Challenge model for Helicobacter pylori infection in human volunteers.

BACKGROUND: A reliable challenge model is needed to evaluate Helicobacter pylori vaccine candidates. METHODS: A cag pathogenicity island negative, OipA positive, multiple antibiotic susceptible strain of H pylori obtained from an individual with mild gastritis (Baylor strain 100) was used to challenge volunteers. Volunteers received 40 mg of famotidine at bedtime and 10(4)-10(10) cfu of H pylori in beef broth the next morning. Infection was confirmed by (13)C urea breath test ((13)C-UBT), culture, and histology. Eradication therapy was given four or 12 weeks post challenge and eradication was confirmed by at least two separate UBTs, as well as culture and histology. RESULTS: Twenty subjects (nine women and 11 men; aged 23-33 years) received a H pylori challenge. Eighteen (90%) became infected. Mild to moderate dyspeptic symptoms occurred, peaked between days 9 and 12, and resolved. Vomitus from one subject contained >10(3) viable/ml H pylori. By two weeks post challenge gastric histology showed typical chronic H pylori gastritis with intense acute and chronic inflammation. The density of H pylori (as assessed by cfu/biopsy) was similarly independent of the challenge dose. A minimal infectious dose was not found. Gastric mucosal interleukin 8 levels increased more than 20-fold by two weeks after the challenge. CONCLUSION: Challenge reliably resulted in H pylori infection. Infection was associated with typical H pylori gastritis with intense polymorphonuclear cell infiltration and interleukin 8 induction in gastric mucosa, despite absence of the cag pathogenicity island. Experimental H pylori infection is one of the viable approaches to evaluate vaccine candidates.

Twice daily (mid-day and evening) quadruple therapy for H. pylori infection in the United States.

BACKGROUND: Quadruple therapy provided inadequate eradication rate when given twice-a-day at breakfast and evening meals. AIM: To test twice daily (mid-day and evening) quadruple therapy for Helicobacter pylori eradication. METHODS: This was a single-centre pilot study in which H. pylori-infected (positive histology and culture and RUT) patients were given 2 x 250 mg of metronidazole and 2 x 250 mg of tetracycline, two Pepto-Bismol tablets, plus one 20 mg rabeprazole tablet twice-a-day for 14 days. H. pylori status was confirmed 4 or more weeks after the end of therapy. RESULTS: Thirty-seven patients including 3 with peptic ulcer disease, 19 asymptomatic infected, 4 GERD, and 11 with NUD. Mid-day quadruple therapy was successful in 92.3% (95% CI: 79-98%) including 96.2% of those with metronidazole-susceptible strains, and in 83.3% (10/12) of those with metronidazole-resistant H. pylori. Compliance was 100% by pill count except in one individual who stopped medication after 12 days because of side-effects and who failed therapy. Moderate or greater side-effects were experienced by five patients. CONCLUSION: Twice-a-day, mid-day, quadruple therapy proved effective using the combination of bismuth subsalicylate and rabeprazole instead of bismuth subcitrate and omeprazole. Detailed studies of different formulations (e.g. 2 x 250 mg versus 1 x 500 mg of metronidazole or tetracycline) and timing of administration (breakfast and evening meal versus mid-day and evening meals) may result in significant improvements in H. pylori eradication regimens.

Meta-analysis: proton pump inhibitor or H2-receptor antagonist for Helicobacter pylori eradication.

