Macrolide resistance in the normal microbiota after Helicobacter pylori treatment.

Large-scale chemoprevention of peptic ulcer disease and gastric cancer through eradication of Helicobacter pylori would expose large population groups to antibiotics, which raises concerns about possible dissemination of antibiotic resistance. The objective of this cohort study was to determine whether a triple therapy, containing omeprazole, clarithromycin, and metronidazole, of H. pylori infection increases the prevalence of macrolide resistance in the normal microbiota. 85 patients with a peptic ulcer disease with verified H. pylori infection and 12 dyspeptic patients without positive findings upon endoscopy were included. Minimal inhibitory concentrations of clarithromycin for Staphylococcus, Streptococcus, Enterococcus and Bacteroides spp. were determined from samples taken before and after treatment, and 1 y later. Before treatment, macrolide resistance was observed in 11%, 31%, 9% and 11% of the staphylococci, streptococci, enterococci and Bacteroides, respectively. The number of resistant isolates remained elevated after 1 y, most notably for staphylococci and streptococci. No development of persistent resistance was detected in the untreated control group. Triple therapy including clarithromycin leads to persistent macrolide resistance in the normal microbiota. A prevalent pool of resistance genes in the normal microbiota constitutes an ecological hazard that needs to be considered before global treatment programmes for eradication of H. pylori are implemented.

Antimicrobial susceptibility of Helicobacter pylori strains in a random adult Swedish population.

BACKGROUND AND AIM: Antimicrobial resistance in Helicobacter pylori is a growing problem and has become an important factor leading to eradication failure. Information on antimicrobial susceptibility is important for selection of an optimum treatment regimen. The resistance rate in a random population has not been studied previously. METHODS: A random Swedish population sample (n = 3000, age 20-1 years) was surveyed using a mailed validated questionnaire assessing gastrointestinal symptoms (response rate of 74%). One-third of the responders was invited, in random order, and accepted an esophagogastroduodenoscopy with biopsies for H. pylori culture and histology. Subjects were not treated for their H. pylori infection but a minimum inhibitory concentration of metronidazole, clarithromycin, amoxicillin, and tetracycline for the H. pylori isolates (n = 333) was determined by agar dilution. Prescribed antibiotic in the area was recorded. RESULTS: Irrespective of symptomatology, 16.2% of the isolated H. pylori strains were resistant to metronidazole, 1.5% to clarithromycin, 0% to amoxicillin, and 0.3% to tetracycline. The antibiotic consumption was low from an international perspective. CONCLUSION: The resistance to the antibiotics was lower than expected from patient sample studies, especially for clarithromycin, most probably due to a restrictive prescription policy in the area. Introduction of a test-and-treat strategy in Sweden would only marginally affect the usage of clarithromycin.

A negative Helicobacter pylori serology test is more reliable for exclusion of premalignant gastric conditions than a negative test for current H. pylori infection: a report on histology and H. pylori detection in the general adult population.

OBJECTIVE: Corpus-dominant gastritis, gastric mucosal atrophy and intestinal metaplasia (IM) associated with Helicobacter pylori infection are all known potential risk markers for the development of gastric cancer. As the accuracy for finding cases at risk in the general population is unknown, we aimed to determine the prevalence of current and/or past H. pylori infection and associated gastric mucosal findings by means of histological survey of a random adult population. MATERIAL AND METHODS: A random Swedish sample (n = 3000, age 20-81 years) was surveyed using a validated gastrointestinal symptom questionnaire with 74% response rate. One-third of the responders were selected at random for esophago-gastro-duodenoscopy with biopsies and H. pylori serology. RESULTS: Of those endoscoped (n = 1000, mean age 53.5, 51% women), 43.0% were H. pylori+ by serology (seropositive), 33.9% had signs of current infection on either histology or culture (gold standard+), and 9.3% were seropositive, but gold standard negative. Corpus atrophy was found in 10% and IM in 13% when gold standard positive, and in a significantly higher number (17% and 21%, respectively) of those with only a serological sign of past infection. Among those who were seronegative, values were 1% and 2%, respectively. Corpus-dominant gastritis was found in 4.1%, all seropositive. CONCLUSION: One-third had an ongoing H. pylori infection, and a further 10% had signs of past infection. Corpus-dominant gastritis was found mostly among the former, while detection of those with corpus atrophy and IM also required a test for past infection. Seronegativity almost excludes precancerous conditions in a screening situation.

