Block 6 Flashcards
What type of antibiotic is penecillin?
Beta Lactam
What is a cephalosporin?
Beta lactam
What type of antibiotic are beta lactams?
Time-dependent bactericidal
What does a time dependent dosing frequency mean?
Need to dose often
Are beta lactams time or concentration dependent?
Time!
What makes a beta lactam a beta lactam?
The beta ring that forms
General rule: Keep abx concentration above MIC for ________ of dosing interval
50%
How does the MOA work?
Beta lactams bind the penicillin-binding proteins cause the cell wall instability
What is the mechansim of action of beta lactams?
Inhibits bacterial cell wall synthesis
Disrupts cell wall integrity
What is the mechansim of resistance of beta lactams?
Hydrolyze the beta-lactam ring
What is a beta-lactamase inhibitor?
It is a drug that works alongside beta lactams to prevent the drug from being inactivated
What are 3 beta lactamase inhibitors?
clavulanate acid, tazobactam, and sulbactam
What bacteria produce the beta lactamases that inactivate beta lactams?
Gram + - staph
Gram - - enterobacterales
What does ESBLs stand for?
Extended-spectrum beta-lactamases
What do ESBLs act upon?
Hydrolyses penicillins, monobactams, and 1st, 2nd, 3rd, and 4th generation cephalosporins
What is a secondary mechanism of resistance of beta lactams?
Altering the binding site of the penecillin binding protein (PMP)
Which bacteria have a modified PMP?
Methicillin-resistant staphylococci (MRSP and MRSA)
What does the altered PMP confer resistance to?
Penecillins, cephalosporing, and carbapenems
What is the exception to the PMPs for cephalosporins?
5th generation cephalosporins
What is the 3rd mechanism of resistance of beta lactams?
Decreased penetration
Block entry
Increase efflux to pump them out
What bacteria type is this mechanism of resistance mostly seen in/?
Gram -
How do you never administer Penecillin G?
IV NEVER!
Why is penecillin not absorbed orally?
Inactivated in low pH
How is amoxicillin/ampicillin given?
Oral, IM, or IV
Where are penecillin concentrations highest?
Kidneys, synovial fluid, liver, lung, skin, soft tissues
How are penecillins metabolized?
Hydrolysis of beta lactam ring
Does penecillin penetrate the BBB?
No
How is penehat is half life of penecillin?
0.5-1 hour
How is penecillin eliminated?
Urine (kidneys)
Do penecillins work on MRSA?
No
What are the 3 penecillin/beta lactamase combos used?
Ampicillin / sulbactam (unasyn)
Amoxacillin / clavulamic acid (clavamox)
Piperacillin / Tazobactam
Oral penecillins cause serious / fatal diarrhea in horses
What are 3 adverse side effects of penecillin?
GI (V, D, inappetance)
Hypersensitivity
Pain or tissue rxn
How are cephalosporins given?
Oral or parental
Which generation of cephalosporins penetrate the CNS?
Gen 3
What is half life of cephalosporins?
1-2 hrs
How are cephalosporins metabolized?
Renally
What is a general rule about the generations of cephalosporins?
Higher the generation, higher the Gram - coverage
What is teh exception to the above rule?
Gen 5 (MRSA coverage)
What is 1st gen oral?
Cephalexin, cefadroxil
What is 1st gen parental?
Cefazolin
What is 3rd gen oral?
Cefpodoxime
What is 3rd gen parental (long acting)?
cefovecin
What is 2nd and 3rd gen parental?
cefoxitin (2), ceftiofur (3), cefotaxime(3), ceftazidime(3)
What are the adverse affects of cephalosporins?
Same as penecillin
*****What bacteria class are intrinsically resistant to cephalosporins?
Enterococci on exam!
What do 1st gen cover?
Great Gram + coverage
Strep and Staph
Good for UTIs and skin infections
How is absorption of cephalexin and cefadroxil (1st gen) in horses and ruminants?
Low
What 1st gen is used in farm animals?
Cephapirin
What does cephapirin treat in farm animals?
Mastitis for intrmammary infusions
When do you use anything above 1st gen cephalosporins?
When there is resistance to 1st gens
When is 2nd gen cefoxitin and cefotetan good?
Septic peritonitis (anaerobic)
What is simplicef?
3rd gen cefpodoxine
What is Convenia?
Cefvecin 3rd gen
What is Convenia used for?
UTIs, skin and soft-tissue infections
What is ceftiofur?
3rd gen
What is ceftiofur used for?
Respiratory infxns in farm animal
What is the only way to administer carbapenems?
IV
What are the 2 carbapenems used in vet med?
Imipenem
Meropenem
What are carbapenems?
Last resort antibiotics
What are carbapenems reserved for?
Multidrug resistant infections
What are Methicillin-resistant Staph resistant to?
All cephalosporins EXCEPT 5th gen!!
What are enterococcus resistant to?
cephalosporins
Strep are susceptible to _____ beta-lactams
ALL
How to lincosamides act?
Bacteriostatic time dependent!
What is the most widely used antimicrobial?
BEta lactams
What was lincomycin isolated from?
Streptomyces
Beta lactams are bactericidal and time dependent
What are the 3 categories of lincosamides?
lincomycin
clindamycin (mostly food animal)
pirlimycin
Is lincomycin affected by food intake
Yes
In terms of distribution where are therapeutic levels achieved?
Synovial fluid, bile, pleural fluid, peritoneal fluid, skin
Is clindamycin or lincomycin better absorbed in GI?
