Prevalence of primary Helicobacter pylori resistance to metronidazole and clarithromycin in The Netherlands

The minimum inhibitory concentrations of metronidazole and clarithromycin were determined for 780 Helicobacter pylori strains collected in 1994 and 1995 from three different regions in The Netherlands. The overall prevalence of primary metronidazole resistance was 17%, with resistance found more frequently in women (24%) than in men (13%). There was no significant difference between the levels of resistance in the three regions. Primary clarithromycin resistance was rare (1%) and relatively infrequent as compared to that found in other countries. Four of the six strains resistant to clarithromycin were also resistant to metronidazole.     

Prospective screening of dyspeptic patients by Helicobacter pylori serology

A 24-year-old Chinese woman presented with cough, chest pain, weight loss, low grade fever and bronchial breath sounds on auscultation. The diagnosis of chronic eosinophilic pneumonia was made on characteristic systemic and pulmonary clinical manifestations, blood eosinophilia and the striking chest radiographic appearance. This rare, idiopathic but benign condition responds well to corticosteroid treatment and the long term prognosis is excellent. The typical chest radiographic pattern of 'photographic negative of pulmonary oedema' in this condition is emphasised.     

Clarithromycin resistance in Helicobacter pylori: prevalence in untreated dyspeptic patients and stability in vitro

Susceptibilities to clarithromycin and metronidazole of 444 Helicobacter pylori isolates cultured from antral biopsies of 444 dyspeptic patients were determined by disc diffusion tests (15 mu g disc for clarithromycin, 5 mu g disc for metronidazole). Susceptibility of 46 of these isolates to erythromycin (5 mu g disc) was also tested. Minimal inhibitory concentrations (MICs) of clarithromycin for 42 selected isolates were determined by a plate dilution method. A zone diameter of 30 mm was defined as a 'cut-off' size differentiating susceptibility and resistance of the organism to clarithromycin, by comparing results obtained with the two methods. Of the 444 isolates, 424 (95.5%) were highly sensitive to clarithromycin, with zone diameters ranging from 30 to 98 mm. Twenty isolates (4.5%) were defined as resistant to clarithromycin, with zone diameters ranging between 6 and 28 mm. The incidence of clarithromycin resistance was similar in men and women and in different age groups, and was not significantly different between patients with peptic ulcer and non-ulcer dyspepsia. Among the 444 isolates, 168 (37.8%) were metronidazole resistant. There was cross resistance between clarithromycin and erythromycin, but not between clarithromycin and metronidazole. Stability of clarithromycin resistance was evaluated by the disc diffusion test and confirmed by the plate dilution method. Among the 20 clarithromycin-resistant isolates, nine (45%) reverted to be sensitive after 25 subcultures on drug-free agar. The findings in this study indicate that the incidence of clarithromycin-resistant H. pylori in untreated dyspeptic patients is low. Cross-resistance occurs between macrolides and resistance to clarithromycin in some strains is reversible.     

Isolation of a genetic locus associated with metronidazole resistance in Helicobacter pylori

We examined the molecular mechanism of metronidazole resistance by constructing a lambda-Zap II phagemid expression library with genomic DNA from a metronidazole-resistance strain of Helicobacter pylori. Twenty-two clones were found to have elevated MTZ resistances in XLOLR strain of E. coli. Phagemids belonging to the twenty two clones were extracted and then retransformed into the XLOLR strain of E. coli. After MTZ selection, five clones could confer metronidazole resistance consistently. According to Southern hybridization and DNA sequencing, the five clones contained a same locus, recA. In addition, transforming the five clones into BL21 strain of E. coli produced a higher resistance to MTZ. Interestingly, electroporation of one of the five phagemid clones into two MTZ sensitive H. pylori yielded MTZ resistant strains. Comparing amino acid sequence in MTZ resistant with sensitive isolates revealed two point mutations at this locus. Above results suggest that mutation in recA may be associated with metronidazole resistance of H. pylori.     

