Data published in Antimicrobial Agents and Chemotherapy suggest that overall reductions in antibiotic use may not be enough to reduce antibiotic resistance, and class-specific changes in antibiotic use also should be considered.
“Many countries worldwide have implemented nationwide campaigns aimed at reducing unnecessary antibiotic use,” Laura Temime, PhD, of the Laboratoire Modélisation et Surveillance des Risques pour la Sécurité Sanitaire, Conservatoire national des Arts et Métiers in Paris, told Infectious Disease News. “However, while these campaigns were often successful — in the sense that antibiotic use did decrease in the short term — their actual impact on antibiotic resistance remains unclear.”
Temime and colleagues developed a model transmission of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA). Using this model, they assessed antibiotic use by antibiotic classes. They evaluated changes in antibiotic use following an antibiotic reduction campaign, and they also analyzed the impact of a 10% reduction in antibiotic use over 1 year, specifically on MRSA dissemination.
According to the model, the frequency of hospital MRSA among carriers of S. aureus decreased from 39% to 36%. The final MRSA frequency among patients in the ICU ranged from 12.4% to 59.5% in ICUs, and from 3.4% to 7.4% in the community. The researchers found that when the use of antibiotics to which all S. aureus are resistant and susceptible increased, the frequency of MRSA decreased in hospital and community settings. But if there was increased use of antibiotics only effective on MSSA or community-acquired MRSA, the frequency of MRSA increased.
“Our research shows that class-specific changes in antibiotic use, rather than overall reductions, need to be considered to properly anticipate the impact of an antibiotic reduction campaign,” Temime said. “We believe that this research may help health policy makers and physicians design more efficient antibiotic reduction campaigns.”
In future studies, Temime said she would like to investigate the impact of coupling hospital and community infections in terms of resistance, specifically whether there is a risk for community-associated bacteria acquiring new resistance genes in the hospital setting before returning to the community.
Disclosure: Temime reports no relevant financial disclosures.