What bacteria is Amikacin effective against?

Amikacin Spectrum of Activity

Amikacin is effective against a wide range of Gram-negative bacteria, particularly multidrug-resistant organisms, and some Gram-positive bacteria, making it a valuable aminoglycoside for severe infections when other antibiotics fail. 1

Gram-Negative Bacteria Coverage

Amikacin demonstrates excellent activity against the following Gram-negative bacteria:

• Enterobacterales family:

  • Escherichia coli
  • Klebsiella species
  • Enterobacter species
  • Proteus species (both indole-positive and indole-negative)
  • Serratia species
  • Citrobacter freundii 1

• Non-fermenting Gram-negative bacilli:

  • Pseudomonas species
  • Acinetobacter species 1

• Multidrug-resistant organisms:

  • Carbapenem-resistant Enterobacterales (CRE) 2
  • Extended-spectrum β-lactamase (ESBL) producing organisms 2

Gram-Positive Coverage

Amikacin has limited activity against Gram-positive bacteria:

• Staphylococcus species 1
• Generally low activity against other Gram-positive organisms 1

Resistance Patterns

Amikacin maintains effectiveness against many resistant organisms due to its unique structure:

• Resists degradation by certain aminoglycoside-inactivating enzymes that affect gentamicin, tobramycin, and kanamycin 1
• Effective against many gentamicin-resistant and tobramycin-resistant strains 3
• Lower resistance rates compared to other aminoglycosides:
  • According to global surveillance data, amikacin resistance in Gram-negative bacteria is generally lower than resistance to gentamicin 2
  • For example, in Klebsiella species, amikacin resistance was 37% compared to 59% for gentamicin 2

Clinical Applications

Amikacin is particularly valuable in the following clinical scenarios:

1. Severe urinary tract infections:

   • Recommended as second-choice therapy for severe pyelonephritis and prostatitis 2
   • Preferred over gentamicin due to better resistance profile 2

2. Hospital-acquired and ventilator-associated pneumonia:

   • Part of combination therapy for severe HAP/VAP caused by multidrug-resistant organisms 2
   • Can be administered via nebulization for pulmonary infections 2

3. Sepsis and bacteremia:

   • Effective for severe Gram-negative bacteremia, including cases with gentamicin-resistant organisms 4

4. Tuberculosis:

   • Second-line injectable drug for drug-resistant tuberculosis 2

5. Acinetobacter baumannii infections:

   • Used in combination therapy for multidrug-resistant A. baumannii 2

Synergistic Effects

Amikacin exhibits important synergistic effects:

• Shows synergy when combined with β-lactam antibiotics against many clinically significant Gram-negative organisms 1
• Combination therapy with antipseudomonal β-lactams is recommended for severe infections 2

Important Clinical Considerations

1. Dosing:

   • Adults: 15 mg/kg/day (maximum 1g/day), typically as a single daily dose 2
   • Reduced dosing for patients >59 years: 10 mg/kg/day 2
   • Dosing adjustments required in renal impairment 2

2. Monitoring:

   • Regular monitoring of renal function
   • Audiometric testing for ototoxicity
   • Therapeutic drug monitoring when available 2

3. Toxicity concerns:

   • Ototoxicity (primarily hearing loss)
   • Nephrotoxicity (higher risk with concurrent nephrotoxic agents) 2

4. Contraindications:

   • Pregnancy (risk of fetal nephrotoxicity and congenital hearing loss) 2

Amikacin's broad spectrum against Gram-negative bacteria, particularly multidrug-resistant strains, makes it a valuable antibiotic for severe infections when other options have failed or are likely to be ineffective due to resistance patterns.