F. Giorgio

Phenotypic and genotypic Helicobacter pylori clarithromycin resistance and therapeutic outcome: benefits and limits

INTRODUCTION Primary clarithromycin resistance is increasing worldwide, and it has been regarded as the main factor reducing the efficacy of Helicobacter pylori therapy. However, the clinical consequence of either phenotypic or genotypic resistance still remains unclear. This study aimed to evaluate: (i) the concordance between phenotypic (culture) and genotypic (real-time PCR) tests in assessing primary clarithromycin resistance; and (ii) the role of both in therapeutic outcome. METHODS A post hoc subgroup study was selected from a double-blind, placebo-controlled trial, enrolling 146 patients with dyspepsia or peptic ulcers never previously treated. Real-time PCR and Etest on bacterial culture for assessing clarithromycin resistance were performed. [(13)C]urea breath test (UBT), histology and rapid urease tests at entry and UBT after 4-8 weeks were used to assess infection and eradication. All patients received a 10 day therapy. RESULTS Prevalence of clarithromycin phenotypic resistance was significantly lower as compared with genotypic resistance (18.4% versus 37.6%, P < 0.001). A concordance between the two methods was present in 71.2% of cases. A significant difference in the eradication rate was seen between clarithromycin-susceptible and -resistant strains, when assessed with either Etest (92.4% versus 55.5%, P < 0.001) or a PCR-based method (94.5% versus 70.9%; P < 0.001). Of note, the eradication rate showed the lowest value (30.7%) when phenotypic bacterial resistance was genetically linked to the A2143G point mutation. CONCLUSIONS This study showed that: (i) there is a relevant discordance between the two methods; and (ii) phenotypic clarithromycin resistance markedly reduces H. pylori eradication when it is linked to a specific point mutation.

Musosal tumour necrosis factor α in diverticular disease of the colon is overexpressed with disease severity.

Aim  Inflammation occurs in diverticular disease (DD), but there is little information on inflammatory cytokines such as tumour necrosis factor α (TNF‐α). The aim of this study was to assess TNF‐α expression in DD and to see whether it is related to the severity of the disease.

Mucosal expression of basic fibroblastic growth factor, Syndecan 1 and tumor necrosis factor-alpha in diverticular disease of the colon: a case-control study.

Background  Inflammation may be detected in diverticular disease (DD), and fibrosis may also develop. We assessed the mucosal expression of bFGF, SD1, and TNF‐α in DD according to the severity of the disease. Moreover, we assessed the response to therapy of these cytokines in acute uncomplicated diverticulitis (AUD).

Helicobacter pylori clarithromycin resistance detected by Etest and TaqMan real‐time polymerase chain reaction: a comparative study

The aim of the work was to compare H. pylori clarithromycin‐resistance according two methods. Etest was performed on H. pylori isolated from gastric biopsy samples. TaqMan Real‐Time‐PCR (RT‐PCR) was performed on paraffin‐embedded gastric biopsy samples of the same patients. Forty‐seven out of 88 strains were resistant to clarithromycin by Etest, whereas RT‐PCR detected this resistance on paraffin‐embedded specimens of 50 patients. RT‐PCR performed on paraffin‐embedded biopsy specimens of 47 patients infected with H. pylori resistant to clarithromycin as detected by Etest, revealed the presence of a resistant strain only in 40 samples. RT‐PCR performed on samples of 41 patients harbouring clarithromycin‐susceptible H. pylori strains showed the presence of 31 susceptible and 10 resistant strains. RT‐PCR detected 18 cases with heteroresistant status. The difference between the two tests in detecting clarithromycin‐resistance was not statistically significant even if RT‐PCR detected more resistant cases. The genotyping resistance on paraffin‐embedded gastric biopsy specimens may be used to establish resistance to clarithromycin before the treatment when culture and susceptibility testing are not available. In case of failure of an empirical clarithromycin‐based triple antimicrobial treatment, RT‐PCR performed on paraffin‐embedded biopsy sample will establish the primary resistance to clarithromycin. In addition, this test can be useful for epidemiological investigation as well as for monitoring the evolution of clarithromycin resistance along the time.

Helicobacter pylori antibiotic resistance and [13C]urea breath test values.

A correlation between delta over baseline (DOB) values of the [(13)C]urea breath test (UBT) and Helicobacter pylori clarithromycin resistance has been reported, suggesting a possible predictive role of UBT in therapeutic outcome. However, available data are limited and conflicting. This study aimed to clarify this issue, assessing the possible relationship between H. pylori resistance towards different antibiotics (clarithromycin, metronidazole and levofloxacin) and UBT values. The data showed similar DOB values between susceptible and resistant strains for clarithromycin (46.9+/-32.3 vs 45.7+/-30.6; P=0.8), metronidazole (46.4+/-29.6 vs 47.4+/-37.9; P=0.8), and levofloxacin (45.0+/-30.2 vs 54.2+/-38.4; P=0.08). Likewise, comparable DOB values were observed between susceptible and multidrug-resistant strains (45.4+/-29.6 vs 54.8+/-44.8; P=0.1). In conclusion, our data failed to find a significant correlation between UBT values and H. pylori antibiotic resistance.

