Pretreatment antimicrobial susceptibilities of paired gastric Helicobacter pylori isolates: antrum versus corpus

Prevalence of antibiotic heteroresistance associated with Helicobacter pylori infection: A systematic review and meta-analysis

BACKGROUND

Heteroresistance is a general term to describe diverse responses to specific antibiotics that can occur due to infection with either multiple bacterial strains or microevolution of a single strain during chronic infection. Due to limited information regarding heteroresistance Helicobacter pylori (H. pylori) infection, the current study was carried out to evaluate the prevalence of this phenomenon.

METHODS

For this study, all potential relevant studies were collected by searching international databases such as ISI Web of Science, PubMed, Scopus, ScienceDirect, ProQuest, Embase, DOAJ, China National Knowledge Infrastructure (CNKI), and Google Scholar. Finally, the frequency of heteroresistance H. pylori infection was measured using the event rate corresponding to 95% confidence intervals.

RESULTS

A total of 26 studies met our criteria; the eligible studies were related to the years 2001-2022. Our results showed that the prevalence of heteroresistance H. pylori strains was 60.1% to clarithromycin, 61.1% to metronidazole, 46.1% to levofloxacin, 3.8% to amoxicillin, and 21.1% to tetracycline. Our literature review also showed discrepancy of antimicrobial susceptibility test in strains isolated from different anatomical sites of the stomach. Heteroresistance H. pylori infection in developing countries is mostly due to infection with multiple H. pylori strains, while in developed countries it is due to microevolution of a single H. pylori strain in response to antibiotic pressure.

CONCLUSIONS

Heteroresistance H. pylori infection interferes with successful therapy and eventually can lead to the treatment failure. If a biopsy is taken from only one gastric site, resistant strains of H. pylori may be underestimated. Considering the role of heteroresistance H. pylori infection in treatment failure, it is very important for gastroenterologists to improve their knowledge about this fact. Regardingly, new guidelines should be developed and designed for the management and treatment of heteroresistance H. pylori infection.

Antibiotic susceptibility, heteroresistance, and updated treatment strategies in Helicobacter pylori infection

In this review, we discuss the problem of antibiotic resistance, heteroresistance, the utility of cultures and antibiotic susceptibility tests in Helicobacter pylori (Hp) eradication, as well as the updated treatment strategies for this infection. The prevalence of antibiotic resistance is increasing all over the world, especially for metronidazole and clarithromycin, because of their heavy use in some geographical areas. Heteroresistance (simultaneous presence of both susceptible and resistant strains in different sites of a single stomach) is another important issue, as an isolate could be mistakenly considered susceptible if a single biopsy is used for antimicrobial tests. We also examined literature data regarding eradication success rates of culture-guided and empiric therapies. The empiric therapy and the one based on susceptibility testing, in Hp eradication, may depend on several factors such as concomitant diseases, the number of previous antibiotic treatments, differences in bacterial virulence in individuals with positive or negative cultures, together with local antibiotic resistance patterns in real-world settings. Updated treatment strategies in Hp infection presented in the guidelines of the Toronto Consensus Group (2016) are reported. These suggest to prolong eradication therapy up to 14 days, replacing the old triple therapy with a quadruple therapy based on proton pump inhibitor (PPI), bismuth, metronidazole, and tetracycline for most of the patients, or as an alternative quadruple therapy without bismuth, based on the use of PPI, amoxicillin, metronidazole, and clarithromycin. The new drug vonoprazan, a first-in-class potassium-competitive acid blocker recently approved in Japan, is also considered to be a promising solution for Hp eradication, even for clarithromycin-resistant strains. Furthermore, there is growing interest in finding new therapeutic strategies, such as the development of vaccines or the use of natural resources, including probiotics, plants, or nutraceuticals.

Resistance to antibiotics and characterization of Helicobacter pylori strains isolated from antrum and body from adults in Mexico

BACKGROUND AND AIMS

Resistance to antibiotics is common in patients with Helicobacter pylori infection in more than one anatomic stomach site. We assessed whether the antibiotic resistance varies according to virulence factors of the bacteria as well as to the age and gender of individuals infected in two anatomic sites.

METHODS

H. pylori strains were isolated from an antral and corpus biopsy from 90 patients with gastric ambulatory who had not received any previous therapy. Susceptibility to metronidazole and clarithromycin was assessed by E-test, and vacA and cagA genotypes were determined by polymerase chain reaction.

RESULTS

Dual resistance to metronidazole and clarithromycin was 3.3% in antrum and 4.4% in the corpus; heteroresistance was 19% and 5.5% for metronidazole and clarithromycin, respectively. Clarithromycin resistance significantly increased with age. Women showed a twofold increased risk for metronidazole-resistant strains in antrum (odds ratio = 2.85, 95% confidence interval 1.09 to 7.42). Virulence factors were not associated with antimicrobial resistance.

CONCLUSION

Prevalence of resistance to clarithromycin may be increasing in this country. Antimicrobial susceptibility tests from different biopsy sites deserve attention.