AIM: To compare H2-receptor antagonists and proton pump inhibitors as adjuvants to triple therapy for Helicobacter pylori eradication. METHODS: H. pylori-infected patients with peptic ulcer were randomized to receive either 300 mg nizatidine or 30 mg lansoprazole plus 1 g amoxicillin and 500 mg clarithromycin taken b.d. for 7 days. H. pylori eradication was assessed 4 weeks after therapy. Using meta-analytical techniques, we combined the results of this study with other randomized controlled comparisons of H2-receptor antagonists and proton pump inhibitors as adjuvants to triple therapy. RESULTS: One hundred and one patients were randomized. H. pylori eradication was 94% (47/50) [95% confidence interval (CI), 83-99%] (intention-to-treat) in the H2-receptor antagonist group vs. 86% (44/51) (95% CI, 74-94%) in the proton pump inhibitor group (P = 0.3). There has been a total of 12 similar studies (1415 patients). The overall efficacy was similar in intention-to-treat analysis: 78% (549/701) with H2-receptor antagonists vs. 81% (575/714) with proton pump inhibitors (odds ratio, 0.86; 95% CI, 0.66-1.12). A non-significant trend favouring H2-receptor antagonist (79% vs. 69%; odds ratio, 1.14; 95% CI, 0.76-1.71; P = 0.5) was seen in the comparison of clarithromycin-containing regimens. In contrast, in non-clarithromycin-containing trials, there was a slight, but significant, advantage with proton pump inhibitors (85% vs. 78%; odds ratio, 0.64; 95% CI, 0.45-0.92; P = 0.02). CONCLUSION: Overall, proton pump inhibitor and H2-receptor antagonist antisecretory agents appear to be similarly effective as adjuvants for H. pylori triple therapy. It is unlikely that the direct anti-H. pylori effect of proton pump inhibitors is responsible for their ability to enhance anti-H. pylori therapy.

Early events in proton pump inhibitor-associated exacerbation of corpus gastritis.

BACKGROUND: Antisecretory therapy may exacerbate Helicobacter pylori corpus gastritis. The rate and mechanism(s) remain unknown. AIM: To investigate the early events in proton pump inhibitor therapy on antral and corpus H. pylori gastritis. METHODS: Nine H. pylori-infected volunteers underwent gastric biopsy with jumbo forceps for culture and histology. Histology was scored in the range 0-5 using a visual analogue scale. The depth of inflammation in gastric pits was scored in the range 1-3 (superficial or less than one-third, one-third to two-thirds and greater than two-thirds of the gastric pit, respectively). Tissue interleukin-1 beta and interleukin-8 levels were measured by enzyme-linked immunoabsorbent assay. Omeprazole, 20 mg b.d., was given for 6.5 days and biopsies were repeated on day 7. RESULTS: Proton pump inhibitor therapy resulted in a fall in H. pylori density in the antrum and corpus. Inflammation and tissue levels of interleukin-8 and interleukin-1 beta decreased in the antrum and increased in the corpus mucosa. There was a significant increase in the depth of inflammation to include the proliferative zone in the corpus. CONCLUSIONS: Within 1 week of starting proton pump inhibitor therapy, there was a marked extension of corpus inflammation into the gastric pit and an increase in corpus mucosal interleukin-1 beta and interleukin-8 levels. H. pylori eradication should be considered for all patients receiving long-term antisecretory therapy.

Folk yoghurt kills Helicobacter pylori.

AIMS: To evaluate a traditional yoghurt used as folk medicine for its ability to kill Helicobacter pylori in vitro. METHODS AND RESULTS: Micro-organisms from the yoghurt were identified and tested in different food substrates for their effects on H. pylori in a co-culture well system. Two yeasts and several strains of lactobacilli were isolated from the yoghurt, and both the yeast and the lactobacilli independently showed cidal activity against H. pylori. The microbes from the original yoghurt also retained their cidal effect when grown in corn meal and soy milk. CONCLUSIONS: The yeast and lactobacilli found in this yoghurt form a hardy symbiotic culture. The organisms secrete soluble factors capable of killing H. pylori, and these factors may include some organic by-products of fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: These yoghurt-derived food preparations could become simple and inexpensive therapies to suppress H. pylori infections in endemic countries.

Citric acid-enhanced Helicobacter pylori urease activity in vivo is unrelated to gastric emptying.

