Julie Morris

The relationship among previous antimicrobial use, antimicrobial resistance, and treatment outcomes for Helicobacter pylori infections

Context Adverse effects of previous antibiotic use in patients with Helicobacter pylori infections are unclear. Contribution This retrospective study examined relationships between resistant H. pylori infections and past antibiotic use in 125 Alaskan Native adults. Clarithromycin-resistant H. pylori isolates were common (prevalence, 30%) and were associated in a dose-response manner with previous use of macrolide antibiotics. Of patients with these resistant isolates, 77% had treatment failure with clarithromycin-based regimens. Implications Previous use of macrolide antibiotics is associated with increased risk for infection with clarithromycin-resistant H. pylori and increased risk for treatment failure with that antibiotic. The Editors Helicobacter pylori is a common pathogen of the gastric mucosa, infecting up to 40% of persons in developed countries and up to 90% of individuals living in developing nations (1, 2). Infection with H. pylori has been shown to be a major cause of gastric and duodenal ulcers and is also associated with chronic gastritis, mucosa-associated lymphoid tissue lymphoma, and adenocarcinoma of the stomach (3-6). Eradication of H. pylori has been reported in up to 95% of patients treated with a combination of antimicrobial agents (7-9). In the United States and elsewhere, antimicrobial resistance to metronidazole and clarithromycin is increasing; resistance to amoxicillin and tetracycline remains uncommon (10-12). Compared with persons with susceptible isolates, persons infected with clarithromycin- or metronidazole-resistant H. pylori have lower cure rates when treated with regimens containing these antimicrobial agents (12-15). In studies that have addressed risk factors associated with resistant H. pylori infection, none to our knowledge have evaluated prediagnosis antimicrobial use as a risk factor for resistance or treatment failure (16, 17). Alaska Nativespersons of Eskimo, Indian, and Aleut descenthave high rates of H. pylori infection, with an overall seroprevalence of 75% for specific antibodies (18). We are conducting a study in urban Alaska Native, rural Alaska Native, and urban non-Native adults to determine and compare reinfection rates after successful eradication of H. pylori. The study in urban Alaska Native adults is completed, and in this group, we sought to determine whether past antimicrobial use was associated with antimicrobial resistance among H. pylori isolates obtained through diagnostic endoscopy. We then determined whether H. pylori antimicrobial resistance affected the outcome of H. pylori treatment. Methods From September 1998 through June 2002, the Arctic Investigations Program of the U.S. Centers for Disease Control and Prevention and the Alaska Native Medical Center (ANMC) conducted a study to determine reinfection rates after successful eradication of H. pylori infection among Alaska Natives living in Anchorage. The ANMC is a 150-bed referral hospital that provides outpatient primary care services for Alaska Natives living in the Anchorage area. The institutional review boards of the Centers for Disease Control and Prevention, the Alaska Area Tribal Health Consortium, and the Indian Health Service approved the study, as did the Alaska Native Health Board. Written informed consent was obtained from all participants. Patients and Data Collection From September 1998 through June 2002, we attempted to recruit all Alaska Natives 18 years of age or older from the Anchorage area who had no history of an immunodeficiency condition or were not taking immunosuppressive medications (such as corticosteroids or cancer chemotherapeutic agents) and were scheduled for esophagogastroduodenoscopy. Alaska Natives who use ANMC for surgical procedures are very likely to receive most of their care from this facility, since no copayment is assessed to persons eligible for care at ANMC. A study nurse recruited 293 persons during the study period, 149 of whom had a positive culture for H. pylori. Since 27 September 1990, patient care information from all outpatient health care visits and outpatient pharmacy encounters at ANMC has been entered into a computerized records system. For this analysis, we recorded all antimicrobial prescriptions for 10 years before diagnosis of H. pylori infection by consulting outpatient records of study participants for whom at least 8 years of pharmacy records were available. We also recorded antimicrobial use during all hospitalizations and emergency department visits at ANMC for each participant in the same 10-year period. An antimicrobial course was defined as a prescription for an antimicrobial drug regardless of dose, duration, and frequency. Biopsy and Culture All participants had up to 3 gastric biopsy specimens taken for culture, antimicrobial susceptibility testing, and histologic examination for H. pylori. Gastric biopsy specimens stored in cysteine freeze medium