Evaluation of the string test for the detection of Helicobacter pylori

Table 1 Results of the 4 tests in detecting Helicobacter pylori

Helicobacter pylori status	CLO test	Histology	Antral biopsy culture	String test culture	Number of patients (n = 30)
+	+	+	+	+	8*
+	+	+	+	-	9
+	+	+	-	-	4
-	-	+	-	-	1
-	-	-	-	-	8

+ denotes positive test; - denotes negative test. * one patient with a positive CLO test but the antral histopathology was not performed. He was counted as a positive case for this study.

Table 2 The sensitivity, specificity, positive predictive value, negative predictive value and the accuracy of the string test compared to endoscopy-based tests

	Sensitivity %	Sensitivity %	PPV %	NPV %	Accuracy %
CLO test	100	100	100	100	100
Antral histology	100	95	89	100	97
Antral biopsy culture	81	100	100	69	77
String test culture	38	100	100	41	57

Table 3 The results of the string test according to the growth rate of cultures from endoscopic biopsies

	Cultures of endoscopic biopsies and growth rate of Helicobacter pylori
	Abundant	Moderate	Scant	No growth
String test negative (n = 22)	1	2	6	13
String test positive (n = 8)	4	1	3	0
Total	5	3	8	14

Table 4 The results of the string test according to the density of Helicobacter pylori on antral histology

	Antral histology and density of Helicobacter pylori
	Marked	Moderate	Mild	None present
String test negative (n = 22)	4	8	2	8
String test positive (n = 8)	4	2	2	0
Total	8	10	4	8