Clinical accuracy of point-of-care urine culture in general practice

Figures & data

Figure 1. Attrition flowchart.

Table 1. Characteristics of samples from 341 patients: test results and distribution of uropathogens from general practice and the microbiological department.

	Index tests	Reference
Both index tests, n = 341
Significant growth	246 (72%)	215 (63%)
E. coli	128 (38%)	176 (51%)
Enterococci	40 (12%)	0 (0%)
S. saprophyticus	15 (4%)	8 (2%)
Other single uropathogen	19 (6%)	25 (7%)
Two uropathogens	44 (13%)	6 (2%)
Index test 1: ID Flexicult™, n = 158
Significant growth	116 (74%)	103 (65%)
E. coli	71 (45%)	89 (56%)
Enterococci	16 (11%)	0 (0%)
S. saprophyticus	7 (4%)	2 (1%)
Other single uropathogen	10 (6%)	10 (6%)
Two uropathogens	12 (8%)	2 (1%)
Index test 2: SSI-Urinary Kit, n = 183
Significant growth	129 (70%)	112 (61%)
E. coli	57 (31%)	87 (48%)
Enterococci	23 (13%)	0 (0%)
S. saprophyticus	8 (4%)	6 (3%)
Other single uropathogen	9 (5%)	15 (8%)
Two uropathogens	32 (17%)	4 (2%)

Percentages in brackets.

Table 2. Accuracy of point-of-care culture in relation to culture at the reference laboratories.

	N	PPV	NPV	SEN	SPE	AGR
All cultures	341	0.77 (0.71–0.82)	0.73 (0.63–0.81)	0.88 (0.83–0.92)	0.55 (0.46–0.64)	0.76 (0.71–0.80)
Enterococci in practice culture excluded	301	0.86 (0.81–0.91)	0.73 (0.63–0.81)	0.87 (0.82–0.92)	0.71 (0.61–0.80)	0.82 (0.77–0.86)
ID Flexicult™	158	0.79 (0.71–0.86)	0.76 (0.60–0.88)	0.90 (0.83–0.95)	0.56 (0.42–0.70)	0.78 (0.71–0.85)
SSI-Urinary Kit	183	0.74 (0.66–0.82)	0.70 (0.56–0.82)	0.86 (0.78–0.92)	0.54 (0.41–0.65)	0.73 (0.66–0.79)
All cultures – photo readings	309	0.84 (0.79–0.89)	0.75 (0.66–0.83)	0.87 (0.81–0.91)	0.71 (0.62–0.79)	0.81 (0.76–0.85)

PPV: positive predictive value; NPV: negative predictive value; SEN: sensitivity; SPE: specificity; AGR: agreement (true positives + true negatives/all).

95% confidence intervals in brackets.

Figure 2. Examples of cultures diagnosed incorrectly in general practice according to the reference standard. A and D: Correctly answered as negative in general practice according to the photograph and as S. saprofyticus 10⁴ CFU/mL and Citrobacter koseri 10⁴ CFU/mL in the microbiological department. B and E: Correctly answered as E. coli 10³ CFU/mL and Enterococcus faecalis 10⁵ CFU/mL in general practice but as negative in the microbiological department. C and F: Incorrectly answered as significant growth in general practice, and as negative and mixed flora in the microbiological department.

Table 3. Identification of uropathogens in general practice compared to the microbiological department.

	Reference (microbiological department)
General practice	E. Coli	Enterococci	S. saprophyticus	Other single pathogen	Two pathogens	No pathogens	Total
E. coli	114	0	3	1	2	8	128
Enterococci	7	0	2	2	0	29	40
S. saprophyticus	3	0	11	0	1	4	19
Other single pathogen	12	0	0	1	0	2	15
Two pathogens	27	0	2	0	1	14	44
No pathogens	13	0	7	4	2	69	95
Total	176	0	25	8	6	126	341