Comparison of the performance of serological kits for Helicobacter pylori infection with European and Asian study populations.

Most commercial kits for the detection of Helicobacter pylori were developed and validated with Western populations, and some have been found to perform less well with Asian populations. This study compared the performances of three serological kits with Swedish and Vietnamese peptic ulcer patients and asymptomatic individuals. The Pyloriset EIA-GIII and HM-CAP ELISA kits indicated that Asian populations had lower antibody titres to H. pylori than European populations. Despite the difference, the Pyloriset EIA-GIII kit performed well with Vietnamese peptic ulcer patients and population controls. The HM-CAP ELISA kit had a significantly lower performance with Asian populations that could not be improved by adjustments to the cut-off level. The Helicoblot 2.1 immunoblot kit performed equally well with Vietnamese and Swedish populations, although the response rate to the 35-kDa band was significantly lower with Vietnamese individuals.

Long-term follow-up of Helicobacter pylori eradication therapy in Vietnam: reinfection and clinical outcome.

AIM: To assess the long-term Helicobacter pylori reinfection rates, as well as the clinical outcome in peptic ulcer disease patients in Vietnam. METHOD: At a 1-year evaluation of H. pylori eradication treatment in 226 peptic ulcer patients, long-term H. pylori status was assessed with serology and/or culture, peptic ulcer status by gastroscopy, and DNA-fingerprinting performed with random amplified polymorphic DNA and restriction fragment polymorphism. RESULT: Follow-up was performed a mean 11 months after the post-treatment evaluation on day 30 after beginning of treatment. The overall reinfection rate was 23.5%, with 58.8% of the strains being identical to the pre-treatment isolates and 41.2% being different. Peptic ulcer was found in 22.9% of the reinfected patients and in 6.3% of the non-reinfected. At the long-term follow-up of successful eradication cases, 89.8% of the patients were free of peptic ulcer disease. The corresponding result was 58.7% in patients in whom H. pylori eradication failed. CONCLUSION: Following successful H. pylori eradication, reinfection with H. pylori in patients in Vietnam was found to be higher than in industrialized countries but the long-term recurrence of peptic ulcer disease was still low. Helicobacter pylori eradication treatment is therefore of value also in developing countries as the rate of peptic ulcer disease was low at the 1-year follow-up.

Helicobacter pylori eradication in children and adolescents by a once daily 6-day treatment with or without a proton pump inhibitor in a double-blind randomized trial.

AIM: To evaluate two simplified Helicobacter pylori eradication treatment alternatives for children and adolescents. METHODS: Study subjects were identified by enzyme-linked immunosorbent assay and immunoblot in a family screening project. Helicobacter pylori infected 10-21 year olds were offered treatment, individuals with abdominal pain underwent upper endoscopy and those with peptic ulcers were excluded. Participants were randomized to either azithromycin 500 mg daily and tinidazole 500 mg two tablets daily in combination with lansoprasole 30 mg daily for 6 days (ATL-group) or with placebo (ATP-group). Urea Breath Test was performed at inclusion and after a minimum of 6 weeks after end of therapy. RESULTS: In total, 131 individuals were randomized, of whom 31 (24%) had undergone upper endoscopy. Full compliance was achieved in 93% (122 of 131). The intention-to-treat eradication rate was 67% (44 of 66) and 58% (38 of 65) for the ATL- and the ATP-group, respectively. CONCLUSION: The double-blind randomized clinical trial did not identify a simplified, successful once daily H. pylori treatment for children and adolescents. Thus, twice daily proton pump inhibitor (PPI)-based triple therapies for 7 days remain as the choice of treatment in children. Further, powerful and controlled studies are needed to elucidate the best treatment strategies for H. pylori eradication in this age group.

The importance of the level of metronidazole resistance for the success of Helicobacter pylori eradication.

