10th lecture - gram negative antibiotics Flashcards
Main gram neg- AB group is?
(and give product examples)
Aminoglycosides, such as:
Streptomycin
Dihydrostreptomycin
Neomycin
Kanamycin
Amikacin
Gentamicin
Tobramycin
Name another group of gram neg. AB in addition to aminoglycosides
Aminocyclitols, such as:
Spectinomycin
Apramycin
Aminoglycosides primarily act against
gram-negative microbes. The effect on gram-positive microbes is limited. They act against some mycobacteria and mycoplasmas.
Aminoglycosides mechanism of action
Bactericidal, inhibit the microbial cell protein synthesis.
Aminoglycosides half-life
Short half-life (1-2 hours).
Aminoglycosides Pharmacokinetics, excretion
Primarily excreted through the kidneys, but accumulate in the kidney tissue (caution in case of renal impairment), medication residues remain in the kidneys for a long period of time which is why the “varoaika”/withdrawal period is long.
Aminoglycosides Interactions/synergism
There is synergistic activity of aminoglycosides in combination with beta-lactam antibiotics.
They also enhance the potency of muscle relaxants and induce neuromuscular blockade (anesthetics).
Aminoglycosides Toxicity
are some of the most toxic antibiotics
(2nd most toxic to be more specific, only 2nd to chloramphenicol/broad spectrum-AB).
Long-term therapy and administration of high doses (mainly neomycin and gentamicin) will lead to nephrotoxicity (acute tubular necrosis).
Treatment with aminoglycosides must be as short-term as possible, however it must be sufficient to destroy the microbes.
Aminoglycosides Side effects
Side effects are ototoxicity and nephrotoxicity (and neurotoxicity).
They cause both vestibular and cochlear damage. The potency of the ototoxic effect is increased by furosemide-type diuretics.
when administered IV Aminoglycosides do what
They slow down heart function and decrease blood pressure.
Oldest 2 aminoglycosides?
Streptomycin and
dihydrostreptomycin
Streptomycin and dihydrostreptomycin side effects
Generally no side effects occur if treatment is less than a week in duration.
In case of long-term treatment they may lead to vestibular damage, ataxia, abnormal coordination and there have been cases of deaths.
Neuromuscular blockade risk when administered with anesthetics.
the most toxic aminoglycoside is
neomycin
Neomycin most frequent side effect is
kidney failure, death.
It is not recommended to administer through the parenteral route.
Neomycin is mainly used for
topical treatment of skin infections, as well as intramammary treatment of mastitis.
e.g. neosporin, bacibact
Name 2 aminoglycosides that are Similar to neomycin but less toxic.
Kanamycin and amikacin
Amikacin is a chemical modification of kanamycin. Its nephrotoxicity and neurotoxicity is slightly lower than that of kanamycin.
Name one of the most commonly used aminoglycosides.
Gentamicin
Primary side effects of gentamicin
nephrotoxicity and neurotoxicity, particularly in the event of long-term treatment.
The damage is mostly reversible (but nevertheless that depends on the duration of treatment).
Medical residue will remain in the tissue for a long period of time, especially in the kidneys.
Name an AB belonging to the Aminocyclitol antibiotics group.
This class includes kanamycin, neomycin, gentamicin, apramycin, spectinomycin.
Spectinomycin (an aminocyclitol) is less toxic compared to
aminoglycosides. its use is limited due to resistance emerging quickly.
Spectinomycin (Aminocyclitol antibiotic) side effetcs and synergism.
As a rule, it does not cause nephrotoxicity and neurotoxicity, however it does increase the potency of neuromuscular blockade.
What classes of AB are effective against gram neg. bacteria?
Aminoglycosides and aminocyclitols
Other antibiotics (other than aminoglycosides and aminocyclitols) with effect against gram negative microbes are (2)
polymyxins like colistin. (polypeptide AB)
only administered parenterla because no GI absorption.
Not recommended for use in vet med!
