Startseite Detection of CagA, VacA, IceA1 and IceA2 virulent genes in Helicobacter pylori isolated from gastric ulcer patients
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Detection of CagA, VacA, IceA1 and IceA2 virulent genes in Helicobacter pylori isolated from gastric ulcer patients

  • Lijuan Fan , Ran Li , Hongyun Li , Jian Zhang und Lingyun Wang EMAIL logo
Veröffentlicht/Copyright: 23. Juli 2018
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Journal of Laboratory Medicine
Aus der Zeitschrift Journal of Laboratory Medicine Band 42 Heft 4

Abstract

Background

Virulence factors of Helicobacter pylori including cagA, vacA, iceA and their association with clinical manifestation varied widely with different subpopulations. The objective of the study was to determine the prevalence of cagA, iceA1, iceA2,vacA, vacA s1/s2, vacA m1/m2, Western type cagA and East Asian type cagA virulence genes in H. pylori isolated from gastric ulcer patients and evaluate the association of these genes with gender, age, smoking and alcohol consumption.

Methods

Gastric biopsy samples from 172 patients were collected. H. pylori virulence genes, cagA, vacA, iceA1, iceA2, vacA s1/s2, vacA m1/m2, Western type cagA and East Asian type cagA were detected using polymerase chain reaction (PCR).

Results

Of the gastric biopsy samples collected, 48.3% of samples grew H. pylori. The vacA (68.7%) was the predominant virulence gene detected and associated with male patients and patients within the age group of 31–40 years. The cagA was the second most common gene detected and significantly associated with alcoholic patients.

Conclusions

H. pylori infection rate was 48.3% and was associated with patients who were smokers or had a history of smoking. The majority of our isolates were positive for any one of the virulence genes tested indicating that these isolates were highly virulent in nature.

Reviewed Publication:

Ahmad-Nejad P. Ghebremedhin B. Edited by:

Keywords: gastric ulcer; H. pylori; virulence genes

Introduction

Helicobacter pylori is associated with gastrointestinal disorders including peptic ulcers, gastric cancer, chronic gastritis and lymphoma [1], [2]. Various factors such as age, ethnicity, geography and socio-economic status contribute to the varied prevalence of H. pylori [1]. H. pylori incidence tends to be low in many developed countries due to improved social-economic status, while it remains high in developing countries [3], [4]. H. pylori is highly prevalent in some countries; however, the disease severity varies from one region to another mainly due to the differences in the virulence factors among the strains [5]. Several virulence factors play an important role in the pathogenesis of the disease, which includs the cytotoxin-associated gene A (cagA), vacuolating cytotoxin A (vacA) and iceA genes [5], [6], [7]. The cagA gene encoded by the CagA protein is found in more than 50% of the H. pylori isolates. The cagA gene is associated with increased production of interleukin-8 (IL-8), mucosal inflammation, nuclear factor-kB activation and the development of peptic ulcer disease (PUD) and gastric cancer (GC). The cagA gene, a marker of the cag pathogenicity island has been associated with PUD, atrophic gastritis and adenocarcinoma [7], [8], [9]. About 60%–70% of H. pylori strains tend to possess the cagA gene [8], [9]. The vacuolating toxin encodes the vacA gene, consists of three variable regions, the signal peptide encoding s region and two alleles (s1 and s2). The s1 region is further subdivided into s1a, s1b and s1c subtypes. The middle region (m region) of the vac gene has two alleles, m1 and m2 [10]. The activity of the vac gene was determined by the combination of s- and m-regions, the s1m1 combination was considered as the most virulent and produces a high amount of toxin, while the combination of s2m2 produces an inactive toxin [10], [11]. The cagA and vacA genes play an important role in determining the clinical outcomes of the infected patients [12]. The iceA gene induced by the contact with human gastric cells produces a high level of IL8 and is highly associated with PUD [13]. The iceA has two alleles, iceA1 and iceA2 [14].

The prevalence of H. pylori virulence factors including cagA, iceA and vacA and their association with clinical manifestation varied widely with different subpopulations [15], [16], [17]. However, studies regarding the prevalence of cagA and iceA, vacA genes are scarce. Hence, the present study determined the prevalence of cagA, iceA1, iceA2, vacA, vacA s1/s2, vacA m1/m2, Western type cagA and East Asian type cagA virulence genes in H. pylori isolated from gastric ulcer patients. The study also evaluated the association of these virulence genes with gender, age, smoking and alcohol consumption.

