Impact of the introduction of a nucleic acid amplification test for Clostridium difficile diagnosis on stool rejection policies

Table 1 Change in the number of stool specimens tested for C. difficile and the rate of positive specimens according to the laboratories between 2013 and 2014

Laboratory	Testing algorithm		Number of rejected samples			Number of positive results
Laboratory	2013	2014	2013	2014	p	2013	2014	p
A	GDH + EIA^a	GDH + NAAT^d	10/133 (7.5)	34/137 (24.8)	< 0.001	9/123 (7.3)	10/103 (9.7)	0.52
B	GDH + EIA^b	GDH + NAAT^d	89/776 (11.5)	83/653 (12.7)	0.47	29/687 (4.1)	46/570 (8.1)	0.003
C	GDH + EIA^b	GDH + NAAT^d	0/244 (0.0)	30/314 (9.6)	< 0.001	21/244 (8.6)	20/284 (7.0)	0.50
D	GDH + EIA^b + TC	GDH + NAAT^d	0/225 (0.0)	0/193 (0.0)	*	18/225 (8.0)	14/193 (7.3)	0.77
Total			99/1378 (7.1)	147/1297 (11.3)	< 0.001	77/1279 (6.0)	90/1150 (7.8)	0.07
E	EIA^c	GDH + EIA^a	6/42 (14.2)	13/44 (29.5)	0.88	2/42 (4.7)	6/31 (19.4)	0.09
F	GDH + EIA^b	GDH + EIA^b	0/73 (0.0)	0/85 (0.0)	*	6/73 (8.2)	4/85 (4.7)	0.37
G	GDH + EIA^b	GDH + EIA^b	47/178 (26.4)	25/152 (16.4)	0.82	20/147 (13.6)	17/127 (13.4)	0.96
H	GDH + EIA^b + TC	GDH + EIA^b + TC	0/228 (0.0)	0/267 (0.0)	*	12/228 (5.3)	8/267 (3.0)	0.20
I	GDH + EIA^b + TC	GDH + EIA^b + TC	23/211 (10.9)	5/162 (3.1)	0.008	17/188 (9.0)	11/157 (7.0)	0.49
Total			76/648 (11.7)	43/710 (6.1)	< 0.001	57/678 (8.4)	46/667 (6.9)	0.30

The number of rejected samples is expressed as the number of samples rejected/total number of samples collected (percent). The number of C. difficille infection (CDI)-positive samples is expressed as the number of CDI-positive samples/total number of samples tested (percent). The number of tests per patient is expressed as the number of tested samples/number of patients (ratio). A to D, laboratories that introduced nucleic acid amplification tests (NAATs). E to I, laboratories that did not introduce NAATs
GDH glutamate dehydrogenase by enzyme immunoassay, EIA toxin enzyme immunoassay, TC toxigenic culture
Statistical analysis was performed using the Chi square test. A p value < 0.05 was considered significant
*Not applicable
Methods: ^aC. Diff. Quik Chek Complete©, Alere (Waltham, MA, USA); ^bC. Diff. Quik Chek GDH©, Alere and TOX A/B Quik Chek©, Alere; ^c. And TOX A/B Quik Chek©, Alere; ^dImmunoCard^® C. difficile GDH, Meridian (Cincinnati, OH, USA) and NAAT illumigene^®, Mridiane

ISSN: 1757-4749