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Factors Associated with Helicobacter pylori Infections in the United States That Are Resistant to Usual Antibiotics
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What is the problem and what is known about it so far?
Helicobacter pylori is a type of bacteria that can cause stomach ulcers. Infection with H. pylori is usually successfully treated with a combination of several antibiotics. However, some H. pylori bacteria are able to grow despite treatment with the usual antibiotics. Such bacteria are “antibiotic resistant.” If doctors knew the information that predicts when a patient will be resistant to treatment, they could be alert for possible resistance before they treat a patient who is at high risk for infection by resistant bacteria. However, no one has fully described what characteristics place patients at risk for H. pylori resistance.
Why did the researchers do this particular study?
To estimate how frequently antibiotic-resistant H. pylori infection occurs in the United States and to identify factors associated with resistance.
Who was studied?
The researchers studied 3624 patients with H. pylori infection who had participated in 1 of 20 studies of treatment of H. pylori infection.
How was the study done?
The researchers of the present study contacted the researchers who led the 20 past studies and collected information on whether each patient's infection was resistant to any of three antibiotics (clarithromycin, metronidazole, and amoxicillin). They also collected patients' characteristics, such as age, state of residence, sex, ethnicity, presence or past occurrence of a stomach ulcer, and method used to test for H. pylori. They then calculated the frequency of resistant H. pylori infection and searched for associations between the patient characteristics and resistance to antibiotics.
What did the researchers find?
Overall, 10% of infections were resistant to clarithromycin, 37% were resistant to metronidazole, and 1% were resistant to amoxicillin. Patients who lived in the northeastern or mid-Atlantic regions of the United States, were older, were women, and had no active ulcer were more likely to have resistance to clarithromycin than patients without these factors. Patients who were women, Asian, or were in 1 of the 20 included studies in the earlier 1990s were most likely to have metronidazole resistance. Amoxicillin resistance was very infrequent and was not associated with any patient characteristics.
What were the limitations of the study?
Resistance patterns for bacteria vary over time, so it is not known whether these results, which were based on data from 1993 to 1999, apply to current times. This study also does not tell us whether knowing that these patients were at risk for resistance would have improved their outcomes.
What are the implications of the study?
Doctors should consider the factors identified to be associated with clarithromycin and metronidazole resistance. When a patient has these factors, doctors may choose to test for resistance or prescribe an alternate antibiotic treatment for H. pylori.
Article and Author Information
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The summary below is from the full report titled “Risk Factors for Helicobacter pylori Resistance in the United States: The Surveillance of H. pylori Antimicrobial Resistance Partnership (SHARP) Study, 1993–1999.” It is in the 1 January 2002 issue of Annals of Internal Medicine (volume 136, pages 13-24). The authors are JM Meyer, NP Silliman, W Wang, NY Siepman, JE Sugg, D Morris, J Zhang, H Bhattacharyya, EC King, and RJ Hopkins.
- Copyright ©2004 by the American College of Physicians