Materials and methods

One hundred and seventy-two consecutive gastric biopsy samples from 172 patients with a gastric ulcer, admitted to the endoscopic section at the Department of Gastroenterology, Jining First People’s Hospital, Shandong Province and the Department of Gastroenterology, Third Affiliated Hospital of Shandong Medical College, Shandong Province, China between September 2015 and December 2017 were collected. Patients who received prior antibiotic therapy within the previous 4 weeks were excluded from the study. An informed consent was obtained from all patients or their legal heir. The hospital Ethics Committee approved the study. Using a sterile container sample was collected aseptically and immediately sent for H. pylori culture.

Isolation and identification of H. pylori

The collected samples were aseptically dissected into two pieces for rapid urease test and H. pylori culture. Using the modified rapid urease agar medium, the rapid urease test was performed [18]. Briefly, after collection one part of the biopsy samples were immediately inoculated into urea agar and incubated at room temperature for 2 h. The change in color of the medium from yellow to red indicates a positive reaction. Helicobacter pylori culture was performed by inoculating the biopsy samples on the modified Columbia agar plates (Merck, Germany) supplemented with horse lysed blood (10%, v/v). The plates were then incubated in an anaerobic condition at 37°C for 2–3 days under microaerobic conditions [19]. After incubation, based on the colony morphology, gram staining, positive oxidase, catalase, and urease tests the organisms were identified as H. pylori. The isolates were stored in Columbia broth supplemented with sterile glycerol (20%, v/v) at −70°C until used.

DNA extraction

The H. pylori isolates were subjected to DNA extraction by the boiling lysis method, briefly, 200 μL of H. pylori culture was incubated at 95°C for 10 min, spun at 14,000 g for 10 min to collect the supernatant containing DNA. Both the DNA samples were stored at −20°C until further analysis. DNA quantification and purity was determined using NanoDrop ND 1000 (Nano-Drop Technologies, Wilmington, DE, USA).

Detection of virulence genes

Detection of cagA, vacA, iceA1 and iceA2 virulence genes were performed using polymerase chain reaction (PCR). The primer sequences, cycling conditions and expected amplicon sizes are described in Table 1. Two duplex PCR was performed to detect the iceA1/iceA2 and cagA/vacA genes separately. PCR was done using a 50 μL master mix containing 5 μL of template DNA, 0.4 μM of each primer, 200 μM of dNTPs, one unit of Taq polymerase enzyme and 5 μL of 10× reaction buffer. After PCR, the amplicons were resolved in 1.5% agarose gel and visualized under a UV transilluminator.

Table 1:

Primer sequence of H. pylori virulence genes.

GenesPrimersSize, bpCycling conditionsReferences
iceA1F: 5′-GTGTTTTTAACCAAAGTATC-3′

R: 5′-CTATAGCCATTATCTTTGCA-3′		24695°C, 1 min; 50°C, 1 min; 72°C, 1 min

(30 cycles)		[20]
iceA2F: 5′-GTTGGGTATATCACAATTTAT-3′

R: 5′-TTTCCCTATTTTCTAGTAGGT-3′		229/334a
cagAF-5′-GATAACAGCCAAGCTTTTGAGG-3′

R-5′-CTGCAAAAGATTGTTTGGCAGA-3′		34994°C, 1 min; 55°C, 1 min; 72°C, 1 min

(35 cycles)		[21]
vacAF-5′-ATGGAAATACAACAAACACAC-3′

R-5′-CTGCTTGAATGCGCCAAAC-3′		286
vacA s1/s2F-5′-ATGGAAATACAACAAACACAC-3′

R-5′-CTGCTTGAATGCGCCAAAC-3′		259/28695°C, 50 s; 58°C, 50 s;

72°C,50 s

(35 cycles)		[1]
vacA m1/m2F-5′-CAATCTGTCCAATCAAGCGAG-3′

R-5′-GCGTCAAAATAATTCCAAGG-3′		567/64295°C, 50 s; 54°C, 50 s;

72°C,50 s

(35 cycles)
Western type cagA (cagT/cag W)F-5′-ACCCTAGTCGGTAATGGG-3′

R-5′-TGCCCTACAMCACCSAAACCAC-3′

F-5′-AAAAATTGACCRACTCAATC-3′

R-5′-GCTTTAGCTTCTGAYACYGC-3′		~218–227 and ~174–17795°C, 1 min; 52°C, 1 min;