BACKGROUND: In a previous study, the use of a citric acid test meal produced a rapid dose-dependent increase in urease activity that was significantly greater than that resulting from a pudding meal, ascorbic acid or sodium citrate. The mechanism was hypothesized to be related to the ability of citric acid to delay gastric emptying and possibly to enhance intragastric distribution of the urea. OBJECTIVE: To compare the effects of sodium citrate, two doses of citric acid and a pudding meal on gastric motor function. METHOD: Eleven normal healthy volunteers were investigated using non-invasive techniques to measure gastric emptying and gastric motility. We evaluated gastric emptying using the Meretek 13Ceebiscuit solid phase gastric emptying breath test, which employs a 340-calorie biscuit containing 200 mg of the edible 13C-blue-green alga Spirulina platensis, after the administration of test meals of pudding, 2 g and 4 g of citric acid and 2 g of sodium citrate. Electrogastrograms (Digitrapper EGG) were also recorded for 30 min before and 180 min after the test meal. RESULTS: Gastric emptying, as assessed by the half-time (T1/2), was delayed similarly with the pudding (136.8 +/- 9 min) and with 4 g of citric acid (144.5 +/- 7 min) (P > 0.7). Sodium citrate (108.7 +/- 6 min) and 2 g of citric acid (110.1 +/- 6 min) had similar effects on gastric emptying (P=0.986), and were significantly less effective in delaying gastric emptying (P < 0.01) compared to pudding or 4 g of citric acid. The electrogastrograms remained normal and there were no differences among meals and no relation with the gastric emptying results. CONCLUSIONS: The increased intragastric urea hydrolysis associated with citric acid test meals cannot be attributed to delayed gastric emptying. Changes in the intragastric distribution of urea or a direct effect of citric acid on the bacteria (e.g. via the cytoplasmic protein, UreI) are more likely to be responsible.

DNA sequence analysis of rdxA and frxA from 12 pairs of metronidazole-sensitive and -resistant clinical Helicobacter pylori isolates.

We previously reported that inactivation of rdxA and/or frxA converted Helicobacter pylori from metronidazole sensitive to metronidazole resistant. To examine the individual roles of rdxA and frxA in the development of metronidazole resistance in H. pylori, we examined the status of rdxA and frxA from 12 pairs of metronidazole-sensitive and -resistant H. pylori isolates obtained following unsuccessful therapy containing metronidazole. Arbitrary primed fingerprinting analyses revealed that the genotypes of 11 sensitive and resistant pairs of strains were essentially identical. Amino acid sequence identities of RdxA and FrxA from the 14 metronidazole-sensitive isolates ranged from 92 to 98% and 95 to 98%, respectively, compared to that of H. pylori J99 (MIC, 1 microg/ml). All strains with high-level metronidazole resistance (MICs, 128 microg/ml) contained premature truncation of both RdxA and FrxA caused by nonsense and/or frameshift mutations. Strains with intermediate resistance to metronidazole (MICs, 32 to 64 microg/ml) contained a single premature truncation and/or altered RdxA and FrxA caused by nonsense, frameshift, and unique missense mutations. The low-level metronidazole-resistant strains (MICs, 8 microg/ml) contained unique missense mutations in FrxA but no specific changes in RdxA. The results demonstrate that alterations in both the rdxA and frxA genes are required for moderate and high-level metronidazole resistance and that metronidazole resistance that develops during anti-H. pylori therapy containing metronidazole is most likely to involve a single sensitive strain infection rather than a coinfection with a metronidazole-resistant strain.

Pattern of primary resistance of Helicobacter pylori to metronidazole or clarithromycin in the United States.

