Effect of specimen collection techniques, transport media, and incubation of cultures on the detection rate of Helicobacter pylori

Centralized isolation of Helicobacter pylori from multiple centers and transport condition influences

AIM: To evaluate the efficacy of centralized culture and possible influencing factors.

METHODS: From January 2010 to July 2012, 66452 patients with suspected Helicobacter pylori (H. pylori) infection from 26 hospitals in Zhejiang and Jiangsu Provinces in China underwent gastrointestinal endoscopy. Gastric mucosal biopsies were taken from the antrum for culture. These biopsies were transported under natural environmental temperature to the central laboratory in Hangzhou city and divided into three groups based on their transport time: 5, 24 and 48 h. The culture results were reported after 72 h and the positive culture rates were analyzed by a χ² test. An additional 5736 biopsies from H. pylori-positive patients (5646 rapid urease test-positive and 90 ¹⁴C-urease breath test-positive) were also cultured for quality control in the central laboratory setting.

RESULTS: The positive culture rate was 31.66% (21036/66452) for the patient samples and 71.72% (4114/5736) for the H. pylori-positive quality control specimens. In the 5 h transport group, the positive culture rate was 30.99% (3865/12471), and 32.84% (14960/45553) in the 24 h transport group. In contrast, the positive culture rate declined significantly in the 48 h transport group (26.25%; P < 0.001). During transportation, the average natural temperature increased from 4.67 to 29.14 °C, while the positive culture rate declined from 36.67% (1462/3987) to 24.12% (1799/7459). When the temperature exceeded 24 °C, the positive culture rate decreased significantly, especially in the 48 h transport group (23.17%).

CONCLUSION: Transportation of specimens within 24 h and below 24 °C is reasonable and acceptable for centralized culture of multicenter H. pylori samples.

Successful isolation of Helicobacter pylori after prolonged incubation from a patient with failed eradication therapy

Helicobacter pylori (H pylori), a gastric pathogen, is a major cause of chronic gastritis and peptic ulcer disease, and is an important risk factor for the development of gastric malignancies. Culture of the bacterium from gastric biopsy is essential for the determination of drug resistance of H pylori. However, the isolation rates of H pylori from infected individuals vary from 23.5% to 97% due to a number of factors such as biopsy preparation, cultural environment, medium and the method adopted. In the present case, we found that a prolonged incubation period of up to 19 d allowed successful isolation of H pylori from a patient who received triple therapy that failed to eradicate the bacterium.

Detection of Helicobacter pylori infection in symptomatic Bulgarian adults

This study assessed the prevalence of Helicobacter pylori in symptomatic Bulgarian adults by means of culture, Gram's stain and an in-house rapid urease test (RUT), and also assessed the H. pylori density by culture. In total, 1441 non-treated and 270 treated patients were evaluated. Most non-treated patients with ulcers (87.7%), gastric malignancy (79.2%) and other gastroduodenal diseases (73.4%) were H. pylori-positive. Among non-treated and treated patients, 75.3% and 54.8%, respectively, of elderly patients, and 78.3% and 56.1%, respectively, of other adults were H. pylori-positive. Two (0.1%) non-treated adults were Helicobacter heilmannii-positive. The accuracy of direct Gram's stain and the in-house RUT were 74.8% and 64.2% in non-treated patients, and 73.7% and 63.0% in treated patients, respectively. Culture was highly accurate (>95%) in both groups. Older age decreased the sensitivity of the RUT in non-treated patients by 10.7% and that of all tests in treated patients by 6.9-8.1%. Incubation for 11 days was required for the growth of 2% and 4% of the strains from treated patients on selective and non-selective medium, respectively. There were no differences in isolation rates between positive fresh (74.2%) and frozen (75.2%) specimens. In non-treated adults, a high H. pylori density (growth in all quadrants of the plates) was more common (43.1%) in ulcer patients than in other patients (25.4%). In conclusion, H. pylori infection was common in Bulgarian patients, and at a high density in >40% of ulcer patients, while H. heilmannii infection was uncommon. Culture provided a highly accurate diagnostic approach. Stomach biopsies from non-treated patients can be frozen for several days. The benefit of reporting H. pylori density, as determined by culture, requires further evaluation.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Helicobacter pylori and Helicobacter heilmannii in children. A Bulgarian study

The aim of the study was to evaluate the prevalence of Helicobacter pylori and Helicobacter heilmannii among 321 children. Gram staining, urease test and culture were performed. Of all patients, 52.6% were H. pylori positive and 0.3% were H. heilmannii positive. H. pylori infection was associated with chronic gastritis in 57.1%, with duodenal ulcer in 75% and with non-ulcer dyspepsia in 25.6%. This infection was more frequent in children aged 11-18 years than in younger patients. Rapid urease test, culture and direct Gram staining showed 42.3, 96.5 and 78.2% sensitivity and 93.2, 100 and 84.6% specificity, respectively. H. pylori was detected in 60.2% of fresh versus 52.8% of frozen specimens and in 64.8% in gastric biopsy versus 25% in gastric mucus specimens. H. pylori growth was detected after nine to 10 days in 6.2% and after 11 days in 1.2%. Culture exhibited the best accuracy of the three diagnostic methods. Frozen biopsy specimens gave reliable H. pylori detection unlike gastric mucus specimens. Eleven days of incubation for H. pylori is recommended. The study confirms an early acquisition of H. pylori infection in Bulgaria. The incidence of H. heilmannii infection in childhood is uncommon but clinically important.