72°C, 1 min

(35 cycles)		[22]
East Asian type cagA (cagT/cag j)F-5′-ACCCTAGTCGGTAATGGG-3′

R-5′-GCAATTTTGTTAATCCGGTC-3′

F-5′-GCATCAGCAGGTAAAGGAGT-3′

R-5′-GCTTTAGCTTCTGAYACYGC-3′		~293–299

~455–461		95°C, 1 min; 52°C, 1 min;

72°C, 1 min

(35 cycles)		[5]

  1. aThe primers yield a fragment of 229 or 334 bp depending on the presence of a repetitive sequence of 105 nucleotides codifying for 35 amino acids in some iceA2 alleles.

Detection of cagA and VacA gene variance

The cagA and vacA variant genes, Western type cagA, East Asian cagA and vacA s1/s2 and vacA m1/m2 genes were detected by PCR. The primer sequences, cycling conditions and expected amplicon sizes were described in Table 1. Four different PCRs were performed to detect the Western type cagA, East Asian cagA, vacA s1/s2 and vacA m1/m2 genes, respectively. The Western type cagA gene PCR was expected to yield two amplicons of sizes ~218–227 and ~174–177 bp. Similarly, the East Asian cagA was expected to yield two amplicons of size ~293–299 bp and ~455–461 bp. The PCR master mix was prepared as described above. After PCR, the amplicons were resolved in 1.8% agarose gel and visualized under a UV transilluminator.

Statistics

Continuous variables were presented as mean and ranges; categorical variables as numbers and percentages. Chi-square tests were performed to determine the statistical significance using MINITAB statistical software (MINITAB ver. 13.1; MINITAB Inc., PA, USA). The data was considered statistically significant if the p-value was <0.05.

Results

Of the 172 patients, 97 (56.4%) were male and 75 (43.6%) were female. The mean age was 46±7.2 (range 19–63) years. Of the included patients, 113 (65.7%) were smokers or had a history of smoking and 108 (62.8%) were alcoholic patients. Demographic details of the patients are given in Table 2. Of the 172 gastric biopsy samples, 118 (68.6%) samples were positive for rapid urease test and 83 (48.3%) samples (48 from male and 35 from female) grew H. pylori. All the samples which isolated H. pylori were found to be positive for the rapid urease test. No significant association was found between H. pylori infection in male and female (27.9% vs. 20.3%; p=0.714) patients and between alcoholic and non-alcoholic (30.2% vs. 18.0%; p=0.971) patients. However, we observed a significant association between H. pylori infection and patients who were smokers or had a history of smoking (26.7%; p=0.006). We found that patients within the age group of 41–50 years were highly likely to be H. pylori positive (18.0%) followed by patients within the age group of 31–40 years (14.5%). However, no significant association was found between the H. pylori infection and different age groups (p=0.979).

Table 2:

Baseline characteristics of patients.

VariablesNo. of patients
Male97 (56.4%)
Female75 (43.6%)
Mean age (SD) years46±7.2
Age, years
 19–3032 (18.6%)
 31–4053 (30.8%)
 41–5064 (37.2%)
 51–6323 (13.4%)
Smoker113 (65.7%)
Non-smoker59 (34.3%)
Alcoholic108 (62.8%)
Non-alcoholic64 (37.2%)

  1. SD, standard deviation.

Of the 83 isolates subjected to PCR, 57 (68.7%) isolates were positive for the vacA gene, 53 (63.9%) isolates were positive for the cagA gene, 46 (55.4%) isolates were positive for the iceA2 gene and 37 (44.6%) isolates were positive for the iceA1 gene. We found that the presence of vacA (49.4% vs. 19.3%; p=0.000) and iceA2 (26.5% vs. 29%; p=0.040) genes were significantly associated with male and female patients, respectively. When analyzed between different age groups vacA (33.7%; p=0.000) and iceA1 (21.7%; p=0.010) genes were significantly associated with the age group of 31–40 years. The presence of cagA gene was significantly associated with alcoholic patients (45.8% vs. 18.1%; p=0.024). There was no significant association between the tested virulence genes and smoking history of the patients (p>0.05). We also found that there was no statistically significant association of the iceA2 gene in relation to gender, age, smoking and alcoholic history of the patients (p>0.05). Details on the distribution of virulence genes among the isolates are given in Table 3.

