Spectinomycin is an antibiotic produced by Streptomyces spectabilis. It is active against gram-negative bacteria and used for the treatment of acute gonorrheal urethritis and proctitis in the male and acute gonorrheal cervicitis and proctitis in the female when due to susceptible strains of Neisseria gonorrhoeae. In vitro studies have shown spectinomycin to be active against most strains of Neisseria gonorrhoeae (minimum inhibitory concentration <7.5 to 20 mcg/mL). Footprint studies indicate that spectinomycin exerts regional effects on ribosomal structure. Spectinomycin hydrochloride is an inhibitor of protein synthesis in the bacterial cell; the site of action is the 30S ribosomal subunit. The antibiotic is not significantly bound to plasma protein. Spectinomycin was discovered 1961. It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system. This antibiotic is no longer available in the United States. Pfizer has discontinued distribution of spectinomycin (Trobicin) in the U.S. The drug continues to be distributed outside the U.S.

Methacycline is a tetracycline antibiotic. Similar to other tetracyclines, it has a wide spectrum of antimicrobial action. It is active against most Gram-positive bacteria (pneumococci, streptococci, staphylococci) and Gram-negative bacteria (E. coli, salmonella, shigella, etc.), and towards agents causing onithosis, psittacosis, trachoma, and some Protozoa. Like other tetracyclines, the general usefulness of methacycline has been reduced with the onset of bacterial resistance. Methacycline inhibits the binding of aminoacyl-tRNA to the mRNA-ribosome complex. Methacycline inhibits cell growth by inhibiting translation. It binds to the 16S part of the 30S ribosomal subunit and prevents the amino-acyl tRNA from binding to the A site of the ribosome. Methacycline is mostly used for the treatment of acute bacterial exacerbations of chronic bronchitis.

Rolitetracycline, launched in the late 1950s, was the first of the semi -synthetic tetracyclines. Rolitetracycline is formed by a Mannich condensation of formaldehyde and pyrrolidine with tetracycline. Rolitetracycline is a pro -drug of tetracycline, in which the pyrrolidine moiety improves bioavailability compared with tetracycline. Rolitetracycline has broad spectrum Gram positive activity in vivo, but pH instability limits use to parenteral administration. Rolitetracycline passively diffuses through porin channels in the bacterial membrane and reversibly binds to the 30S ribosomal subunit, preventing binding of tRNA to the mRNA-ribosome complex, and thus interfering with protein synthesis.

Kanamycin A is aminoglycoside anti-bacterial agent. Active against many strains of Gram-negative bacteria and Gram-positive Staphylococcus aureus and epidermis. Some strains of Mycobacterium bacterium are sensitive. Most active in alkaline solution. It binds to bacterial ribosomes and reduces mRNA translation hence reduces protein biosynthesis. However, it also exhibits some toxic effects towards mammalian cells.

Dihydrostreptomycin is an antibiotic compound derived from streptomycin by reduction with hydrogen. The primary mechanism of action of the antibiotic dihydrostreptomycin is binding to and modifying the function of the bacterial ribosome, thus leading to decreased and aberrant translation of proteins, in addition it binds mechanosensitive channel of large conductance (MscL) and modifies its conformation, thus allowing the passage of K+ and glutamate out of, and dihydrostreptomycin into, the cell. It has about the same degree of antibacterial activity as streptomycin, but it is less effective against some gram-negative microorganisms. Because it has a higher risk of irreversible deafness, and its effectiveness is no greater that that of streptomycin, dihydrostreptomycin is no longer used clinically. To date dihydrostreptomycin is approved for veterinary use to treat bacterial infections.

Phenylmercuric borate is classified as antimicrobial preservative. It is bactericidal against many Gram-positive and Gram-negative species. Fungicidal activity has been demonstrated against Candida albicans and Aspergillus niger. Phenylmercuric borate (PHB) is very rapidly incorporated into the cells of Escherichia coli. On the membrane, an important part of PHB seems to be associated with the ribosomes and particularly to the ribosomal proteins. Phenylmercuric borate solution is indicated for the treatment of tonsillitis, otitis, vulvovaginitis, furuncles, anthrax and ulcers, pyoderma, impetus, gingivitis and stomatitis. The regular hand disinfection with a liquid soap containing phenylmercuric borate enhanced urinary excretion of mercury indicating an increase in total daily absorption of the toxic metal. The additional amounts of mercury absorbed through the use of mercury contained in skin disinfectants are potentially dangerous for human.

