Helicobacter pylori: bacteriology and laboratory diagnosis

Global prevalence of Helicobacter pylori infection between 1980 and 2022: a systematic review and meta-analysis

BACKGROUND

Few studies have examined the temporal trends of Helicobacter pylori prevalence worldwide. We aimed to identify the changes in global prevalence of H pylori infection between 1980 and 2022.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Embase, MEDLINE, Scopus, and Web of Science, with no language restrictions, for observational studies on the prevalence of H pylori infection published between Jan 1, 1980, and Dec 31, 2022. Conference papers, meta-analyses, reviews, and case reports were excluded. We divided the study timeframe into four periods: 1980-90, 1991-2000, 2001-10, and 2011-22. Summary data were extracted from each selected publication. The prevalence of H pylori and its temporal trend were analysed according to WHO region, World Bank income level, WHO universal health coverage service coverage index of the country or region, sex and age of the patient, study type, and diagnostic method. The pooled prevalence was estimated by a random-effect meta-analysis, and the significance of the associated factors was analysed by multivariable meta-regression. This study is registered with the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY), 2022100026.

FINDINGS

Of the 56 967 records identified, 5236 were included in the quality assessment stage and 224 studies-from 71 countries or regions from all six WHO regions and including 2 979 179 individuals-were included in the final analysis. Significant heterogeneity was found between studies (I²=99·9%). The estimated global prevalence of H pylori infection decreased from 58·2% (95% CI 50·7-65·8) in the 1980-90 period to 43·1% (40·3-45·9) in the 2011-22 period. Prevalence was relatively static between 1991 and 2010 but declined sharply between 2011 and 2022, with the largest decline in the WHO African region. Overall, a lower prevalence of H pylori infection was reported in younger people, high-income countries, or countries with high levels of universal health coverage, and by retrospective studies. Studies based on serological diagnostic methods generally reported higher H pylori prevalence than studies based on non-serological methods (53·2% [49·8-56·6] vs 41·1% [38·1-44·2]) and fluctuated less over time.

INTERPRETATION

This meta-analysis shows a declining trend of H pylori prevalence globally, particularly in the 2011-22 period. These results could help to inform future health policy on prevention and management of this important infection. However, a considerable degree of heterogeneity exists between studies and further population-based epidemiological studies are needed.

FUNDING

None.

Helicobacter pylori Dormant States Are Affected by Vitamin C

Helicobacter pylori colonizes human gastric mucosa, overcoming stressful conditions and entering in a dormant state. This study evaluated: (i) H. pylori's physiological changes from active to viable-but-non-culturable (VBNC) and persister (AP) states, establishing times/conditions; (ii) the ability of vitamin C to interfere with dormancy generation/resuscitation. A dormant state was induced in clinical MDR H. pylori 10A/13 by: nutrient starvation (for VBNC generation), incubating in an unenriched medium (Brucella broth) or saline solution (SS), and (for AP generation) treatment with 10xMIC amoxicillin (AMX). The samples were monitored after 24, 48, and 72 h, 8-14 days by OD₆₀₀, CFUs/mL, Live/Dead staining, and an MTT viability test. Afterwards, vitamin C was added to the H. pylori suspension before/after the generation of dormant states, and monitoring took place at 24, 48, and 72 h. The VBNC state was generated after 8 days in SS, and the AP state in AMX for 48 h. Vitamin C reduced its entry into a VBNC state. In AP cells, Vitamin C delayed entry, decreasing viable coccal cells and increasing bacillary/U-shaped bacteria. Vitamin C increased resuscitation (60%) in the VBNC state and reduced the aggregates of the AP state. Vitamin C reduced the incidence of dormant states, promoting the resuscitation rate. Pretreatment with Vitamin C could favor the selection of microbial vegetative forms that are more susceptible to H. pylori therapeutical schemes.

Clinical and laboratory importance of detecting Helicobacter pylori coccoid forms for the selection of treatment

Helicobacter pylori grows and multiplies in the gastrointestinal tract (GIT) in about half of the world’s population. The prevalence of diseases associated with this bacterium is steadily increasing, which makes it necessary to search for optimal therapy aimed at eradication of this bacterium. Such diseases, for example, include gastric ulcer (GU) and chronic gastritis (CG). Unfortunately, modern possibilities for eradication therapy do not always make it possible to cure patients, and relapses often occur if it is cured. Nowadays, a particular topical issue has arisen, which concerns the resistance of Helicobacter pylori to therapies, because the effectiveness of medication used in clinics decreases every year. One of the mechanisms favouring tolerance to antibiotics is the transformation into a different morphological form – coccoid. This form of the bacterium was discovered quite a long time ago. Nevertheless, the question of its importance in clinical practice remains open to this day. Modern studies are aimed at understanding the role of coccoid forms of H. pylori in the survival of the population of these bacteria and at clarifying their role in the pathogenesis of gastrointestinal diseases. It is not known whether it is necessary to evaluate the contamination of a given morphological form of a bacterium of the gastric mucosa in clinical practice and its influence on the development of diseases etc. This article presents an overview and analysis of modern ideas about H. pylori coccoid forms and answers to the main questions posed in the last 10 years regarding the study of coccoid forms. Additionally, our results present a comparison of expression of virulence factors in coccoid and spiral forms of H. pylori.

[Evolution of the sensitivity of 235 strains of Helicobacter pylori from 1995 to 1998 and impact of antibiotic treatment]

BACKGROUND

The aim of this study was to investigate the sensitivity of Helicobacter pylori to the antibiotics used in its eradication over a period of four years and to determine the influence of previous treatment on sensitivity.

MATERIAL AND METHODS

During the period from 1995 to 1998 we determined the sensitivity of 235 consecutive Helicobacter pylori isolates to amoxicillin, metronidazole, clarythromycin and tetracycline by means of E-test methodology. The MIC values found were related with the prior use of eradicating treatment.

RESULTS

The percentage of resistant strains were as follows: 23.5% to metronidazole, 12.9% to clarythromycin and 0.7% to tetracycline; none of the strains was resistant to amoxicillin. There were no significant changes in percentage of resistance to the drugs studied over the 4-year period. Resistance to metronidazole and clarythromycin was significantly higher (p 5 0.03 and p < 0.001 respectively) in strains isolated from patients who had received previous treatment.

CONCLUSIONS

Monitorization of H. pylori sensitivity to the drugs used in its eradication is particularly important in patients who have undergone prior treatment.

Helicobacter pylori and endoscopy

Helicobacter pylori is possibly the most common bacterial infection of humans and is now recognized as the most important acquired cause of peptic ulceration. Epidemiological evidence also recently implicated this bacterium in the pathogenesis of gastric cancer. The mechanism of spread of the organism, by either the faecal-oral or oral-oral route, raises the possibility of transmission of this organism from infected patients to hospital staff particularly those involved in endoscopy. The evidence for an increased risk to endoscopists is contradictory, varying from none to a five-fold increase. This review summarizes the evidence for mode of transmission and risk to hospital staff from this important bacterium.