Diagnosis of urinary tract infection in children: fresh urine microscopy or culture?
Fresh unspun and unstained urine specimens from 342 children with previous urinary tract infection (UTI) or symptoms compatible with a UTI were examined by microscopy at a magnification of x 400 in a mirrored counting chamber by a clinician, and sent for culture in a microbiology laboratory; 200 samples were also plated onto dip-slides. When microscopy and culture results were discrepant, further urine samples were collected until a diagnosis of UTI (24) or sterile urine (318) could be confirmed. Initial microscopy correctly identified 23 of 24 UTIs and 286 of 318 sterile urines; 1 false-positive result was caused by vaginal contamination with lactobacilli. 32 specimens (9%) gave an equivocal result on microscopy; the 1 other true-positive result was identified correctly on microscopy of the next urine specimen obtained. Culture of the initial urines correctly identified all 24 UTIs, but only 82% of the negative samples. Of the samples from uninfected children, 35 (11%) showed a mixed growth which was sterile on repeat sampling, and 21 (6.6%) initially grew a false-positive pure growth of more than 10(5) colony-forming units/ml of one organism. True UTIs were associated with bacterial counts above 10(7)/ml. Microscopy by a clinician represents a cheaper, quicker, and more reliable screening test for UTI in children than does routine culture in a microbiology laboratory.
Department of Child Health, Royal Victoria Infirmary, Newcastle upon Tyne.
D
D
Vickers
T
T
Ahmad
M G
MG
Coulthard
D000293:Adolescent; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D015169:Colony Count, Microbial / Q000592:standards; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008853:Microscopy; D008858:Microscopy, Phase-Contrast / Q000592:standards; D011446:Prospective Studies; D012008:Recurrence; D012680:Sensitivity and Specificity; D013997:Time Factors; D014552:Urinary Tract Infections / Q000175:diagnosis* / Q000382:microbiology / Q000652:urine