AIMS: To evaluate the role of antibiotic susceptibility for the treatment outcome of proton pump inhibitor-dependent and independent Helicobacter pylori eradication regimens. METHODS: In a placebo-controlled clinical study of peptic ulcer patients with H. pylori infection, patients were randomized to receive lansoprazole, clarithromycin and tinidazole twice-daily, clarithromycin and tinidazole once-daily with lansoprazole or with placebo. Helicobacter pylori status was assessed by culture and antibiotic susceptibility by E-test minimal inhibitory concentration (MIC) in 205 clinical isolates. RESULTS: Primary resistance to clarithromycin and metronidazole was 1 and 76%, respectively. In metronidazole susceptible strains eradication rates were similar at > 90% for all treatment groups (P = 0.49). With low-level metronidazole resistance (4 microg/mL < MIC < 256 microg/mL), eradication rates were similar at >75% (P = 0.80). The major difference was found at high-level metronidazole resistance (MIC >or= 256 microg/mL) with 95%, 58% and 21% eradication in the lansoprazole, clarithromycin and tinidazole twice-daily, lansoprazole, clarithromycin and tinidazole once-daily and placebo, clarithromycin and tinidazole once-daily groups, respectively (P < 0.001). CONCLUSION: In the absence of antibiotic resistance, a once-daily therapy of only clarithromycin and tinidazole can achieve a high rate of H. pylori eradication. Such a combination could offer a simpler and cheaper treatment option for developing countries. The standard, twice-daily proton pump inhibitor-based triple therapy was shown to be efficient in H. pylori eradication even in the presence of high-level metronidazole resistance.

Unexpected decrease with age of Helicobacter pylori seroprevalence among Swedish blood donors.

Blood donors are often used as proxies for the general population in studies of Helicobacter pylori epidemiology. Our aim was to test if the age-specific seroprevalence rates among blood donors match with the corresponding rates in a random population sample. This descriptive study was based on sera obtained from 3,502 blood donors representing all Swedish counties and cities. An age-stratified random population sample of 1,030 from Stockholm County served as comparison. Sera were analyzed by an in-house enzyme-linked immunosorbent assay for H. pylori immunoglobulin G antibodies. In the population sample, we found the expected increase with age in the seroprevalence of H. pylori infection. This was true also among young blood donors, while the prevalence-by-age curve showed a deflection downward among blood donors who are >/= 50 years of age. In this age group, the probability of being seropositive was reduced by 73% (95% confidence interval [CI], 63 to 81%) relative to the population sample. Overall, the adjusted odds ratio for H. pylori seropositivity among blood donors was decreased by 43% (95% CI, 28 to 55%). Thus, it appears that blood donors who are H. pylori seropositive selectively disappear from the blood donor cohort. We speculate that H. pylori-seropositive blood donors may tolerate repeated bleedings less well than do noninfected individuals and/or that the general well-being among those who are infected may be somewhat impaired. Our unexpected observation indicates that blood donors may be less suitable as proxies for the general population in analytic studies of H. pylori infection and that the underlying cause needs further study.

Helicobacter pylori eradication and peptic ulcer healing: the impact of deleting the proton pump inhibitor and using a once-daily treatment.

AIM: To compare cheaper and simpler once-daily regimens, with and without a proton pump inhibitor, with standard, twice-daily, triple therapy. METHODS: A randomized, placebo-controlled, treatment trial in Vietnam allocated 296 Helicobacter pylori-infected patients with peptic ulcer of >or= 5 mm to one of three regimens: (i) twice-daily: lansoprazole 30 mg, clarithromycin 250 mg and tinidazole 500 mg; (ii) once-daily: lansoprazole 60 mg, clarithromycin 500 mg and tinidazole 1000 mg; (iii) once-daily: placebo, clarithromycin 500 mg and tinidazole 1000 mg. H. pylori status was assessed by culture and immunoblot, ulcer healing by endoscopy and side-effects by structured questionnaires. RESULTS: Per protocol eradication (N = 256) was higher with standard therapy (87%) than with once-daily therapy (72%), and both were better than once-daily therapy without proton pump inhibitor (39%). Per protocol ulcer healing after standard therapy (83%) was not significantly better than that after once-daily therapy (73%), but better than that after therapy without proton pump inhibitor (65%). Side-effects were reported at similar rates in all groups. CONCLUSIONS: Proton pump inhibitor was needed for optimal eradication and ulcer healing. Twice-daily administration showed improved success rates when compared with once-daily therapies. Peptic ulcer healing was achieved even in patients treated with antibiotics only, confirming the central role of H. pylori in the pathophysiology of peptic ulcer disease.

