Detection of bacteriuria by microscopy and dipslide culture in general practice

Abstract

Background: Patients presenting with symptoms of urinary tract infections account for 2-5% of contacts in general practice, but only about half of them have significant bacteriuria. A definite diagnosis depends on a microbiological test demonstrating a significant number of bacteria. In general practice the diagnosis is often reached by a microscopic analysis or a dipslide culture test. Only a few studies have looked at the validity of urine examinations when performed in general practice, and the results are diverging. We need more knowledge about the validity of tests for detection of uropathogenic bacteria in general practice.

Aim: To validate detection of bacteriuria by urine microscopy and dipslide culture in general practice.

Method: Urine specimens with a known quantity of bacteria (Escherichia coli, Proteus mirabilis, Enterobacter cloacae, Staphylococcus epidermidis and Enterococcus faecalis) were sent to 25 general practices for microscopic examination and dipslide culture. No prior instruction in testing procedure was given. The results of a standardised culture method performed by skilled bacteriologists at the bacteriological laboratory were used as gold standard. Results: Significant bacteriuria was identified by microscopy with a sensitivity of 95% and a specificity of 83%. The corresponding figures for urine culture were 95% and 96%, respectively. The morphology of bacteria was interpreted correctly in 80% of microscopic examinations, and 60% of the bacteria strains were classified correctly concerning their motility. Conclusion: Microscopy and dipslide are valid methods for detecting significant bacteriuria in general practice.

Key Words:

• urinary tract infections
• diagnosis
• bacteriuria
• microscopy
• family practice