Prevalence of and risk factors for Helicobacter pylori infection in a multi-racial dyspeptic Malaysian population undergoing endoscopy

The aim of the present study was to determine the risk factors for Helicobacter pylori in a dyspeptic Malaysian population. A cross-sectional survey of 1060 consecutive patients presenting with dyspepsia at the Endoscopic Unit, University Hospital, Kuala Lumpur, Malaysia from January 1994 to July 1995 was undertaken. All patients answered a detailed questionnaire and underwent endoscopy, with two antral biopsies taken for diagnosis of H. pylori using a rapid urease test. An overall H. pylori prevalence of 49.0% was recorded. Helicobacter pylori prevalence in relation to the major endoscopic diagnoses were as follows: non-ulcer dyspepsia (NUD) 31.2%; duodenal ulcer (DU) 91.4%; and gastric ulcer (GU) 74.1%. The prevalence among the races were as follows: Malay 16.4%; Chinese 48.5%; and Indians 61.8%. Multiple logistic regression analysis identified the following as independent risk factors: > 45 years old 1.5 (1.1,2.0); male gender 1.6 (1.2,2.1); ethnic group: Chinese 2.5 (1.7,3.7); Indians 4.9 (3.2,7.5); level of education: low 2.3 (1.5,3.5); middle 1.7 (1.1,2.6); and smoking 1.6 (1.2,2.3). Analysis was also performed on DU, GU and non-UD patients separately; in both DU and GU patients, H. pylori prevalence was high regardless of age, sex, race or level of education. However, in DU patients, Indian race had an independent risk factor (Odds ratio = 7.8 (1.2,48.4)). The findings in the NUD group reflected the findings in the ?all patients' group; > 45 years old, male gender, Indian and Chinese race, and low level of education were also significant, independent risk factors. The overall differences in H. pylori prevalence between the different subgroups were mainly due to differences in the NUD group. The increased risk of H. pylori infection in Chinese and Indians points to either an inherent ethnic genetic predisposition or to socio-cultural practices peculiar to the particular race which may be responsible for transmission of the infection.     

Salivary-specific immunoglobulin G in the diagnosis of Helicobacter pylori infection in dyspeptic patients

OBJECTIVES: Helicobacter pylori infection is arguably the most common chronic bacterial infection in humans. The high prevalence and the association with peptic ulceration and gastric cancer indicate that simple, noninvasive methods for diagnosis of the infection are needed. In this study, the accuracy of salivary diagnosis for H. pylori infection was assessed. METHODS: Saliva and serum samples of 152 dyspeptic patients were tested for H. pylori IgG and IgA by an in-house ELISA. All patients underwent gastroscopy with biopsy. RESULTS: One hundred thirty-one patients (86%) were found to be H. pylori positive on histology. Duodenal ulcer was found in 67 patients; 85 had no macroscopic lesion. Salivary and serum H. pylori IgG as well as serum H. pylori IgA titers were significantly higher in H. pylori-positive than in H. pylori-negative patients. The sensitivity and specificity of salivary H. pylori IgG were 82% and 71%, respectively; the positive and negative predictive values were 95% and 40%, respectively; and the accuracy 81%. The corresponding figures for serum H. pylori IgG were 97% and 91%; 98% and 83%; and 96%. Those for serum H. pylori IgA were 80% and 52%; 91% and 30%; and 76%. The sensitivity of salivary H. pylori IgG in detecting duodenal ulcer was 83% (56/67) that of serum H. pylori IgG was 97% (65/67) (odds ratio = 0.15; confidence interval = 0.02-0.8; p = 0.02). CONCLUSIONS: Salivary H. pylori IgG was a fairly sensitive and accurate indicator of gastric H. pylori colonization, with a high positive predictive value in our population. Data, however, suggest that salivary H. pylori IgG measurements do not compare favorably with serology.     

Prevalence and determinants of Helicobacter pylori infection in preschool children: a population-based study from Germany

Branching enzyme (BE) belongs to the amylolytic family which contains four highly conserved regions. These regions are proposed to play an important role in catalysis as they are thought to be necessary for catalysis and/or binding the substrate. Only one arginine residue was found to be conserved in a catalytic center at the same position in all known sequences of BEs from various species as well as in the alpha-amylase enzyme family. In mBEII, a conserved Arg residue 384 is in catalytic region 2. We have used site-directed mutagenesis of the Arg-384 residue in order to study its possible role in BE. Previous chemical modification studies (H. Cao and J. Preiss, 1996, J. Prot. Chem. 15, 291-304) suggest that it may play a role in substrate binding. Replacement of Arg-384 by Ala, Ser, Gln, and Glu in the active site caused almost total inactivation. However, a conservative mutation of the conserved Arg-384 by Lys resulted in some residual activity, approximately 5% of the wild-type enzyme. The kinetics of the purified mutant R384K enzyme were investigated and no large effect on the Km of the substrate amylose for BE was observed. Thus, these results suggest that conserved Arg residue 384 in mBEII plays an important role in the catalytic function of BEs but may not be directly involved in substrate binding.     

