Novel pharmaceutical molecules against emerging resistant gram-positive cocci.

INTRODUCTION: methicillin- and also vancomycin (glycopeptide)-resistant Gram-positive organisms have emerged as an increasingly problematic cause of hospital-acquired infections, also spreading into the community. Vancomycin (glycopeptide) resistance has emerged primarily among Enterococci, but the MIC values of vancomycin for the entire Staphylococcus species are also increasing worldwide.
MATERIAL AND METHODS: the aim of our review is to evaluate the efficacy and tolerability of newer antibiotics with activity against methicillin-resistant and glycopeptide-resistant Gram-positive cocci, on the ground of our experience at a tertiary care metropolitan Hospital, and the most recent literature evidences in this field.
RESULTS: Quinupristin-dalfopristin, linezolid, daptomycin, and tigecycline show an excellent in vitro activity, comparable to the activity of vancomycin and teicoplanin for methicillin-resistant staphylococci, and superior to the one that vancomycin for vancomycin-resistant isolates. Dalbavancin, televancin, and oritavancin are new lipoglycopeptide agents with excellent activity against Gram-positive cocci, and have superior pharmacodynamics properties compared to vancomycin. We review the bacterial spectrum, clinical indications and practical use, pharmacologic properties, and expected adverse events and contraindications associated with each of these novel antimicrobial agents, compared with the present standard of care. DISCUSSION: linezolid activity is substantially comparable to that of vancomycin in patients with methicillin-resistant Staphylococcus aureus (MRSA) pneumonia, although its penetration into the respiratory tract is exceptionally elevated. Tigecycline has activity against both Enterococus species and MRSA; it is also active against a broad spectrum of Enterobacteriaceae and anaerobes, which allows for use intraabdominal, diabetic foot and surgical infections. Daptomycin has a rapid bactericidal activity for Staphylococcus aureus and it is approved in severe complications, such as bacteremia and right-sided endocarditis. It cannot be used to treat pneumonia and respiratory diseases, due to its inactivation in the presence of pulmonary surfactant.