Table 2.

Contingency tables detailing comparison of surrogate markers to the ‘gold-standard’ for UTI diagnosis (bacterial culture), in a cohort of renal transplant recipients

(1) Leukocyte esterase*			(2) Nitrite			(3) Combined dipsticks
	Culture positive	Culture negative		Culture positive	Culture negative		Culture positive	Culture negative
Leukocyte positive	6 (11%)	40 (76%)	Nitrite positive	2 (4%)	2 (4%)	Both positive	0 (4%)	2 (4%)
Leukocyte negative	6 (11%)	1 (2%)	Nitrite negative	10 (19%)	39 (73%)	Both negative	4 (8%)	1 (2%)
(4) Pyuria			(5) ATP*			(6) IB*
	Culture positive	Culture negative		Culture positive	Culture negative		Culture positive	Culture negative
Pyuria positive	9 (17%)	35 (66%)	ATP >50 nmol/l	3 (6%)	0 (0%)	IB positive	1 (2%)	22 (41%)
Pyuria negative	3 (6%)	6 (11%)	ATP <50 nmol/l	9 (17%)	41 (77%)	IB negative	11 (21%)	19 (36%)
(7) Combined ATP and IB**
	Culture positive	Culture negative
ATP >50, IB positive	1 (2%)	0 (0%)
ATP <50, IB negative	0 (0%)	18 (34%)

*denotes Fisher’s exact test <0.05. **denotes Fisher’s exact test =0.0556 (not quite significant). See Methods for an explanation of the surrogate markers used. Key: IB, intracellular bacteria.

Data not included in the contingency tables: with respect to combined dipstick tests; 6 patients (10%) were leukocyte positive/nitrite negative and culture positive; 37 patients (70%) were leukocyte positive/nitrite negative and culture negative; 2 patients (4%) where leukocyte negative/nitrite positive and culture positive; 1 patient (2%) was where leukocyte negative/nitrite positive and culture negative. With respect to combined ATP and IB; 9 patients (17%) were IB positive/ATP <50 and culture positive; 22 patients (41%) were IB positive/ATP <50 and culture negative; 3 patients (6%) were IB negative/ATP >50 and culture positive; 0 patients were IB negative/ATP >50 and culture negative.