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Best Tests September 2006

Including: Full colour PDF of ‘best tests’ September 2006. UTI PDF

Laboratory Investigation of UTI

Key messages

Women with symptoms of uncomplicated urinary tract infection do not require urine culture

About half of all women will have a UTI in their lifetime and one quarter will have recurrent infections. Women with symptoms of uncomplicated UTI do not require urine culture. Streamlining the diagnostic process could improve patient satisfaction and decrease costs without compromising care.

Screening for asymptomatic bacteriuria is not recommended except in pregnant women

The occurrence of asymptomatic bacteriuria increases with age. Patients with asymptomatic bacteriuria do not benefit from antibiotic treatment. Unnecessary antibiotic treatment leads to increased adverse effects, emergence of resistant organisms and cost associated with the use of antibiotics.

The national trends in requesting urine cultures are interesting:

  • In early childhood there is an increase in the number of urine cultures performed. UTIs occur in as many as 5 percent of girls and 1 to 2 percent of boys. Presentation is variable, ranging from non-specific symptoms to systemic illness.
    Urine culture is always appropriate in children when UTI is suspected.
  • Urine culture is uncommon in men between the ages of 10 to 30 years, but increases to a fairly constant rate between the ages of 50 to 80 years. This may be mainly attributable to prostatic enlargement.
    In men urine infection is always considered complicated and urine culture is always appropriate when UTI is suspected.
  • In women there is an increase in urine cultures in the 70 to 79 year age group. This may be attributable to screening for asymptomatic bacteriuria. We cannot be sure what contribution inappropriate screening for asymptomatic bacteriuria plays in this increase.
    Patients with asymptomatic bacteriuria do not benefit from antibiotic treatment.

Consider the difference between rates of urine culture for women and men

In all age groups, women have more urine cultures requested than men. Nationally, the ratio of urine testing is approximately 1.0 male : 2.5 female. Much of the difference may be accounted for by urine cultures in pregnancy and the higher rates of complicated UTIs in women. However we feel part of the difference is unnecessary urine cultures being performed for uncomplicated UTIs in women.

If you would like to check the appropriateness of your own urine culture testing in women you may like to undertake the ‘Laboratory Investigation of UTI: Clinical Audit’ which is available from bpacnz. This is a simple audit and is approved as a RNZCGP CQI activity.