Antibiotic use-and misuse-is the main driver for selection of antibiotic resistant bacteria. This has led many countries to implement interventions designed to reduce overall antibiotic consumption. Now, using methicillin resistant Staphylococcus aureus (MRSA) as an example, Laura Temime of the Conservatoire National des Arts et Metiers, Paris, and collaborators warn that simply reducing antibiotics consumption does not necessarily reduce resistance. The research is published online ahead of print in Antimicrobial Agents and Chemotherapy.
The success of antibiotic reduction programs depends on which antibiotics are reduced, because some select more strongly for resistance than others. For instance, in the case of S. aureus, reducing use of clindamycin and methicillin lead to decreased resistance, while reducing use of penicillins does not, since most S. aureus, including MRSA, are already resistant to penicillin, explains Temime.
Additionally, efforts to reduce antibiotic use must be coordinated between hospitals and the community, since either can feed resistant bacteria into the other, undermining reduction efforts, says Temime.
In 2002-2003, a national program reduced antibiotic use in France by 10 percent. However, it fell short of the full potential for reducing resistance because it failed to target those antibiotics that generate the most resistance, says Temime. She and her collaborators developed a mathematical model of MRSA circulation, which correctly simulated that reduction, post-facto. They then performed a number of simulations of reductions in antibiotic use, which demonstrated the complexities of reduction efforts.