wall or biofilm. Cystitis
is often treated for seven to ten days initially, and reculture
is indicated a few days following cessation of
treatment. In refractory or severe cases, culturing a
few days after the onset of antimicrobial therapy can
be useful to detect early treatment failure, with the
understanding that negative results do not necessarily
indicate successful treatment. Pyelonephritis should
be treated for a minimum of two weeks.