Michael S. Osato

Bismuth-Based Quadruple Therapy Using a Single Capsule of Bismuth Biskalcitrate, Metronidazole, and Tetracycline Given With Omeprazole Versus Omeprazole, Amoxicillin, and Clarithromycin for Eradication of Helicobacter pylori in Duodenal Ulcer Patients: A Prospective, Randomized, Multicenter, North American Trial

OBJECTIVES:This multicenter, randomized, active-controlled trial assessed efficacy of bismuth-based quadruple therapy with omeprazole, bismuth biskalcitrate, metronidazole, and tetracycline (OBMT) using a single-triple capsule of BMT compared with triple therapy with omeprazole, amoxicillin, and clarithromycin (OAC) in treatment of patients with Helicobacter pylori infection and duodenal ulcers.METHODS:Patients with active duodenal ulcer or diagnosed within the past 5 yr and with infection documented by 13C-urea breath test plus histology or culture were randomly assigned to 10-day course of OBMT using a single-triple capsule containing bismuth biskalcitrate 140 mg, metronidazole 125 mg, and tetracycline 125 mg given as three capsules q.i.d. with omeprazole 20 mg b.i.d., or a 10-day course of OAC, omeprazole 20 mg plus amoxicillin 1 g plus clarithromycin 500 mg, all b.i.d. Eradication was confirmed by two negative urea breath tests at >1 month and >2 months after therapy.RESULTS:One hundred thirty-eight patients received OBMT and 137 OAC. Modified intent-to-treat eradication rates were 87.7% for OBMT and 83.2% for OAC (95% CI = −3.9%–12.8%; p = 0.29). OBMT eradicated 91.7% metronidazole-sensitive and 80.4% metronidazole-resistant strains (p = 0.06). OAC eradicated 92.1% clarithromycin sensitive and 21.4% clarithromycin-resistant strains (p < 0.001). Adverse events occurred in 58.5% of OBMT patients and 59.0% of OAC patients.CONCLUSIONS:OBMT regimen using the single-triple capsule is as efficacious and well-tolerated as the widely used OAC regimen for H. pylori eradication. This OBMT therapy largely overcomes H. pylori metronidazole resistance, present in 40% of patients in this study.

Helicobacter pylori in North and South America before Columbus

We present a molecular epidemiologic study, based on an analysis of vacA, cagA and cag right end junction genotypes from 1042 Helicobacter pylori isolates, suggesting that H. pylori was present in the New World before Columbus. Eight Native Colombian and Alaskan strains possessed novel vacA and/or cagA gene structures and were more closely related to East Asian than to non‐Asian H. pylori. Some Native Alaskan strains appear to have originated in Central Asia and to have arrived after strains found in South America suggesting that H. pylori crossed the Bering Strait from Asia to the New World at different times.

Esomeprazole-based Helicobacter pylori eradication therapy and the effect of antibiotic resistance: results of three US multicenter, double-blind trials

OBJECTIVES:To determine the efficacy of once-daily esomeprazole plus antibiotics for eradication of Helicobacter pylori, to assess the effect of antibiotic resistance on eradication rate, and to define the rate of emergent resistance.METHODS:Three separate randomized trials were performed in H. pylori–positive patients with a duodenal ulcer or history of documented duodenal ulcer within 5 yrs: 1) esomeprazole (40 mg once daily), amoxicillin (1 g b.i.d.), and clarithromycin (500 mg b.i.d.; this combination will be referred to as EAC) versus esomeprazole (40 mg once daily) plus clarithromycin (500 mg twice daily; this combination will be referred to as EC); 2) EAC versus esomeprazole (40 mg once daily; E); and 3) EC versus E. Therapy was given for 10 days. Endoscopy and biopsies for CLOtest, histology, and culture with susceptibility testing were done at baseline and 4 wk after completion of therapy.RESULTS:Per-protocol and intent-to-treat eradication rates, respectively, were as follows. For EAC versus EC in study 1 (N = 448), 84 versus 55% and 77 versus 52% (p < 0.001); for EAC versus E in study 2 (N = 98), 85 versus 5% and 78 versus 4% (p < 0.001); for EC versus E in study 3 (N = 66), 50% versus 0 and 46% versus 0 (p < 0.05). The 15% of patients in the combined studies with baseline clarithromycin resistance had significantly lower rates of eradication than those with susceptible strains (EAC: 45 vs. 89%; EC: 13 vs. 61%). Emergent resistance was less common after treatment with EAC [2/6 (33%)] than with EC (23/27 [85%]).CONCLUSIONS:Ten-day triple therapy with once-daily esomeprazole plus twice-daily amoxicillin and clarithromycin achieves an eradication rate virtually identical to that of the twice-daily proton pump inhibitor–based triple therapies. Baseline clarithromycin resistance, present in 15% of patients, predicts a markedly decreased rate. Use of an amoxicillin-containing regimen may decrease emergence of clarithromycin resistance.

