One of the most important problems faced by health care providers today is antimicrobial resistance. For years, the Centers for Disease Control and Prevention has been educating providers regarding the judicious use of antibiotics to stem the problem of resistance.1 Despite these efforts, inappropriate use of antibiotics in primary care is still a major problem. One estimate suggests that 50% of prescriptions for respiratory tract infections, which account for approximately half of the antibiotics prescribed in the community setting, are unnecessary.2 This type of behavior is a major problem because it is well established that excessive and inappropriate use of antibiotics can lead to the development of resistance in communities.3,4 Whether these same behaviors can lead to the development of resistance among the individuals who are taking them inappropriately is less clear at this time, particularly in the primary care setting.
To examine whether the use of antibiotics leads to the development of resistance among individuals, Costelloe and colleagues performed a systematic review and meta-analysis of studies investigating subsequent antibiotic resistance among individuals prescribed antibiotics in primary care.5 They identified 4373 potential studies, but only 24 met the inclusion criteria and were included in the review. Two independent reviewers assessed the quality of the eligible studies and extracted the data. For studies that had similar outcomes, meta-analyses were conducted when possible. Their main aim was to identify if there was an association between antibiotic use and development of resistance among individuals in the primary care setting. In addition, researchers wanted to quantify the strength and duration of such association.
Researchers found a significant increase in resistance from both urinary [odds ratio (OR) 2.5, 95% confidence interval (CI) 2.1-2.9] and respiratory (OR 2.4, 95% CI 1.4-3.9) isolates after 2 months of antibiotic treatment. Patients continued to experience higher resistance rates for up to a year with 12-month odd ratios of 1.33 (95% CI 1.2-1.5) and 2.4 (95% CI 1.3-4.5) for urinary and respiratory isolates, respectively. Longer duration and multiple courses of antibiotics were associated with higher rates of resistance. However, no antibiotic in particular was associated with a greater likelihood of inducing resistance. One of the limitations in this analysis was the heterogeneity of the studies included. Despite the authors’ efforts, residual heterogeneity was a problem for some time periods of the pooled analysis of both urinary and respiratory bacteria. Another limitation was that a positive publication bias was noted for urinary bacteria studies, but not enough studies were available to assess publication bias for respiratory flora. Lastly, adherence with antibiotics was not assessed as most of the studies were retrospective.
In conclusion, this analysis provides evidence of a strong association between recent antibiotic use and the development of resistance among individuals in the primary care setting. Moreover, it quantifies this risk, which appears to be greater the more antibiotics a patient receives, and persists for up to a year following initial antibiotic use. What this means for clinicians is ...