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Nephrology

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G/TUES/NEP1 REDEFINING URINARY TRACT INFECTIONS BY BACTERIAL COLONY COUNTS

M. Coulthard1, M. Kalra1, A. Nelson2, T. Smith2, J. Perry2.1Royal Victoria Infirmary, Newcastle, UK; 2Freeman Hospital, Newcastle, UK

Objectives: To determine the best urinary bacterial concentration to diagnose urinary infections.

Design: Prospective quantitative culture of serially diluted paired urines from 203 children aged 2 weeks to 17.7 years.

Results: 36/203 children had a urinary tract infection (UTI), with the same likely uropathogen cultured at concentrations within 25-fold in both urines (E coli in 32). The colony counts were mean 1.7×107/ml, range 106 to >108/ml. Among the 167 children without a UTI, 12 (7%) had positive cultures on the first sample according to standard criteria (likely uropathogen, ⩾105/ml), but had a UTI excluded because the second sample was sterile (7), or had a colony count more than 25-fold different (5) (contaminated pairs had 11× greater variation in colony counts than infected pairs, p<0.0001, CI 4–36). All 9 (5%) children who had a mixed culture with ⩾105/ml of a uropathogen (heavy mixed growth) in the first sample, had a urine infection excluded by the second sample.

Conclusion: Diagnosing a UTI as ⩾105 bacteria/ml gives a false-positive rate of 7.2%. Using ⩾106/ml would require changes in laboratory techniques, but would correctly diagnose all the UTIs, and reduce the false-positives to 4.8%. Using ⩾106/ml in 2 urine samples would reduce it to 0.6%. Urines with heavy mixed growths should be considered to be contaminated.

G/TUES/NEP2 URINARY MICROSCOPY FOR THE EARLY DIAGNOSIS OF URINARY TRACT INFECTION: HOW GOOD ARE WE IN PRACTICE?

I. Verber.University Hospital of North Tees, Stockton on Tees, UK

Introduction: The link between early childhood urinary tract infections (UTIs) and renal scarring is well recognised. Although much effort, using imaging techniques, has gone into detecting children with risk factors the only …

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