Evaluation of a selective transport medium for gastric biopsy specimens to be cultured for Helicobacter pylori

Penicillin‑binding protein 1A mutation‑positive Helicobacter pylori promotes epithelial‑mesenchymal transition in gastric cancer via the suppression of microRNA‑134

Evidence suggests that Helicobacter pylori (H. pylori) is not only the main cause of gastric cancer (GC), but is also closely associated with its metastasis. One of the major virulence factors in H. pylori is the cytotoxin-associated gene A (CagA). With the growing proportion of amoxicillin-resistant H. pylori strains, the present study aimed to explore the effects of CagA- and penicillin-binding protein 1A (PBP1A) mutation-positive H. pylori (H. pylori_CagA+/P+) on GC cells, and its clinical significance. The clinical significance of H. pylori_CagA+/P+ infection was analyzed in patients with GC. In vitro, GC cells were infected with H. pylori_CagA+/P+ to investigate whether it was involved in the epithelial-mesenchymal transition (EMT) of SGC-7901 cells using immunofluorescence and western blot analysis. The results of clinical analysis demonstrated that, although CagA-negative H. pylori infection had no significant association with the characteristics of patients with GC, H. pylori_CagA+/P+ infection was significantly associated with various clinicopathological parameters, including invasion depth, lymphatic metastasis and distant metastasis. In vitro, the results indicated that H. pylori_CagA+/P+ promoted proliferation, invasion and EMT of SGC-7901 cells. MicroRNA (miR)-134 was downregulated in H. pylori_CagA+/P+ infected tissues compared with in those with H. pylori_CagA+/P- infection. miR-134 overexpression significantly reversed H. pylori_CagA+/P+ infection-associated cell proliferation, invasion and EMT. Furthermore, the results revealed that Forkhead box protein M1 (FoxM1) was a direct target of miR-134, and FoxM1 knockdown impeded H. pylori_CagA+/P+-induced EMT. In conclusion, the present study demonstrated that miR-134 may suppress the proliferation, invasion and EMT of SGC-7901 cells by targeting FoxM1, and may serve a protective role in the process of H. pylori_CagA+/P+-induced GC. These findings may lead to an improved understanding of H. pylori_CagA+/P+-associated poor clinical characteristics in patients with GC.

Prevalence of CagA and antimicrobial sensitivity of H. pylori isolates of patients with gastric cancer in Egypt

BACKGROUND

Helicobacter pylori (H. pylori) infection has been recognized as a significant threat for gastric cancer. However, studies that investigated the oncogenic factors and antimicrobial resistance of H. pylori in Egyptian isolates with gastric cancer are rare. The current study aimed to examine: (1) The pattern of antimicrobial resistance of H. pylori isolates of Egyptian gastric cancer patients, and (2) the prevalence of Cytotoxin-associated gene A (CagA).

METHODS

Samples were collected from patients with gastric cancer. Isolation of H. pylori was performed using Columbia blood agar supplemented with 10% horse blood, and selective supplement of H. pylori for 3 to 5 days at 37 °C under microaerophilic condition. Isolates were identified by biochemical traits of H. pylori: oxidase, urease and catalase tests. Antimicrobial susceptibility of H. pylori isolates was examined against five antimicrobial agents using disc diffusion method. After that, extraction of DNA and Polymerase Chain Reaction (PCR) were performed to amplify the target genes.

RESULTS

Twelve samples were collected from six males and six females Egyptian patients with cancer with an age range from 22 to 65 years. These cases are scarce and samples were collected over a period of almost eleven months. All isolates were confirmed as positive H. pylori through colony morphology and biochemical tests. The most effective antibiotic found was ciprofloxacin whereas all isolates showed resistance to metronidazole and erythromycin. The target CagA oncogene gene with expected product size was reported and seven (out of twelve) isolates (58%) were identified as CagA positive.

CONCLUSION

The current study is unique in two main aspects. First, it reported the pattern of antimicrobial susceptibility and prevalence of CagA gene in H. pylori from Egyptian patients. Second, it exclusively recruited isolates from gastric cancer patients which were confirmed by clinical and laparoscopic examination. The moderately high prevalence of CagA gene in Egyptian cancer patients calls for more vigilance against that oncogene.