Prevalence of antimicrobial resistance in eighty clinical isolates of Helicobacter pylori

The actions of different adrenoceptor antagonists on gastric potential difference (PD), electrical current (I) and resistance (R) were studied, using the voltage clamp technique. In an isolated gastric mucosal tissue, 5% ethanol was able to reduce the PD and I across the gastric mucosa. Direct incubation with propranolol 10(-4) mol/l either from the mucosal or submucosal sides attenuated such effects. Intraperitoneal administration of propranolol (2.5-10 mg/kg), a nonselective beta-adrenoceptor blocker with significant membrane-stabilizing activity, given 30 min before the preparation of the gastric tissue, not only alleviated the fall in PD and I across the gastric mucosa, but also increased the R of the stomach tissue. Butoxamine, a selective beta2-antagonist, produced the similar but less significant effects in the same experimental setting. Metroprolol, a beta1-adrenoceptor blocker, given by the similar doses did not produce significant effects. Nonselective beta-adrenoceptor blocker, nadolol but not the beta- and alpha-adrenoceptor blocker, labetalol, also significantly preserved the decrease of PD induced by ethanol, but to a lesser extent. These findings suggest that blockade of the beta2-receptors in the gastric mucosa together with membrane-stabilizing activity could improve the integrity of the gastric mucosa, and these effects are probably acting through its direct action on the tissue.     

Prevalence of Helicobacter pylori resistance to several antimicrobial agents in a region of Germany

To evaluate the prevalence of resistance among Helicobacter pylori in Germany, the minimum inhibitory concentrations of amoxicillin, tetracycline, clarithromycin, and metronidazole were determined by means of the E test, for 271 Helicobacter pylori isolates cultured from biopsies taken during routine endoscopies in 1996 and 1997. The prevalence of metronidazole resistance was 32.1%, with resistance found more frequently in women (38.5%) than in men (24.4%). Clarithromycin resistance was rare (3.3%). Eight of nine strains resistant to clarithromycin were also resistant to metronidazole. Resistance to either metronidazole or clarithromycin was significantly (P=0.022) higher in patients with duodenal ulcer. No strain was found to be resistant to amoxicillin or tetracycline.     

Incidence of Helicobacter pylori infection in Ghanaian patients with dyspeptic symptoms referred for upper gastrointestinal endoscopy

There is a lack of information in the United Kingdom on the prevalence of third molars in older patients. The aim of this study was therefore to define the pattern of lower third molar retention in UK dental practice attenders aged 35 years and over. A random sample of 599 eligible patients from a rural dental practice were included in the study. Information was obtained from clinical notes and panoramic radiographs. Data collected included age, gender, presence or absence of lower third molars, number of teeth present in the lower arch and eruption status. Two hundred and sixty-four (44.1 per cent) had at least one lower third molar present (mean age = 57.1 years) while 335 (55.9 per cent) had no lower third molars (mean age = 50.2 years). The data suggest that a greater proportion of men than women retain at least one lower third molar although this finding was not statistically significant. Seventy per cent of retained lower third molars reported in the study were fully erupted. Sixty per cent were vertically placed. There was an association between age and number of teeth present (chi 2 = 38.85, 4DF, P < 0.05), older patients having fewer lower teeth. These data suggest that a large number of patients can expect to keep their lower third molars beyond the age of 35 years and that in many cases a conservative "wait and see' policy for lower third molars in the early twenties is appropriate.     

Prevalence of gastric cancer in a large group of healthcare workers routinely exposed to Helicobacter pylori

Secondary data analysis of the Society of Gastroenterology Nurses and Associates Endoscopic Disinfectant Survey was undertaken to answer the question, "What was the prevalence of gastric cancer among endoscopy personnel who were routinely exposed to Helicobacter pylori (HP) in their work environment?" This large sample of healthcare personnel (4,001) was occupationally exposed to both endoscopic disinfectants and HP. There is a known positive relationship between the prevalence of HP infection, gastritis, and gastric cancer. Results indicated that zero respondents reported gastric cancer in this sample.     

Metronidazole- and clarithromycin-resistant Helicobacter pylori in dyspeptic patients in western Sydney as determined by testing multiple isolates from different gastric sites

