Antibiotics Flashcards
1
Q
Penicillin G
A
- beta lactam
- degraded by beta-lactamases
- mainly used in large animals
- acid labile so do not give PO
- contains K and procaine salts
- procaine salt is long acting and can cause CNS sings
- used for UTI
- also does gram “-“ anaerobes
2
Q
Aminopenicillins (amoxicillin)
A
- beta lactam antibiotic
- disrupts GI flora
- no CNS signs
3
Q
Extended spectrum penicillins ( ticarcillin)
A
- beta lactam
- improved Q3 activity (good for Pseudomonas)
- susceptible to beta-lactamase
4
Q
Cephalosporins
A
-beta lactam
-very similar to penicillins (cross-hypersensitivity)
-NOT highly protein bound
1st gen: oldest, better gram + coverage (Cephalexin)
2nd gen: not used often because we lose some gram + effects
3rd gen: greater Gram - spectrum but lose some Gram + coverage, greater resistance to b-lactamase, more expensive (Ceftiofur) -BBB penetration
5
Q
Imipenem
A
- beta lactam
- belongs to the Carbapenem family
- anaerobes and Gram +
- limit use to high resistant cases
6
Q
Beta-Lactamase inhibitors (clavulanic acid)
A
-beta lactam
7
Q
*Beta Lactam Drugs
A
- penicillin (UTI) and cephalosporins
- biggest problem = resistance (beta-lactamase production, changes in penicillin binding protein structures, impenetrable membrane pores on the bug, mutations and plasmid)
- contain a 4 member beta-lactam ring (antibacterial activity, hydrostatic instability, microbial resistance)
- bacteria cell wall needs to be replenished all the time, these drugs add peptidoglycan polymers to the cell wall and causes it to burst
- TIME dependent
- safe
- acidic, hydrophilic (short half life)
- only penetrates BBB when meningitis is present
- most effective against Gram +
- most are PO, cleared by kidney
- not very protein bound
8
Q
Cephalexin
A
- beta lactam
- first generation Cephalosporins
- DOGS only
- PO
- treatment for pyoderma
9
Q
Ceftiofur
A
- beta lactam
- 3rd generation Cephalosporin
- used in food animals
10
Q
*Aminoglycosides
A
- concentration dependent
- first isolated from Strep
- synergistic with beta-lactams, but clinical effect is not predictable
- hydrophilic base
- attack Gram - aerobes, some gram + (staph)
- can be nephrotoxic (high levels accumulate in the renal cortex), neurotoxic, ototoxic
- causes irreversible inhibition of protein synthesis by binding to ribosomal subunit 30s, which is lethal to many bacteria
- drugs must be transported into organism by energy and O2 dependent transporter (ineffective against anaerobes)
- NOT orally absorbed
- renal elimination
- used for UTI in combination with Penicillins
- resistance is limited (decreased membrane transport, altered ribosomal binding site)
11
Q
Gentamycin
A
- Aminoglycosides
- DOGS and CATS
12
Q
Amikacin
A
- Aminoglycosides
- Dogs, horses, neonatal foals
13
Q
*Phenicols
A
- all are organic bases, lipophilic
- great tissue distribution
14
Q
Chloramphenicol (SA)
A
- Phenicols
- reversible inhibitor of ribosomal 50 protein synthesis
- bacteriostatic
- enzyme-catalyzed
- resistance: plasmid, frequently in multi-drug resistant organisms
- absorbed via all routes
- hepatic elimination
- species dependent half life
- major concern is human toxicity (bone marrow suppression)
- NEVER use in food animals
- gives cats GI issues
15
Q
Flophenicol (LA)
A
- Phenicol
- OK for food animals
16
Q
*Lincosamides
A
- reversible inhibition of ribosomal protein 50 synthesis
- effective against anaerobes
17
Q
Linconmycin
A
-Lincosamides
18
Q
*Tetracyclines
A
- bacteriostatic agents
- reversible inhibition of protein synthesis by 30s ribosomal subunit
- accumulated in macrophages
- resistance = alteration in transporter
- amphoteric compounds