BACKGROUND: Therapy for Helicobacter pylori is generally empiric despite the fact that resistance to metronidazole and clarithromycin compromise therapeutic efficacy. The aim of this study was to aid clinicians in choosing a course of therapy for H pylori infection in the United States. METHODS: The frequency of primary clarithromycin and metronidazole resistance among H pylori isolated from patients enrolled in US-based clinical trials between 1993 and 1999 was reviewed in relation to patient age, sex, region of the United States, and test method (Etest and 2 agar dilution procedures). RESULTS: Clarithromycin and metronidazole resistance rates were based on the results of 3439 pretreatment Etest determinations and 3193 agar dilution determinations. Sex and age were available on 900 and 823 individuals, respectively. Metronidazole resistance was 39% by Etest and 21.6% by agar dilution (P<.001). Clarithromycin resistance was 12% by Etest and 10.6% by agar dilution. Amoxicillin or tetracycline resistance was rare. Metronidazole and clarithromycin resistance was more common in women than men (eg, 34.7% vs 22.6% for metronidazole and 14.1% vs 9.7% for clarithromycin (P =.01 and P =.06, respectively). Antibiotic resistance increased gradually up to age 70 years, then declined significantly (P<.05) regardless of test method. Regional differences in antimicrobial resistance did not occur. CONCLUSIONS: While age and sex had significant effects on resistance rates, regional differences were not present. The high prevalence of resistance to metronidazole and clarithromycin may soon require the performance of antimicrobial susceptibility testing of H pylori isolates prior to initiating treatment.

Etiology of Crohn's disease: the role of Mycobacterium avium paratuberculosis.

Crohn's disease is a chronic inflammatory bowel disease characterized by transmural inflammation and granuloma formation. Several theories regarding the etiology of Crohn's disease have been proposed, one of which is infection with Mycobacterium avium subspecies paratuberculosis (M. paratuberculosis), which causes a similar disease in animals, and is present in the human food chain. Considerable evidence supports the presence of M. paratuberculosis in the intestinal tissues of many patients with Crohn's disease including culture, detection of homologous mycobacterial DNA, detection of the mycobacterial insertion sequence IS900 by both PCR and in situ hybridization in tissues, and a serologic immune response to recombinant M. paratuberculosis antigens. Despite this evidence, and our personal belief that M. paratuberculosis is a cause of Crohn's disease, widespread acceptance of this hypothesis will require evidence that specific anti-mycobacterial chemotherapy will cure the disease.

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.

Comparative efficacy of new investigational agents against Helicobacter pylori.

BACKGROUND: Emergence of antibiotic resistant Helicobacter pylori has necessitated the identification of alternate therapies for the treatment of this infection. AIM: To assess the in vitro efficacy of two investigational agents: DMG-MINO CL 344 (a N,N-dimethylglycylamido derivative of minocycline), and davercin, a cyclic carbonate of erythromycin A as compared to older antibiotics (clarithromcyin, azithromycin, minocycline, tetracycline, ofloxacin, ciprofloxacin, cefixime) against clinical isolates of H. pylori. METHODS: Testing was performed using the agar dilution method approved by the NCCLS subcommittee on antimicrobial susceptibility testing, Helicobacter pylori working group. Under these guidelines, Mueller-Hinton agar containing 5% aged sheep blood was used. All incubations were done under CampyPak Plus conditions for 72 h at 37 degrees C. The drug concentrations in the agar ranged from 0.016 to 16 microg/mL. Twenty-one clarithromycin-resistant and 16 clarithromycin-susceptible clinical isolates of H. pylori obtained from patients with duodenal ulcer were used. H. pylori ATCC 43504 was used as the control in all determinations. RESULTS: Against clarithromycin susceptible isolates, all antimicrobial agents except the fluoroquinolones were highly effective. Against clarithromycin-resistant H. pylori, the MIC50/MIC90 values showed that the tetracyclines and cefixime were the most efficacious agents. The fluoroquinolones and macrolides were ineffective. Macrolide cross-resistance was detected. CONCLUSION: Macrolide cross-resistance prevents the use of this entire class of antimicrobials when clarithromycin resistance is present. Tetracyclines and cefixime are possible alternative agents for the treatment of H. pylori infection in these patients.

