DR. MABANAG - AMINOGLYCOSIDES, SPECTINOMYCIN & TETRACYCLINE Flashcards
BACTERIA RIBOSOMES
70 S RIBOSOMES
SUBDIVIDED TO:
50 S
30 S
EUKARYOTES RIBOSOMES
80 S RIBOSOMES
How Ribosomes Work
- The tRNA loaded with particular amino acids enters the ribosome at the A site
- The tRNA’s anticodon has to match the codon (group of 3 nucleotides) on the mRNA
- In the P site of the ribosome, a peptide bond forms between the previous amino acid and the new amino acid formed
- The empty tRNA exits the E site
- This process repeats for the whole length of the
mRNA and the polypeptide chain continues to grow
INHIBITORS OF 30S RIBOSOMAL SUBUNIT
A-S-T
○ Aminoglycosides
○ Spectinomycin
○ Tetracycline
INHIBITORS OF 50S RIBOSOMAL SUBUNIT
ML-CO
○ Macrolides
○ Lincosamides
○ Chloramphenicol
○ Oxazolidinones
Block the initiation of translation and causes the misreading of mRNA
AMINOGLYCOSIDES
Block the attachment of tRNA to the ribosome
TETRACYCLINES
Each interferes with a distinct step of protein synthesis
STREPTOGRAMINS
Prevent continuation of protein synthesis
MACROLIDES
Prevents peptide bonds from being formed
CHLORAMPHENICOL
Prevents continuation of protein synthesis
LINCOSAMIDES
Interfere with the initiation of protein synthesis
OXAZOLIDINONES
Used most widely in combination with other agents to treat drug-resistant organisms
AMINOGLYCOSIDES
are better given in combination for added spectrum of activity and synergism
AMINOGLYCOSIDES
- Used in combination with other TB drugs for treatment of mycobacteria infections such as Tuberculosis
- Outside of the urinary tract, aminoglycosides are not very effective, and it should be added with other drugs.
○ For urinary tract infections, monotherapy is enough
AMINOGLYCOSIDES
usually used for TB
STREPTOMYCIN (AMINOGLYCOSIDES)
EYE AND EAR INFECTIONS
NEOMYCIN (AMINOGLYCOSIDES)
Obsolete. Formerly used as 2nd line drug for TB
KANAMYCIN (AMINOGLYCOSIDES)
irreversible inhibitors of protein synthesis (30s and 50s subunit of ribosomes) though the precise mechanism of bacterial activity is still unclear
AMINOGLYCOSIDES
3 WAYS IN INHIBITING PROTEIN SYNTHESIS
- Interference with the initiation complex of
peptide formation - Misreading of mRNA
● Causes incorporation of incorrect amino acids into peptide and results in nonfunctional protein - The breakup of polysomes into nonfunctional monosomes
● Occurs simultaneously, the overall effect is irreversible and leads to cell death
○ After IV administration, aminoglycoside concentration is highest in the ____ and in the _____
1.KIDNEYS
2. EARS
○ why the side effects are in the kidneys and inner ear
AMINOGLYCOSIDES ADVERSE EFFECTS
1.NEPHROTOXIC
2. OTOTOXIC
in INFECTIVE ENDOCARDITIS
Synergistic killing effect
○ Achieve bactericidal activity in the treatment of enterococcal endocarditis
Penicillin + aminoglycoside
○ Shorten therapy duration for Viridans streptococcal endocarditis
○ The duration for Viridans streptococcal endocarditis is 2 weeks but the usual duration is longer.
Penicillin + aminoglycoside
AMINOGLYCOSIDES ADVERSE EFFECTS
1.NEPHROTOXIC
2. OTOTOXIC
3. CURARE LIKE EFFECTS - HIGH DOSE (Reversible by Calcium gluconate or Neostigmine)
4. HYPERSENSITIVITY
Mainly used as a second-line agent for the treatment of tuberculosis
STREPTOMYCIN
ENTEROCOCCAL ENDOCARDITIS
2-week therapy: Viridans enterococcal endocarditis
Penicillin + Streptomycin:
for susceptible strains when aminoglycoside is selected as adjunct therapy
GENTAMICIN