New transport medium for cultural recovery of Helicobacter pylori

We developed a new transport medium (GESA--Helicobacter pylori transport medium [publication no. WO/2014/019696, patent pending no. PCT/EP2013/002292; Liofilchem s.r.l., Roseto degli Abruzzi, Teramo, Italy]) for recovery of Helicobacter pylori from gastric biopsy samples. GESA transport medium, in a semisolid state, provides the optimal conditions for maintaining the viability of the microorganism over time. The efficacy of the transport medium was assessed through in vitro and ex vivo experiments. We were able to recover different suspensions of H. pylori ATCC 43629 and H. pylori 13 A in GESA transport medium stored at 4 °C for up to 10 days. In particular, with a starting inoculum of ∼ 10(5) CFU, after 7 days of storage, 150 ± 25 CFU and 40 ± 7 CFU of the reference and clinical strains were detected, respectively. H. pylori colonies were isolated from gastric specimens taken from both the antrum and the fundus in 68 (90.66%) of 75 urea breath test (UBT)-positive patients. Moreover, GESA transport medium allowed the recovery and isolation of H. pylori colonies from additional biopsy samples from 13 of the 75 detected subjects at up to 10 days of biopsy sample storage at 4 °C. Finally, GESA transport medium preserved its characteristics when stored at 4°C for 1 year from its preparation, thus allowing good recovery of H. pylori. GESA transport medium can be considered a standardized transport medium with high performance that optimizes the recovery rate of H. pylori grown by culture.

Evaluation of a serum-free transport medium supplemented with cyanobacterial extract, for the optimal survival of Helicobacter pylori from biopsy samples and strains

The purpose of this work was to evaluate the use of an alternative transport medium supplemented with a cyanobacterial extract (CE), free of animal derivatives, to preserve the viability of Helicobacter pylori strains during long-term transportation and allow its recovery from biopsy samples. The transport media evaluated were Mueller-Hinton broth 0.3% agar (MH) and 0.3% of CE (MH-CE). MH broth 5% fetal calf serum (FCS) was used as the reference medium (MH-FCS). Biopsy samples from 134 patients, H. pylori NCTC 11638 and six clinical isolates were studied. A higher recovery (p ≤ 0.001) at 4°C was obtained in MH-CE than in MH-FCS after 96 h of storage. Only MH-CE allowed recovery after 120 h. The H. pylori recovery at room temperature after 96 h was higher (p ≤ 0.005) in MH-CE than in MH-FCS. Similar survival rates were observed in biopsy samples conserved in MH-CE and MH-FCS at 4°C. The recovery after 48 h at room temperature in MH-CE was higher (p ≤ 0.05) than MH-FCS and was the only medium allowing recovery after 72 h. The MH-CE medium is a simple, inexpensive and animal derivatives-free transport medium that can be used to preserve H. pylori viability and its recovery from biopsy samples.

Liquid culture medium for the rapid cultivation of Helicobacter pylori from biopsy specimens

The goal of this study was to develop a liquid culture medium for the rapid isolation, cultivation, identification and subsequent antibiotics susceptibility testing of Helicobacter pylori directly from biopsy specimens. Five liquid media were tested: Ham's F-12, Brucella broth, tryptic soybroth, brain heart infusion broth and Mueller-Hinton broth. After optimisation of the medium, it was applied in order to investigate biopsy samples from 150 patients with gastro-duodenal disorders and compared with traditional culture methods, microscopy and an H. pylori-specific TaqMan real-time polymerase chain reaction (PCR). The most reliable and rapid growth of H. pylori, even at a small inoculum size, was obtained in Ham's F-12 medium with 5% horse serum. The developed system allowed the primary isolation of H. pylori in clinical samples and provided 87% sensitivity and 100% specificity.

Involvement of mast cells in gastritis caused by Helicobacter pylori: a potential role in epithelial cell apoptosis

BACKGROUND

The role(s) of mast cells (MC) in gastric mucosal inflammation caused by Helicobacterpylori is (are) still debated.

AIM

To determine whether there is an association between MC density and epithelial cell apoptosis in antral gastric mucosa infected by H pylori.

PATIENTS AND METHODS

Biopsy specimens from 122 H pylori-positive subjects with chronic active gastritis, 84 patients with non-steroidal anti-inflammatory drug-induced gastritis and 48 volunteers were included. H pylori genotypes were determined by PCR amplification of bacterial cultures. Immunohistochemical analysis was performed on tissue microarrays with anti-CD117, anti-chymase, anti-tryptase, anti-myeloperoxidase, anti-Bcl-2, anti-Bcl-x, anti-Bax and anti-caspase 3 antibodies.

RESULTS

Of the 122 patients infected with H pylori, 76 (62.3%) harboured cagA positive strains. H pylori isolates belonged to the vacAs1/m1 genotype in 82 (67%) cases, to the vacAs2/m2 genotype in 23 (18.8%) cases and to the vacAs1/m2 genotype in 17 (13.9%) cases. 61 (50%) H pylori isolates were babA2+. In patients infected with H pylori, the density of MC, and in particular the number of MC-associated epithelial cells, was correlated with a high number of apoptotic epithelial cells. Moreover, the density of MC was correlated with the number of neutrophils infiltrating the antral gastric mucosa, and was strongly increased in patients infected with cagA, vacAs1/m1 and babA2 positive strains.

