Antimicrobial resistance to drugs: a mathematical model to guide treatment decisions

Multidrug resistance (MDR) is an increasing problem for the treatment of infectious diseases; nearly 500,000 new cases of multidrug-resistant tuberculosis emerge each year, and a large number of hospital-acquired infections are caused by resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). Recently, the first case of antibiotic-resistant gonorrhea was documented, and the World Health Organisation (WHO) has warned that “unless action is taken now [against antibiotic-resistant infections], we will not have any cure available for common infectious diseases”.

In a new study published in BMC Medicine, Uri Obolski and Lilach Hadany from Tel Aviv University used a mathematical modeling approach to investigate mechanisms of bacterial antibiotic resistance and predict the best strategy to minimize MDR.

Three different strategies are commonly used to treat infection and reduce the emergence of MDR. In the cycling regime, all patients are given the same drug, which is periodically switched; in the mixing strategy each patient is given a randomly-selected drug, and in the combining strategy several antibiotics are given to each patient.

Obolski and Hadany show that the optimal strategy for controlling MDR depends upon the mechanism by which bacteria acquire resistance. When resistance occurs via stress-induced horizontal gene transfer, the authors recommend that cycling and mixing are the most effective strategies, and how fast bacteria respond to environmental changes determines the preference between these two strategies.

Albert Sotto and Jean-Philippe Lavigne from Montpellier University comment on the implications of these findings, discussing how there is currently a lack of new antibacterial agents in development. They recommend that the mechanisms of MDR should be taken into account when making decisions about antibiotic treatment.

Future work building on this research should address how to incorporate bacterial mechanisms of MDR into clinical decision making, as well as developing new agents to treat MDR and campaigns to educate healthcare workers, in a multidisciplinary approach to overcome antibiotic resistance.

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