at 80 C were ground in a sterile tissue grinder with heat-inactivated fetal bovine serum and inoculated to 3 types of solid media: blood agar (tryptic soy agar with 5% sheep blood); chocolate agar; and brucella agar containing 10% horse blood, trimethoprim, vancomycin, and polymyxin B. All cultures were incubated at 37 C under microaerophilic conditions and high humidity (12% CO2, 98% humidity) for up to 10 days. Positive cultures were usually identified after 3 to 5 days of incubation. Isolates were identified as H. pylori on the basis of positive catalase, oxidase, and urease reactions; typical uniform, small, translucent colonies; curved gram-negative bacilli on Gram-stained smears; susceptibility to cephalothin (30 g); and resistance to nalidixic acid (30 g). Minimum inhibitory concentrations (MICs) for clarithromycin, amoxicillin, metronidazole, and tetracycline were determined by using agar dilution. Helicobacter pylori isolates were defined as susceptible if the MIC was within the following limits: less than or equal to 0.25 g/mL for clarithromycin, less than or equal to 0.25 g/mL for amoxicillin, less than 8 g/mL for metronidazole, and less than 2 g/mL for tetracycline. Helicobacter pylori isolates with MICs above these limits were classified as resistant (19). In participants who had many cultures of their H. pylori isolates, the highest MIC determined from all of the cultures was used for analysis. Culture results were not available to providers before initiation of treatment. Treatment and Follow-up Each participants attending physician decided whether to initiate treatment and selected the treatment regimen. Patients who were treated received a 2-week course of a combination of 2 or 3 antibiotics plus lansoprazole. A study nurse called each patient approximately every 3 days to document adherence. Successful eradication of H. pylori was defined as negative results on a urea breath test (BreathTek UBT, Meretek Diagnostics, Inc., Nashville, Tennessee) 8 weeks after initiation of treatment. Statistical Analysis Statistical analysis was performed by using StatXact 5 (Cytel Software Corp., Cambridge, Massachusetts) and SAS software (SAS Institute, Inc., Cary, North Carolina). Confidence intervals for binomial proportions were computed by using the Casella procedure (20). Bivariate associations were examined by using the chi-square test or the Fisher exact test for dichotomous variables. The Wilcoxon rank-sum test was used for comparisons of continuous variables. Logistic regression was used to test univariable dose-response relationships and multivariable associations with antimicrobial resistance. Variables were considered for the multivariable models if their univariable P value was less than 0.25, with the exception of sex, which was included in all models. The numbers of courses of macrolides, clarithromycin, erythromycin, azithromycin, and metronidazole were entered into the multivariable models as indicator variables ( 1 course or 0 courses), while the number of all other courses of antibiotics was entered as an interval variable. Variables were considered confounders and remained in the model if their exclusion changed the value of the coefficients of interest by more than 15%. All P values are two-sided, and confidence intervals are exact when appropriate. Results One hundred forty-nine persons with culture-confirmed H. pylori infection were enrolled in the study. Of these, 125 who had documented health encounters for at least 8 years before enrollment (84%) were included for analysis. The median age of participants was 46.5 years (range, 22.2 to 88.7 years). Eighty-two (66%) were women, and all were Alaska Natives. Pharmacy records were available for a median of 8.6 years (range, 8.0 to 9.6 years). A median of 11 (range, 0 to 68) antimicrobial courses was prescribed during the 8 to 10 years before enrollment (mean, 1.52 courses per year). For -lactam antimicrobial agents and macrolide antimicrobial agents, the median number of courses prescribed was 5 (range, 0 to 31) and 1 (range, 0 to 11), respectively. The median number of courses for all other classes of antimicrobial agents prescribed (including metronidazole) was 3 (range, 0 to 30). Thirteen patients (10%) had received previous treatment for H. pylori infection in the 10 years before enrollment. Clinical symptoms included heartburn (75%), nausea (72%), vomiting (40%), and hematemesis (11%). Endoscopic findings included hemorrhagic or superficial ulcerations of the gastric mucosa in 56 patients (45%), duodenal ulcers in 4 (3%), and gastric ulcers in 8 (6%). Two specimens of the gastric mucosa were obtained for culture from 105 participants (84%) at the time of diagnosis. Seventeen patients (14%) had a single specimen submitted for culture, and 3 (2%) had 3 or more specimens. Among the 125 participants, 83 (66%) were found to have H. pylori isolates resistant to metronidazole, 37 (30%) were found to have H. pylori isolates resistant to clarithromycin, 7 (6%) were found to have H. pylori isolates resistant t