Table 3:

Detection and distribution of H. pylori virulence genes.

VariablesCulture positive (n=172)Distribution of virulence genes among the isolates (n=83)
cagAvacAiceA1iceA2
Male48 (27.9%)34 (41.0%)41 (49.4%)20 (24.1%)22 (26.5%)
Female35 (20.3%)19 (22.9%)16 (19.3%)17 (20.5%)24 (29.0%)
χ2-Testp=0.714p=0.121p=0.000p=0.532p=0.040
19–30 years15 (8.7%)8 (9.6%)12 (14.5%)7 (8.4%)10 (12.0%)
31–40 years25 (14.5%)21 (25.3%)28 (33.7%)18 (21.7%)14 (16.9%)
41–50 years31 (18.0%)17 (20.5%)14 (16.9%)6 (7.2%)16 (19.3%)
51–63 years12 (7.0%)7 (8.4%)3 (3.6%)7 (7.2%)6 (7.2%)
χ2-Testp=0.979p=0.095p=0.000p=0.010p=0.815
Smoker46 (26.7%)28 (33.7%)33 (39.8%)19 (22.9%)24 (29.0%)
Non-smoker37 (21.5%)25 (30.1%)24 (29.0%)18 (21.7%)22 (26.5%)
χ2-Testp=0.006p=0.528p=0.502p=0.503p=0.507
Alcoholic52 (30.2%)38 (45.8%)37 (44.6%)27 (32.5%)31 (37.3%)
Non-alcoholic31 (18.0%)15 (18.1%)20 (24.1%)10 (12.0%)15 (18.1%)
χ2-Testp=0.971p=0.024p=0.528p=0.081p=0.076

  1. Bold values indicates statistical significant values.

Among the isolates tested for virulence genes, 20 isolates, each were positive for cagA and iceA2 genes alone, respectively. In the combinational analysis, we found that 18 (21.7%) isolates were positive for both vacA and iceA2 genes, which was the most predominant combination detected. The cagA and vacA, cagA and iceA1 were the next most common combinations detected, respectively, in each of the 12 (14.5%) isolates. Three isolates were positive for the cagA, vacA and iceA1 genes, three isolates were positive for the cagA, iceA1 and iceA2 genes. Another three isolates were positive for all the tested (cagA, vacA, iceA1, iceA2) virulence genes (Table 4). In the present study, 89.2% (74/83) of H. pylori isolates were positive for at least one of the tested virulence genes (cagA, vacA, iceA1, iceA2) which implies that a majority of the H. pylori isolates had virulence potential as evidenced by the detection of virulence genes.

Table 4:

Detection and combination of H. pylori virulence genes.

Gene combinationsNo. of isolates (n=83)
cagA20 (24.1%)
vacA13 (15.7%)
iceA18 (9.6%)
iceA220 (24.1%)
cagA+vacA12 (14.5%)
cagA+iceA112 (14.5%)
vacA+iceA16 (7.2%)
vacA+iceA218 (21.7%)
cagA+vacA+iceA13 (3.6%)
cagA+iceA1+iceA23 (3.6%)
vacA+iceA1+iceA22 (2.4%)
cagA+vacA+iceA1+iceA23 (3.6%)

Of the 83 isolates tested for vacA and cagA gene variance, 52 (62.7%) isolates were positive for the vacA s1/s2 gene, 61 (73.5%) isolates were positive for the vacA m1/m2 gene, 12 (14.5%) isolates were positive for the Western type cagA gene and 56 (67.5%) isolates were positive for the East Asian type cagA gene. We found that the presence of vacA s1/s2 (42.2% vs. 20.5%; p=0.024) and East Asian type cagA (28.9% vs. 38.6%; p=0.004) genes were significantly associated with male and female patients, respectively. When analyzed between different age groups the vacA s1/s2 (28.9%; p=0.000) gene was significantly associated with the age group of 31–40 years. The presence of the vacA m1/m2 gene was significantly associated with non-smoking patients (42.2% vs. 31.3%; p=0.000). The presence of the vacA s1/s2 gene was significantly associated with alcoholic patients (49.4% vs. 13.3%; p=0.000). We also found that there was no statistically significant association of the Western type cagA gene in relation to gender, age, smoking and alcoholic history of the patients (p>0.05). Details on the distribution of vacA and cagA variance genes among the isolates are given in Table 5. Analysis of the vacA variance genes showed that five (6%) isolates amplified only the vacAs1 gene, seven (8.4%) isolates amplified only the vacAs2 gene, four (4.8%) isolates amplified only vacAm1 gene and six (7.2%) isolates amplified the only vacAm2 gene, the presence of these genes did not differ significantly (p>0.05).

