Helicobacter pylori antibiotic resistance in Iran

Table 3 Susceptibility rates of 120 isolates to selected antibiotics by modified disk diffusion method

Antibiotics	Disc content (µg)	Zone size breakpoint (resistance) (mm)	Resistant isolates (%)
Metronidazole	5	16	34.2 resistant
			23.3 intermediate
Clarithromycin	2	Any zone	16.7
Amoxicillin	10	11	1.6
Tetracycline	30	20

Table 1 Primer sets used in this study

Gene	Primers	Expected fragment(bp)	References
23S rRNA	CLA 18: 5"-AGTCGGGACCTAAGGCGAG-3"	1 400	10
(set 1)	CLA 21: 5"-TTCCCGCTTAGATGCTTTCAG-3"
23S rRNA	CLA 18: 5"-AGTCGGGACCTAAGGCGAG-3"	700	15
(set 2)	CLA 3: 5"-AGGTCCACGGGGTCTTG-3"
RdxA	RdxA1: 5"-AATTTGAGCATGGGGCAGA-3"	850	24
(set 3)	RdxA2: 5"-GAAACGCTTGAAAACACCCCT-3"

Table 2 Frequency of single and multi-drug resistance based on listed methods of detection

Antibiotics	Method of detection
	Disc diffusion		23S rRNA PCR-RFLP		rdxA gene deletion
	n	%	n	%	n	%
Amoxicillin only	1/120	0.8
Amoxicillin and metronidazole	1/120	0.8
Clarithromycin only	15/120	12.5	19/120	15.8
Clarithromycin and metronidazole	5/120	4.2
Metronidazole only	63/120	52.5			6/120	5
Metronidazole and amoxicillin	1/120	0.8
Metronidazole and clarithromycin	5/120	4.2
Tetracycline	0/120	0