It is unknown whether antibiotic susceptibility testing of antral isolates alone is representative of Helicobacter pylori susceptibility. We aimed to determine: (i) the prevalence of metronidazole- and clarithromycin-resistant strains in infected dyspeptic patients; and (ii) whether there is consistency in the susceptibility to metronidazole and clarithromycin among isolates cultured from different gastric sites. Antral, body and fundus biopsies were taken from 242 consecutive patients and cultured on blood agar under micro-aerophilic conditions for 5-7 days. Isolates from 66 patients (13 had one, 15 had two and 38 had three isolates) were tested for susceptibility to metronidazole and clarithromycin using previously validated disc diffusion tests. Of the 66 patients, 42 (64%) had strains resistant to metronidazole while four (6.1%) had clarithromycin-resistant strains. The prevalence of metronidazole resistance was not significantly different between men and women (65% vs 60%) or across different age groups. In five (9.4%) of the 53 patients with multiple isolates, discrepant results for metronidazole susceptibility were observed: susceptible antral and body isolates but resistant fundus isolates in two cases and susceptible antral isolates but resistant body and fundus isolates in the others. Clarithromycin susceptibilities were consistent among the isolates cultured from different gastric sites in all patients. It is concluded that metronidazole-resistant strains of H. pylori are common while clarithromycin-resistant strains are rare. Metronidazole susceptibility testing of antral isolates does not appear to be representative of isolates from the body and fundus in a subset of patients.     

The influence of microaerophilia and anaerobiosis on metronidazole uptake in Helicobacter pylori

Resistance of Helicobacter pylori to metronidazole during therapy for gastroduodenal ulcers is claimed to be responsible for failure to eradicate the pathogen and thus the disease. Resistance to metronidazole and other nitroimidazoles is rare and documented only for anaerobes; the mechanism of resistance in typical microaerophiles, like Helicobacter, is not known. We have studied metronidazole uptake using high performance liquid chromatography in metronidazole sensitive and resistant strains of H. pylori under conditions of microaerophilia and in anaerobiosis. The uptake of metronidazole was faster in sensitive strains than resistant ones and was also increased in anaerobiosis. Drug uptake and the rate of cell kill was found to be dependent upon the relative oxygen tension of the environment and the cell density, both of which determine the redox conditions of the media. We suggest that resistance displayed in microaerophilia, but which disappears in anaerobiosis, may not involve futile cycling nor the induction of superoxide dismutase and catalase. We further propose that resistant organisms may have alterations in the pattern of pyruvate metabolism as documented for anaerobic bacteria and protozoa and that resistance in microaerophilia may involve the relative efficiencies of detoxifying oxygen in susceptible and resistant strains of H. pylori.     

Prevalence of Helicobacter pylori infection in asymptomatic children

OBJECTIVE: To determine the prevalence of Helicobacter pylori infection in a sample of asymptomatic Australian children. METHODOLOGY: A prospective observational study, during a 3 month period, of consecutive children aged 0 to 14 years undergoing minor elective surgical procedures in a Day Surgical Unit at a Melbourne paediatric hospital. Subjects without gastrointestinal symptoms or a family history of peptic ulcers had sociodemographic data recorded and serum collected. Serum anti-H. pylori immunoglobulin G antibodies were measured by an enzyme immunoabsorbent assay previously validated in children from the same population. RESULTS: H. pylori antibodies were present in 21/147 (14.3%) children aged 3 months to 14 years. Prevalence was not influenced by age or sex, but was greatest in children whose parents migrated from developing nations and lowest in children with Caucasian Australian or Western European parents (25.8 vs 5.9%; P < 0.001). An inverse relationship between social class and infection was also observed (P = 0.02). Multivariate analysis demonstrated the father's ethnic background as the only significant independent risk factor for H. pylori infection (P = 0.002). CONCLUSIONS: Although seroprevalence of H. pylori appears to be lower in Australian children than in developing countries there are some ethnic groups at substantially greater risk for the acquisition of H. pylori infection and its complications.     

Helicobacter pylori infection: prevalence and clinical relevance in a large company

Although gastrointestinal (GI) illnesses account for considerable sick absenteeism, there have been few workplace studies of GI disorders. We determined the prevalence of Helicobacter pylori infection by serology and assessed its relation to upper GI tract complaints, personal ulcer history, and family history of stomach cancer in 6,143 employees (mean age, 40.4 years) at BASF's main chemical production facilities in Ludwigshafen, Germany. Employees were recruited during occupational health clinic visits (n = 4,488) and through broad communications efforts (n = 1,655). Participation among clinic attendees was 66%, and this recruitment method was particularly effective in reaching shift employees. Positive immunoglobulin G (IgG) serology (38.2%), ulcers (4.9%), nonulcer dyspepsia (20.4%), and a family history of stomach cancer (6.1%) were common occurrences in this work setting. Further diagnostic evaluation and eradication therapy was recommended for 795 employees (12.9%), based on a combination of positive serology and either upper GI tract complaints or family stomach cancer history, and has been completed for 541 employees. A weak but consistent association was seen between positive serology and cigarette smoking, and shift work was found to be associated with positive serology, but not with ulcer or nonulcer dyspepsia occurrence.     

