Oral doxycycline for non-systemic urinary tract infections (UTIs) due to P. aeruginosa and other Gram negative uropathogens

Excerpt

Stamey was the first to introduce the concept of “urinary spectrum” of orally administered antibiotics to treat non-systemic urinary tract infections (UTIs), i.e., cystitis or catheter associated bacteriuria (CAB). His concept was based on the principle that renally eliminated antibiotics are concentrated to high levels, i.e., supra-serum in urine in patients with intact renal function. Since antimicrobial susceptibility is in large part “concentration dependent,” Stamey reasoned it would be possible to eradicate aerobic Gram negative uropathogens from urine if achievable urinary concentrations exceeded the minimal inhibitory concentration (MIC) of the uropathogen [1]. Clinicians have long pondered why some Gram negative uropathogens are eradicated from urine even when reported as “resistant.” Stamey stressed that serum bases susceptibility testing is relevant only for pathogens in the blood. He and subsequently others showed that it was easy to eradicate “resistant” E. coli from the urine using oral penicillin based on this pharmacokinetic principle [2‐4]. Oral antibiotics in particular should be viewed as having a urinary spectrum which may be different from its serum spectrum (Table 1). …