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.

Ertapenem is a carbapenem antibiotic marketed by Merck as Invanz. The bactericidal activity of ertapenem results from the inhibition of cell wall synthesis and is mediated through ertapenem binding to penicillin binding proteins (PBPs). In Escherichia coli, it has strong affinity toward PBPs 1a, 1b, 2, 3, 4 and 5 with preference for PBPs 2 and 3. Ertapenem has been designed to be effective against Gram-negative and Gram-positive bacteria. The most common drug-related adverse experiences in patients treated with INVANZ, including those who were switched to therapy with an oral antimicrobial, were diarrhea (5.5%), infused vein complication (3.7%), nausea (3.1%), headache (2.2%), vaginitis in females (2.1%), phlebitis/thrombophlebitis (1.3%), and vomiting (1.1%). The coadministration with probenecid to extend the half-life of ertapenem is not recommended.

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.

Moxifloxacin is a synthetic antibacterial agent developed by Bayer AG (initially called BAY 12-8039) for oral and intravenous administration. Moxifloxacin, a fluoroquinolone, is available as the monohydrochloride salt of 1-cyclopropyl-7-[(S,S)-2,8diazabicyclo[4.3.0]non-8-yl]-6-fluoro-8-methoxy-1,4-dihydro-4-oxo-3 quinoline carboxylic acid. Moxifloxacin is marketed worldwide (as the hydrochloride) under the brand names Avelox, Avalox, and Avalon for oral treatment. In most countries, the drug is also available in the parenteral form for intravenous infusion. Moxifloxacin is also sold in an ophthalmic solution (eye drops) under the brand names Vigamox, and Moxeza for the treatment of conjunctivitis (pink eye). Its antibacterial spectrum includes enteric Gram-(−) rods (Escherichia coli, Proteus species, Klebsiella species), Haemophilus influenzae, atypical bacteria (Mycoplasma, Chlamydia, Legionella), and Streptococcus pneumoniae, and anaerobic bacteria. It differs from earlier antibacterials of the fluoroquinolone class such as levofloxacin and ciprofloxacin in having greater activity against Gram-positive bacteria and anaerobes.

Quinupristin is an antibiotic compound and a semisynthetic derivative of pristinamycin Ia. Quinupristin is a combination of three peptide macrolactones. Quinupristin is used in combination with dalfopristin, another antibiotic, under the trade name Synercid. Synercid is indicated for treatment of complicated skin and skin structure infections caused by methicillin-susceptible Staphylococcus aureus or Streptococcus pyogenes. The mechanism of action of quinupristin is inhibition of the late phase of protein synthesis in the bacterial ribosome. Quinupristin binds to 23S rRNA within the 50S ribosomal subunit and prevents elongation of the polypeptide as well as causing incomplete chains to be released. Adverse reactions to Synercid include inflammation at infusion site, rash, nausea, vomiting and others.

Gatifloxacin is a recently developed antibacterial agent differing from earlier fluoroquinolones by the presence of a methoxy group at the C-8 position. The presence of the methoxy group has conferred improved antibacterial activity against both Gram-positive and Gram-negative organisms, making gatifloxacin a broad-spectrum antimicrobial agent applicable in many clinical settings. Gatifloxacin is sold under the brand Zymar and is indicated for the treatment of bacterial conjunctivitis caused by susceptible strains of the following organisms: Aerobic Gram-Positive Bacteria: Cornyebacterium propinquum, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mitis, Streptococcus pneumoniae and Aerobic Gram-Negative Bacteria: Haemophilus influenza. The antibacterial action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase, which allows the untwisting required to replicate one DNA double helix into two. Notably the drug has 100 times higher affinity for bacterial DNA gyrase than for mammalian. In addition, Gatifloxacin inhibits bacterial topoisomerase IV. This enzyme is an enzyme known to play a key role in the partitioning of the chromosomal DNA during bacterial cell division. The mechanism of action of fluoroquinolones including gatifloxacin is different from that of aminoglycoside, macrolide, and tetracycline antibiotics. Therefore, gatifloxacin may be active against pathogens that are resistant to these antibiotics and these antibiotics may be active against pathogens that are resistant to gatifloxacin. There is no cross-resistance between gatifloxacin and the aforementioned classes of antibiotics. Cross-resistance has been observed between systemic gatifloxacin and some other fluoroquinolones.

Dalfopristin is a pristinamycin-like component of anti-bacterial drug called Synercid which also containes quinupristin (quinupristin:dalfopristin ratio is 30:70 (w/w)). The drug was approved by FDA and used for the treatment of skin diseases caused by Staphylococcus aureus or Streptococcus pyogenes. Dalfopristin binds to the RNA of the 50S ribosomal subunit and thus inhibits the late phase of protein synthesis.

Cefdinir is an extended-spectrum, semisynthetic cephalosporin, for oral administration. As with other cephalosporins, bactericidal activity of cefdinir results from inhibition of cell wall synthesis. Cefdinir is stable in the presence of some, but not all, β-lactamase enzymes. Cefdinir is indicated for the treatment of: Community-Acquired Pneumonia, Acute Exacerbations of Chronic Bronchitis, Acute Maxillary Sinusitis, Pharyngitis/Tonsillitis and Uncomplicated Skin and Skin Structure Infections. Side effects include diarrhea, vaginal infections or inflammation, nausea, headache, and abdominal pain. Concomitant administration of 300-mg cefdinir capsules with 30 mL Maalox® TC suspension reduces the rate (Cmax) and extent (AUC) of absorption by approximately 40%. As with other β-lactam antibiotics, probenecid inhibits the renal excretion of cefdinir.

Cefepime is a fourth-generation cephalosporin antibiotic, which was developed in 1994. Cefepime has a broad spectrum in vitro activity that encompasses a wide range of Gram-positive and Gram-negative bacteria. Within bacterial cells, the molecular targets of cefepime are the penicillin binding proteins (PBP). It is FDA approved for the treatment of pneumonia, febrile neutropenia, uncomplicated UTI, uncomplicated skin infection and complicated intraabdominal infections. Common adverse reactions include rash, hypophosphatemia, diarrhea. Cefepime is metabolized to N-methylpyrrolidine (NMP) which is rapidly converted to the N-oxide (NMP-N-oxide). Urinary recovery of unchanged cefepime accounts for approximately 85% of the administered dose. Less than 1% of the administered dose is recovered from urine as NMP, 6.8% as NMP-N-oxide, and 2.5% as an epimer of cefepime. Because renal excretion is a significant pathway of elimination, patients with renal dysfunction and patients undergoing hemodialysis require dosage adjustment.

Fosfomycin (marketed under the trade names Monurol and Monuril) is a broad-spectrum antibiotic. Monurol (fosfomycin tromethamine) sachet contains fosfomycin tromethamine, a synthetic, broad spectrum, bactericidal antibiotic for oral administration. Monurol is indicated only for the treatment of uncomplicated urinary tract infections (acute cystitis) in women due to susceptible strains of Escherichia coli and Enterococcus faecalis. Fosfomycin is a phosphoenolpyruvate analogue produced by Streptomyces that irreversibly inhibits enolpyruvate transferase (MurA), which prevents the formation of N-acetylmuramic acid, an essential element of the peptidoglycan cell wall.