The Susceptibility of Urinary Pathogens in Complicated Urinary Tract Infections
Richard D. David, MD, FACS
Urology Specialists of Southern California,
Board Certified Adult & Pediatric Urology,
Associate Clinical Professor of Urology at UCLA,
Los Angeles, California, USA
The bacterial etiology and antimicrobial susceptibilities of genitourinary infections continue to evolve as patient populations and treatment strategies change. To enable adequate pathogen coverage against both Gram-positive and Gram-negative bacteria, and antimicrobial penetration into target tissues at required concentrations, antimicrobial treatment should be tailored to individual patient variables. Differences in pathogen susceptibilities must be accounted for. Continued monitoring of changes in etiological patterns and uropathogen susceptibility will ensure appropriate and effective treatment.
Different classes of antibiotics work by affecting different bacterial structure components or processes and the susceptibility patterns are examined. Continuous monitoring of the changing patterns of resistance is critical to the choice of an antibiotic and the current schemes are discussed, particularly as they apply to the United States and Canada. In general, resistance rates are lower for fluoroquinolones than for antibiotics such as ampicillin and trimethoprim-sulfamethoxazole (TMP-SMX).
The susceptibility patterns of fluoroquinolones against genitourinary pathogens is examined in detail. There have been no reports of a pathogen that is levofloxacin-resistant but ciprofloxacin-susceptible although the converse in not true. Ampicillin and TMP-SMX have limited efficacy for the treatment of genitourinary infections and fluoroquinolones like levofloxacin are a recommended option in the empiric treatment of complicated urinary tract infections. In cases where quinolone resistance has been confirmed, it is most likely due to multidrug resistant bacteria. These bacteria are usually also resistant to ampicillin and TMP-SMX and thus we must practice good infection control measures.