Master Aminoglycoside Overview with Picmonic for Nursing RN

Gentamicin is used for gram-negative infections such as Pseudomonas aeruginosa and Proteus mirabilis but not for Neisseria or Legionella. Its clinical use is limited due to its side effects of ototoxicity and nephrotoxicity, and it cannot be given orally due to its lack of intestinal absorption. Combined with vancomycin or a beta-lactam antibiotic, gentamicin can treat serious infections caused by gram-positive cocci (Staphylococcus aureus, Enterococcus, and some Streptococci).

Neomycin is a popular topical aminoglycoside for eye, ear, and skin infections. It is not used as a systemic treatment, as it is highly ototoxic and nephrotoxic. It is used to reduce the risk of infection during intestinal surgery by eliminating intestinal bacteria. And because aminoglycosides are not absorbed well into the body through the GI tract, the risk of side effects is much lower when using it as a bowel prep for surgery. Neomycin can be used to treat hepatic encephalopathy by reducing ammonia-producing bacteria in the gut, but it's not the first-line option.

This aminoglycoside is used for Pseudomonas, Enterobacter, and Serratia infections. This medication can be given in the form of suspension, inhalation, or injection. Like other drugs in its class, it can lead to nephrotoxicity and ototoxicity, so patients should be carefully monitored if they have renal disease. This medication's key mechanism is the inhibition of translocation.

Tobramycin is used for gram-negative infections. It has slightly better coverage than gentamicin when treating pseudomonal infections of the lungs. It cannot be given orally but it is used in ophthalmic infections for bacterial conjunctivitis (Tobrex). It can also be inhaled via a nebulizer and given via an injection into a muscle or as an IV infusion. This drug leads to nephrotoxicity and ototoxicity.

Streptomycin was the first aminoglycoside discovered and is used for mycobacterium tuberculosis infections. Streptomycin still can be used for TB, but it is infrequent because of the bacteria's resistance and the availability of newer, more effective TB drugs. It is given via injection into a muscle, usually the thigh or upper buttocks. This drug has the side effects of nephrotoxicity and ototoxicity.

Unlike bacteriostatic agents, which simply stop bacteria from reproducing, bactericidal agents actually cause bacterial cell death. Aminoglycosides bind to the 30S ribosomal subunit of bacteria and cause misreading of mRNA during protein synthesis. The production of nonfunctional proteins disrupts cell membrane integrity and key metabolic processes. They do not directly affect DNA replication, but inhibiting proper protein synthesis impairs bacterial growth and division. A higher concentration of medication leads to quicker eradication of the infection.

Aminoglycosides require oxygen for uptake because their entry mechanism into bacterial cells depends on an energy-dependent transport system known as "energy-dependent phase I." This system uses the bacterial electron transport chain and requires oxygen to generate the proton motive force. This force is needed for the active transport of aminoglycosides across the inner bacterial membrane.

Aminoglycosides are synergistic with β-lactam antibiotics. This synergy occurs because β-lactams disrupt the bacterial cell wall, enhancing aminoglycoside penetration. This combination is especially effective in treating serious infections like endocarditis caused by Gram-positive organisms such as Enterococcus.

Aminoglycosides are typically used to treat serious infections caused by aerobic gram-negative bacilli. The most frequent use of these antibiotics is empiric therapy for serious infections, including septicemia, complicated intraabdominal infections, UTIs, and nosocomial upper respiratory tract infections.

The aminoglycoside Neomycin is often used for bowel surgery prep to suppress bowel flora and decrease the risk of infection after surgery. Remember, aminoglycosides are not absorbed well into the body through the GI tract, so the risk of side effects is much lower when using them for bowel surgery preparation.

Bacterial transferases inactivate aminoglycosides by acetylation, phosphorylation, or adenylation.