Studies Regarding the Mechanism of False Negative Urea Breath Tests With Proton Pump Inhibitors

OBJECTIVE:The mechanism of false negative urea breath tests (UBTs) results among proton pump inhibitor (PPI) users is unknown. We studied the time course of PPI-associated negative UBT, the relation to Helicobacter pylori density, and whether gastric acidification would prevent false negative UBT results.METHOD:In the UBT experiment, H. pylori–infected volunteers received omeprazole 20 mg b.i.d. for 13.5 days. UBTs with citric acid were done before, after 6.5 days of PPI, and 1, 2, 4, 7, and 14 days after therapy. In the culture and histology experiment, after a wash-out of >5 months, nine of the original subjects were rechallenged with omeprazole for 6.5 days. Antral and corpus biopsies for histology and culture were done before and 1 day after PPI administration.RESULTS:Thirty subjects (mean age 42 yr) were enrolled. UBTs were significantly reduced on day 6.5 (p = 0.031); 10 subjects (33%) developed transient negative UBTs. The UBT recovered in all but one subject by the fourth day post-PPI and in all subjects by day 14. In the culture and histology experiment, upon PPI rechallenge, three of nine subjects (33%) had negative UBTs. H. pylori density, whether measured by culture or histology, decreased with PPI therapy; antral biopsies became histologically negative in five subjects and corpus biopsies in three subjects.CONCLUSION:PPI-induced negative UBT results were related to the anti-H. pylori effect of the PPI. Acidification of the stomach did not prevent false negative UBT results. Three days is likely the minimum delay from stopping PPI until one should perform a test for active infection. A delay of 14 days is preferred.

Natural History of Helicobacter pylori Infection in Childhood: 12-Year Follow-up Cohort Study in a Biracial Community

We assessed the pattern of acquisition and loss of Helicobacter pylori infection in a cohort of 212 children from a biracial community with a homogeneous socioeconomic class. The children were followed over 12 years (1973-1974 to 1985-1986) from childhood to young adulthood. H. pylori status was assessed by the presence of serum IgG antibodies to H. pylori. At ages 7-9, 19% of children had H. pylori infection (40% of blacks vs. 11% of whites; P = .0001); 12 years later, 33% were seropositive. The higher prevalence among blacks remained (P = .0001). During follow-up, 22% of children became infected; the rate of acquisition was fourfold greater among blacks than among whites (P = .001). Over the 12-year period, infection was lost in 50% of whites compared with 4% of blacks who either remained infected or became reinfected. H. pylori infection in childhood is affected by both acquisition and loss of infection in different ethnic groups. This observation is critical for understanding the epidemiology and transmission of H. pylori infection.

Discrimination between Cases of Duodenal Ulcer and Gastritis on the Basis of Putative Virulence Factors of Helicobacter pylori

ABSTRACT The BabA, cagA, and vacA statuses of 827 Helicobacter pylori isolates were used in logistic regression models to discriminate duodenal ulcer from gastritis. Only BabA was a candidate for a universal virulence factor, but the low c statistic value (0.581) indicates that none of these factors were helpful in predicting the clinical presentation.

Analysis of rdxA and Involvement of Additional Genes Encoding NAD(P)H Flavin Oxidoreductase (FrxA) and Ferredoxin-Like Protein (FdxB) in Metronidazole Resistance of Helicobacter pylori

