Antibacterial agents Skin and skin structure infections are most often caused by Grampositive bacteria such as streptococci and staphylococci. The number of these infections that are caused by methicillin-resistant Staphylococcus aureus (MRSA) has rapidly increased in recent years in both the community and hospital settings. MRSA skin infections experienced in the community can usually be effectively treated with the oral use of trimethoprim-sulfamethoxazole, clindamycin, or doxycycline. Hospitalized patients with skin and skin structure infections (e.g., cellulitis, major abscess, wound infection) caused by MRSA usually require, at least initially, intravenous treatment with an antibiotic. Vancomycin continues to be highly effective for the treatment of most patients with these infections, but a number of options are available including linezolid (Zyvox), daptomycin (Cubicin), telavancin (Vibativ), and ceftaroline (Teflaro). Linezolid is available in formulations that may be administered intravenously or orally. In 2014, three new antibiotics— dalbavancin (Dalvance—Durata), tedizolid phosphate (Sivextro— Cubist), and oritavancin diphosphate (Orbactiv—The Medicines Company)—have been approved for the treatment of acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible microorganisms. Based on the provisions of the Generating Antibiotic Incentives Now (GAIN) title of the Food and Drug Administration (FDA) Safety and Innovation Act, each of these antibiotics has been designated as a Qualified Infectious Disease Product (QIDP) because it is intended to treat a serious or life-threatening infection. Drugs receiving the QIDP designation are provided an expedited review of their application and qualify for an additional 5 years of marketing exclusivity. Dalbavancin, tedizolid, and oritavancin are considered on an individual basis in the following discussions. Dalbavancin (Dalvance—Durata) is a lipoglycopeptide that is a mixture of five closely related active homologs. It interferes with bacterial cell wall synthesis and exhibits a bactericidal action; and its properties are most similar to those of telavancin. Dalbavancin is administered by intravenous infusion and is specifically indicated for the treatment of adult patients with ABSSSI caused by susceptible isolates of the Gram-positive microorganisms Staphylococcus aureus (S. aureus) (including methicillin-susceptible and methicillin-resistant strains), Streptococcus pyogenes (S. pyogenes), Streptococcus agalactiae (S. agalactiae), and Streptococcus anginosus (S. anginosus) group (including S. anginosus, S. intermedius, and S. constellatus). It should only be used to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. The results of in vitro studies suggest that dalbavancin is also active against vancomycin-susceptible Enterococcus faecium and Enterococcus faecalis (E. faecalis), as well as vancomycin-intermediate S. aureus. Dalbavancin, tedizolid phosphate, oritavancin diphosphate, and vedolizumab