CONCLUSIONS

Taken together, these data show that the density of MC can be considered as a histopathological criterion of gastritis activity in patients infected with H pylori.

Methodology and transport medium for collection of Helicobacter pylori on a string test in remote locations

BACKGROUND

Helicobacter pylori can be isolated from patients using the string test but contaminating oral and nasopharyngeal microflora need to be suppressed by rapid plating out onto selective culture media. Recently, use of this diagnostic method was enhanced by using a novel transport medium to collect specimens from subjects in a remote Australian clinic over 1300 km from the laboratory.

METHODS

Retrieved string tests were transported to the laboratory in chilled polystyrene boxes in 5 ml screw-cap bottles with 3 ml of a brain heart infusion broth plus antibiotics. These were 20 g/ml vancomycin, 10 g/ml trimethoprim, 10 g/ml cefsulodin, and 10 g/ml amphotericin B. A comparison was made between subjects who gargled with a chlorhexidine mouthwash before swallowing the string test and those who did not.

RESULTS

Forty-five urea breath test-positive subjects were tested and H. pylori was isolated from 34 of them. Successful culture was achieved from string tests that were in transit for up to 29 hours and where the maximum temperature in the transport box was 14 degrees C. The additional use of a mouthwash had a marked effect on the isolation rate. H. pylori was cultured from 75% of subjects who gargled but only from 39% who did not.

CONCLUSIONS

This methodology and transport medium can broaden the use of the string test to more remote geographic areas where endoscopy is not feasible so that H. pylori isolates may still be obtained for diagnostic and epidemiologic studies. The value of this promising methodology of collection and transport should be assessed in a controlled study.

Culturing Helicobacter pylori from clinical specimens: review of microbiologic methods

Helicobacter pylori is probably the most common chronic bacterial infection of humankind, and is usually acquired first in childhood. Microbiologic culture of H. pylori is the "gold standard" for diagnosis in a patient with suspected infection. Although not currently recommended for routine use, culture allows testing for susceptibility to antimicrobials, especially in populations with a high prevalence of drug resistance. Gastric biopsies are the specimens most commonly used to culture H. pylori, but stool, vomitus, saliva, and dental plaque offer opportunities. This review examines the current methods used to culture H. pylori from biologic specimens and suggests useful hints to enhance its recovery rate.

Relationship between Helicobacter pylori babA2 status with gastric epithelial cell turnover and premalignant gastric lesions

BACKGROUND

Helicobacter pylori blood group antigen binding adhesin (BabA) mediates bacterial adherence to human blood group antigens on gastric epithelium. Although strains harbouring babA2 were recently found to be associated with peptic ulcer and gastric cancer, the role of babA2 in cellular turnover, severity of gastritis, and premalignant changes is poorly understood.

AIM

We correlated H pylori babA2, vacuolating toxin (vacA), and cytotoxin associated gene A (cagA) genotypes with the severity of gastric inflammation and epithelial cell turnover in a group of Chinese patients from an area with a high incidence of gastric cancer.

PATIENTS AND METHODS

H pylori isolates were obtained from 104 Chinese patients who participated in a gastric cancer prevention programme. Genotype variants of babA2, vacA, and cagA were determined by polymerase chain reaction. Antrum and corpus histopathology was examined according to the updated Sydney classification. Apoptosis was scored by terminal uridine deoxynucleotidyl nick end labeling (TUNEL) and proliferation by Ki-67 immunostaining.

RESULTS

Of the 104 patients, 102 (98.1%) harboured cagA(+) strains and all had vacA s1 genotype. The babA2(+) strains were found in 83 (79.8%) patients and were associated with higher lymphocytic infiltration (p=0.028), presence of glandular atrophy (odds ratio (OR) 7.5, 95% confidence interval (CI) 2.3-24.3), and intestinal metaplasia (OR 7.4, 95% CI 2.2-25.3) in the antrum. Increased epithelial proliferation was also noted in individuals infected with babA2(+) strains (p=0.025). Strains harbouring cagA(+)/vacA s1 genotypes lacked this association in the absence of babA2.

CONCLUSIONS

The presence of babA2(+) H pylori strains alone or in combination with cagA(+) and vacA s1 was associated with the presence of preneoplastic gastric lesions.