Clindamycin
How are lincosamides absorbed?
Oral and parental
Is clindamycin affected by food intake?
No
How are they excreted?
Through bile, urine, and feces
Where are they metabolized?
In the liver
Do lincosamides enter the brain?
Roughly 40% penetration
What is teh mechansim of action of lincosamides?
Binding of 50s ribosomal subunit
Prevents peptide synthesis, similar to macrolides
What are constitutive resistance (MLSBc)?
Bacteria that show high-level resistance to all MLSB antibiotics
What are inducible cross-resistance (MLSBi)?
Bacteria resistat to macrolides but initially fully susceptible to clindamycine (lincosamides)
What are MLSB antibitoics?
Those that act on teh 50s ribosome subunit
What is the mechanism of resistance?
Alter the binding site
What are the 2 types of resistance?
Constitutive resistance
Inducible cross-resistance
What must be done if during the antibiotic susceptibility test clindamycin is susceptible but erythromycin is resistant ?
A D -test (inducible cross-resistance)
What is the gene that causes resistance?
erm gene
Are lincosamide broad spectrum?
Yes
Gram - usually resistant
What does pirlimycin have an FDA label for?
Staph and strep for INTRAmammary infusion
clinical and subclinical mastitis
Is lincosamide a broad spectrum?
Moderate-broad
What animals are lincomycin labeled for?
Swine, honeybees, dogs, and cats
What can linco treat in pigs?
Erysipelas (penecillin G is best tho I think
What can linco treat in chickens?
Pododermatitis - bublefoot - (staph)
What can linco treat in honeybees?
American foulbrood
Paenibacillus (USDA monitored disease)
Why is clindamycin better?
Better absorbed, more active, and less toxic than linco
What does clindamycin treat?
Skin and dental infections
What should you avoid the use of lincosamydes on?
Enterococcus
ALL GRAM - and Campylobacter
- Enterobacterales
-pseudomonas aeruginosa
-pasteutella
-bordetella
What are side effects of clindamycine?
Fatal diarrhea in horses, rabbits, and other herbivores
What happens in cats with clindamycine?
Esophageal strictures
Like linocosamides, macrolides are what?
Bacteriostatic and time dependent
How do you administer macrolides?
ORAL and parenteral
Do macrolides cross the BBB?
No
For macrolides, tissue concentration can be higher than serum
Do macrolides cross the placenta?
Yes
Where are macrolides metabolized?
Liver
What is the mechanism of action for macrolides/
Binding of 50s ribosomal subunit
What enzyme is responsible for the methylation of adenine?
erm
What is the mechanism of resistance for macrolides?
Enzymatic inactivation
What is a Gram + macrolide that is a use?
***Rhodococcus equi
What are Gram - that macrolides work on?
Bovine respiratory complex (Mannheimia, Pasteurella, Haemophilus) and Bordatella
What is a good antibiotic for mycoplasma and bordetella
Azithromycin
What is a good antibiotic for Bovine respiratory disase, mastitis, and foot rot?
Tulathromycin
Tilmicosin
Erythromycin
What are good antibiotics for equines for rhodococcus equi, strep equi, lawsonia?
Azithromycin
Clarithromycin
Erythromycin
What is a good antibiotic to treat swine respiratory diseases?
Tulathromycin
What is ineffective in treating mycoplasma and chlamydophila in cats?
Azithromycin
Do not use macrolides on enterococcus
What bacteria are resistent to macrolides?
Enterobacterales (E. Coli, Klebsiella)
Pseudomonas aeruginosa
Should macrolides be used in horses, rabbits, and other small mammals?
No - used in foals
What percent of veterinarians were aware of opioid misuse by a staff member or client?
44%
Has gabapentin been described to demonstrate analgesic efficacy in cat’s joints?
No!
Opioid prescription has increase ____ in vet hospitals?
41.2%
The number of vet patients with controlled substance prescriptions from 4 or more vets more than _______ from 2024-2019
Tripled
How do you treat staph?
First gen cephalosporin
How do you treat strep?
First gen cephalosporin or amoxacillin
What can oxytet not be used on?
Lactating dairy cows
In addition to beta lactams
Macrolides and lincosamides what are 3 more antibiotic categories?
Tetracyclines
Phenicols
Aminoglycosides
What are tetracyclines?
Broad spectrum, bacteriostatic, time dependent
What additional things can tetracyclines treat?
Blood borne pathogens
What is something in dogs that oxytet can treat?
Salmon poinsoning (Neorickettsia helminthoeca)
Can you use oxytet in nonlactating dairy cows
Yes!
What are the 3 types of tetracyclines?
Oxytet
Doxy
Mynocycline
Shoud you use doxy for UTIs?
no
What are 2 things that are intrinsically resistant to tetracyclines?
Pseudomonas aeruginosa
Proteus mirabilis
Is E. coli resistant?
Mostly, yes
What are 3 adverse side effects of tetracyclines?
Nephrotoxic
Yellowing of teeth
Esophageal stricture in cats
What are the 2 types of phenicols?
Chloramphenicol and florfenicol
What are the characteristics of phenicols?
Bacteriocidal/bactericidal and time dependent
Do phenicols cross the BBB?
Yes!
What can you not use chloramephenicols in?
Food animal!!!
What can you use flofenicol in for cattle?
BRD
Foot rot
What can chloramphenicols cause in humans?
Aplastic anemia