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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

From: Urinary ATP and visualization of intracellular bacteria: a superior diagnostic marker for recurrent UTI in 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%)       
  1. *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.
  2. 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.