P145
THE USE OF POSITIVE DIP STICK TESTING FOR LEUCOCYTES IS A COST
EFFECTIVE METHOD FOR URINARY TRACT INFECION SCREENING IN PATIENTS
WITH RENAL TRANSPLANTS.
Davison, N1, Lal, A2, Farrell, M1, May, A2, Almond, M1
1
Renal Unit, Southend University Hospital NHS Foundation Trust, 2Renal Unit, Basildon and
Thurrock University Hospitals NHS Foundation Trust
INTRODUCTION: Symptomatic and asymptomatic urinary tract infections and asymptomatic
bacteruria are important to detect and treat in post renal transplant patients. The gold standard is to
collect mid stream urine (MSU) samples for microscopy, culture and sensitivity (MCS). We have
investigated whether urine dip stick could be used to screen samples and reduce the number of urine
samples that are sent for MCS processing by the laboratory.
METHODS: MSU samples were collected from 64 consecutive patients (in 2 district general
hospitals [DGH]) attending renal transplant follow up clinics. All samples were dipped and the
presence of leucocytes and nitrites were recorded and then sent to the microbiology department for
MCS. A positive MCS was defined as: 1. Definite UTI (UTI symptoms present, WCC > 50, culture
+ve); 2. Asymptomatic Bacteruria (no UTI symptoms, WCC <50, culture +ve); 3. Asymptomatic UTI
(no UTI symptoms, WCC > 50, and culture +ve).
RESULTS:
Dipstick Result
Test for Leucocytes and Nitrites combined positive
Test for Leucocytes and Nitrites combined negative
Test for Nitrites positive
Test for Nitrites negative
Test for Leucocytes positive
Test for Leucocytes negative
MCS positive
1
2
1
2
3
0
MCS negative
0
61
0
61
17
44
The sensitivity and specificity of leucocytes and nitrites being both positive on the dip stick for
identifying a positive MCS were 33% and 100% respectively, for nitrites alone they were 33% and
100% respectively and for leucocytes alone they were 100% and 72%.
Further analysis was done on the 7 patients at one DGH who had >50 WCC on MCS but a negative
culture, 6 of these patients were positive on dip stick for leucocytes and negative for nitrites.
CONCLUSIONS: 3 of 64 (4.7%) patients had a positive MCS. The sensitivity and specificity of
leucocytes and nitrites on urine dip were not sufficient to replace MCS for detecting urinary infection.
However if only urine with positive leucocytes on dip were cultured, no urinary infections would be
missed. This practice would result in a reduction by 69% of the samples being sent to the
microbiology department at a cost saving of £2274 per 100 patients/per year. This small study
suggests that only sending samples with a positive urine dip stick for leucocytes could be an effective
strategy for identifying infection as well as reducing costs in post renal transplant patients.
.