ABSTRACT Metronidazole (Mtz) is a critical ingredient of modern multidrug therapies for Helicobacter pylori infection. Mtz resistance reduces the effectiveness of these combinations. Although null mutations in a rdxA gene that encodes oxygen-insensitive NAD(P)H nitroreductase was reported in Mtz-resistant H. pylori, an intact rdxA gene has also been reported in Mtz-resistant H. pylori, suggesting that additional Mtz resistance mechanisms exist in H. pylori. We explored the nature of Mtz resistance among 544 clinical H. pyloriisolates to clarify the role of rdxA inactivation in Mtz resistance and to identify another gene(s) responsible for Mtz resistance in H. pylori. Mtz resistance was present in 33% (181 of 544) of the clinical isolates. There was marked heterogeneity of resistance, with Mtz MICs ranging from 8 to ≥256 μg/ml.rdxA inactivation resulted in Mtz MICs of up to 32 μg/ml for 6 Mtz-sensitive H. pylori strains and 128 μg/ml for one Mtz-sensitive strain. Single or dual (with rdxA) inactivation of genes that encode ferredoxin-like protein (designatedfdxB) and NAD(P)H flavin oxidoreductase (frxA) also increased the MICs of Mtz for sensitive and resistant strains with low to moderate levels of Mtz resistance. fdxB inactivation resulted in a lower level of resistance than that from rdxAinactivation, whereas frxA inactivation resulted in MICs similar to those seen with rdxA inactivation. Further evidence for involvement of the frxA gene in Mtz resistance included the finding of a naturally inactivated frxA but an intact rdxA in an Mtz-resistant strain, complementation of Mtz sensitivity from an Mtz-sensitive strain to an Mtz-resistant strain or vice versa by use of naturally inactivated or functionalfrxA genes, respectively, and transformation of an Mtz-resistant Escherichia coli strain to an Mtz sensitive strain by a naturally functional frxA gene but not an inactivated frxA gene. These results are consistent with the hypothesis that null mutations in fdxB,frxA, or rdxA may be involved in Mtz resistance.

Regional Differences in Metronidazole Resistance and Increasing Clarithromycin Resistance among Helicobacter pylori Isolates from Japan

ABSTRACT The patterns of antibiotic resistance in Helicobacter pylori were assessed in two different regions in Japan. Overall, prevalences of resistance to metronidazole and clarithromycin were 12.4 and 12.9%, respectively. While there was no difference in clarithromycin resistance, the prevalence of metronidazole resistance was significantly higher in Kyoto (23.8%) than in Sapporo (8.1%). From 1996 to 1999, the prevalence of metronidazole resistance did not change but the prevalence of clarithromycin resistance doubled (from 9.1 to 18.7%).

Isolation of Helicobacter pylori From Sheep—Implications for Transmission to Humans

OBJECTIVES:When and how Helicobacter pylori (H. pylori) originally entered the human population as well as how the infection is transmitted in different communities is unknown. We previously showed that Sardinian shepherds had almost a 100% prevalence of H. pylori and that the prevalence was higher than that of their same-household siblings.Aim:To examine whether H. pylori infection might be transmitted from sheep.METHODS:Milk and gastric tissue were cultured and analyzed by PCR amplification using three sets of primers Helicobacter genus–specific 16S rRNA and two sets of primers specific for H. pylori vacA gene.RESULTS:Helicobacter DNA was demonstrated in 60% (38/63) of milk samples and in 30% (6/20) of sheep tissue samples. H. pylori vacA gene was amplified in five of 38 milk samples, and in two of six sheep tissue samples respectively. H. pylori were cultured from sheep milk and tissue samples and confirmed as H. pylori on the basis of colony morphology, positive biochemical reactions, and negative Gram stain. Sequence analysis of 16S rRNA PCR products from these isolates demonstrated 99% identity with H. pylori.CONCLUSIONS:Together, the presence of H. pylori in sheep stomach in the absence of associated gastritis and recovery of H. pylori from sheep milk and gastric tissue suggest that sheep may be a natural host for H. pylori.

Real-Time Quantitative PCR for Detection of Helicobacter pylori

ABSTRACT Helicobacter pylori is one of the most common chronic infections in humans, in whom it is a key etiological factor in peptic ulcer disease, gastric mucosa-associated lymphoid tissue lymphoma, and gastric adenocarcinoma. Humans are the bacteriums only host. Here we report the development of a real-time quantitative (Q) PCR-based assay to measure ureC gene copy number to detect H. pylori, based on the fact that there is only one copy of the ureC gene per bacterium. Upon optimization of LightCycler Q-PCR conditions, we obtained a standard curve with a linear range (correlation coefficient = 1) across six logs of DNA concentration. We were able to accurately quantify as few as 1,000 bacteria in our assay. Analysis of variance on 15 randomly selected clinical samples showed good reproducibility of this assay. Comparison of Q-PCR results with bacterial culture and histopathological results from an additional 85 clinical biopsy samples showed a significant difference for the presence of H. pylori. Many samples that were negative for H. pylori by culture and histopathology were positive by Q-PCR. Contamination of PCR by H. pylori or H. pylori genetic material could not be ruled out. In summary, we developed a rapid, sensitive, and real-time Q-PCR method for detecting H. pylori. This technique offers a significant improvement over other available methods for detecting H. pylori in clinical and research samples.