Rethinking urinary antibiotic breakpoints: analysis of urinary antibiotic concentrations to treat multidrug resistant organisms

The present study analyzed whether renally eliminated antibiotics achieve sufficient urinary concentrations based on their pharmacokinetic/pharmacodynamic principles to effectively eradicate organisms deemed resistant by automated susceptibility testing. Lower median minimum inhibitory concentrations against enterobacteriaceae were noted for ceftriaxone, cefepime, and doripenem when comparing Etest to Vitek . All Pseudomonas aeruginosa isolates were susceptible to cefepime, ciprofloxacin, and doripenem with both susceptibility methods, but higher median minimum inhibitory concentrations were observed with Etest . Urine concentrations/time profiles were calculated for standard doses of ceftriaxone, cefepime, doripenem, and ciprofloxacin. The data presented in the current study suggests high urine concentrations of antibiotics may effectively eradicate bacteria which were determined to be resistant per in vitro susceptibility testing.