Aminoglycosides and Spectinomycin

Question 1

Mechanism of action of aminoglycosides

Answer 1

Causes misreading of the code on the mRNA template

binds to a specific component of the 30s ribosomal subunit

Question 2

A 72 kg patient with creatinine clearance of 80 mL/min has agram negative infection. Amikacin is administered intramuscularly at a dose of 5 mg/kg every 8h, and the patient begins to respond. After 2days, Creatinine clearance declines to 40 mL/min. Assuming that no indormation is available about amikacin plasma levels, what would be the msot reasonable approach to management

Answer 2

Decrease the dosage to 18- mg every 8h

• a decrease of the amikacin dose in proportion to decreased creatinine clearance.

Question 3

CLinical uses of aminoglycosides

Answer 3

Gentamycin is used with ampicillin for synergistic effects in the treatment of enterococcal endocarditis

• Effective againist AEROBES
• Poor oral absorption
• Combination with other Abx

Question 4

The antibacterial action of aminoglycosides is _________dependent

Answer 4

Concentration

Question 5

Postantibiotic effect

Answer 5

Aminoglycosides continue to exert its effect for several hours after level falling below MIC

Question 6

A diabetic patient has been diagnosed with otitis externa. the best approach to the management is?

Answer 6

Hospitalized and treatment started with gentamicin plus ticarcillin

• Aminoglycoside plus a wider spectrum penicillin is most suitable

Question 7

Ototoxicity of aminoglycosides

Answer 7

Auditory impairment is more likey with amikacin and kanamycin

Vestibular dysfunction is more likely with gentamicin and tobramycin

Question 8

Most nephrotoxic aminoglycosides

Answer 8

Gentamicin and Tobramycin

Question 9

Ototoxicity of aminiglycosides can be inreased by _________

Answer 9

Loop diuretics

Question 10

This drug has characteristics almost identidcal to those of gentamicin but has much weaker activity in combination with Penicillin against enterococci

Answer 10

Tobramycin

Question 11

Your 23 year old female patient is pregnant and has gonorrhea. The medical history includes anaphylaxis following exposure to amoxicillin. The most appropriate drug to use is _________

Answer 11

Azithromycin

Question 12

_____is the agent most likely to cause skin reactions

Answer 12

Neomycin

Question 13

Mechanism of resistance of amnoglycosides

Answer 13

plasmid mediated formation of inactivating enzymes (gorup transferase)

Question 14

_______an aminocyclitol related to the aminoglycosides. Backup drug. adminsitered IM as a singe dose of treatment of gonorrhea

Answer 14

Spectinomycin

Question 15

Aminoglycosides can cause _______ at high doses and may cause respiratory paralysis

Answer 15

Neuromuscluar blockade (Curare-like)

Reversible by treatment with calcium and neostigmine, but ventilatory support may be required