Nitrofurantoin quadruple therapy for Helicobacter pylori infection: effect of metronidazole resistance.

BACKGROUND: Antibiotic resistance has increasingly been recognized as the major cause of treatment failure for Helicobacter pylori infection. New therapies for patients with metronidazole- or clarithromycin-resistant H. pylori are needed. AIM: To investigate the role of nitrofurantoin quadruple therapy for the treatment of H. pylori. METHODS: Patients with confirmed H. pylori infection received nitrofurantoin (100 mg t.d.s.), omeprazole (20 mg b.d.), Pepto-Bismol (two tablets t.d.s.), and tetracycline (500 mg t.d.s.) for 14 days. Four or more weeks after the end of therapy, outcome was assessed by repeat endoscopy with histology and culture or urea breath testing. RESULTS: Thirty patients were entered, including 25 men and five women; the mean age was 54.9 years. The most common diagnoses were duodenal ulcer (23%) and GERD (18%). The intention-to-treat cure rate was 70% (95% CI: 50.6-85%). Nitrofurantoin quadruple therapy was more effective with metronidazole-sensitive strains (88%; 15 out of 17) than with metronidazole-resistant strains (33%; three out of nine; P=0.008). Two of the treatment failures had pre-treatment isolates susceptible to metronidazole, which were resistant after therapy. CONCLUSIONS: Because nitrofurantoin quadruple therapy performed inadequately in the presence of metronidazole resistance, we conclude that nitrofurantoin is unlikely to find clinical utility for the eradication of H. pylori.

Analysis of metronidazole, clarithromycin and tetracycline resistance of Helicobacter pylori isolates from Korea.

Antibiotic resistance in Helicobacter pylori varies according to geographical region. We studied the primary resistance rates among 652 H. pylori isolated from Korea in relation to collection date, disease presentation, age and gender. Resistance rates were 40.6% (metronidazole), 5.9% (clarithromycin), 5.3% (tetracycline), 0% (amoxycillin), 1.5% (furazolidone) and 1.5% (nitrofurantoin). Resistance to metronidazole and clarithromycin increased from 1994 to 1999 (from 33.3 to 47.7% and 4.8 to 7.7%, respectively), but the differences only reached significance when rates of metronidazole resistance in women were compared with those in men (48.6 versus 36.9%).

Comparison of the Etest and the NCCLS-approved agar dilution method to detect metronidazole and clarithromycin resistant Helicobacter pylori.

Although the NCCLS has approved the agar dilution method as the test of choice for antimicrobial susceptibility testing of Helicobacter pylori, a critical evaluation of this method in clinical trials to detect antibiotic resistance has not been performed. This study compares the Etest and agar dilution methods for detection of metronidazole and clarithromycin resistance in clinical isolates of H. pylori. MIC data were gathered from US-based clinical trials. The Etest was performed on Mueller-Hinton sheep blood agar plates following incubation for 4 days under 12% CO(2). The agar dilution test was performed according to the recently approved NCCLS methodology using aged sheep blood in a Mueller-Hinton agar base. Metronidazole resistance as determined by Etest was significantly higher than that determined by agar dilution (39%; 690/1768 vs. 25. 1%; 367/1465)(P<0.01). Clarithromycin resistance as determined by Etest was higher than that determined by agar dilution, but was not significantly different (12.5%; 209/1671 vs. 10.6%; 150/1414)(P>0.5). Inter-patient metronidazole resistance showed that the MIC values for identical isolates tested by both methods were equivalent in 58% (109/188). Of the 42% with a >2log(2) difference in MIC values, 17. 6% had a change in susceptibility pattern. For clarithromycin, 71.4% (237/332) of the MIC values for identical isolates tested by both methods had equivalent MIC values. Of the MIC values with a >2log(2) difference in MIC values, only 3% showed a change in susceptibility pattern. Intra-patient variability, i.e. paired isolates from the same patient, was assessed only for metronidazole. Of the 1393 paired isolates tested by Etest, 38.8% were shown to be resistant. Almost 69% of the Etest MIC determinations were deemed equivalent and 16.7% had a change in susceptibility pattern. Of the 639 paired isolates tested by agar dilution, 23.9% were resistant to metronidazole. Almost 72% of the agar dilution MIC values were equivalent and 11.3% of the determinations had a change in susceptibility pattern. Clarithromycin resistance rates are similar, when determined by either test method. The Etest yields a significantly higher prevalence of metronidazole resistance among H. pylori compared with the agar dilution method and both methods yield discordant results, when isolates from different parts of the same stomach are compared. Neither method is reliable in determining metronidazole resistance in H. pylori.

