What are the adverse effects of tetracyclines?
Staining of unerupted teeth
What animals is gentamycin used in?
Pigs, but no other food animals
How do ionophores work?
Complex with Na+ in cell membrane
Produce passive extracellular transport of K+
Intracellular influx of H+
Kills bacteria + coccidian by lowering intracellular pH
Why is there sometimes an anti-anabolic effect with the use of tetracyclines?
high doses cause binding to mitochondrial ribosomes
Elevated BUN with pre-existing renal disease
How is linezolid metabolized?
Oxidation but it is non-enzymatic and does not involve hepatic microzome system
how is neomycin used?
Orally for enteric infections (food animal)
Topically for skin + ear + eye infections
What are tetracyclines used for in small animals medicine?
Respiratory + Urinary tract infections
Psittacosis in birds
How does linezolid work?
Inhibits bacterial protein synthesis by interfering with translation
Why is the use of lincosamides contraindicated in some animals?
Produce severe, often fatal diarrhea due to altered GI flora involving C. Diff
What animals is most sensitive to ionophore toxicity?
What is the basic structure of the aminoglycosides?
Contain amino sugars in glycosidic linkage
How is chloramphenicol absorbed?
From GI tract and distributed to all tisuses including CNS and eye
What type of CNS infection is clindamycin used for?
How are lincosamides adminstered?
PO + Paraenterally + Topically
What are the four major uses for linezolid?
What are the regulations when it comes to the use of oxyteracyclines in food animals?
Extralabel Withdrawl time = 28 days for intrauterine treatment Test milk after intrauterine treatment
Extralabel withdrawl time = 28 days IM/SC treatment
Milk withdrawl time = 96 hours
Withdrawal time = 14 days
What impairs absorption of tetracylcines?
Divalent or trivalent cations
Avoid milk, antacids, or iron salts for three hours before and after administration
What are the ionophores derived from?
polyther from Streptomyces
What is the distribution pattern of florfenicol?
Widely distributed, including CNS
What does it mean when something has concentration dependent killing?
Increasing concentrations kill an increasing population of bacteria
Adverse effect are time dependent
How is tylosine adminstered?
IM or PO, BID or SID - Swine + Calves + Lambs + Dogs + Cats
What situations are aminoglycosides most often used?
Gram-negative enteric bacteria
Suspicion of sepsis or endocarditis
What are the three ways that aminoglycosides interact with the 30s subunit causing the block of protein synthesis?
Block initiration of protein synthesis
Block further translation and elicit premature termination
Incorporation of incorrect amino acid
What is gentamicin and amikacin used against specifically?
(Wider spectrum of activity)
What are the restrictions to absorption of erythromycin?
Gastric acids destroy base
need to modify formula for oral admin
Enteric coated or film-coated
What is pirlimycin used for?
What is the mechanism of action for tetracyclines?
Inhibition of bacterial protein synthesis
Bind reversibly to 30S ribosomes + prevent access of aminacyl tRNA to receptor site on mRNA-ribosome complex
Prevents addition of AA to growing peptide chain
How is resistance developed against eryhtromycin?
Active pump mechanism
Ribosomal protection by inducible or constitutive production of methylase enzymes = modification of ribosomal target
Macrolide hydrolysis by esterases
Chromosomal mutations that alter 50S ribosomal protein
What ionophores are used for prevention of coccidiosis in broilers?
Why does erythromycin react with chloramphenicol and clindamycin?
All these drugs bind to similar spots on the 50s subunit
What is the basic structure of macrolides?
Macrocylic lactone ring which sugars are attached
What are the regulations of chloramphenicol use in food animals? Why?
Due to residue0induced toxicity in humans
Why does iatrogenic endotoxicosis occur with phenicol adminstration?
Rapid killing of gram (-) bacteria
What is lincomycin used for?
Swine - control/txt of swin dysentery
How is clarithromycin administered?
PO, BID - Dogs + Cats + Ferrets
What are the restrictions for tildiprosin when using it with food animals?
