Urinary tract infections (UTIs) are among the most common
bacterial infections in humans. Even though physicians have been treating UTIs for 60 years, there has been no standardized approach regarding the rational choice of
antimicrobial agents and optimal
treatment duration for these
infections. This review discusses the pharmacologic basis for the treatment of UTIs. Although most
antibiotics concentrate well in the urine and can eradicate most of the sensitive uropathogens that cause lower UTI,
antibiotics given for the treatment of
pyelonephritis must concentrate and kill bacteria embedded within the renal parenchyma. Investigators once believed that
antibiotics must concentrate in sufficient amounts in the urine of infected patients to be effective in treating
pyelonephritis. In fact, the efficacy of an
antibiotic in the treatment of
pyelonephritis is proportional to its capacity to converge in high concentration not only in urine but also in the renal parenchyma because serum and urine levels of
antibiotics are poor predictors of the intrarenal levels. Other factors should also be taken into consideration in the management of UTIs, such as the time of day
antibiotics are given because significant time-dependent differences have been observed in the pharmacokinetics and rate of excretion in urine of several
antibiotics. Finally, the authors review the recent development in the inflammatory response in the urinary tract that may explain the clinical features of UTI and may be useful in the diagnosis as well as better management of UTI.