Classification of a Brevundimonas strain detectable after PCR with a Helicobacter-specific primer pair

In a study for the isolation of new Helicobacter strains, biopsy samples were taken from the gastric mucosa of dogs and subjected to PCR amplification using a Helicobacter-specific primer pair (H276f and H676r, directed to the 16S rDNA) to identify members of this genus in the specimens. From one Helicobacter positive sample, a bacterial strain was isolated which displayed a characteristic band after PCR amplification with the Helicobacter-specific primer pair. The isolate designated H2/98-FUNDUS was motile, oxidase-, catalase- and aminopeptidase-positive and grew only under microaerophilic conditions at 37 degrees C. The bacterium was classified by a polyphasic approach, including analysis of the isoprenoid quinones, fatty acids, polar lipids and partial 16S rDNA sequence. Analysis of the 16S rDNA sequence (1003 bases) indicated that the strain H2/98-FUNDUS is a member of the genus Brevundimonas and most closely related to Brevundimonas aurantiaca DSM 4731T (99.5% sequence similarity). Isolate H2/98-FUNDUS contained a predominant ubiquinone Q-10 and a fatty acid profile with the major compounds C18:1 and C16:0. In the polar lipid extract, phosphatidylglycerol, six unknown phospholipids, one unknown phosphoglycolipid, two unknown glycolipids and two unknown aminolipids were detected. All these results indicate that H2/98-FUNDUS represents a new member of the genus Brevundimonas which gives a positive signal upon PCR employing the Helicobacter-specific primer pair.

Comparison of fluorescent in situ hybridization and conventional culturing for detection of Helicobacter pylori in gastric biopsy specimens

In this study, we have investigated 201 gastric biopsy specimens obtained from dyspeptic patients for the presence of Helicobacter pylori. By means of fluorescent in situ hybridization (FISH) with rRNA-targeted fluorescence-labeled oligonucleotide probes specific for H. pylori, this pathogen was detected in 63 biopsy specimens. By using conventional culturing, H. pylori was isolated from 49 of these 63 gastric biopsy specimens. In contrast, FISH failed to identify H. pylori in four samples from which the pathogen was cultured. The lowest sensitivity was obtained by using the urease test. H. pylori was detected indirectly by this method in 43 of 67 biopsy specimens, which were positive for the pathogen as determined by FISH and/or culturing. All 49 H. pylori isolates that were detected by FISH and culturing underwent antimicrobial susceptibility testing for clarithromycin, a macrolide drug that is a key component in the therapy of peptic ulcer disease caused by this pathogen. Clarithromycin susceptibility testing of cultured isolates was carried out by the E-test, whereas FISH was used on biopsy specimens to detect clarithromycin-resistant mutant strains. No discrepancies were found between these two methods. Thirty-seven strains were clarithromycin sensitive, and eight H. pylori isolates were resistant to the macrolide. From another four biopsy specimens, a mixture of clarithromycin-sensitive and -resistant strains was identified by both methods. Thus, FISH is a reliable technique for determining the clarithromycin susceptibility of this pathogen. Taken together, FISH is a more sensitive and rapid technique than culturing for detection of H. pylori in gastric biopsy specimens. However, in the microbiology routine diagnostic laboratory, the combination of both FISH and conventional culturing significantly increases the sensitivity in detection of H. pylori.

Accurate diagnosis of Helicobacter pylori. Culture, including transport

Bacteriology laboratories are interested in culturing H. pylori for several reasons: (1) to investigate its growth requirements and metabolism; (2) for diagnostic purposes; (3) to establish the antibiotic susceptibility of isolates; (4) to identify potential virulence factors; and (5) to investigate microbial host-cell interactions. Despite the reasons listed, culture of H. pylori from gastric biopsy specimens is becoming less popular among clinical laboratories and physicians. The main reason is that it has become generally accepted that culture techniques are too demanding with many factors that must be controlled, in addition to simple and less expensive methods now available. Some of the disadvantages of culture include (1) special conditions for specimen transportation, (2) speed in processing of the sample to increase the probability of recovering the organism, (3) the use of expensive and complicated media with special conditions for maintenance, (4) the need for special incubation conditions, and (5) the length of time necessary to obtain a result for establishing treatment options in the patient. This article reviews aspects of H. pylori culture that could explain use being relegated to only a few clinical laboratories, some regional laboratories, and reference centers. There are several misconceptions in relation to culture techniques, such as transport and the processing of biopsy specimens. This article has mentioned simple and clear points that optimize the recovery rates of H. pylori by culture.

Transport and storage of fresh and frozen gastric biopsy specimens for optimal recovery of Helicobacter pylori

The viability of Helicobacter pylori in vitro and in gastric biopsy specimens was determined. Recovery rates were 94, 87, and 77% from biopsy specimens in Portagerm pylori in cooled containers after 1, 2, and 3 days of transport, respectively (n = 307), and 97% if stored and shipped in glycerol broth at -70 degrees C (n = 232).