Different trends in antibiotic resistance rates at a university teaching hospital.

OBJECTIVES: To investigate long-term trends in antibiotic resistance of common bacterial species isolated at a university hospital and in its intensive care units (ICUs). METHODS: Levels of antibiotic resistance of common bacterial pathogens were investigated at the Karolinska Hospital during the 12-year period 1988-99. Resistance rates were analyzed for the entire hospital, as well as for ICUs combined. RESULTS: At the Karolinska Hospital, we found increased ciprofloxacin resistance among Escherichia coli isolates, from 0% in 1991 to 11% in 1999. In the ICUs, the corresponding increase was from 0% to 4.8% during the same period. Co-trimoxazole resistance levels increased from 7.5% to 14%, with lower levels for the ICUs. For ampicillin, cefuroxime, and gentamicin, the levels of resistance were similar in the whole hospital and in the ICUs. Among Pseudomonas aeruginosa isolates, imipenem resistance was higher in the ICUs. For ciprofloxacin, resistance increased from 2.5% in 1991 to 13% in 1999 in the whole hospital, with similar figures for the ICUs. CONCLUSION: The resistance rates at the Karolinska Hospital were still generally low, but were increasing for some antibiotic-microbe combinations. The results emphasize the importance of including all sectors of a hospital in resistance surveillance studies, and also the value of long surveillance periods.

New species-related MIC breakpoints for early detection of development of resistance among gram-negative bacteria in Swedish intensive care units.

The frequency of decreased antibiotic susceptibility among 534 Gram-negative aerobic bacilli from patients admitted to intensive care units at eight hospitals in Sweden during 1997 was evaluated. MICs of cefepime, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem and piperacillin-tazobactam were determined using Etest. Reduced susceptibility (resistant and intermediate/indeterminate susceptible strains) was defined according to the MIC breakpoints of the British Society for Antimicrobial Chemotherapy (BSAC), the National Committee for Clinical Laboratory Standards (NCCLS) and the new species-related breakpoints of the Swedish Reference Group for Antibiotics (SRGA). The BSAC/NCCLS/SRGA breakpoints for susceptible category (mg/L) of Enterobacteriaceae are: cefepime, not available (NA)/8/0.5; ceftazidime, 2/8/2; ceftriaxone, NA/8/0.5; ciprofloxacin, 1/1/0.12; gentamicin, 1/4/2; imipenem, 4/4/1; and piperacillin-tazobactam, NA/16/16. The most frequently isolated organisms were Escherichia coli (n = 160; 30%), Klebsiella spp. (n = 84; 16%), Enterobacter spp. (n = 77; 14%), Pseudomonas aeruginosa (n = 64; 12%) andProteus spp. (n = 28; 5%). Decreased susceptibility among E. coliusing the BSAC/NCCLS/SRGA respective breakpoints (%) were: cefepime, NA/0/2; ceftazidime, 2/2/2; ceftriaxone, NA/1/2; ciprofloxacin, 2/2/8; gentamicin, 21/0/3; imipenem, 0/0/2; and piperacillin-tazobactam, NA/4/4. Corresponding levels of decreased susceptibility (%) among Klebsiellaspp. were: cefepime, NA/0/5; ceftazidime, 2/1/2; ceftriaxone, NA/1/10; ciprofloxacin, 4/4/19; gentamicin, 25/2/5; imipenem, 0/0/0; and piperacillin-tazobactam, NA/10/10; and among Enterobacter spp. were: cefepime, NA/1/19; ceftazidime, 30/29/30; ceftriaxone, NA/30/36; ciprofloxacin, 3/3/15; gentamicin,18/0/0; imipenem, 0/0/5; and piperacilllin-tazobactam, NA/27/27. In conclusion, the species-related SRGA breakpoints detected Gram-negative isolates with decreased susceptibility in comparison with the native population with higher frequency than did the NCCLS breakpoints. The BSAC breakpoints for susceptible organisms were similar to NCCLS for ciprofloxacin and imipenem, and similar to SRGA for ceftazidime but lower than both NCCLS and SRGA for gentamicin, causing a much higher frequency of decreased susceptibility to gentamicin.