Table 5:

Distribution of vacA and cagA gene variance among the isolates (n=83).

VariablesDistribution of vacA and cagA gene variance among the isolates (n=83)
vacA s1/s2vacA m1/m2Western type cagAEast Asian type cagA
Male35 (42.2%)32 (38.6%)5 (6%)24 (28.9%)
Female17 (20.5%)29 (34.9%)7 (8.4%)32 (38.6%)
χ2-Testp=0.024p=0.099p=0.220p=0.004
19–30 years8 (9.6%)12 (14.5%)1 (1.2%)13 (15.7%)
31–40 years24 (28.9%)21 (25.3%)1 (1.2%)15 (18.1%)
41–50 years11 (13.3%)18 (21.7%)8 (9.6%)20 (24.1%)
51–63 years9 (10.8%)10 (12%)2 (2.4%)8 (9.6%)
χ2-Testp=0.000p=0.106p=0.101p=0.350
Smoker28 (33.7%)26 (31.3%)5 (3.6%)29 (34.9%)
Non-smoker24 (28.9%)35 (42.2%)7 (10.8%)27 (32.5%)
χ2-Testp=0.706p=0.000p=0.322p=0.337
Alcoholic41 (49.4%)39 (47%)6 (7.2%)36 (43.4%)
Non-alcoholic11 (13.3%)22 (26.5%)6 (7.2%)20 (24.1%)
χ2-Testp=0.000p=0.687p=0.327p=0.657

  1. Bold values indicates statistical significant values.

When compared between vacA and vacA s1/s2, vacA m1/m2 gene-positive isolates; a total of 32 (38.6%) isolates amplified the vacA s1/s2, vacA m1/m2 genes. Three isolates which were positive for the vacA gene did not amplify either vacA s1/s2 or vacA m1/m2 genes. Five and seven isolates which were positive for the vacA s1/s2 and vacA m1/m2 genes, respectively, did not amplify the vacA gene. When compared between cagA and cagA Western and East Asian type gene-positive isolates; four isolates which were positive for the cagA gene did not amplify either the cagA Western type or cagA East Asian type genes. Two and eight isolates which were positive for the cagA Western type and cagA East-Asian type genes, respectively, did not amplify the cagA gene.

Discussion

H. pylori, a causative agent of gastric ulcers, can lead to the development of GC [23]. Although the H. pylori prevalence is declining in many developed countries [24], [25], it remains high in developing countries and ranges from 70% to 90% [3], [4], [26], [27]. The association of H. pylori with various gastrointestinal diseases makes it a major health problem, worldwide [1], [2], [28]. In our study, the H. pylori prevalence rate among patients with gastric ulcer was 48.3%. A study from Pakistan, reported the prevalence of H. pylori at a rate of 53% and 80%, respectively, in patients with duodenal ulcer and individuals presenting symptoms of various upper gastrointestinal diseases [29], [30]. This was higher than that reported (48.3%) in our study from gastric ulcer patients. Another study from Bangladesh conducted in patients with a gastric ulcer reported H. pylori prevalence at a rate of 75% which was higher than that reported in our study [26]. A study from Singapore which assessed H. pylori infection in patients with gastric ulcer using a Campylobacter-like organism (CLO) test and the histology reported a prevalence rate of 67.5%, which is higher than that reported in our study [31]. A study from Mongolia which included dyspeptic patients from all parts of Mongolia reported an overall H. pylori infection at a rate of 80%, which was higher than that reported in our study [32]. The prevalence of H. pylori in our study is lower than that reported from dyspeptic patients in Bhutan (86%) [33]. Among the dyspeptic patients, the prevalence of H. pylori in African countries including Morocco (75.5%), Ethiopia (65.7%) and Nigeria (93.6%) was higher than that reported in our study [34], [35], [36]. Due to rapid urbanization in China, the prevalence of H. pylori infection has decreased and could be a reason for the low prevalence of H. pylori in our study [24]. In our study, there was no significant association between the presence of H. pylori infection and gender (p=0.714) and alcohol consumption (p=0.971). Smoking is considered as one of the independent risk factors for H. pylori infection; in our study, we found a significant (p=0.006) association between the presence of H. pylori and patients who were smokers or had a history of smoking [37].

