Urinary tract infection

Abstract 

Symptomatic urinary tract infections (UTI) are either uncomplicated or complicated. Uncomplicated infections occur in healthy women in the community and are usually caused by Escherichia coli. Complicated infections are associated with anatomical, functional, or metabolic abnormalities of the urinary tract that disable the natural innate host defences and lead to tissue injury. Patients with symptomatic infections will have >10⁵ bacteria/ml and inflammatory cells in freshly voided urine. A third group is commonly seen whose symptoms may suggest UTI, but in whom there is no objective evidence for infection. Careful history, examination and investigation are important to avoid repeated and unnecessary courses of antibiotics. Infection is determined by bacterial virulence offset by a complex of innate host defences and some acquired immunity. Urine flow and regular and complete bladder emptying are the first priority; any cause of urine stagnation will promote infection. Investigation is, therefore, primarily aimed at ensuring there is no obstruction and that the bladder voids to completion. This is achieved with plain X-ray, ultrasound of kidneys and the bladder after voiding, and urine flow rate. Acute uncomplicated infection does not require more than 3 days antibiotics. Asymptomatic bacteriuria requires treatment only in infants, pregnancy and before urological intervention. For recurrent and complicated infections, it is mandatory to identify the organism and its sensitivity.

Keywords: antibiotic, bladder, innate host defence, urinary tract infection

• 1 In immunosuppressed patients.