Withdrawl time for meat - 21 days
Do not use in female cattle over 20 months
What drugs should not be used with linezolid?
How does plazomicin differ from the other aminoglycocides?
Devoid of nephrotoxic + ototoxic effects
Not influenced by bacterial enzymes that modify/inactivate aminoglycosides
What are ways that resistance against aminoglycosides occurs?
Plasmid mediated chemical changes of enzymes that adenylate + phosphorylate + acetylate aminoglycoside drugs
Resistance may involve alteration of bacterial ribosomes which aminoglycosides attach
Cannot enter the cell
What is tildipirosin used for?
BRD - Mannheimia haemolytica + Pasteurella multocida + Histophilus somni
Control of BRD - MH + PM + HS
What side effects do you see in dogs, cats, cattle, and swine from the use of lincosamides?
Neuromuscular blockade at high doses or when used with anesthetics
What is used with clindamycin for preventative purposes? Why?
Avoid C. diff-mediated pseudomembranous colitis associated with clindamycin in dogs
What is the mechanism of action for lincosamides?
Bind to 50S ribosomal subunits of bacteria = protein syntehsis inhibition
What are the three common tetracyclines used in small animals?
What is the mechanism of action for erythromycin?
Inhibition of protein synthesis of susceptible bacteria
Binds reversibly to 50S subunit to prevent translocation of AA
What is the major use of ionophores?
Poultry + swine feed efficiency + anticoccidial activity
What is clindamycin used for?
Dogs/Cats = Peridontal disease + osteomyelitis + dermatitis + deep soft tissue infections caused by gram + infections + TOXOPLASMOSIS
Dogs = Neoporosis
How is tilmicosin adminstered?
SC, every 72 hours - Cattle
What does it mean to have post-antibiotic effect?
Antibacterial activity persists beyond the time that the antibiotic is measurable
how does tobramycin compare to gentimycin?
More potent anti-pseudomonal activity + reduced nephrotoxicity
How do tetracyclines aid in contracted tendons in foals?
Inhibit collagen-based contractions in myofibroblasts
What do ionophores do within the rumen?
Select for Gram + bacteria, shifting the bacterial community to Gram (-)'s
This increases the production of propionic acid and decreases the production of acetic and butyric acids
What are the adminstration requirements for gamithromycin in food animals?
SC in beef and non-lactating cattle only
Not for use in female dairy cows over 20months of age or calves that will be used for veal
What specific bacteria do tetracyclines work against in small animal medicine?
How is azithromycin administered?
SID, PO - Dogs + Cats + Foals
What are lincosamides active against?
Aerobic gram-positive cocci
Several anaerobic gram-negative/positive
Why should PO and parenterally admin be avoided in horses?
Danger of disrupting ruminal or colonic microflora
Which of the tetracyclines can pentrate the CNS, eyes, and prostate?
How do aminoglycosides get into the cell?
Oxygen dependent transport
Why is it thought that tetracyclines work well with cat absecesses?
Contain L-form bacteria that lack cell walls and are sensitive to tetracyclines
What are the three important characteristics of aminoglycosides when it comes to their pharmokinetics?
None is absorbed after oral administration
None pentrate CSF readily
Normal kidney rapidly excretes them all
How do tetracyclines enter the bacterial cell?
When are tetracyclines used for cat abscesses?
Those that do not respond to B-lactams
What are the characteristics of distribution when it comes to erythromycin?
Passes through placeneta
Penetrates prostatic fluid
DOES NOT GO INTO CNS
What is the protocol for Florfenicol in food animals?
Approved for use in cattle and swine
Respiratory disease + foot rot in cattle
What is the mechanism of action for chloramphenicol?
Reversibly binds to 50S subunti
What are the five derivatives of erythromycin?
Why do tetracyclines tend to stain teeth?
Formation of tetracyclein-calcium phosphate complex in enamel and dentine
What is the predominant activity of linezolid?
