Antibiotics Flashcards
Name the beta lactams
Penicillins, cephalosporins, monobactams, carbapenems
Penicillins, cephalosporins, monobactams, and carbapenems are what type of agents
Beta lactams
What is the mechanism of B lactams
irreversibly inhibit peptidoglycan polymers in cell wall to cause them to burst, inhibit penicillin binding proteins whch are enzymes that form cross links in membranes
Are beta lactams time or concentration dependent
Time
What type of organism do beta lactams work best on
G+
How are most B lactams absorbed
Orally then rapidly distributed to ECF
What type of clearance do B lactams have?
Kidney
Do B lactams cross the BBB
No (Except in inflammation)
Are B lactams bound to plasma proteins
Not much
What are the three mechanisms of resistance to beta lactams
- b lactamase production via mutation or insertion
- change structure of PBPs
- Chance lack of penetration thru memb pores
What are the 5 subgroups of penicillins
Natural b-lactamase resistant aminopenicillins extended spectrum augmented
What type of animals are natural penicillins mainly used in
Large animal (horses and intra-mammary in food animal)
How should natural penicillins be given
IM - NOT ORALLY because acid-labile
Are natural penicillins degraded by b-lactamase
YES!
What concerns are there for natural penicillin use
Long acting can cause residues in food animals, can cause CNS signs
What orgs do natural penicillins kill
G+ and G- (anaerobes only)
What is a drawback of B-lactamase resistant penicillins?
Narrower spectrum - confirm sensitivity
What is the first line of drugs for treatment in small animals
Aminopenicillins (amoxicillan/ampicillan)
What are the routes of administration of Aminopenicillins
Oral (amoxicillan), IV/IM (ampicillan)
What are the side effects of Aminopenicillins
GI flora disruption - nausea and V
What are the three classes of penicillins which are most broad spectrum
aminopenicillins, extended spectrum, augmented
What benefit exists in extended spectrum penicillins?
Improved Q3 (G- aer), especially pseudomonas! (IV use)
Are extended spectrum penicillins susceptible to b-l’ase?
Yes
Describe augmented penicillins
Combination of broad spectrum agent + b-l’ase inhibitor
What is the toxicity for augmented penicillins
GI toxicity in horses, rabbits, hamsters and guinea pigs
What type of effect do penicillins have on orgs
Bacteriocidal
What type of antibiotic are cephalosporins
B-lactam
What is the mechanism of action of cephalosporins
bacteriocidal cell wall inhibitors via PBP
Are cephalosporins time or conc dependent
Time
What is the form of excretion for cephalosporins
Renal
What cautions exist for cephalosporins
Can be cross reactive in penicillin sensitive animals
Are cephalosporins protein bound
No
Describe cephalosporin generations
Go in sequence of oldest to youngest, newer have better gram negative coverage and better resistance to b-l’ase
What spectrum do 1st generation cephalosporins cover
Q1 and Q2, some Q3
What type of drug is cefazolin
First generation cephalosporin
What kind of drug is cephalexin
1-cephalosporin
What is the first line of use cephalosporin in SA
1-gen
What spectrum do 2nd generation cephalosporins cover
Same as 1-gen but with greater Q3
Do 2-cephalosporins cover pseudomonas?
No
Do 1-cephalosporins cover pseudomonas?
No
What spectrum do 3rd generation cephalosporins cover
Q1 and 2 with better gram negative than 2-gen
What kind of antibiotic is cefpodoxime
3-cephalosporin
Name a 1-cephalosporin
Cephalexin, cefazolin
Name a 2-cephalosporin
Cephoxitin, cefotetan
Name a 3-cephalosporin
ceftiofur, cefpodoxime
What species is cephalexin approved in
Dogs only
What Rx should treat bacterial pyoderma
cephalexin (1-cephalosporin_
What method of admin should be used for 3-cephalosporins
parenteral depending on species
Restrictions on 1-gen cephalosporins
Food animals now may use- major use must follow route/dose/freq restrictions (no ELDU), minor ok to use
What are the toxicities of cephalosporins
Cross hypersensitivity with penicillins, GI upset (give with meal), chronic use causing overgrowth of candida/pseudomonas
What kind of agent is Imipenem?
Beta lactam from carbapenem class
What spectrum does Imipenem have
anaerobes and gram + aerobes
What mechanism of action does bacitracin have
Cell wall inhibitor by inhibiting phosphorylation (like vancomycin)
What organisms are killed by bacitracin
G+
What mechanism of action does vancomycin have
Cell wall inhibitor by inhibiting phosphorylation (like bacitracin)
What is the method of administration for vancomycin
IV (po for GI issues)
How is vancomycin excreted
Renally
What are the toxicities of vancomycin
Ototoxic, nephrotoxic, tissue irritant