47 Questions
Which of the following is NOT a member of the aminoglycoside class?
Erythromycin
Which ring structure is common among aminoglycosides?
Hexose ring
Why should aminoglycosides be taken on an empty stomach?
To avoid interaction with acidic pH
What is the primary mechanism of action of aminoglycosides?
Inhibition of protein synthesis
What enhances the transport of aminoglycosides across the cell membrane?
Presence of oxygen
All are established mechanisms of resistance to aminoglycosides, Except?
Inhibition of protein synthesis
What is the half-life of aminoglycosides in serum?
2-3 hours
Which of the following best describes the dosing preference for aminoglycosides?
Once daily
What type of killing do aminoglycosides exhibit?
Concentration-dependent killing
How are aminoglycosides mainly eliminated from the body?
A and B
In what condition can aminoglycoside concentrations increase in specific parts of the body?
Meningitis
What type of antibiotic when administered with aminoglycosides may exhibit synergistic killing against certain bacteria?
Beta-lactam or vancomycin
Which type of bacteria are aminoglycosides primarily used against?
Aerobic Gram-negative bacteria
In which scenario are aminoglycosides almost always used in combination with a β-lactam antibiotic?
When there is concern for drug-resistant pathogens
Which class of drugs are aminoglycosides often combined with to extend empiric coverage?
β-lactam antibiotics
What characteristic makes aminoglycosides more likely to be ototoxic and nephrotoxic?
Continued therapy for more than 5 days
Which type of damage can vestibulotoxicity caused by aminoglycosides result in?
Vertigo, ataxia, and loss of balance
Which aminoglycosides are known to cause auditory damage?
Neomycin, Amikacin, and Kanamycin
What is the primary toxicity associated with aminoglycosides at certain threshold concentrations?
Nephrotoxicity
Which dosing strategy results in a greater total time above the threshold concentration with aminoglycosides?
Multiple smaller doses
Among Neomycin, Tobramycin, and Gentamicin, which aminoglycoside is the most nephrotoxic?
All have similar nephrotoxicity
Which aminoglycosides are considered the most vestibulotoxic?
Streptomycin and Gentamicin
In what form have creams, ointments, and solutions containing gentamicin sulfate been used?
Treatment of infected burns, wounds, or skin lesions
What is the maximum daily dosage of streptomycin for adults?
1 g
What is the most serious toxic effect with streptomycin?
Vestibular function disturbance
What adverse effect can streptomycin cause if given during pregnancy?
Deafness in the newborn
Why should aminoglycosides NOT be used as single agents for therapy of pneumonia?
Poor penetration of infected lung tissue
Which bacterial strains are NOT inhibited by Gentamicin according to the text?
Anaerobes
Which local conditions contribute to the limited activity of aminoglycosides in treating pneumonia?
Low pH and low oxygen tension
Which bacterium is Streptomycin NOT commonly used to treat?
Staphylococcus aureus
What type of reactions are considered uncommon with gentamicin use?
Hypersensitivity reactions
Which condition is most likely to result from prolonged use of gentamicin?
Nephrotoxicity
Which aminoglycoside is known to have almost the same antibacterial spectrum as gentamicin but is slightly more active against Pseudomonas aeruginosa?
Tobramycin
Which aminoglycoside is resistant to many enzymes that inactivate gentamicin and tobramycin?
Amikacin
Which aminoglycoside is available for inhalation form and as ophthalmic ointment or drops for the treatment of Superficial Eye Infections?
Tobramycin
Which aminoglycoside is an alternative treatment for drug-resistant gonorrhea?
Spectinomycin
Which aminoglycoside is more toxic in terms of its effects on the auditory portion of the eighth nerve?
Amikacin
Which bacteria are generally resistant to neomycin?
Mycobacteria, Pseudomonas aeruginosa and streptococci
Why is neomycin generally limited to topical and oral use?
Associated toxicity with parenteral use and higher resistance rates
For which condition can paromomycin be used?
Intestinal infections with parasites
Which drug is limited to the treatment of Multi-Drug-Resistant Tuberculosis?
Kanamycin
What is the main route of excretion for absorbed neomycin?
Urine
Where are solutions containing neomycin primarily used when infection is present?
Joints
What is the primary use of neomycin for oral administration?
Preparation for bowel surgery
Which group of drugs have significant nephrotoxicity and ototoxicity according to the text?
Aminoglycosides
How is neomycin primarily eliminated from the body?
Through feces
What can act as antidotes in cases of kanamycin toxicity resulting in curare-like neuromuscular blockade and respiratory arrest?
Calcium gluconate and neostigmine
Study Notes
Aminoglycosides Overview
- Aminoglycosides are primarily used against gram-negative bacteria
- They inhibit protein synthesis by binding to the 30S ribosomal subunit
Mechanism of Action
- The primary mechanism of action of aminoglycosides is by binding to the 30S ribosomal subunit, inhibiting protein synthesis
- Polymyxin enhances the transport of aminoglycosides across the cell membrane
Pharmacokinetics
- Aminoglycosides have a half-life of 2-3 hours in serum
- They are mainly eliminated from the body through the kidneys
- Dosing preference for aminoglycosides is once-daily dosing
Resistance
- All mechanisms of resistance to aminoglycosides have been established, except for target modification
- Resistance to aminoglycosides can occur through enzymatic modification, target modification, and altered permeability
Adverse Effects
- Aminoglycosides are ototoxic and nephrotoxic due to their high positive charge and ability to accumulate in the inner ear and kidneys
- Ototoxicity can result in irreversible auditory damage
- Nephrotoxicity can occur at certain threshold concentrations
- Aminoglycosides can also cause vestibulotoxicity, resulting in balance and coordination problems
Specific Aminoglycosides
- Gentamicin, tobramycin, and amikacin are commonly used aminoglycosides
- Neomycin is not absorbed orally and is primarily used topically or orally for gut decontamination
- Streptomycin is used to treat tuberculosis and is teratogenic
Indications and Contraindications
- Aminoglycosides are used against gram-negative bacteria, such as Pseudomonas aeruginosa and E. coli
- They are often used in combination with β-lactam antibiotics for broad-spectrum coverage
- Aminoglycosides should not be used as single agents for therapy of pneumonia due to limited activity in the lungs
- Gentamicin is not effective against Streptococcus, anaerobes, and methicillin-resistant Staphylococcus aureus
Test your knowledge about aminoglycoside antibiotics including Streptomycin, Neomycin, Kanamycin, and more. Learn about their structure, mechanism of action, and clinical uses.
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