H. pylori possess several virulence factors which are associated with various gastrointestinal diseases [5], [6], [7]. H. pylori adheres to the mucosa of the stomach, colonizes it, persists for a long time and leads to an inflammatory response. The colonization of H. pylori as such does not cause infection; however, it can increase the risk of developing various gastrointestinal diseases including gastric ulcer, GC and lymphoma [38]. Specific analysis of H. pylori virulence factors can predict post H. pylori infectious disorders [38]. In our study, vacA (68.7%) was the predominant gene detected among our isolates followed by cagA (63.9%), iceA2 (55.4%) and iceA1 (44.6%) genes. A meta-analysis which investigated the association of H. pylori virulence factors with GC reported that the presence of cagA and vacA genes were significantly associated with GC [38]. In our study, 63.9% isolates were positive for the cagA gene which is higher (50%) than that reported in the biopsy samples collected from gastric patients from Northeast China [23]. The presence of cagA in our study is lower than that reported in India (90.9%), detected in the biopsy samples from gastric ulcer patients, which also reported a significant association between peptic ulcer and the presence of the cagA gene [39]. Another study from India reported that 77.27% of biopsy samples from acid-peptic disease were positive for the cagA gene, which was higher than that reported in our study. The study also reported that the presence of the cagA gene was significant in female patients; however, in our study there was no significant (p=0.121) difference found between the two genders [40]. Another study from Thailand reported that 98.2% of their gastric biopsy samples from dyspeptic patients were positive for the cagA gene [41]. In contrast, a lower rate of the cagA gene was reported in biopsy samples from gastric ulcer patients from Saudi Arabia (30%) and stool samples from asymptomatic individuals from Japan [1], [42]. The presence of the cagA in our study is much lower than that reported in H. pylori isolated from gastric biopsy samples from Korea (99%) [22].

We reported that 14.5% and 67.5% of our isolates were positive for Western and East Asian type cagA genes, respectively. As previously reported, East Asia type cagA was more prevalent in Asian countries, the majority of our isolates were positive for the East Asian type cagA gene compared to the Western type cagA gene [43]. In contrast, a study from Northeast China reported that 31% of their biopsy samples from gastric ulcer patients were positive for the Western type cagA gene which is higher and 20% of their samples were positive for the East Asian type cagA gene which is lower than that reported in our study [23]. In contrast, a study which determined the prevalence of H. pylori infection and genotypes of virulence factors in a Nepalese population reported, a higher rate of the Western type cagA gene (94.1%) compared to the East Asian type cagA gene (5.9%) [44]. The East Asian cagA is more virulent than Western type cagA [45], [46]. Additionally, the East Asian cagA gene plays a potential role in the development of gastric diseases caused by H. pylori infections [47]. Thus, the high presence of the East Asian cagA gene in our isolates indicates that our isolates are highly virulent in nature. Also, the significant association of the East Asian cagA gene with female patients (p=0.004) in our study indicates that they may be at high risk of H. pylori infection with significant clinical manifestation.

In our study, 68.7% isolates were positive for the vacA gene which was higher than that reported from India (4.5%) [40]. The vacA m1/m2 (73.5%) was the predominant vacA variant gene reported in our study. It has been reported that the presence of vacAs1 and m1 genotypes may indicate an increased risk of peptic ulcer and GC in Latin America and the Middle East [38]. In our study, 38.6% of isolates were positive for vacA s1/s2 and vacA m1/m2 genes indicating that the patients from whom these isolates were isolated are at a risk of GC in addition to the gastric ulcer they harbor. A study from Saudi Arabia reported the combined vacA s1/s2 gene in 30% of isolates and vacA m1/m2 in 0% of H. pylori isolates from gastric ulcer patients which were lower than that reported from our study [1]. The study reported that vacA s1/s2 was the predominant genotype in gastric ulcer patients; in contrast, vacA m1/m2 was the predominant genotype in our study [1]. We found that the vacA and vacA s1/s2 genes were significantly associated with male patients and patients within the age group of 23–40 years. Additionally, vacA s1/s2 was significantly associated with alcoholic patients. In our study, the co-occurrence of vacA variance and cagA variance gene combinations did not differ significantly (p>0.05), hence were not discussed in detail.

