Methicillin sodium anhydrous is a sodium salt of methicillin (methicillin). Methicillin is an antibiotic formerly used in the treatment of bacterial infections caused by organisms of the genus Staphylococcus. Methicillin is a semisynthetic derivative of penicillin. It was first produced in the late 1950s and was developed as a type of antibiotic called penicillinase-resistant penicillin—it contained a modification to the original penicillin structure that made it resistant to a bacterial enzyme called penicillinase (beta-lactamase). Compared to other penicillins that face antimicrobial resistance due to β-lactamase, it is less active, can be administered only parenterally, and has a higher frequency of interstitial nephritis, an otherwise-rare adverse effect of penicillins. However, the selection of meticillin depended on the outcome of susceptibility testing of the sampled infection, and since it is no longer produced, it is also not routinely tested for anymore.

LEFAMULIN is a pleuromutilin antibiotic under development for the treatment of community-acquired bacterial pneumonia, as well as acute bacterial skin and skin structure infections. It inhibits bacterial protein synthesis by binding to the peptidyl transferase center of the 50S ribosome, resulting in the cessation of bacterial growth.

Omadacycline is a tetracyclin-derivative antibiotic, originated in Tufts University, and later co-developed by Merck and Paratek Pharmaceuticals. The drug was approved for treatment of community-acquired pneumonia, and for treatment of acute bacterial skin and skin structure infections. Omadacycline tosylate is available as tablets and in injectable form.

Delafloxacin (CAS registry number 189279-58-1) was described as WQ-3034 by Wakunaga Pharmaceutical Co., Ltd., Osaka & Hiroshima, Japan. It was first licensed in 1999 to Abbott Park, IL, and further developed as ABT-492. Delafloxacin (Baxdela), a fluoroquinolone antibiotic, is currently being developed by Melinta Therapeutics. It is a novel investigational fluoroquinolone in development for the treatment of uncomplicated gonorrhea, and acute bacterial skin and skin structure infections. Delafloxacin shows MICs remarkably low against Gram-positive organisms and anaerobes and similar to those of ciprofloxacin against Gram-negative bacteria. It remains active against most fluoroquinolone-resistant strains, except enterococci. Its potency is further increased in acidic environments (found in many infection sites). Delafloxacin is active on staphylococci growing intracellularly or in biofilms. Delafloxacin is a dual-targeting fluoroquinolone, capable of forming cleavable complexes with DNA and topoisomerase IV or DNA gyrase and of inhibiting the activity of these enzymes in both Gram-positive and Gram-negative bacteria. On Oct 24, 2016, Melinta Therapeutics Submitted Baxdela New Drug Application for hospital-treated skin infections.

Tedizolid phosphate is an oxazolidinone prodrug which in the body is dephosphorylated to the active compound tedizolid. The antibacterial activity of tedizolid is mediated by binding to the 50S subunit of the bacterial ribosome resulting in inhibition of protein synthesis. Tedizolid inhibits bacterial protein synthesis through a mechanism of action different from that of other non-oxazolidinone class antibacterial drugs; therefore, cross-resistance between tedizolid and other classes of antibacterial drugs is unlikely. Tedizolid is bacteriostatic against Gram Positive bacteria such as enterococci, staphylococci, and streptococci. No drug-drug interactions were identified with tedizolid.

Oritavancin is an glycopeptide antibiotic with bactericidal activity effective in treating infections caused by Gram-positive organisms. It treats complicated skin and skin structure infections. This drug demonstrates similar activity to vancomycin, but it has stronger activity against Staphylococcus and Enterococcus. The pharmacokinetics and pharmacodynamics of oritavancin appear to be favourable and once-daily dosing is likely. The incidence of multi-drug resistant bacteria is increasing and explorations into additional treatment options are essential. Oritavancin is marketed under the brand name Orbactiv. Orbactiv is indicated for the treatment of adult patients with acute bacterial skin and skin structure infections caused or suspected to be caused by susceptible isolates of designated Gram-positive microorganisms. Oritavancin has the following mechanism of action: 1) Inhibition of the transglycosylation (polymerisation) step of cell wall biosynthesis by binding to the stem peptide of peptidoglycan precursors 2) Inhibition of the transpeptidation (crosslinking) step of cell wall biosynthesis by binding to the peptide bridging segments of the cell wall 3) Disruption of bacterial membrane integrity, leading to depolarisation, increased permeability and rapid cell death.

