Evaluating the specificity of a new type of urine collection bag for infants

For diagnosing urinary tract infection (UTI) in infants, the urine collection bag is a common sampling method. It has several advantages versus other methods but a high risk of contamination makes culture results difficult to evaluate. Previous studies report a specificity ranging from 14% to 84%. The objective of this study was to evaluate the specificity of a new type of urine collection bag.

Urine samples were collected from healthy infants with a new type of collection bag. As the urine is expected to be sterile, any bacterial growth would be considered a contamination.

Forty-four samples were included: 40 samples showed <10,000 cfu/ml of mixed growth or no growth at all, three samples showed <10,000 cfu/ml of single-strain growth and one sample showed >10,000<100,000 cfu/ml of single-strain growth. No samples showed any growth >100,000 cfu/ml.

According to Kass criteria, 97.7% of the samples would exclude a UTI and 2.3% would be considered inconclusive. None of the samples had a contamination level that, falsely, would be interpreted as positive. Further studies will be valuable as a specificity of 97.7% suggests that this collection device could give the clinician a non-invasive option for diagnosing UTI in infants.