In our study, 46 (55.4%) isolates were positive for the iceA2 gene and 37 (44.6%) isolates were positive for the iceA1 gene. Chomvarin et al. [41] who determined the association between the various genotypes of H. pylori and its clinical manifestations in Thai dyspeptic patients, reported that an overall 45.5% and 33.1% of the samples were positive for the iceA1 and iceA2 genes, respectively. Of this 35% and 40% of the gastric ulcer samples were positive for iceA1 and iceA2, respectively, which is lower than that reported in our study [41]. A study from Saudi Arabia which determined the prevalence of cagA and iceA genes from biopsy samples of patients with both gastric and peptic ulcers reported that 81.7% of the samples were positive for the iceA gene, of which 92.3% were from peptic ulcer and 75% were from gastritis cases [48]. We found that a majority of our isolates were positive for any one of the tested virulence genes indicating that these isolates are highly virulent in nature. As reported earlier, the presence of vacA and cagA genes is associated with GC, the high prevalence of these genes among our isolates may warrant a monitoring for GC in patients from whom these strains are isolated.

Conclusions

The H. pylori infection rate in our study was 48.3% and was associated with patients who were smokers or had a history of smoking. The vacA gene (68.7%) was the predominant virulence gene detected and was associated with male patients and patients within the age group of 31–40 years. The cagA gene was the second most common gene detected and was significantly associated with alcoholic patients. As reported earlier, the predominance of this gene warrants a close monitoring for GC in patients from whom these strains were isolated. The majority of our isolates were positive for any one of the virulence genes tested indicating that these isolates were highly virulent in nature.

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: The project was funded by the Shandong Provincial Health Department (No. 2015WSA08008).

  3. Employment or leadership: None declared.

  4. Honorarium: None declared.

  5. Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

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Received: 2018-05-17
Accepted: 2018-06-27
Published Online: 2018-07-23
Published in Print: 2018-08-28

©2018 Walter de Gruyter GmbH, Berlin/Boston

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Artikel in diesem Heft

  1. Frontmatter
  2. Editorial
  3. Challenges of laboratory diagnostics in the elderly
  4. Geriatric Laboratory
  5. The SENIORLAB study in the quest for healthy elderly patients
  6. Laboratory diagnostics in dementia
  7. Red blood cell counts and indices in the elderly German population
  8. Original Article
  9. Failure of the holotranscobalamin assay in vitamin B12-deficient patients
  10. Endocrinology
  11. Serum vitamin D receptor levels in gestational diabetes mellitus
  12. Infectiology and Microbiology
  13. Detection of CagA, VacA, IceA1 and IceA2 virulent genes in Helicobacter pylori isolated from gastric ulcer patients
  14. Congress Abstracts
  15. German Congress of Laboratory Medicine: 15th Annual Congress of the DGKL (German Society of Clinical Chemistry and Laboratory Medicine) and the 3rd Symposium on Biomedical Analysis
https://doi.org/10.1515/labmed-2018-0059
Schlagwörter für diesen Artikel
gastric ulcer; H. pylori; virulence genes
Creative Commons
BY-NC-ND 3.0

Artikel in diesem Heft

  1. Frontmatter
  2. Editorial
  3. Challenges of laboratory diagnostics in the elderly
  4. Geriatric Laboratory
  5. The SENIORLAB study in the quest for healthy elderly patients
  6. Laboratory diagnostics in dementia
  7. Red blood cell counts and indices in the elderly German population
  8. Original Article
  9. Failure of the holotranscobalamin assay in vitamin B12-deficient patients
  10. Endocrinology
  11. Serum vitamin D receptor levels in gestational diabetes mellitus
  12. Infectiology and Microbiology
  13. Detection of CagA, VacA, IceA1 and IceA2 virulent genes in Helicobacter pylori isolated from gastric ulcer patients
  14. Congress Abstracts
  15. German Congress of Laboratory Medicine: 15th Annual Congress of the DGKL (German Society of Clinical Chemistry and Laboratory Medicine) and the 3rd Symposium on Biomedical Analysis
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