The Relationship between Previous Fluoroquinolone Use and Levofloxacin Resistance in Helicobacter pylori Infection

The relationship between prior fluoroquinolone use and levofloxacin resistance in Helicobacter pylori infection is unknown. Among 125 enrolled patients, 8.8% had H. pylori isolates that were resistant to levofloxacin. Levofloxacin resistance was associated with any prior fluoroquinolone use over the previous 10 years and with the total number of fluoroquinolone courses prescribed (P<.001).

Alaska Sentinel Surveillance for Antimicrobial Resistance in Helicobacter pylori Isolates from Alaska Native Persons, 1999–2003

Background:  Previous studies in Alaska have demonstrated elevated proportions of antimicrobial resistance among Helicobacter pylori isolates.

Evaluation of seaFAST, a rapid fluorescent in situ hybridization test, for detection of Helicobacter pylori and resistance to clarithromycin in paraffin-embedded biopsy sections.

ABSTRACT A commercially available rapid fluorescent in situ hybridization (FISH) test, (seaFAST H. pylori Combi-Kit; SeaPro Theranostics International, Lelystad, The Netherlands) was used to simultaneously detect the presence of Helicobacter pylori and determine clarithromycin susceptibility in paraffin-embedded biopsy sections. The FISH method was found to be 97% sensitive, 94% specific for the detection of H. pylori and comparable to agar dilution for the detection of resistance to clarithromycin.

Characterization of Helicobacter pylori cagA and vacA Genotypes among Alaskans and Their Correlation with Clinical Disease

ABSTRACT Helicobacter pylori infection is common in Alaska. The development of severe H. pylori disease is partially determined by the virulence of the infecting strain. Here we present vacA and cagA genotype data for H. pylori strains isolated from Alaskans and their correlation with clinical disease. We enrolled patients scheduled for esophagogastroduodenoscopy and positive for H. pylori infection. Gastric biopsy specimens from the stomach antrum and fundus were cultured. We performed PCR analysis of the H. pylori vacA gene and for the presence of the cagA gene and cagA empty site. We genotyped 515 H. pylori samples from 220 Native and 66 non-Native Alaskans. We detected the cagA gene in 242/286 (85%) persons; of 222 strains that could be subtyped, 95% (212) were non-Asian cagA and 3% (6) were East Asian cagA. After removing mixed infections (n = 17), 83% of H. pylori strains had either the vacA s1m1 (120/269) or s2m2 (103/269) genotype. Sixty-six percent (68/103) of H. pylori strains with the vacA s2m2 genotype also contained the cagA gene. Infection with an H. pylori strain having the cagA gene or vacA s1m1 genotype (compared with s1m2 and s2m2) was associated with a decreased risk of esophagitis (P = 0.003 and 0.0003, respectively). Infection with an H. pylori strain having the vacA s1m1 genotype (compared with s1m2 and s2m2) was associated with an increased risk of peptic ulcer disease (PUD) (P = 0.003). The majority of H. pylori strains in this study carried the non-Asian cagA gene and either the vacA s1m1 or s2m2 genotype. A majority of H. pylori strains with the vacA s2m2 genotype also contained the cagA gene. There was an association of H. pylori genotype with esophagitis and PUD.

Reinfection after successful eradication of Helicobacter pylori : a 2-year prospective study in Alaska Natives

Background  Limited information exists regarding risk factors for reinfection after cure of Helicobacter pylori infection.

Alaska Sentinel Surveillance Study of Helicobacter pylori Isolates from Alaska Native Persons from 2000 to 2008

ABSTRACT Helicobacter pylori infection is more common in Alaska Native persons than in the general U.S. population, with seroprevalence to H. pylori approaching 75%. Previous studies in Alaska have demonstrated elevated proportions of antimicrobial resistance among H. pylori isolates. We analyzed H. pylori data from the Centers for Disease Control and Preventions sentinel surveillance in Alaska from January 2000 to December 2008 to determine the proportion of culture-positive biopsy specimens with antimicrobial resistance from Alaska Native persons undergoing endoscopy. The aim of the present study was to monitor antimicrobial resistance of H. pylori isolates over time and by region in Alaska Native persons. Susceptibility testing of H. pylori isolates to metronidazole, clarithromycin, amoxicillin, and tetracycline was performed using agar dilution. Susceptibility testing for levofloxacin was performed by Etest. Overall, 45% (532/1,181) of persons undergoing upper endoscopy were culture positive for H. pylori. Metronidazole resistance was demonstrated in isolates from 222/531 (42%) persons, clarithromycin resistance in 159/531 (30%) persons, amoxicillin resistance in 10/531 (2%) persons, and levofloxacin resistance in 30/155 (19%) persons; no tetracycline resistance was documented. The prevalence of metronidazole, clarithromycin, and levofloxacin resistance varied by region. Female patients were more likely than male patients to demonstrate metronidazole (P < 0.05) and clarithromycin (P < 0.05) resistance. No substantial change in the proportion of persons with resistant isolates was observed over time. Resistance to metronidazole, clarithromycin, and levofloxacin is more common among H. pylori isolates from Alaska Native persons than those from elsewhere in the United States.

