Antibiotics for Drug-Resistant Bacterial Infections

Methicillin- and Vancomycin-Resistant Staphylococcus Aureus (MRSA/VRSA)

Credit: NIAID

Credit: NIAID

Overview: MRSA and VRSA are strains of Staphylococcus aureus, a gram-positive bacterium that causes hundreds of thousands of infections per year in the United States. These clinically significant strains of Staphylococcus have developed resistance to beta-lactam antibiotics like penicillins and cephalosporins. Some strains have emerging resistance to newer antibiotics like linezolid, daptomycin, and tigecycline. For MRSA, the first line of treatment is the glycopeptide antibiotic vancomycin, which can be expensive and time consuming to administer. Moreover, many clinicians believe that the efficacy of vancomycin against MRSA is inferior to that of anti-staphylococcal beta-lactam antibiotics against methicillin-susceptible Staphylococcus aureus. Several newly discovered strains of VRSA show antibiotic resistance to vancomycin and teicoplanin. 

Currently, fifth generation cephalosporins are used in the treatment of MRSA but they hold much smaller market share compared to generics like vanvomycin and teicoplanin (latter approved in EU). Coagulase-negative staphylococci have flourished in nosocomial environments where broad-spectrum cephalosporins have been used and glycopeptide-resistant enterococci and S. aureus have also emerged. To combat this emerging resistance, the United States, under the Generating Antibiotics Incentives Now Act (GAIN Act), has developed a shortened regulatory and review process for Qualified Infectious Disease Products (QIDPs) for antibiotics and antifungals.

Potential Regulatory Benefits: Qualified Infectious Disease Product Exclusivity, Fast-Track, Accelerated Review.

Market: The global MRSA therapeutics market stood at $1.45 billion in 2006, which then grew at a compound annual growth rate (CAGR) of 12.9% to reach $2.7 billion in 2011. The market is expected to grow at a CAGR of 3.4% over the next eight years to reach $3.5 billion by 2019. A first in class, extended spectrum antibiotic would provide another route to combat emerging resistance across a wide range of severe gram-positive infections and potentially peak at $450 million per year in global sales [6].