Aerobic gram-positive organism
What are tetracyclines used for in large animals?
Local + systemic bacterial infections in sheep, cattle, horse, and swine
Feed additive/growth promoters in cattle and swine
What are the six groups of drugs that act as inhibitors on protein synthesis?
How is doxycycline secretion diifferent?
Intestinal excretion is major route of elimination
Which of the tetracylcines are not nephrotoxic?
What is the veterinary feed directive?
Intends to limit antibiotic use for therapeutic needs instead of production
Recommends drug manufacturers VOLUNTARILY stop labeling drugs as "promoting animal growth"
What is the difference between monogastric and ruminal animals when it comes to ionophore absorption?
More complete and metabolism is slower = increased toxicity
What animals is lincosamides contraindicated in?
What do aminoglycosides act on?
Inhibiting protein synthesis of susceptible organisms
Inhibit funciton of the 30S subunit of bacterial ribosomes
What are the distribution characterisitics of clindamycin?
Gets into breast milk
Reaches high concentrations in teh bone
Does not get into the CNS
How are ionophores excreted?
Elminated by feces
What is a good way to get aminoglycocides to work against gram +'s?
Use with beta lactam
Which of the phenicosl produces aplastic anemias?
What are the adverse effects of chloramphenicol?
bone marrow depression
Due to inhibition of protein synthesis in host mitochondria
How is florfenicol metabolized?
1/3 metabolized by the liver
2/3 of drug excreted as parent
What is chloramphenicol used for in dogs, cats, horses, ad birds?
Local and systemic infections
Respiratory + CNS + Ocular
Due to Anaerobes + Salmonella
What are the adverse reactions to erythromycin?
Elevated hepatic enzymes
How is florfenicol given to swine?
What is the absorption rate of tetracyclines? What is the exception?
60 to 90%
Cholortetracycline - 35%
When are macrolides effective?
Alternative agents to penicillin when patient is allergic and/or when in renal failure
What are the adverse effects of the penicols?
How are tetracyclines excreted?
Glomerular filtration, with small amounts being excreted into the bile
How is erythromycin administered?
PO or IM TID - Dogs + cats + foals
IM SID - Cattle + Sheep + Swine
What does tetracycline work against?
Gram +/- aerobes/anaerobes
How is linezolid adminstered?
IV or Oral
What does plazomicin act against?
What is the major characteristic of aminoglycocides that give them their properties?
How is erythromycin excreted?
Lost in feces in large amounts
5% excreted in urine
What two drugs have contraindications with erythromycin?
What is gamithromycin used for?
BRD - Manneimia haemolytica + Pasteurella multocide + Histophilus somni + Mycoplasma bovis
Control of BRD - M.H. and P.M.
What are the characteristics of metabolism for tetracyclines? Which one differs and how?
Metabolism is very minimal in domestic animals
Exception = minocylcine, metabolized by the liver
How is florfenicol given to cattle?
IM, one dose than another 48 hours later
How is tulathromycin administerd?
one SC injection against cattle and swine respiratory infectiosn
What are the gram negative rods that aminoglycocides are most effective against?
What ionophores are used in the feed for growth promotion and feed efficiency?
What are the three lincosamides?
What specific bacteria do tetracyclines kill in large animals?
What drug are lincosamides mixed with to treat toxoplasmosis?
When is chloramphenicol bacteriocidial?
How does chloramphenicol cause aplastic anemia in humans?
Why it is banned in food products
What three tetracyclines are most commonly used in large animals?
When are aminoglycosides bactericidal?
Aerobic conditions, unknown why
What two tetracyclines are used for cat abscesses?
Where do superinfections caused by tetracyclines tend to occur?
due to prolonged adminstration
How is chloramphenicol metabolized?
75% for cats
90% for dogs
How should aminoglycosides be given since that have a large PAE?
Single, large dose will be the most efficective
Why does chloramphenicol cause anemia?
Inhibits the uptake of iron in mitochondira present in erythropoeitic cells in bone marrow