Ceftaroline is a fifth-generation broad-spectrum cephalosporin with potent antimicrobial activity against Gram-positive and Gram-negative pathogens. Ceftaroline is the bioactive metabolite of ceftaroline fosamil, an N-phosphonoamino water-soluble cephalosporin prodrug, which is rapidly converted in vivo upon the hydrolysis of the phosphonate group by plasma phosphatises. Ceftaroline fosamil is being developed by Forest Laboratories, under a license from Takeda. In 2010, the U.S. Food and Drug Administration (FDA) approved ceftaroline fosamil for use in the treatment of acute bacterial skin and skin structure infections as well as community-acquired pneumonia. Ceftaroline has bactericidal activity against methicillin-resistant Staphylococcus aureus, therefore serving as an attractive alternative agent for the treatment of methicillin-resistant Staphylococcus aureus bacteremia when approved agents are contraindicated or treatment failures have occurred. Like other β-lactams, ceftaroline’s mechanism of action is mediated by binding to the penicillin-binding protein (PBP), the enzyme mediating the cross-linking transpeptidation of the peptidoglycan which are the terminal steps in completing formation of the bacterial cell wall. MRSA strains have a mutated PBP2a which prohibits β-lactam antibiotics from accessing its active site that mediates the transpeptidation reaction. Ceftaroline possesses an ethoxyimino side-chain mimicking a portion of a cell wall structure, which acts as a “Trojan horse”, allosterically opening and facilitating access to the active site of the PBP2a. Based on clinical trial data to date, ceftaroline appears to be safe and well-tolerated. Since ceftaroline is a cephalosporin, it has caused serious hypersensitivity reactions in patients who are allergic to cephalosporins and among some patients with penicillin allergies.

TELAVANCIN (VIBATIV®) is a lipoglycopeptide antibacterial that is a synthetic derivative of vancomycin. It exerts concentration-dependent, bactericidal activity against Gram-positive organisms in vitro. TELAVANCIN (VIBATIV®) inhibits cell wall biosynthesis by binding to late-stage peptidoglycan precursors, including lipid II. It also binds to the bacterial membrane and disrupts membrane barrier function. TELAVANCIN (VIBATIV®) is indicated for the treatment of adult patients with complicated skin and skin structure infections caused by susceptible isolates of the following Gram-positive microorganisms: Staphylococcus aureus (including methicillin-susceptible and -resistant isolates), Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group (includes S. anginosus, S. intermedius, and S. constellatus), or Enterococcus faecalis (vancomycin-susceptible isolates only). It is also indicated for the treatment of adult patients with hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP), caused by susceptible isolates of Staphylococcus aureus (both methicillin-susceptible and -resistant isolates). It should be reserved for use when alternative treatments are not suitable.

Tigecycline (INN) is an antibiotic used to treat a number of bacterial infections. It is a first in class glycylcycline that is administered intravenously. For the treatment of infections caused by susceptible strains of the designated microorganisms in the following conditions: Complicated skin and skin structure infections caused by Escherichia coli, Enterococcus faecalis (vancomycin-susceptible isolates only), Staphylococcus aureus (methicillin-susceptible and -resistant isolates), Streptococcus agalactiae, Streptococcus anginosus grp. (includes S. anginosus, S. intermedius, and S. constellatus), Streptococcus pyogenes and Bacteroides fragilis. Complicated intra-abdominal infections caused by Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Enterococcus faecalis (vancomycin-susceptible isolates only), Staphylococcus aureus (methicillin-susceptible isolates only), Streptococcus anginosus grp. (includes S. anginosus, S. intermedius, and S. constellatus), Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides vulgatus, Clostridium perfringens, and Peptostreptococcus micros. Tigecycline, a glycylcycline, inhibits protein translation in bacteria by binding to the 30S ribosomal subunit and blocking entry of amino-acyl tRNA molecules into the A site of the ribosome. This prevents incorporation of amino acid residues into elongating peptide chains. Tigecycline carries a glycylamido moiety attached to the 9-position of minocycline. The substitution pattern is not present in any naturally occurring or semisynthetic tetracycline and imparts certain microbiologic properties to tigecycline. In general, tigecycline is considered bacteriostatic; however, TYGACIL has demonstrated bactericidal activity against isolates of S. pneumoniae and L. pneumophila. In vitro studies have not demonstrated antagonism between tigecycline and other commonly used antibacterials.

Daptomycin is a lipopeptide antibiotic used in the treatment of systemic and life-threatening infections caused by Gram-positive organisms. Daptomycin has a distinct mechanism of action, disrupting multiple aspects of bacterial cell membrane function. It inserts into the cell membrane in a phosphatidylglycerol-dependent fashion, where it then aggregates. The aggregation of daptomycin alters the curvature of the membrane, which creates holes that leak ions. This causes rapid depolarization, resulting in a loss of membrane potential leading to inhibition of protein, DNA, and RNA synthesis, which results in bacterial cell death. Daptomycin is bactericidal against Gram-positive bacteria only. It has proven in vitro activity against enterococci (including glycopeptide-resistant enterococci (GRE)), staphylococci (including methicillin-resistant Staphylococcus aureus), streptococci, corynebacteria and stationary-phase Borrelia burgdorferi persisters.