Risk of development of in vitro resistance to amoxicillin, clarithromycin, and metronidazole in Helicobacter pylori.

We have studied initial killing, morphological alterations, the frequency of occurrence, and the selective growth of resistant subpopulations of Helicobacter pylori during exposure to amoxicillin, clarithromycin, or metronidazole by bioluminescence assay of intracellular ATP levels, microscopy, and a viable count assay. We found an induction of spheroplasts and a decrease in intracellular ATP levels after 21 h of exposure to high concentrations of amoxicillin. During clarithromycin exposure the onset of a decrease in intracellular ATP levels started after prolonged incubation, and with the highest concentration of clarithromycin an induction of coccoid forms was seen after 68 h. Metronidazole exposure resulted in the strongest initial decrease in intracellular ATP levels, and coccoid forms were seen after 21 h of exposure to high concentrations of metronidazole. Amoxicillin caused a low-level increase in resistant subpopulations, which indicates a need for surveillance of the amoxicillin susceptibility of H. pylori in order to detect decreasing susceptibility. No increase in the numbers of resistant subpopulations was demonstrated during clarithromycin exposure. Metronidazole selected resistant subpopulations, which caused high-level resistance in H. pylori.

Pharmacodynamic effects of antibiotics and acid pump inhibitors on Helicobacter pylori.

Pharmacodynamic studies of Helicobacter pylori exposed to amoxicillin, clarithromycin, metronidazole, omeprazole, and lansoprazole were performed with microscopy, viable count determination, and bioluminescence assay of intracellular ATP. The pharmacodynamic parameters determined were change in morphology, change in cell density, postantibiotic effect (PAE), and control-related effective regrowth time (CERT). The PAE is delayed regrowth after brief exposure to antibiotics or acid pump inhibitors. CERT was defined as the time required for the bacteria to resume logarithmic growth and return to the pre-exposure inoculum in the test culture minus the corresponding time for the control culture. CERT measures the combined effect of initial killing and PAE. There was a good concordance between the bioluminescence assay and viable counts for determining CERT, which makes this parameter useful for pharmacodynamic studies of the effects of antibiotics and acid pump inhibitors on H. pylori. Amoxicillin and metronidazole produced a strong, concentration-dependent initial decrease in CFU per milliliter, but there was a less prominent initial change in intracellular ATP in these cultures. Amoxicillin caused a long PAE when assayed by the bioluminescence assay but no PAE or a negative PAE when assayed by viable count determination. However, amoxicillin showed similar long CERTs with both methods. The pharmacodynamic effects of amoxicillin were concentration dependent up to a maximum response, indicating that concentrations above this level do not increase the antibiotic effect. The PAEs and CERTs of clarithromycin and metronidazole were concentration dependent with no maximum response. With omeprazole and lanzoprazole, there was no PAE or CERT.

Immediate repeat course of amoxycillin, metronidazole and omeprazole to eradicate Helicobacter pylori.