Susceptibilities to clarithromycin, amoxycillin and metronidazole of Helicobacter pylori isolates from the antrum and corpus in Tokyo, Japan, 1995-2001

The aim of this study was to determine the susceptibilities to clarithromycin, amoxycillin and metronidazole of Helicobacter pylori isolates from the antrum and corpus of Japanese patients examined during the period 1995-2001. There was an increase, from 6.2% in 1995 to 22.1% in 2000-2001, in the proportion of patients infected with clarithromycin-resistant H. pylori. Of patients infected with clarithromycin-resistant H. pylori, 39.1% were infected with both clarithromycin-susceptible and -resistant H. pylori. Furthermore, the MIC90 of clarithromycin for H. pylori rose from < 1 mg/L in 1995-1998 to 8 mg/L in 1999. In contrast, the MIC90s of amoxycillin and metronidazole were < or = 0.125 and 4 mg/L, respectively, throughout the study period. The results showed that, while most H. pylori isolates were susceptible to amoxycillin and metronidazole, resistance to clarithromycin among H. pylori isolates increased markedly in Japan during 1995-2001. The results also indicated a need to test the susceptibility of H. pylori isolates from more than two samples obtained from two different sites in the stomach of a single patient in order to diagnose the presence of clarithromycin-resistant H. pylori correctly.

Laboratory diagnosis and susceptibility profile of Helicobacter pylori infection in the Philippines

Background

Helicobacter pylori diagnosis and susceptibility profile directs the applicability of recommended treatment regimens in our setting. To our knowledge, there is no published data on the culture and local susceptibility pattern of Helicobacter pylori in the Philippines.

Methods

52 dyspeptic adult patients undergoing endoscopy from the Outpatient Gastroenterology clinic of the University of the Philippines-Philippine General Hospital underwent multiple gastric biopsy and specimens were submitted for gram stain, culture, antimicrobial sensitivity testing, rapid urease test and histology. Antimicrobial susceptibility testing was done by Epsilometer testing (Etest) method against metronidazole, clarithromycin, amoxicillin, and tetracycline.

Results

Sixty percent (60%) of the study population was positive for H. pylori infection (mean age of 44 years ± 13), 70% were males. H. pylori culture showed a sensitivity of 45% (95% CI [29.5–62.1]), specificity of 98% (95%CI [81.5–100%]), positive likelihood ratio of 19.93 (95% CI [1.254–317.04]) and a negative likelihood ratio of 0.56 (95% CI [0.406–0.772]). All H. pylori strains isolated were sensitive to metronidazole, clarithromycin, amoxicillin and tetracycline.

Conclusion

Knowledge of the antibiotic susceptibility patterns in our setting allows us to be more cautious in the choice of first-line agents. Information on antibiotic susceptibility profile plays an important role in empiric antibiotic treatment and management of refractive cases.

Mixed-infection of antibiotic susceptible and resistant Helicobacter pylori isolates in a single patient and underestimation of antimicrobial susceptibility testing

Antibiotic resistance among Helicobacter pylori has been increasing worldwide and has begun to affect the overall efficacy of current antibiotic regimens adversely. We examined 220 pairs of H. pylori isolates obtained from both the antrum and corpus of separate patients; 109 (50%) harbored antibiotic-resistant H. pylori: amoxicillin (0.5%), clarithromycin (5.9%), furazolidone (1.4%), metronidazole (45.5%), nitrofurantoin (1.4%), and tetracycline (6.8%). Heteroresistance among the two biopsy sites from each patient was present in 41 of the 109 patients (38%) with antibiotic resistant H. pylori (e.g. 34% with resistant strains would be misclassified as susceptible if a biopsy of the antrum alone used for antimicrobial susceptibility testing). DNA fingerprinting genotype analysis was carried out on the 41 pairs of isolates with heteroresistance. While different patients had different fingerprinting patterns, each pair of isolates showed identical or similar fingerprinting patterns. These results suggest that antibiotic-resistant H. pylori typically develop from pre-existing susceptible strain rather than coinfection with a different strain. The minor differences in genotype (degeneration of genotype) seen reflect one of the processes for development of genetic diversity in H. pylori. No biopsy single site can be considered representative for antimicrobial susceptibility testing.

Fluorescence in situ hybridization vs. epsilometer test for detection of clarithromycin-susceptible and clarithromycin-resistant Helicobacter pylori strains in gastric biopsies from children

AIM

To compare the results of culture and epsilometer test with fluorescence in situ hybridization for the detection of Helicobacter pylori and the presence of clarithromycin-susceptible and clarithromycin-resistant strains in antral biopsies from children.

METHODS

Antral biopsies from 149 unselected children were investigated prospectively; 15 had previously received anti-H. pylori therapy. H. pylori status was defined by histology, rapid urease test and 13C-urea breath test. Fluorescence in situ hybridization was applied on fresh tissue with probes specific for the clarithromycin-susceptible wild type and three clarithromycin-resistant mutants. Susceptibility to clarithromycin was tested by epsilometer test in two laboratories.

RESULTS

Culture and fluorescence in situ hybridization gave negative results in all 66 H. pylori-negative children (specificity, 100%). Of 83 infected children, cultures were successful in 75 (90%), epsilometer test in 71 (86%) and fluorescence in situ hybridization in 77 (93%). Eleven children (13%) showed discrepant results between the applied methods, indicating mixed infection. Clarithromycin-resistant isolates were identified in 16 of 73 previously untreated children.

CONCLUSIONS

Primary resistance to clarithromycin is common (22%) in H. pylori isolates from children living in Germany. Fluorescence in situ hybridization is an excellent, fast method for the detection of H. pylori and clarithromycin-resistant mutants in gastric biopsies. Multiple biopsies identify mixed infections, indicating that clarithromycin-resistant and clarithromycin- susceptible strains are not evenly distributed within the stomach.