DIAGNOSIS OF URINARY-TRACT INFECTION BY URINE MICROSCOPY USING A DISPOSABLE COUNTING CHAMBER

Routine urinalysis is performed as a screening test for urinary tract infection (UTI), but is not very reliable. We assessed the usefulness of microscopic examination of unspun urine using a disposable slide wi th counting chambers for the diagnosis of UTI caused by a variety of s pecies of bacilli. One hundred and seventy-two urine samples were obta ined from 113 subjects (60 male and 53 female), including 84 inpatient s, aged 20-96 years. The urine samples were examined for bacteriuria a nd pyuria using a counting chamber, and the reliability of this method in predicting significant bacteriuria defined by routine urine cultur e and Gram stain of urine smears was analyzed. Significant bacteriuria was diagnosed in 68 urine samples, including 34 from indwelling cathe ters, from 52 patients mostly having underlying diseases. Only 12 of t he positive urine samples contained E. coli, with a variety of other b acilli including cocci found in the rest. The counting chamber method detected bacteriuria in 64 of these 68 positive samples (sensitivity = 94%). Specificity was 88%. While the sensitivity and specificity of p yuria (WBC > 10 mul-1) were 79 and 71%, respectively, both sensitivity and negative predictive value were as high as 97% when bacteriuria or pyuria was present. We demonstrated that urine microscopy on a dispos able counting chamber is a simple, sensitive and time- and cost-saving method for the diagnosis of UTI caused by a variety of bacterial spec ies including cocci.