Diagnostic accuracy of tests for Helicobacter pylori in an Alaska Native population.

AIM To evaluate the accuracy of two non-invasive tests in a population of Alaska Native persons. High rates of Helicobacter pylori (H. pylori) infection, H. pylori treatment failure, and gastric cancer in this population necessitate documentation of infection status at multiple time points over a patients life. METHODS In 280 patients undergoing endoscopy, H. pylori was diagnosed by culture, histology, rapid urease test, (13)C urea breath test (UBT), and immunoglobulin G antibodies to H. pylori in serum. The performances of (13)C-UBT and antibody test were compared to a gold standard defined by a positive H. pylori test by culture or, in case of a negative culture result, by positive histology and a positive rapid urease test. RESULTS The sensitivity and specificity of the (13)C-UBT were 93% and 88%, respectively, relative to the gold standard. The antibody test had an equivalent sensitivity of 93% with a reduced specificity of 68%. The false positive results for the antibody test were associated with previous treatment for an H. pylori infection [relative risk (RR) = 2.8]. High levels of antibodies to H. pylori were associated with chronic gastritis and male gender, while high scores in the (13)C-UBT test were associated with older age and with the H. pylori bacteria load on histological examination (RR = 4.4). CONCLUSION The (13)C-UBT outperformed the antibody test for H. pylori and could be used when a non-invasive test is clinically necessary to document treatment outcome or when monitoring for reinfection.

Reinfection after successful eradication of Helicobacter pylori in three different populations in Alaska

We performed a study to determine rates of reinfection in three groups followed for 2 years after successful treatment: American Indian/Alaska Native (AI/AN) persons living in urban (group 1) and rural (group 2) communities, and urban Alaska non-Native persons (group 3). We enrolled adults diagnosed with H. pylori infection based on a positive urea breath test (13C-UBT). After successful treatment was documented at 2 months, we tested each patient by 13C-UBT at 4, 6, 12 and 24 months. At each visit, participants were asked about medication use, illnesses and risk factors for reinfection. We followed 229 persons for 2 years or until they became reinfected. H. pylori reinfection occurred in 36 persons; cumulative reinfection rates were 14·5%, 22·1%, and 12·0% for groups 1, 2, and 3, respectively. Study participants who became reinfected were more likely to have peptic ulcer disease (P = 0·02), low education level (P = 0·04), or have a higher proportion of household members infected with H. pylori compared to participants who did not become reinfected (P = 0·03). Among all three groups, reinfection occurred at rates higher than those reported for other US populations (<5% at 2 years); rural AI/AN individuals appear to be at highest risk for reinfection.

Persistence of antibody to Hepatitis A virus 20 years after receipt of Hepatitis A vaccine in Alaska

Hepatitis A vaccine is recommended for children ≥1 year old to prevent hepatitis A virus (HAV) infection. However, the duration of vaccine‐induced immunity is unknown. We evaluated a cohort of Alaska Native persons 20 years after HAV vaccination. Children aged 3‐6 years had been previously randomized to receive three doses of HAV vaccine (360 ELISA units/dose) at: (i) 0,1,2 months; (ii) 0,1,6 months; and (iii) 0,1,12 months. We measured anti‐HAV antibody concentrations every 2‐3 years; described geometric mean concentrations (GMC) and the proportion with protective antibody (≥20 mIU mL‐1) over time; and modelled the change in GMC using fractional polynomial regression. Of the 144 participants, after 20 years 52 (36.1%) were available for the follow‐up (17, 18, 17 children in Groups A, B and C, respectively). Overall, 46 (88.5%) of 52 available participants had anti‐HAV antibody concentrations ≥20 mIU mL‐1, and overall GMC was 107 mIU mL‐1. Although GMC levels were lower in Group A (60; CI 34‐104) than in Group B (110; CI 68‐177) or Group C (184; CI 98‐345) (B vs C: P=.168; A vs B/C: P=.011), there was no difference between groups after adjusting for peak antibody levels post‐vaccination (P=.579). Models predicted geometric mean concentrations of 124 mIU mL‐1 after 25 years, and 106 mIU mL‐1 after 30 years. HAV vaccine provides protective antibody levels 20 years after childhood vaccination. Lower antibody levels in Group A may be explained by a lower initial peak response. Our results suggest a booster vaccine dose is unnecessary for at least 25‐30 years.