Activity of quinupristin/dalfopristin against gram-positive bacteria: clinical applications and therapeutic potential.

In recent years there has been a dramatic worldwide increase in the prevalence of multiple drug-resistant strains of common Gram-positive bacteria. This highlights the need for a new class of antibiotic with activity against these organisms. Quinupristin/dalfopristin, the first injectable streptogramin antibiotic, has a unique spectrum of activity, encompassing most Gram-positive cocci (including multi-drug-resistant strains), respiratory pathogens and anaerobes, Gram-positive, and a prolonged post-antibiotic effect. Quinupristin/ dalfopristin is active in vitro against multi-drug-resistant isolates of Staphylococcus aureus, coagulase-negative staphylococci, penicillin-resistant pneumococci and vancomycin-resistant Enterococcus faecium. Clinical case reports have shown that the combination is active against intra-abdominal, aortic graft, bacteraemia and hydrocephalus shunt infections caused by multi-drug-resistant enterococci, particularly E. faecium. In almost all of these clinical situations the enterococcal infection had displayed resistance to all other antimicrobial therapies. Preliminary clinical data have demonstrated the activity of quinupristin/ dalfopristin against S. aureus bacteraemia, and quinupristin/dalfopristin may also prove useful in the treatment of pneumococcal infections. Thus, possible future applications of the combination include the treatment of multi-drug-resistant strains of staphylococci, streptococci and enterococci. Quinupristin/dalfopristin may prove useful in the treatment of staphylococcal infections in children, invasive systemic pneumococcal infections, and nosocomial and community-acquired Gram-positive infections in patients unable to tolerate beta-lactam antimicrobial agents or glycopeptide antibiotics.