Long-term persistence of resistant Enterococcus species after antibiotics to eradicate Helicobacter pylori.

BACKGROUND: Antibiotic treatment selects for resistance not only in the pathogen to which it is directed but also in the indigenous microflora. OBJECTIVE: To determine whether a widely used regimen (clarithromycin, metronidazole, and omeprazole) for Helicobacter pylori eradication affects resistance development in enterococci. DESIGN: Cohort study. SETTING: Endoscopy units at 3 community hospitals in Sweden. PATIENTS: 5 consecutive dyspeptic patients who were colonized with H. pylori, had endoscopy-confirmed duodenal ulcer, and received antibiotic treatment, and 5 consecutive controls with dyspepsia but no ulcer who did not receive treatment. MEASUREMENTS: Fecal samples were obtained from patients and controls before, immediately after, 1 year after, and 3 years after treatment. From each patient and sample, enterococci were isolated and analyzed for DNA fingerprint, clarithromycin susceptibility, and presence of the erm(B) gene. RESULTS: In treated patients, all enterococci isolated immediately after treatment showed high-level clarithromycin resistance due to erm(B). In 3 patients, resistant enterococci persisted for 1 to 3 years after treatment. No resistance developed among controls. CONCLUSION: A common H. pylori treatment selects for highly resistant enterococci that can persist for at least 3 years without further selection.

An anthroposophic lifestyle and intestinal microflora in infancy.

The intestinal flora is considered to have an impact on the development of the immune system. In the anthroposophic lifestyle, a diet comprising vegetables spontaneously fermented by lactobacilli, and a restrictive use of antibiotics, anti-pyretics and vaccinations, is typical. The aim of this study was to assess the gut flora in infants in relation to certain lifestyle characteristics associated with anthroposophy. Sixty-nine children < 2 years of age with an anthroposophic lifestyle, and 59 infants of a similar age with a traditional lifestyle, were clinically examined and questionnaire replies assessed. Fecal samples were analyzed by bacterial enumeration, bacterial typing through biochemical fingerprinting and by measuring microflora-associated characteristics (MACs). The numbers of colony-forming units (CFU)/g of feces were significantly higher for enterococci and lactic acid bacteria in children who had never been exposed to antibiotics (5.5 x 107 vs. 2.1 x 107; p < 0.001 and 10 x 107 vs. 4.1 x 107; p < 0.01, respectively). Furthermore, the number of enterococci was significantly higher in breastfed and vegetarian infants (p < 0.01). The diversity (Simpson's diversity index) of lactobacilli, as determined by biochemical fingerprinting, was higher in infants born at home than in those born in hospital (p < 0.01). Several MACs were related to specific lifestyle features, and infants with an anthroposophic lifestyle had a higher proportion of acetic acid and a lower proportion of propionic acid in their stool as compared to the control children. In conclusion, lifestyle factors related to the anthroposophic way of life influenced the composition of the gut flora in the infants. These differences may contribute to the lower prevalence of atopic disease previously observed in children in anthroposophic families.

Free-living amoebae promote growth and survival of Helicobacter pylori.

Transmission routes of Helicobacter pylori remain poorly understood. The finding of bacterial DNA in water suggests the involvement of environmental factors. Here we report successful co-cultivation of H. pylori with Acanthamoeba castellanii, which circumvents the requirement of this bacterium for precise microaerobic conditions and a large supply of nutrients in order to grow. H. pylori was able to propagate and remain viable for several weeks in the presence of amoebae under experimental conditions. Intact, metabolically active bacteria could be demonstrated in vacuoles. The putative dependence of H. pylori on free-living amoebae in nature could be important with respect to transmission and prevalence, as shown for some other pathogenic bacteria.