Correlation between clarithromycin resistance, virulence factors and clinical characteristics of the disease in Helicobacter pylori infected patients in Shahrekord, Southwest Iran

Extent of Virulence and Antibiotic Resistance Genes in Helicobacter pylori and Campylobacteria

Helicobacter pylori, a member of the clade campylobacteria, is the leading cause of chronic gastritis and gastric cancer. Virulence and antibiotic resistance of H. pylori are of great concern to public health. However, the relationship between virulence and antibiotic resistance genes in H. pylori in relation to other campylobacteria remains unclear. Using the virulence and comprehensive antibiotic resistance databases, we explored all available 354 complete genomes of H. pylori and compared it with 90 species of campylobacteria for virulence and antibiotic resistance genes/proteins. On average, H. pylori had 129 virulence genes, highest among Helicobacter spp. and 71 antibiotic resistance genes, one of the lowest among campylobacteria. Just 2.6% of virulence genes were shared by all campylobacterial members, whereas 9.4% were unique to H. pylori. The cytotoxin-associated genes (cags) seemed to be exclusive to H. pylori. Majority of the isolates from Asia and South America were cag2-negative and many antibiotic resistance genes showed isolate-specific patterns of occurrence. Just 15 (8.8%) antibiotic resistance genes, but 103 (66%) virulence genes including 25 cags were proteomically identified in H. pylori. Arcobacterial members showed large variation in the number of antibiotic resistance genes and there was a positive relation with the genome size. Large repository of antibiotic resistance genes in campylobacteria and a unique set of virulence genes might have important implications in shaping the course of virulence and antibiotic resistance in H. pylori.

Isolation, antimicrobial resistance and virulence characterization of Salmonella spp. from fresh foods in retail markets in Hangzhou, China

Salmonella can cause severe foodborne diseases. This study investigated the prevalence of Salmonella spp. in fresh foods in Hangzhou market and their harborage of antibiotic resistance and virulence genes, antibiotic susceptibility, and pathogenicity. A total of 500 samples (pork, n = 140; chicken, n = 128; vegetable, n = 232) were collected over a one-year period. Salmonella was found in 4.2% (21) of samples with the detection rate in pork, chicken and vegetables as 4.3% (6), 6.3% (8), and 3% (7), respectively. One Salmonella strain was recovered from each positive sample. The isolates were identified as six serotypes, of which S. Enteritidis (n = 7) and S. Typhimurium (n = 6) were the most predominant serotypes. The majority of isolates showed resistance to tetracycline (85.7%) and/or ciprofloxacin (71.4%). Tetracycline resistance genes showed the highest prevalence (90.5%). The occurrence of resistance genes for β-lactams (blaTEM-1, 66.7%; and blaSHV, 9.5%) and aminoglycosides (aadA1, 47.6%; Aac(3)-Ia, 19%) was higher than sulfonamides (sul1, 42.9%) and quinolones (parC, 38.1%). The virulence gene fimA was detected in 57.1% of isolates. Gene co-occurrence analysis implied that resistance genes were associated with virulence genes. Furthermore, selected S. Typhimurium isolates (n = 4) carrying different resistance and virulence genes up-regulated the secretions of cytokines IL-6 and IL-8 by Caco-2 cells in different degrees, suggesting that virulence genes may play a role in inflammatory transcription. In in vivo virulence test, microbiological counts in mouse feces and tissues showed that all included S. Typhimurium were able to infect mice, with one strain showing significantly higher virulence than others. In conclusion, this study indicates Salmonella contamination in fresh foods in Hangzhou market poses a risk to public health and it should be closely monitored to prevent and control foodborne diseases.

The prevalence of clarithromycin-resistant Helicobacter pylori isolates: a systematic review and meta-analysis

Background

Knowledge of global clarithromycin (CLA)-resistant rates of Helicobacter pylori (H. pylori) is crucial for decision of the most appropriate eradication therapies with good clinical outcomes. Therefore, this review and meta-analysis aimed to evaluate the global prevalence of the CLA resistance in H. pylori to provide some guidance for selecting the first-line antibiotics.

Method

A comprehensive search was performed for relevant literature until April 2021 in PubMed, Embase, and Web of Science databases. Freeman-Tukey double arcsine transformation was performed to estimate the weighted pooled prevalence of resistance.

Results

The meta-analysis included 248 articles. The prevalence of CLA-resistant H. pylori was 27.53% (95% CI [25.41-29.69]). The heterogeneity between reports was significant (I² = 97.80%, P < 0.01). The resistance rate increased from 24.28% in 2010-2017 to 32.14% in 2018-2021 (P < 0.01). Iran, with 38 articles, has the most report. Nevertheless, Switzerland, Portugal, and Israel had the highest resistance rates (67.16%, 48.11%, and 46.12%, respectively). The heterogeneity between the continents and the antimicrobial susceptibility methods also interpreted standard guidelines and breakpoints was insignificant (P > 0.05).

Conclusion

Overall CLA resistance rate was 27.53%, worldwide. The difference in CLA resistance rate among the included studies can be due to several reasons such as differences in antibiotic prescription rates in various geographic areas, use of different breakpoints or inaccurate criteria in performed studies, and the emergence of multidrug-resistant (MDR) strains.

Detection of A2143G, A2142C, and A2142G Point Mutations with Real-Time PCR in Stool Specimens from Children Infected with Helicobacter pylori

Reports have indicated an increasing prevalence of clarithromycin resistance in children relative to adults. Thus, it is important to investigate primary clarithromycin resistance before therapy to avoid treatment failure. A2142G, A2143G, and A2142C point mutations in the peptidyltransferase region of the 23S ribosomal RNA (rRNA) of Helicobacter pylori (H. pylori) strains isolated from children with gastrointestinal symptoms and asymptomatic children were evaluated via real-time polymerase chain reaction (RT-PCR) using fecal DNA samples. The presence of H. pylori was determined using a fecal H. pylori antigen enzyme-linked immunosorbent assay (ELISA) kit from the stools of children (n = 543). A2143G, A2142C, and A2142G point mutations were detected via RT-PCR and confirmed by sequencing the 23S rDNA. Fecal H. pylori antigen testing was positive in 101 symptomatic (49) and asymptomatic (52) children. A significant difference was found between the 0–5- and 5–18-year-old groups in terms of the A2143G and A2142G point mutations (p = 0.001). The A2142C mutation was not detected. There was a significant difference in the A2143G mutation between the symptomatic and asymptomatic 5–18-year-old children (p = 0.019). Macrolides are frequently used to treat upper respiratory tract infections in children due to their selective pressure effect. We suggest that H. pylori strains carrying mutations in the 23S RNA subunit conferring clarithromycin resistance may lead to an intense inflammatory response in the gastric epithelial cells, allowing them to proliferate more rapidly and causing possible diarrhea, halitosis, or abdominal pain in children.