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.

Linezolid is an antibiotic used for the treatment of infections caused by Gram-positive bacteria that are resistant to other antibiotics. Linezolid appears to be unique in that it blocks the initiation of protein production. Most common adverse reactions include diarrhea, vomiting, headache, nausea, and anemia. Linezolid has the potential for interaction with adrenergic and serotonergic agents. And with monoamine oxidase inhibitors because it’s nonselective inhibitor of monoamine oxidase.

Trimethoprim (TMP) is an antibiotic is used for the treatment of initial episodes of uncomplicated urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter species, and coagulase-negative Staphylococcus species, including S. saprophyticus. Cultures and susceptibility tests should be performed to determine the susceptibility of the bacteria to trimethoprim. Therapy may be initiated prior to obtaining the results of these tests. Trimethoprim is rapidly absorbed following oral administration. It exists in the blood as unbound, protein-bound, and metabolized forms. Ten to twenty percent of trimethoprim is metabolized, primarily in the liver; the remainder is excreted unchanged in the urine. The principal metabolites of trimethoprim are the 1- and 3-oxides and the 3'- and 4'-hydroxy derivatives. The free form is considered to be the therapeutically active form. Approximately 44% of trimethoprim is bound to plasma proteins. Trimethoprim blocks the production of tetrahydrofolic acid from dihydrofolic acid by binding to and reversibly inhibiting the required enzyme, dihydrofolate reductase. This binding is very much stronger for the bacterial enzyme than for the corresponding mammalian enzyme

Clindamycin phosphate is the prodrug of clindamycin with no antimicrobial activity in vitro but can be rapidly converted in vivo to the parent drug, clindamycin, by phosphatase ester hydrolysis. It is indicated in the treatment of serious infections caused by susceptible anaerobic bacteria: Lower respiratory tract infections including pneumonia, empyema, and lung abscess caused by anaerobes; Skin and skin structure infections; Gynecological infections including endometritis, nongonococcal tubo-ovarian abscess, pelvic cellulitis, and postsurgical vaginal cuff infection caused by susceptible anaerobes; Intra-abdominal infections; Septicemia; Bone and joint infections. Orally and parenterally administered clindamycin has been associated with severe colitis, which may end fatally. Abdominal pain, gastrointestinal disturbances, gram-negative folliculitis, eye pain and contact dermatitis have also been reported in association with the use of topical formulations of clindamycin. Clindamycin has been shown to have neuromuscular blocking properties that may enhance the action of other neuromuscular blocking agents

Sulfamethoxazole is a synthetic antibacterial drug,which is used in combination with trimethoprim (Bactrim, Septra) for the treatment or prevention of infections that are proven or strongly suspected to be caused by bacteria. Sulfamethoxazole acts by inhibiting folic acid synthesis via enzyme called dihydropteroate synthase.

Vancomycin is a branched tricyclic glycosylated nonribosomal peptide produced by the fermentation of the Actinobacteria species Amycolatopsis orientalis (formerly Nocardia orientalis). Vancomycin became available for clinical use >50 years ago. It is often reserved as the "drug of last resort", used only after treatment with other antibiotics had failed. Vancomycin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections: Listeria monocytogenes, Streptococcus pyogenes, Streptococcus pneumoniae (including penicillin-resistant strains), Streptococcus agalactiae, Actinomyces species, and Lactobacillus species. The combination of vancomycin and an aminoglycoside acts synergistically in vitro against many strains of Staphylococcus aureus, Streptococcus bovis, enterococci, and the viridans group streptococci. The bactericidal action of vancomycin results primarily from inhibition of cell-wall biosynthesis. Specifically, vancomycin prevents the incorporation of N-acetylmuramic acid (NAM)- and N-acetylglucosamine (NAG)-peptide subunits from being incorporated into the peptidoglycan matrix; which forms the major structural component of Gram-positive cell walls. The large hydrophilic molecule is able to form hydrogen bond interactions with the terminal D-alanyl-D-alanine moieties of the NAM/NAG-peptides. Normally this is a five-point interaction. This binding of vancomycin to the D-Ala-D-Ala prevents the incorporation of the NAM/NAG-peptide subunits into the peptidoglycan matrix. In addition, vancomycin alters bacterial-cell-membrane permeability and RNA synthesis. There is no cross-resistance between vancomycin and other antibiotics. Vancomycin is not active in vitro against gram-negative bacilli, mycobacteria, or fungi.

Chloramphenicol is a broad-spectrum antibiotic that was first isolated from Streptomyces venezuelae in 1947. The drug was subsequently chemically synthesized. It has both a bacteriostatic and bactericidal effect; in the usual therapeutic concentrations it is bacteriostatic. Chloramphenicol is used for the treatment of serious gram-negative, gram-positive, and anaerobic infections. It is especially useful in the treatment of meningitis, typhoid fever, and cystic fibrosis. It should be reserved for infections for which other drugs are ineffective or contraindicated. Chloramphenicol, a small inhibitor of bacterial protein synthesis, is active against a variety of bacteria and readily enters the CSF. It has been used extensively in the last decades for the treatment of bacterial meningitis. In industrialized countries, chloramphenicol is restricted mostly to topical uses because of the risk of induction of aplastic anemia. However, it remains a valuable reserve antibiotic for patients with allergy to β-lactam antibiotics or with CNS infections caused by multiresistant pathogens.

FLOPRISTIN is one of the components of the experimental drug NXL103 (XRP 2868), along with linopristin. Both are semi-synthetic streptogramin antibiotics derived from the Streptomyces genus. NXL103 has a spectrum of antibacterial activity that indicates it has the potential to be effective in the treatment of skin and skin structure infections, including those caused by methicillin-resistant Staphylococcus aureus, as well as community-acquired pneumonia. NXL103 has completed Phase II trials.

Evernimicin (SCH 27899) is an oligosaccharide antibiotic. It nteracts with the large ribosomal subunit (50S) and inhibits bacterial protein synthesis. Evernimicin exerts activity against a wide spectrum of gram-positive bacteria and activity against some gram-negative bacteria. Evernimicin was being studied for the treatment of susceptible bacterial infections however its development has been discontinued.

MRX-I is a potent oxazolidinone antibiotic against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae, penicillin-intermediate S. pneumoniae, and vancomycin-resistant enterococci. MRX-I demonstrated comparable or slightly higher activity than linezolid and was active against enterococci resistant to both vancomycin and teicoplanin. In addition, MRX-I exhibited bactericidal activities against staphylococci and streptococci but was bacteriostatic against enterococci. MRX-I inhibits formation of functional 70S initiation complex essential for bacterial protein synthesis, leading to the cessation of bacterial growth. Oral MRX-I was associated with a greater bioavailability and exposure when administered with food, and minimal accumulation of MRX-I occurred after multiple-dose administration. Oral MRX-I was well tolerated at single doses of up to 1,200 and 800 mg q12h for up to 28 days; all adverse events were mild to moderate in severity, and there was no drug discontinuation due to adverse events.