E2: Antimicrobials Flashcards
What is the goal of antimicrobial stewardship?
To achieve minimum unintentional consequences
Order from broadest to most narrow spectrum of activity: Primary use drugs, secondary use drugs, tertiary use drugs
Tertiary (broadest) - Secondary- Primary (most narrow)
What do antibiotics target and block in bacteria?
Cross-linking reaction (on the cell wall)
Which classes of AMs disrupt the bacterial cell wall?
B-lactams (e.g. Penicillins)
Glycopeptides
Which classes of AMs disrupt inhibit bacterial DNA synthesis?
Quinolones
Fluroquinolones (e.g. Enrofloxacin)
Which classes of AMs inhibit protein biosynthesis in bacteria (2 that affect the 30s ribomal subunit and 2 that affect 50s)?
30s: Tetracycline, Aminoglycosides
50s: Macrolides, Chloramphenicol
Which classes of AMs interferes the bacterial metabolic pathway?
Trimethoprim
Sulfonamides
Which mode of administration is counterindicated for penicillin? What types of bacteria is this AM effective against?
IV
Gram-positive
How do third generation cephalosporins differ from earlier generations?
Third have a wider spectrum of activity
How do third generation cephalospirns differ from penicillins?
3rd gen cepha: more stable in face of change pH and temperature
What type of antibiotic is Imipenem? What is it used to treat in horses?
Broad/wide spectrum Carbapenem (B-lactamase), Tertiary use drug
Severe joint infections, MRSA
(works agaist anaerobes incl B. fragilis)
What type of antibiotic are gentamycin, tobramycin and amikacin? What is a significant side effect and at what dose does this occur? When will you be able to detect this side effect and when will you see overt signs?
Aminoglycosides
Side effect: Tubular necrosis at low doses over long time, dectected in 3-5 days, overt in 7-10days
What are fluroroquinoloes often used for in foals?
What side effect must you look out for?
Salmonellosis
Side effect: Lameness (cartilage damage)
What comboination of AMs is used against Rhoddococcus? What is a common side effect?
Azithromycin + Rifampin
Side effect: Hyperthermia when exposed to sunlight (caution owner to keep foal in cool barn, or monitor closely when outside)
What class of AM is found in high concentrations in urine where it has a bactericidal effect? Where else can it be found in high concentrations?
Sulfonamides
CSF
Give an example of a short acting, intermediate acting and long-acting tetracycline.
Short: Oxytetracycline, tetracycline, chlortetracycline
Intermediatre: Methacycline, Desmethylchortetracycline
Long: Doxycycline, minocycline
What are major side effects associated with tetracyclines?
Severe diarrhea
Calcium chelation (discolored teeth, impairs bone healing)
Hypotension, collapse w/rapid IV injection
Nephrotoxic (potentially)
WBC chemotacis and phagocytosis inhibition
What does chloramphenicol cause in humans?
Aplastic anemia
What is the drug of choice to treat Rickettsia and Mycoplasma?
Tetracyclines
What are some Primary use Drugs commonly used?
Gentamycin
Penicillin
What is one commonly used Secondary use Antimicrobials?
Enrofloxacin
What are some Tertitary use Antimicrobial? What disease group warrents the use of these?
Vancomycin (Glycopeptide)
Chloramphenicol (Phenicol)
Septic joint disease
List a few considerations for antimicrobial choice.
Agent present
Antimicrobial susceptibility of agent
Penetration of antimicrobial
Owner compliance with regimen prescribed
Route of administration
Host factors
Cost
Withdrawal time (e.g. competition or race horse)
With which drug do B-lactams have a synergistic effect which may prevent replases and failures in serious infections with frequent tolerant organisms?
Aminoglycosides
T/F: B-lactams are only active against growing bacteria, static organisms are unaffected and may persist.
True
What antiboitic type is used for Pseudomonas aeruginosa? When may this antibiotic be ineffective?
Aminoglycosides
With anaerobes in a low-oxygen environment
Also not great for Strep
What antibiotic is potent against aerobic gram-negative infections?
Fluoroquinolones
Which drugs when combined with sulfonamides, produce a sequential blockade of microbial enzyme systems resulting in a bactericidal action?
Trimethoprim
Pyrimethamine
(added to sulfa = Potentiated sulfonamides)
What is required in the host for successful therapy with sulfonamides, due to their bacteriostatic nature?
Adequate cellular and humoral defense mechanisms