- most observed PO but can hurt esophagus so must follow it with water, painful injection
- classified according to actions (short acting/H2O soluble, long acting/ lipid soluble, intermediate acting)
- gram -/+ and mycoplasmas
- cross-resistance to aminoglycosides and sulfonamides
- effective for gram - UTIs
- can really hurt esophagus if not given with water
19
Q
Oxytetracyclin
A
- Tetracyclines
- renal elimination
- only for LA
- intermediate acting
20
Q
Doxycyclin
A
- Tetracyclines
- NOT IN COWS / SHEEP
- hepatic elimination
- long acting
- used for ehrlichiosis in dogs
- BBB penetration
21
Q
*Fluoroquinolones
A
- newest group
- weak organic acids
- also called quinolones
- inhibits bacterial DNA gyrase
- accumulates in phagocytes (prolongs the effects)
- concentration dependent
- broad spectrum with Gram - and aerobes
- ineffective against anaerobes and most streps
- mixed renal and hepatic elimination
- safe in most species, high doses can cause nephrotoxicity, local tissue irritations, and mild GI upsets
- contraindications: can cause blindness in cats
- promotes its own resistance
- avoid combinations with NSAIDs
22
Q
Enrofloxacin
A
-Fluoroquinolones
23
Q
Marbofloxacin
A
- Fluoroquinolones
- best one
24
Q
*Macrolides
A
- all contain a lactone ring (basic) and lipophilic
- reversible inhibition of ribosomal protein 50 synthesis
- bacteriostatic
- gram +, few gram - and intracellular organisms
- accumulated in neutrophils
- well absorbed in all routes
- mixed elimination
- major side effects include the GI system
- CAUTION in adult horses
- strong cross resistance, usually involves alteration of ribosomal binding site
- binds directly to many other drugs
25
Clindamycin
- Lincosamide
| - used in dogs and cats for oropharyngeal infections
26
Azithromycin
- Macrolides
- less GI effects
- good for respiratory infections
27
Tylosin
- Macrolides
| - develops slow resistance
28
*Polypoptides
-
29
Vancomycin
-Polypoptides
30
Bacitracin
-Polypoptides
31
Polymixin
-Polypoptides
32
*Potent Sulfonamides
- oldest group of synthetic antibiotics
- organic acids
- classified according to water solubility (systematic infections), lipid solubility, tissue distribution, duration of action
- interfere with folic acid synthesis necessary for pyrimidine synthesis
- bacteriostatic at usual levels
- gram +/-
- resistance really limits it's effects, high cross resistance, altered PABA levels, altered DHP synthesis, microbial breakdown uses sulfas for its own synthesis
- elimination via kidney and liver
- interfere with folic acid metabolism
- side effects: local tissue irritation, keratoconjunctivitis sicca, renal crystallization, idiosynchratic immune reactions, acute reactions are rare but severe
- fucks up protein binding on renal secretion of acid drugs
33
Sulfas + Trimethoprim
- Potent Sulfonamides
| - bacterial combination of the two drugs
34
Rifampin
-antibiotic
35
Metronidazole
- antibiotic
- concentration dependent
- active against anaerobes, protozoal organisms
- used for Giardia
- PROHIBITED in food animals !
- very lipophilic
- unknown mechanism of action, most likely generates reactive O2 species that disrupt DNA
- food increases bioavailability in dogs
- use it in shunt patients before surgery to decrease bacterial load and ammonia production
- Common GI issues come with it, neurotoxicity is a big deal with it (mostly in cats)
- competes for the same CYP450 family
- BBB penetration
36
Antibiotics that cross BBB (per his slide)
Chloramphenicol
Doxycycline
Metronidazole
3rd gen Cephalosporins in case of meningitis
37
concentration dependent
fluoroquinolones
aminoglycosides
metronidazole