Furazolidone- and nitrofurantoin-resistant Helicobacter pylori: prevalence and role of genes involved in metronidazole resistance.

The prevalence of furazolidone, nitrofurantoin, and metronidazole resistance among Helicobacter pylori strains was assessed with 431 clinical isolates. Fifty-two percent were metronidazole resistant, compared to 2% (7 of 431) with resistance to furazolidone and nitrofurantoin. All seven furazolidone- and nitrofurantoin-resistant isolates were also metronidazole resistant. rdxA, frxA, and fdxB knockouts did not result in furazolidone or nitrofurantoin resistance. These data suggest that furazolidone and nitrofurantoin may be good alternatives to metronidazole for treating H. pylori infection.

Use of a dry-plasma collection device to overcome problems with storage and transportation of blood samples for epidemiology studies in developing countries.

Studies are difficult in areas lacking modern facilities due to the inability to reliably collect, store, and ship samples. Thus, we sought to evaluate the use of a dry plasma collection device for seroepidemiology studies. Plasma was obtained by fingerstick using a commercial dry plasma collection device (Chemcard Plasma Collection Device) and serum (venipuncture) from individuals in Kazakhstan. Plasma samples were air dried for 15 min and then stored desiccated in foil zip-lock pouches at 4 to 6 degrees C and subsequently shipped to the United States by air at ambient temperature. Serum samples remained frozen at -20 degrees C until assayed. Helicobacter pylori status was determined by enzyme-linked immunosorbent assay (HM-CAP EIA) for the dry plasma and the serum samples. The results were concordant in 250 of the 289 cases (86.5%). In 25 cases (8.6%), the dry plasma samples gave indeterminate results and could not be retested because only one sample was collected. Five serum samples were positive, and the corresponding dry plasma samples were negative; one serum sample was negative, and the corresponding plasma sample was positive. The relative sensitivity and specificity of the Chemcard samples to serum were 97.6 and 97.9%, respectively, excluding those with indeterminate results. Repeated freeze-thawing had no adverse effect on the accuracy of the test. We found the dry plasma collection device to provide an accurate and practical alternative to serum when venipuncture may be difficult or inconvenient and sample storage and handling present difficulties, especially for seroepidemiologic studies in rural areas or developing countries and where freeze-thawing may be unavoidable.

Frameshift mutations in rdxA and metronidazole resistance in North American Helicobacter pylori isolates.

In Helicobacter pylori, the oxygen-insensitive nitroreductase RdxA is likely to activate metronidazole (Mtz) by reduction and formation of cytotoxic intermediates. Mutations in rdxA have been associated with Mtz resistance in H. pylori. In vitro Mtz susceptibilities of 17 randomly selected H. pylori isolates were determined by the agar dilution method. DNA sequence analysis of rdxA alleles of eight susceptible isolates (MIC range: 0.25-1.0 mg/L) and nine resistant isolates (MIC range: 16-256 mg/L) showed that six of nine Mtz-resistant H. pylori isolates contained insertion or deletion mutations ('indel' mutations). One isolate contained a substitution mutation at codon position 148 that resulted in the introduction of a premature stop codon. Creation of stop codons within the rdxA coding sequence by either frameshift or substitution mutations resulted in premature translation termination and expression of putatively truncated RdxA polypeptides.

