MRSA--the tip of the iceberg

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) strains cause serious nosocomial infections all over the world. Overall, approximately 20% of S. aureus isolates in Europe are reported as methicillin-resistant, whereas in US hospitals the prevalence ranges from 33% to 55%. The past few years have also witnessed an increase in life-threatening community-acquired infections caused by Panton-Valentine leukocidin-producing MRSA in the USA. Increasing use of glycopeptides for treatment of community-acquired MRSA infections may result in higher rates of glycopeptide resistance. Since 1996, five vancomycin-intermediate S. aureus (VISA; vancomycin MIC = 8-16 mg/L) strains have been identified in Europe, Asia and the USA, and vancomycin-resistant S. aureus (VRSA) strains (vancomycin MIC > or = 32 mg/L) have also been reported in the USA between 2002 and 2005. Most infections with VISA and VRSA have occurred in a setting of heavy prior use of glycopeptides and other antimicrobial agents. Emergence of reduced vancomycin susceptibility in S. aureus increases the possibility that currently available antimicrobial agents may become ineffective for treating systemic infections, especially bacteraemia, endocarditis and osteomyelitis. Ceftobiprole is a novel broad-spectrum cephalosporin with expanded activity against Gram-positive bacteria, including MRSA. Ceftobiprole is refractory to the development of endogenous resistance both in vitro and in vivo. The additional activity of ceftobiprole against MRSA strains makes it a potentially important addition to currently available agents.