Bacterial Cystitis, Acute, Uncomplicated

PATHOGENS

• Uncomplicated UTI: >95% of these infections are due to a single organism.
• Culprit pathogens:
  • E. coli (75-95%)
    • Groups B2 and D are most likely to cause UTIs. Uropathogenic E. coli (UPEC) have "fitness elements" that provide them with an advantage in this extraintestinal niche.
  • Other Enterobacteriaceae (e.g., K. pneumoniae, P. mirabilis)
  • S. saprophyticus
  • Uncommon pathogens: P. aeruginosa, Group D Streptococci
  • Rare pathogens: H. influenzae, M. tuberculosis, anaerobes, Salmonella, Shigella, adenovirus type 11, Ureaplasma, Mycoplasma, Enterococcus spp., Group B Streptococci
    • Enterococcus spp. and group B Streptococcus alone rarely cause uncomplicated cystitis (see excellent Hooton NEJM 2013 reference[8]).
      • These two organisms are recovered from midstream urine specimens of ~10% of women with cystitis but are rarely (1%) also isolated from paired catheter urine specimens.