Helicobacter pylori infection in children of Texas.

BACKGROUND: Acquisition of the Helicobacter pylori infection usually occurs in childhood. The prevalence of infection differs among ethnic groups and in adults is inversely related to the socioeconomic status of the individual's family during childhood. This study investigates the seroprevalence of H. pylori infection in children of different ethnic groups in relation to socioeconomic class and investigates the prevalence of acute H. pylori infection among children who have had recent onset of abdominal pain. METHODS: Serum samples were collected from 797 children, aged 6 months to 18 years, of various socioeconomic and ethnic backgrounds, at a large urban children's hospital. H. pylori status was determined by an anti-H. pylori immunoglobulin (Ig)G enzyme-linked immunosorbent assay (ELISA) validated for pediatric use. To determine the prevalence of acute H. pylori infection, children brought to the emergency center with abdominal symptoms without diarrhea and overt signs of acute abdomen were evaluated with both serology and the 13C-urea breath test. Acute H. pylori was defined as a positive 13C-urea breath test result and negative IgG serology for H. pylori. RESULTS: The overall seroprevalence of H. pylori was 12.2% and increased with age (e.g., 8.3% at 6-11.9 months and 17.9% at 13 years). The prevalence was inversely related to socioeconomic status (6.6%, moderate to high vs. 15%, low socioeconomic status). The difference in seroprevalence among blacks (16.8%), Hispanics (13.3%), and whites (8.3%; P < 0.01) could be accounted for by differences in socioeconomic status. Eighteen percent of children who were evaluated at the emergency center for recent-onset abdominal pain had acute H. pylori infections. CONCLUSIONS: Socioeconomic status, not ethnic group, is the more important risk factor for acquisition of H. pylori infection during childhood. Acute H. pylori infection was a relatively common cause of recent-onset, nonsurgical abdominal pain.

Isolation and characterization of tetracycline-resistant clinical isolates of Helicobacter pylori.

Tetracycline is an important component of combination therapies for Helicobacter pylori eradication. Twenty-nine tetracycline-resistant isolates requiring MICs ranging from 4 to 16 microgram/ml were isolated from Korean (22 of 460) and Japanese (7 of 105) patients. Interestingly, all of the 29 tetracycline-resistant isolates exhibited cross-resistance to metronidazole, and the cross-resistance was transferred to tetracycline-sensitive H. pylori strains.

Characterization of a culture method to recover Helicobacter pylori from the feces of infected patients.

BACKGROUND: Helicobacter pylori is difficult to culture from stool. Multiple efforts from multiple laboratories have been unsuccessful, and the optimal conditions to recover H. pylori from stool are still not known. Recovery of H. pylori from feces of infected individuals is important for the performance of molecular epidemiological investigations, especially in children, where their symptoms do not warrant endoscopy to recover the organism. METHODS: Fresh fecal specimens (noncathartic) were obtained from 19 known H. pylori-infected patients and were processed to recover the organism. Fresh fecal specimens (noncathartic) were also obtained from three known H. pylori-negative individuals (controls) to determine whether H. pylori could be isolated from stools seeded with known concentrations of the organism. Treatment of the fecal suspensions with cholestyramine, a basic anion exchange resin that binds bile acids, was used in an attempt to enhance recovery of H. pylori by sequestering bile acids that are inhibitory to H. pylori growth. H. pylori was identified based on colony morphology, cell morphology, Gram's stain, biochemical reactions, and polymerase chain reaction for two H. pylori genes. RESULTS: Among 19 patients, H. pylori was cultured at least once from 3 and three times from 2 (5 of 19). Feces that were seeded with H. pylori and obtained from three H. pylori-negative volunteer controls yielded positive recovery in all instances. CONCLUSION: We have confirmed that it is possible to culture H. pylori from human stool, but the procedure for optimal recovery has still not been defined.