What antibiotics are classified as aminoglycosides?

Aminoglycoside Antibiotics: Classification and Members

Aminoglycosides are a class of potent bactericidal antibiotics that act by creating fissures in the outer membrane of bacterial cells and inhibiting protein synthesis on the 30S subunit of the bacterial ribosome. The antibiotics classified as aminoglycosides include gentamicin, tobramycin, amikacin, streptomycin, kanamycin, neomycin, and plazomicin.

Primary Aminoglycoside Antibiotics

Commonly Used Aminoglycosides

• Gentamicin: Most commonly used aminoglycoside 1, 2
• Tobramycin: Particularly effective against Pseudomonas aeruginosa 1, 3
• Amikacin: Often effective against organisms resistant to other aminoglycosides 4, 5
• Streptomycin: One of the oldest aminoglycosides, now with limited specific indications 1, 5

Less Commonly Used Aminoglycosides

• Kanamycin: Used for serious gram-negative infections where Pseudomonas is not suspected 5
• Neomycin: Primarily limited to topical, irrigation, and oral preparations due to toxicity 5
• Plazomicin: A newer aminoglycoside option 1

Clinical Applications

Aminoglycosides are particularly active against:

• Aerobic gram-negative bacteria 6
• Can act synergistically against certain gram-positive organisms 6

They are indicated for:

• Serious infections caused by susceptible gram-negative bacteria 2
• Treatment of bacterial septicemia 2
• Serious infections of the CNS, urinary tract, respiratory tract, and other systems 2
• Often used in combination therapy for synergistic effects 1

Important Characteristics

• Concentration-dependent killing: Higher peak concentrations result in more effective bacterial killing 1
• Post-antibiotic effect: Antibacterial activity continues even after serum levels become undetectable 1
• Synergistic effects: Work well in combination with other antibiotics 1
• Limited oral absorption: Aminoglycosides are poorly absorbed from the gastrointestinal tract 5

Toxicity Concerns

Aminoglycosides are associated with significant adverse effects:

• Nephrotoxicity: Can cause renal damage, though usually reversible 7, 8
• Ototoxicity: Can cause permanent hearing loss, particularly concerning with in utero exposure 8
• Neuromuscular blockade: Can aggravate muscle weakness in patients with myasthenia gravis or parkinsonism 4

Dosing Considerations

• Single daily dosing is often preferred due to concentration-dependent killing and post-antibiotic effect 6
• Therapeutic drug monitoring is recommended, especially in patients with impaired renal function 1
• Dosage adjustments are necessary in patients with renal impairment 4, 2

Special Populations

• Pregnancy: Aminoglycosides like tobramycin should be avoided if possible, especially in the first trimester, due to potential risks of ototoxicity and nephrotoxicity to the fetus 3
• Pediatric patients: Should be used with caution in premature and neonatal infants due to renal immaturity 4
• Elderly: May have reduced renal function requiring dose adjustments 4

Aminoglycosides remain important antibiotics in our armamentarium against serious bacterial infections, particularly with the rise of multidrug-resistant organisms, but must be used judiciously given their potential for toxicity.