Tildipirosin is a semisynthetic derivative of the naturally occurring 16-membered macrolide tylosin. Tildipirosin is intended for parenteral treatment of respiratory disease in cattle and swine. Tildipirosin will be administered as a single-dose injection: subcutaneously in cattle and intramuscularly in swine. The anticipated optimal clinical dose is 4 mg/kg bw. Tildipirosin is not used in human medicine. It is marketed under the brand name Zuprevo. As for other macrolides, the antimicrobial activity of tildipirosin is due to its binding to the ribosomal 50S subunit of bacterial cells thereby inhibiting bacterial protein synthesis. The in vitro antimicrobial activity against Gram-negative and Gram-positive pathogens indicates that tildipirosin is effective against a range of bacterial pathogens frequently associated with bovine and swine respiratory disease. Comparison of minimum inhibitory versus bactericidal concentrations shows that generally the antimicrobial action of tildipirosin is bacteriostatic.

Tylvalosin (TVS) is a third-generation macrolide drug used for prophylaxis and treatment of mycoplasma. Tylvalosin, the active ingredient of Aivlosin 625 mg/g Water Soluble Granules (ECO Animal Health, UK), is a modern macrolide that has shown its effectiveness in the control of porcine proliferative enteropathy, EP and swine dysentery. Aivlosin is indicated for the control of porcine proliferative enteropathy (PPE) associated with Lawsonia intracellularis infection in groups of swine in buildings experiencing an outbreak of PPE. Tylvalosin tartrate is a macrolide antibiotic that has antibacterial activity against Gram-positive, some Gram-negative organisms and mycoplasma. It acts by inhibiting protein synthesis in the bacteria cell.

Gamithromycin, the active pharmaceutical ingredient of ZACTRAN is a novel 7a-azalide that has been developed for treatment and prevention of bovine respiratory disease (BRD). The compound belongs to the 15-membered semi-synthetic macrolide antibiotics of the azalide sub-class with a uniquely positioned alkylated nitrogen at the 7a-position of the lactone ring. Macrolide antibiotics in general have bacteriostatic action by inhibiting bacterial RNA dependent protein biosynthesis, but can also be bactericidal. They reversibly bind to 23S ribosomal RNA in the 50S-subunit of prokaryotic ribosomes and prevent protein elongation during the translocation process. In vitro data show that gamithromycin has both bactericidal and bacteriostatic actions at least at the higher concentrations found in lung tissue. The broad spectrum antimicrobial activity of gamithromycin includes Mannheimia haemolytica, Pasteurella multocida and Histophilus somni, the bacterial pathogens most commonly associated with BRD. Gamithromycin administered subcutaneously is well absorbed and fully bioavailable, and safe for the target animal receiving doses up to five times the recommended dose at 30 mg ⁄ kg body weight. Following s.c. administration, gamithromycin is extensively and rapidly distributed to lung tissue, the site of respiratory infection.

Hygromycin B is a water-soluble antibiotic purified from the bacterium Streptomyces hydroscopicus.It kills bacteria, fungi and higher eukaryotic cells by inhibiting protein synthesis. It has been reported to interfere with translocation and to cause mistranslation at the 70S ribosome.Hygromycin B is used as a selective agent in molecular genetics experiments on a wide variety of eukaryotic and prokaryotic species. Under the trade name Hygromix, Hygromycin B is used in chickens as an aid in the control of infections of the following intestinal parasites: large roundworms (Ascaris galli), cecal worms (Heterakis gallinae) and capillary worms (Capillaria obsignata) and in Swine as an aid in the control of infections of the following intestinal parasites: large roundworms (Ascaris suis), nodular worms (Oesophagostomum dentatum) and whipworms (Trichuris suis).