The A2143G point mutation of clarithromycin resistance affects Helicobacter pylori eradication

To the Editor: Primary clarithromycin resistance is regarded as the main factor reducing the efficacy of Helicobacter pylori eradication therapy. Three point mutations (A2143G, A2142G, and A2142C) are responsible of >90% clarithromycin resistance cases in Western countries and some microbiologic observations have found that they are linked with different minimal inhibiting concentration values in vitro. Indeed, high minimal inhibiting concentration values have been associated with either the A2143G or with the A2142G. However, such a relevant basic issue has been scantly investigated in order that the clinical impact of these studies is largely unknown. On these bases, we performed a retrospective comparison of the prevalence of these point mutations between cured H. pylori and eradication failure patients. Paraffin-embedded antral biopsies of consecutive patients who had received standard triple therapies were retrieved. The A2142C, A2142G, and A2143G point mutations were detected by molecular analysis after DNA extraction by using TaqMan real-time polymerase chain reaction, a method largely described and validated by our group. For statistical analysis, the overall rate and the odds ratio (OR) with their 95% confidence intervals were calculated for each observation. Differences between groups were statistically compared by using the Student t test for unpaired data, and the Fisher exact probability test. Differences were considered significant at 5% probability level. The study enrolled 68 consecutive patients, including 46 eradicated and 22 eradication failing patients. The real time-polymerase chain reaction detected a mutate resistant strain in 31 (45.5%) cases. In detail, the A2143G point mutation was present in 22 (70.9%) patients, the A2142G in 6 (19.3%), and the A2142C in 3 (9.8%). According to therapy outcome, a clarithromycin resistant genotype was observed more frequently in eradication failure than cured patients (72.7% vs. 32.6%; P=0.0017; OR=5.5, 95% CI=1.7-16.9). However, only the prevalence of the A2143G point mutation was significantly higher in those patients who failed eradication as compared with cured patients (54.5% vs. 21.7%; P=0.0066; OR=4.3, 95% CI=1.4 12.8), whereas the other 2 point mutations were similarly distributed (A2142G+A2142C: 18.1% vs. 10.8%, respectively; P=0.2; OR= 1.8, 95% CI=0.4-7.5). In conclusion, we found a high prevalence of A2143G point mutation in the patients who failed standard triple therapy, suggesting its potential role in predicting therapy success. Indeed, the prevalence of such a point mutation remained constantly high in the last 15 years in our geographic area. Of note, the present study found that A2143G mutate genotype prevalence was significantly higher in those patients who failed therapy as compared with cured patients, being present in 2 each 3 of patients eradication failure patients. On the contrary, the frequency of other point mutations— A2142G and A2142C—was low and a similar prevalence between patients with different therapy outcome was observed; therefore, their presence seems to play a marginal role in the clinical practice.

Expression of basic fibroblastic growth factor, syndecan 1 and tumour necrosis factor α in resected acute colonic diverticulitis

Inflammation and fibrosis are present in both colonic diverticulitis and Crohns disease (CD). The molecular pattern of basic fibroblastic growth factor (bFGF) and syndecan 1 (SD1) expression is altered in stenosing CD, but their expression in resected complicated colonic diverticulitis (ACD) is unknown.

OC.03.6 INFLIXIMAB THERAPY DOWNREGULATION OF BASIC FIBROBLAST GROWTH FACTOR/SYNDECAN 1 LINK: A POSSIBLE MOLECULAR PATHWAY OF MUCOSAL HEALING IN ULCERATIVE COLITIS

Background It is known that syndecan 1 in inflammatory bowel diseases is able to migrate from epithelial basolateral site to the stromal area and apical surface of epithelium with a consequent activation and modulation of basic fibroblast growth factor (bFGF), and this process sustains mucosal healing of ulcers. On the other hand, tumour necrosis factor (TNF) a mucosal levels are directly related to the entity of the damage in these disorders. Aim of the study A ‘post-hoc’ retrospective study was performed to estimate mucosal TNF a in rectal biopsies of subjects with ulcerative colitis (UC) before and after effective infliximab therapy and its relationship with syndecan 1, bFGF and endoscopic mucosal healing. Material and methods Paraffin-embedded rectal samples from 12 patients with UC responders to infliximab were analysed for TNF a, syndecan 1 and bFGF before and 6 months after therapy using a real-time reverse transcriptase polymersase chain reaction. Additionally, syndecan 1 location was evaluated by immunohistochemistry. Samples from 12 subjects with irritable bowel symptoms without endoscopic/ histological abnormalities represented the control group. Mucosal healing induced by the treatment was defined by an endoscopic Mayo subscore changing from 2e 3t o 0. ANOVA plus StudenteNewmaneKeuls was used for statistical analysis. Results The authors found that in the active disease, an increase in TNF a (p<0.001) is accompanied by raised levels of either syndecan 1 (p<0.005) and bFGF (p<0.005) compared with the control group 1

P.27 H. PYLORI ANTIBIOTIC RESISTANCE AND 13C UREA BREATH TEST VALUES

ture was available for the 92% of the infected patients. Resistance to: M was found in 61% of the strains, C in 47.1% of the strains, and L in 18.3% of the strains. Double resistance to: C+M was found in 36.5% of the strains; C+L in 11.3% of the strains; and M+L in 14.7%. 10.2% of the strains were resistant to M+C+L. Considering resistance to a single antibiotic, resistance to M was more frequent in women (p<0.001); considering the double resistance, women were also more likely to have resistance to both antibiotics in CM group (p<0.001), CL group (p=0.0005), and ML group (p=0.01); women were finally more probable to harbour strains also resistant to all 3 antibiotics tested (p=0.004). Conclusions: 1. The prevalence of strains resistant to Clarithromycin and Metronidazole is now very high accounting for the poor results with conventional triple therapy. 2. Levofloxacin resistance has reached 18% making it unlikely that this frequently used salvage regimen will be effective in the future. New treatment regimens and new anti-microbial agents are urgently needed. # B. Gastric diseases 3. H. pylori basic/diagnosis/therapy