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.

Assessment of different methods for staining Helicobacter pylori in endoscopic gastric biopsies

The recent implication of Helicobacter pylori in the pathogenesis of gastritis-peptic ulcer syndrome and its relevance for the development of upper gastrointestinal malignancy warrant efficient methods for the detection and demonstration of the organism in biopsy specimens. We have compared 5 staining methods, namely, haematoxylin and eosin (H & E), immunohistochemistry (IHC), the silver staining HpSS, the alcian yellow-toluidine blue (Leung) method (A-Y) and Genta staining, for the demonstration of the organism in gastric biopsies taken from antrum, body and fundus of 118 patients who presented to our hospital with upper gastrointestinal symptoms. We found no significant differences in the efficacy of H & E, IHC, HpSS and A-Y in the demonstration of H. pylori in all 3 gastric sites. The least reproducible stain in our hands was the Genta stain. We conclude that H & E is adequate for the initial assessment of gastric biopsies in symptomatic upper gastrointestinal patients. This is because it is a well-tested, cheap and easy staining method, requiring a relatively short period of time to perform, with highly reproducible results. It has an added advantage of enabling simultaneous assessment of morphological changes accompanying H. pylori infection. When the density of the organism is expected to be low, we recommend addition of HpSS staining because of its high sensitivity and low cost. The disadvantages of the other staining methods (IHC, A-Y and Genta) are discussed.

Duodenal ulcer relapse is not always associated with recurrence of H. pylori infection: a prospective three-year follow-up study

BACKGROUND

Long-term data concerning the reappearance of Helicobacter pylori infection and duodenal ulcer (DU) recurrence after successful eradication are still few and conflicting. Inadequate histological assessment or use of indirect tests for the determination of H. pylori and bias in the selection of patients to be controlled can influence reported results. The aim of this study was to determine the rate of recurrence of H. pylori infection and ulcer relapse in a population of cured DU patients followed up for 3 years irrespective of their symptomatology.

METHODS

Between 1992 and 1994, 126 patients with DU disease were treated with double or triple therapy. Patients using nonsteroidal antiinflammatory drugs or aspirin or receiving maintenance antisecretory therapy were excluded. H. pylori infection was assessed by three bioptic tests from both the antrum and the body (culture, urease, histopathological examination). After 2 months from cessation of treatment, DU had healed and H. pylori infection was cured in 102 of 126 patients (81%). These patients were endoscopically followed up after 1 and 3 years, respectively, and were advised to contact us at symptom recurrence. At 1 and 3 years, we studied 95 (93.2%) and 79 (77.4%) patients, respectively, of the 102 who were cured. The other patients were untraceable or refused endoscopy because they were asymptomatic.

RESULTS

After 1 year, no patient had H. pylori recurrence, whereas three patients had a relapse of DU without evidence of infection. After 3 years, recurrence of H. pylori occurred in six patients (annual rate, 2.5%), DU relapsed in five H. pylori-positive patients (6.3%) and in two H. pylori-negative patients (annual rate, 1.9%). Fasting gastrin and acid secretion values studied in all relapsed patients were within the normal range except for one H. pylori-positive patient.

CONCLUSIONS

Recurrence of H. pylori infection is very low where treatment is effective, but a DU relapse, not related to acid hypersecretion, can occur in a small percentage of cured patients.

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

Since the means of culturing Helicobacter pylori may not be available in some laboratories, prolonging the survival of this organism during transportation is a major concern in terms of improving detection rates. A selective transport medium was evaluated for the preservation of H. pylori from 254 gastric biopsy specimens collected from a rural area in China where culturing is not feasible. Gastric biopsy specimens were inoculated in sterile broth consisting of brain heart infusion (BHI) broth, horse serum, and yeast extract supplemented with vancomycin, amphotericin B, and nalidixic acid (VAN). Of the 254 biopsy specimens, 238 were identified by histology to have H. pylori infection. Total rates of recovery of H. pylori from the H. pylori-positive gastric biopsy specimens stored in the BHI-VAN broth ranged from 76 to 46% after storage of specimens for 5 to 9 days. In conclusion, the selective medium is useful for prolonging the survival of H. pylori in gastric biopsy specimens for which immediate culture is not feasible.