Aminoglycosides

• Aminoglycosides that are derived from Streptomyces have -mycin suffixes, whereas those derived from Micromonospora end in -micin.
• Aminoglycosides binds to the 30S ribosomal subunit
• Aminoglycosides are bacteriocidal.
• Examples of aminoglycosides include

  • streptomycin
  • gentamicin
  • tobramycin
  • amikacin
• . Aminoglycosides may only be used as monotherapy for UTIs.
• Resistance can be caused by

  1. decreased uptake of the drug when the oxygen-dependent transport system for aminoglycosides is absent
  2. plasmid-associated synthesis of enzymes
• Aminoglycosides do not penetrate to CNS, are given parenterally, and is excreted in urine.
• Side effects of aminoglycosides include

  • otototoxicity
  • nephrotoxicity
  • paralysis
  • skin rash
• Aminoglycosides inhibit the release of acetylcholine from motor neurons at the neuromuscular junction, and cause weakness or paralysis.
• Streptomycin is often used against mycobacterium tuberculosis, which thrives in oxygen-rich lung tissue.
• Tobramycin is given topically to treat eye infections, or in a nebulized form to treat Pseudomonas aeruginosa infections in people with cystic fibrosis.
• Aminoglycosides  is used mainly against aerobic Gram negative bacteria like Proteus species, Escherichia coli, Klebsiella pneumoniae, Enterobacter species, and Serratia species.
• A combination of aminoglycosides and beta-lactams is used to treat Gram-positive enterococci infections like infective endocarditis.
• Bacterial resistance to the aminoglycosides and can be seen in certain strains of P. aeruginosa, S. aureus, and Enterobacter species.
• Aminoglycosides also have teratogenic effects, such as deafness, and thus they’re contraindicated in pregnancy.
• Aminoglycosides can be used alone to treat Gram-negative aerobic bacteria, but could also treat Gram-positive bacteria if combined with a cell wall synthesis inhibitor, like a beta-lactam antibiotic, or with vancomycin.