Can bacterial virulence factors predict antibiotic resistant Helicobacter pylori infection?

Table 1 Polymerase chain reaction primers used in this study

Primer	Primer sequence	Gene	Product size (bp)
CAGA-F	5’-GATAACAGGCAAGCTTTTGATG-3’	cagA	349
CAGA-R	5’-CTGCAAAAGATTGTTTGGCAGA-3’
VA1-F	5’- ATGGAAATACAACAACAAACACAC-3’	vacA signal region	259/286 (s1/s2)
VA1-R	5’ – CTGCTTGAATGCGCCAAAC-3’
VAG-F	5’ – CAATCTGTCCAATCAAGCGAG-3’	vacA middle region	567/642 (m1/m2)
VAG-R	5’- GCTTCAAAATAATTCCAAGG-3’

Table 2 Demographic and clinical characteristics of Helicobacter pylori-infected patients included in the study

	Number of gastric biopsy specimens n (%)
	All patients 165 (100)	Treatment Naïve 105 (63.6)	Previously treated 60 (36.4)
Gender
Female	69 (41.8)	31 (29.5)	38 (63.3)
Male	96 (58.2)	74 (70.5)	22 (36.7)
Age
mean ± SD	49.2 ± 15.8	50.3 ± 16.3	47.4 ± 14.7
Histology findings
Chronic gastritis	130 (78.8)	78 (74.3)	52 (86.7)
Intestinal metaplasia	23 (13.9)	16 (15.2)	7 (11.7)
No data available	11 (6.7)	10 (9.5)	1 (1.7)
Normal mucosa	1 (0.6)	1 (1.0)	0 (0.0)
Endoscopic findings
Gastritis	92 (55.8)	57 (54.3)	35 (58.3)
Normal	32 (19.4)	19 (18.1)	13 (21.7)
Gastric/duodenal ulcer	21 (12.7)	15 (14.3)	6 (10.0)
No data available	17 (10.3)	11 (10.5)	6 (10.0)
Atrophic mucosa	1 (0.6)	1 (1.0)	0 (0.0)
Other1	2 (1.2)	2 (1.9)	0 (0.0)

¹Other endoscopic findings: 1 intestinal metaplasia and erosion: 1 portal hypertensive gastropathy.

Table 3 Clarithromycin resistance rates and the distribution of resistance-mediating mutations

Genotype	Number of gastric biopsy specimens n (%)			P value1
	All patients 165 (100)	Treatment Naïve 105 (63.6)	Previously treated 60 (36.4)
ClarithromycinS (WT)	65 (39.4)	52 (49.5)	13 (21.7)	< 0.001
ClarithromycinR	100 (60.6)	53 (50.5)	47 (78.3)
Point mutations
A2147G	78 (78)	44 (83)	34 (72.3)	NS
A2146G	8 (8)	3 (5.7)	5 (10.6)	NS
A2146C	6 (6)	3 (5.7)	3 (6.4)	NS
A2146C + A2147G	5 (5)	3 (5.7)	2 (4.3)	NS
A2146G + A2147G	2 (2)	0 (0)	2 (4.3)	NS
A2146G + A2146C	1 (1)	0 (0)	1 (2.1)	NS

¹Treatment-naïve versus previously treated patients (Fisher’s exact test). Clarithromycin^S: Sensitive to clarithromycin; Clarithromycin^R: Resistant to clarithromycin.

Table 4 Fluoroquinolone resistance rates and the distribution of resistance-mediating mutations

Genotype	Number of gastric biopsy specimens n (%)			P value1
	All patients 165 (100)	Treatment Naïve 105 (63.6)	Previously treated 60 (36.4)
FluoroquinoloneS (WT)	132 (80.0)	89 (84.8)	43 (71.7)
FluoroquinoloneR	33 (20.0)	16 (15.2)	17 (28.3)	NS
Point mutations
gyr91 D91Y	18 (54.5)	10 (62.5)	8 (47.1)	NS
gyr91 D91N	6 (18.2)	2 (12.5)	4 (23.5)	NS
gyr91 D91G	2 (6.1)	0 (0.0)	2 (11.8)	NS
gyr91 D91N + gyr91 D91G	2 (6.1)	1 (6.3)	1 (5.9)	NS
gyr91 D91N +gyr91 D91Y	2 (6.1)	1 (6.3)	1 (5.9)	NS
gyr87 N87K	1 (3.0)	1 (6.3)	0 (0.0)	NS
gyr87 N87K + gyr91 D91N + gyr91 D91G	1 (3.0)	0 (0.0)	1 (5.9)	NS
gyr87 N87K + gyr91 D91N + gyr91 D91G + gyr91 D91Y	1 (3.0)	1 (6.3)	0 (0.0)	NS

¹Treatment-naïve versus previously treated patients (Fisher’s exact test). Fluoroquinolone^S: Sensitive to fluoroquinolones; Fluoroquinolone^R: Resistant to fluoroquinolones.

Table 5 Antimicrobial susceptibility results for both clarithromycin and fluoroquinolone

Genotype	Number of gastric biopsy specimens n (%)			P value1
	All patients 165 (100)	Treatment Naïve 105 (63.6)	Previously treated 60 (36.4)
Susceptible (to both)	60 (36.4)	49 (46.6)	11 (18.3)	< 0.05
Resistant (to at least one)	105 (63.6)	56 (53.3)	49 (81.6)
Susceptible/resistant to one	137 (83.0)	92 (87.6)	45 (75.0)
Resistant to both	28 (17.0)	13 (12.4)	15 (25.0)	0.05

¹Treatment-naïve versus previously treated patients (Fisher’s exact test).

Table 6 Distribution of Helicobacter pylori virulence-factor genotypes among infected patients in Ireland n (%)

Genotype	Overall (n = 165)	Treatment naïve (n = 105)	Previous treatment (n = 60)	P value1
cagA status
Positive	37 (22.4)	25 (23.8)	12 (20)	NS
Negative	128 (77.6)	80 (76.2)	48 (80)
vacA allele
S1	113 (68.5)	78 (74.3)	35 (58.3)
S2	52 (31.5)	27 (25.7)	25 (41.7)	< 0.05
M1	47 (28.5)	31 (29.5)	16 (26.7)
M2	118 (71.5)	74 (70.5)	44 (73.3)	NS
S1/M1	39 (23.6)	26 (24.8)	13 (21.7)	NS
S1/M2	74 (44.8)	52 (49.5)	22 (36.7)	NS
S2/M1	8 (4.8)	5 (4.8)	3 (5.0)	NS
S2/M2	44 (26.7)	22 (21.0)	22 (36.7)	< 0.05

¹Treatment-naïve versus previously treated patients (Fisher’s exact test).