INTRODUCTION
The recognition of Helicobacter pylori (H. pylori) infection as the main causative agent for gastro duodenal disorders had a drastic effect on related fields of research. As with most bacterial infections, successful treatment of H. pylori infection is highly dependent on the proper use of antibiotics. Additionally, various studies have demonstrated that the successful eradication of H. pylori is associated with a significant decrease in the incidence of duodenal ulcers1. Unfortunately, reports of antibiotic-resistant H. pyloriisolates have been increasing, and these do not respond to currently available therapeutic regimens.
The current treatment regimen for H. pylori infection consists of a proton pump inhibitor (PPI) and two commonly used antibiotics, such as metronidazole and amoxicillin or clarithromycin. As well, various other antibiotics have been suggested for use in combination with PPIs, including furazolidone, erythromycin, and tetracycline2,3.
Treatment of H. pylori infection with commonly available antibiotics is typically recommended for several digestive conditions, including peptic ulcers4. Although various antibiotics are used to treat H. pyloriinfections globally, current data indicates an increasing resistance to most traditional drugs5. Unfortunately, the efficacy of the recommended regimens has declined to an unacceptable level, and high antibiotic resistance rates have been reported among H. pylori strains isolated in northern Iran. The purpose of this report is to describe the case of a 31-year-old woman with two peptic ulcers in the duodenal antrum, who carried an H. pylori isolate that was resistant to seven antibiotics.
CASE REPORT
In 2010, the presence of H. pylori was detected in a 31-year-old woman with gastric cancer. The H. pyloriisolate was therefore cultured and tested for antibiotic susceptibility, using the agar dilution and disk diffusion methods6,7. Endoscopic observation indicated two 1×1cm peptic ulcers in the duodenal antrum, and there was no history of antibiotic or omeprazole use during the 5 months prior to her endoscopic surgery. Two antral biopsy specimens were obtained, and the first specimen was used for rapid urea testing (RUT) (Shim-Anzim, Iran). Within 2h of surgery, the second specimen was shipped in thioglycolate broth (Merck, Germany), within a cold-storage container, to a diagnostic laboratory.
Bacterial culture and serial plating was used to select a single, typical colony of H. pylori, as previously described6. Briefly, a 200µL sample of the homogenized biopsy issue was smeared on Columbia Agar plates (Merck, Germany), which were supplemented with 7% fetal calf serum and selectab tablets (MAST, UK), and incubated at 37°C under microaerophilic atmosphere for 7 days. H. pylori strain NCTC 11637 was used as a positive control for our susceptibility tests. Our results indicated that the patient’s H. pyloriisolate was resistant to all seven antibiotics that were tested: amoxicillin, tetracycline, clarithromycin, metronidazole, furazolidone, erythromycin, and ciprofloxacin.
DISCUSSION
As antibiotic resistance increases, therapeutic regimens to treat H. pylori infections may become less effective. Given the extended use ofmetronidazole and clarithromycin for gastrointestinal and upper respiratory diseases, the risk of strains developing resistance may also be increasing. Thus, the emergence of the highly resistant isolate described in this case should indicate the importance of performing antibiotic susceptibility testing prior to initiating antibiotic treatment. Based on this case, clinicians should consider the possibility that all patients infected with H. pyloriare resistant, unless data obtained from susceptibility tests indicates otherwise.
This case also highlights the need for alternative antibiotics, especially for treating patients who carry such antibiotic resistant strains. Under certain conditions, treatment regimens should be based on up-to-date, local, antibiotic resistance patterns, which can be obtained by assessing antibiotic resistance among local patients, and thus used to optimize therapeutic regimens and prevent treatment failure. Remarkably, the success of antibiotic treatments for H. pylori infection is affected by the possible occurrence of resistance phenomena. The distribution of resistance among H. pylori strains is a major outcome of overgrowth by a small population of resistant bacteria8.
Clearly, in regions with a high rate of H. pyloriinfection, it is likely that resistant strains can be isolated from the local community. Thus, public health measures play a critical role in preventing wide spread antibiotic resistance. Clinicians have expressed considerable interest regarding the ongoing use of the current formula for H. pylorieradication (PPI + amoxicillin and clarithromycin or metronidazole) in Iran, although it would not be surprising if this formula were to failin the future. Development of alternative regimens for the eradication of H. pylori would be an invaluable advancement, although all alternative antibiotics would need to be specifically evaluated for use in various populations.
In conclusion, this report should alert the Iranian medical community that a super-resistant H. pylori strain exists in the region. To prevent the spread and re-emergence of these rogue isolates, adherence to infection control recommendations, antibiotic susceptibility screening, and surveillance are all necessary. The use of antibiotics as first-line treatments may be appropriate if they are selected based on local data and susceptibility test results.
