Microbiological investigations in this age group need careful interpretation in the light of the clinical findings and presenting symptoms. A study in an elderly care unit showed that these investigations are often inappropriately requested and their results may be incorrectly interpreted.
During one month on the unit, 34 urine specimens were sent to the microbiology laboratory from 19 of the 41 patients admitted. Of the 19 patients tested, 11 had a significant growth but on further review it was only possible to make a clinical diagnosis of UTI in five of these patients (26.3% of those tested). Although a dipstick result was recorded in 11 patients, a clinical diagnosis of UTI could be made in just three patients (both dipsticks and microbiological cultures may be positive in asymptomatic bacteriuria as well as in genuine UTIs).5
Clinical information provided on the request form was often limited and five urine specimens were sent from one patient, possibly as a result of the patient being moved between different wards. Whether the specimen had been taken from a urinary catheter was not recorded in five patients. This information was needed because in the absence of clinical features suggesting infection, organisms from catheter specimens do not require treatment and limiting catheter use is advised whenever possible.1,5
Irrespective of the microbiological results, older patients (including those with non-specific symptoms such as feeling tired or generally unwell) require review and clinical assessment before a diagnosis of UTI can be made.4 Inappropriate antibiotic treatment for asymptomatic bacteriuria may divert attention from the correct underlying diagnosis. It will not reduce the possibility of future symptomatic infections and increases the risk of resistance and side effects.4, 5 Care in requesting and interpreting the results of microbiological investigations in these patients is needed to avoid overdiagnosis of UTI.
1. Furuno JP, et al. Implementing long-term care infection control guidelines into practice: a case-based approach. Ann Longterm Care 2010; 18(2): 28-33
2. Barkham TMS, et al. Delay in the diagnosis of bacteraemic urinary tract infections in elderly patients. Age and Ageing 1996: 25: 130–32
3. Woodford HJ, George J. Diagnosis and management of urinary tract infection in hospitalized older people. J Am Geriatr Soc. 2009; 57:107–14
4. Cormican M, et al. Interpreting asymptomatic bacteriuria. BMJ 2011; 343: 363–67
5. Diagnosis of UTI. Quick Reference Guide for Primary Care. British Infection Association and Health Protection Agency [Updated 2011] www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1194947404720