Over the last three decades, there has been the recognition of a very disturbing trend of antibiotic resistance amongst a wide variety of pathogens that are causing serious disease in patients residing in the community, in long-term care facilities, and in hospitals. Especially troublesome have been Streptococcus pneumoniae that may be resistant to penicillin and/or fluoroquinolones; Staphylococcus aureus, including all methicillin-resistant S. aureus (MRSA) variants, and rarely, those that may be resistant to vancomycin, linezolid, or daptomycin; Enterococcus spp. that are not susceptible to ampicillin, vancomycin, linezolid, or daptomycin; extended-spectrum β-lactamase-producing (ESBL) Escherichia coli and Klebsiella pneumoniae resistant to numerous agents; multidrug-resistant (MDR) Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter spp.; carbapenem-resistant K. pneumoniae, E. coli, and other Enterobacteriaceae; clindamycin-resistant Bacteroides fragilis; and Mycobacterium tuberculosis organisms resistant to all available drugs.

The pharmaceutical industry has responded to this grave concern and has developed a variety of agents, for example quinupristin–dalfopristin, linezolid, daptomycin, telavancin, and dalbavancin, which generally inhibit the growth of gram-positive bacteria; ceftaroline and ceftibiprole, which are cephalosporin class drugs that inhibit gram-positive organisms, including MRSA, and gram-negative bacteria; and tigecycline, which possesses inhibitory activity for a wide range of gram-positive, gram-negative, and anaerobic bacteria. As these antibiotics are used more frequently, it may be easier to precisely establish the indications for their use, their potential to cause toxicities and drug–drug interactions, and to identify the preferred agent for a specific infection.