AIM: To investigate a repeat treatment regimen with the same antibiotic combination of amoxycillin and metronidazole in patients with continuing Helicobacter pylori infection. METHODS: Eighty-two patients with severe peptic ulcer disease and concurrent Helicobacter pylori infection were treated with a two week regimen of omeprazole (40 mg once daily), amoxycillin (750 mg t.d.s.) and metronidazole (400 mg t.d.s.). Upper gastrointestinal tract endoscopy was performed before, and approximately 2 months after, completion of antibiotic therapy. Biopsies were taken for rapid urease testing and the histological demonstration of H. pylori infection. Patients with persistent H. pylori infection at follow-up endoscopy were re-treated with a second and identical antibiotic treatment course. A subsequent endoscopic examination with accompanying biopsies was performed at least 6 weeks after the second treatment course and after a further 6, 18 and 30 months. RESULTS: Eradication of H. pylori was achieved in 69 patients (84%, 95% CI: 75-90%) after the first treatment. Four patients (4/82 = 5%) were withdrawn from the study because of side-effects. All of the remaining nine patients had their H. pylori infection eradicated after the second treatment course (95% CI: 70-100%). Seventy-eight patients had a follow-up examination after a median 30 months of the initial eradication of H. pylori, and all but one remained free of infection and none had an ulcer relapse. CONCLUSIONS: This study demonstrates that patients with persistent H. pylori infection after completing a primary course of omeprazole (40 mg once daily), amoxycillin (750 mg t.d.s.) and metronidazole (400 mg t.d.s.) will probably respond to a repeat course of treatment with the same antibiotic combination.

The diagnostic value of enzyme immunoassay and immunoblot in monitoring eradication of Helicobacter pylori.

55 patients with severe ulcer disease and H. pylori infection, successfully treated with antimicrobials, were followed-up with repeated blood samples for up to 32 months. Sera were analysed by enzyme immunoassay (EIA) for IgG and IgA antibodies and by IgG immunoblot. The EIA for IgG antibodies showed a high sensitivity (100%), while IgA antibodies above the cut-off level were found in 55% of the patients. At a median of 77 days after onset of treatment, approximately 50% of the patients showed a significant decrease (> or = 50%) of IgG or had titres below the cut-off level. All patients but 1 had a significant decrease of IgG after 6-12 months. The decrease was slower for IgA. The H. pylori-specific 116 kDa and 19.5 kDa bands were found in all pre-treatment samples, but the decrease in median intensity of the bands was slower than for the IgG EIA. In the 32-months post-treatment samples, both bonds had an intensity still above 50% of the pre-treatment value. The study showed that the IgG EIA is a useful method for monitoring eradication of H. pylori. Immunoblot can detect previous H. pylori infection in EIA negative Individuals.

Morphologic conversion of Helicobacter pylori from bacillary to coccoid form.

The morphologic conversion of Helicobacter pylori from bacillary to coccoid form was studied by microscopy, viable count on agar plates, and bioluminescence assay of bacterial ATP. When morphologic conversion from bacillary to coccoid form was detected by microscopy, the viable counts and the bacterial ATP decreased. No viable count was found after nine days of incubation, but bacterial ATP was still present. In these cultures in which only the coccoid form of Helicobacter pylori was present, there was no accumulation of extracellular ATP, indicating no leaky cells. During the transition phase from the bacillary to the coccoid form of Helicobacter pylori, the addition of fresh medium increased the intracellular ATP 26-fold. The coccoid form of Helicobacter pylori had a 1000-fold lower ATP level per cell compared to the bacillary form, which indicates a decreased metabolic activity in the coccoid form. Addition of fresh medium to the coccoid cultures from days 9 and 10 increased the ATP level twofold. However, no conversion from coccoid to bacillary form was found in these cultures during prolonged incubation in fresh broth for four weeks. Such conversion needs to be demonstrated before it is proven that the coccoid form of Helicobacter pylori is responsible for transmission and relapse of infection.