Ceftolozane is a novel a cephalosporin-class antibacterial drug. In combination with a beta-lactamase inhibitor tazobactam (ZERBAXA, ceftolozane/tazobactam ) ceftolozane, is currently indicated for the treatment of the adult patients with complicated intra-abdominal infections caused by designated Gram-negative and Gram-positive microorganisms and complicated urinary tract infections caused by certain Gram-negative bacteria, including those caused by multi-drug resistant Pseudomonas aeruginosa. To reduce the development of drug-resistant bacteria and maintain the effectiveness of ZERBAXA and other antibacterial drugs, ZERBAXA should be used only to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. Safety and effectiveness in pediatric patients have not been established.

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.

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.

Ceftazidime is a semisynthetic, broad-spectrum, beta-lactam antibiotic, used especially for Pseudomonas and other gram-negative infections in debilitated patients. Ceftazidime is used to treat lower respiratory tract, skin, urinary tract, blood-stream, joint, and abdominal infections, and meningitis. The drug is given intravenously (IV) or intramuscularly (IM) every 8–12 hours (two or three times a day), with dose and frequency varying by the type of infection, severity, and/or renal function of the patient. Injectable formulations of ceftazidime are currently nebulized "off-label" to manage Cystic Fibrosis, non-Cystic Fibrosis bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Ceftazidime is generally well-tolerated. When side effects do occur, they are most commonly local effects from the intravenous line site, allergic reactions, and gastrointestinal symptoms. According to one manufacturer, in clinical trials, allergic reactions including itching, rash, and fever, happened in fewer than 2% of patients. Rare but more serious allergic reactions, such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and erythema multiforme, have been reported with this class of antibiotics, including ceftazidime. Gastrointestinal symptoms, including diarrhea, nausea, vomiting, and abdominal pain, were reported in fewer than 2% of patients.

Cefotetan is a semisynthetic cephamycin antibiotic that is administered intravenously or intramuscularly. The drug is highly resistant to a broad spectrum of beta-lactamases and is active against a wide range of both aerobic and anaerobic gram-positive and gram-negative microorganisms. It is FDA approved for the treatment of urinary tract infection, lower respiratory tract infection, skin and skin structure infections, gynecologic infection, intra-abdominal infection, and bone and joint infection; and for prophylaxis of postoperative infection. The bactericidal action of cefotetan results from inhibition of cell wall synthesis. The methoxy group in the 7-alpha position provides cefotetan with a high degree of stability in the presence of beta-lactamases including both penicillinases and cephalosporinase of gram-negative bacteria. Common adverse reactions include diarrhea and nausea. As with other cephalosporins, high concentrations of cefotetan may interfere with measurement of serum and urine creatinine levels.

Cefoxitin is a cephamycin antibiotic often grouped with the second-generation cephalosporins. It is active against a broad range of gram-negative bacteria including anaerobes. The methoxy group in the 7a position provides cefoxitin with a high degree of stability in the presence of beta-lactamases, both penicillinases and cephalosporinases, of gram-negative bacteria. The bactericidal action of cefoxitin results from inhibition of cell wall synthesis.

Cefazolin is a semisynthetic cephalosporin analog with broad-spectrum antibiotic action due to inhibition of bacterial cell wall synthesis. By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, cefazolin inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins. Cefazolin is used to treat bacterial infections of the skin, moderately severe bacterial infections involving the lung, bone, joint, stomach, blood, and urinary tract. It is clinically effective against infections caused by staphylococci and streptococci species of Gram positive bacteria. This drug also can be used for perioperative prophylaxis.

Metronidazole was synthesized by France's Rhone-Poulenc laboratories and introduced in the mid-1950s under the brand name Flagel in the US, while Sanofi-Aventis markets metronidazole globally under the same trade name, Flagyl, and also by various generic manufacturers. Metronidazole is one of the rare examples of a drug developed as ant parasitic, which has since gained broad use as an antibacterial agent. Metronidazole, a nitroimidazole, exerts antibacterial effects in an anaerobic environment against most obligate anaerobes. Metronidazole is indicated for the treatment of the following infections due to susceptible strains of sensitive organisms: Trichomoniasis: symptomatic, asymptomatic, asymptomatic consorts; Amebiasis: acute intestinal amebiasis (amebic dysentery) and amebic liver abscess; Anaerobic bacterial infections; Intra-abdominal infections, including peritonitis, intra-abdominal abscess, and liver abscess; Skin and skin structure infections; Gynecologic infections, including endometritis, endomyometritis, tubo-ovarian abscess, and postsurgical vaginal cuff infection; Bacterial septicemia; Bone and joint infections, as adjunctive therapy; Central Nervous System infections, including meningitis and brain abscess; Lower Respiratory Tract infections, including pneumonia, empyema, and lung abscess; Endocarditis. Metronidazole is NOT effective for infections caused by aerobic bacteria that can survive in the presence of oxygen. Metronidazole is only effective against anaerobic bacterial infections because the presence of oxygen will inhibit the nitrogen-reduction process that is crucial to the drug's mechanism of action. Once metronidazole enters the organism by passive diffusion and activated in the cytoplasm of susceptible anaerobic bacteria, it is reduced; this process includes intracellular electron transport proteins such as ferredoxin, transfer of an electron to the nitro group of the metronidazole, and formation of a short-lived nitroso free radical. Because of this alteration of the metronidazole molecule, a concentration gradient is created and maintained which promotes the drug’s intracellular transport. The reduced form of metronidazole and free radicals can interact with DNA leading to inhibition of DNA synthesis and DNA degradation leading to death of the bacteria. The precise mechanism of action of metronidazole is unknown. Metronidazole has a limited spectrum of activity that encompasses various protozoans and most Gram-negative and Gram-positive anaerobic bacteria. Metronidazole has activity against protozoans like Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis, for which the drug was first approved as an effective treatment.