organisms in UTIs

Last reviewed 01/2018

In acute uncomplicated infection, the organisms are those normally colonising the perineum:

  • E. coli - 65 to 80% of all UTIs
  • Proteus
  • Klebsiella
  • Enterobacter
  • Candida
  • Enterococci
  • Staphylococci - especially, Staph. saprophyticus in young, fit adults, especially women

In complicated UTI’s, more unusual organisms are found - such as:

  • Pseudomonas aeruginosa
  • Staphylococcus epidermidis
  • Klebsiella
  • Enterobacter
  • Proteus
  • Enterococcus (1)

Occasionally, organisms secondary to systemic disease arising elsewhere - such as:

  • Tuberculosis
  • Salmonellosis

Rarely, viruses:

  • adenovirus types 2 and 11, in children
  • Herpes simplex

In sexually active young men and women infection with Chlamydia trachomatis should be considered (2).

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