Heterogeneity in susceptibility to metronidazole among Helicobacter pylori isolates from patients with gastritis or peptic ulcer disease

Combination therapies that include metronidazole (MTZ) are the most successful therapies used in eradicating Helicobacter pylori. In this study, the prevalence and the relevance of heterogeneity in susceptibility to MTZ among H. pylori populations of 156 patients were evaluated. The results of this study show that 37 patients (24%) were infected with MTZ-resistant H. pylori (MIC > or = 8 micrograms/ml). Furthermore, 33% (52 of 156) of the patients were found to be infected with H. pylori populations heterogeneous for their susceptibility to MTZ. The reassessment of the MICs of MTZ for these 52 H. pylori populations revealed MTZ resistance in 28 of them, increasing the number of MTZ-resistant H. pylori populations among the 156 patients to 65 (42%). Out of 20 isolates, 2 (10%) heterogeneous in their susceptibility to MTZ also appeared to be heterogeneous at the genome level as determined by randomly amplified polymorphic DNA fingerprinting. In conclusion, the results show the limitations and risk of possible misinterpretations when only a single colony, picked from the primary H. pylori populations isolated from patients, is analyzed for its susceptibility to MTZ.     

Prevalence and pattern of Helicobacter pylori gastritis in the gastric cardia

OBJECTIVES: Helicobacter pylori has a predilection for antral colonization. Local acid production is the major determinant of colonization. Because production is low in the antrum and cardia, H. pylori should also colonize the cardia. We therefore investigated the histologic pattern of gastritis and the prevalence of H. pylori in the cardia compared with the antrum and corpus. METHODS: From 135 H. pylori-infected patients with gastritis, ulcer disease, or reflux esophagitis, biopsies were obtained from the antrum, corpus, and cardia. The prevalence, topography, and histologic parameters of gastritis were examined. RESULTS: All 135 patients had active antral H. pylori gastritis: in the cardia, 132 of these patients (97.7%) showed active gastritis, and 124 patients (91.9%) had H. pylori visible on staining. Gastritis of the cardia in most patients resembled antral gastritis, but the density of bacteria and the inflammatory responses were less marked. The most striking finding in the cardia of patients with gastroesophageal reflux was a lower density of bacteria compared with antrum and corpus. Intestinal metaplasia was found in 32 patients in antral mucosa (23.7%) versus 28 patients in the cardia (20.7%), versus 11 patients in the corpus (8.1%), and was multifocal in 17 patients (12.6%). CONCLUSIONS: H. pylori gastritis commonly involves the cardia. The histologic density of the bacteria and inflammatory responses are lower than in the antrum. Intestinal metaplasia in the cardia is a common finding in H. pylori gastritis. The cause of the lower bacterial density in the cardia of patients with reflux esophagitis needs further investigation.     

Nitazoxanide, a potential drug for eradication of Helicobacter pylori with no cross-resistance to metronidazole

Nitazoxanide, a thiazolide compound, and its desacetyl derivative, tizoxanide, have antimicrobial properties against anaerobic bacteria, as well as against helminths and protozoa. Because the treatment of Helicobacter pylori infection may be jeopardized by metronidazole resistance, nitazoxanide and tizoxanide were tested in vitro against these bacteria. The MICs of these two compounds were determined by agar dilution and were compared to those of metronidazole. Exposure to subinhibitory concentrations of nitazoxanide was also carried out by the method of Szybalski (W. Szybalski and V. Bryson, J. Bacteriol. 64:489-499, 1952). The MICs of nitazoxanide and tizoxanide for 103 strains ranged from 0.25 to 8 microg/ml, with the MIC at which 50% of strains are inhibited (MIC50) being 1 microg/ml and the MIC90 being 4 microg/ml, and no resistant strain was detected, whereas strains resistant to metronidazole were detected. When 10 strains were successively subcultured on medium containing nitazoxanide, no significant change in the MICs of this compound was observed. A pilot study of nitazoxanide for the treatment of H. pylori infection was carried out with 86 patients in association with 20 mg of omeprazole. An eradication rate of 83% (95% confidence interval, 64% to 94%) was obtained in a per-protocol analysis in the group receiving 1 g of nitazoxanide orally twice daily, and a few side effects were observed. The failures could not be explained by the selection of resistant strains since the MICs of nitazoxanide were similar for six pairs of isolates (proven to be the same strain by random amplified polymorphic DNA analysis in four cases) cultured before and after the treatment failure. Nitazoxanide exhibits good antimicrobial activity against H. pylori without the problem of acquired resistance which is encountered with metronidazole and has been demonstrated to have a satisfactory effect in a dose-ranging pilot study. It is therefore a good candidate to be included in treatment regimens aimed at the eradication of H. pylori.