Antibiotics Flashcards
what are some of the common antibiotics in small animals
- Amoxycillin (a semi-synthetic penicillin)- Clavulanic Acid (“Noroclav”, “Amoxyclav”, “Clavulox”)
- Enrofloxacin (“Baytril”)
what are some of the common antibiotics in equines
• Procaine Penicllin (“Norocillin”, “Depocillin”) • Gentamicin (“Gentam”)
what are some of the common antibiotics in production animals
- Oxytetracycline (“Alamycin”, “Engemycin”, “Oxytet”)
* [Procaine Penicillin (“Norocillin”, “Depocillin”, “Duplocillin”)]
why are culture and sensitivity tests sometimes not performed prior to treatment
results take a while to come in (up to a week) and an animal may die int he meantime.
explain Empirical therapy
and when it is considered
initial treatment without diagnosis of the problem,
it is considered:
• frequently for rural systems –no access to microbiology
• therapy may be needed immediately-ethical considerations
• microbiological results may be unusable
• economic considerations
explain some ways of selecting empirical therapy options
- books and papers
- four quadrant therapy
- experience
- be careful of updated science, but can sometimes prove more useful then books
four quadrant therapy - other factors: licenced: on-label, off-label; WHP?; cost of Tx vs cost of animal/herd; practicalities of dosing
list four quadrant therapy for equines, dogs, cats and ruminants
Equine dogs and cats:
• aminoglycoside + (potentiated) beta-lactam
• fluoroquinolone + (potentiated) beta-lactam
• dogs/cats: “Baytril n’ Clav”
• equine: “PenGent”
Ruminants
• no standard for four quadrant therapy. Gentamicin and enrofloxacin banned.
• oxytetracycline not very good against anaerobes
• procaine penicillin not very good against Gram-ves
• Practicals of administration, eg. few oral antibiotics available, a major problem
True or false
when giving antibiotic dosages it is ok to trust the label dosage.
FALSE
it is expensive to re-register the drug and therefore many companies do not update the dose
it is important to always perform dose calculation tests.
explain implications of the withholding period
Long: drug persist for a long time, effect may be better
short: doesn’t persist for a long time or even enter that compartment
influences on antibiotic choice:
- time until slaughter
- severity of disease
- location of disease
true or false
never give a lactating cow a dry cow therapy
TRUE
due to the milk withholding period
• lactating cow intramammaries ~1.5-3d • dry cow intramammaries ~49d
what are some of the reasons for treatment failure?
- infectious disease process: the antibiotics fixed the bacteria but not the neoplasia.
- inappropriate antibiotic used e.g. gentamicin poor against streptococcalsep
- inappropriate dose
- inappropriate route of admin
- inappropriate length of treatment
- poor immune system
- could be more then one agent causing problem
- misleading C&S results from contamination
explain MIC and S/R
- MIC provides the minimum concentration of an antibiotic that will inhibit/prevent the growth of bacteria
- Susceptible/sensitive (S) or resistant (R) provides an overall prediction of whether a standard dose of antibiotic will inhibit/prevent the growth of bacteria
both are predictors of what will happen with a particular type of antibiotic at a concentration in an area.
What are some limitations of in vitro antibiotic sensitivity testing and C & S…?
- higher doses then used in C&S can sometimes overcome resistance
- shows the species variation between human plasma and patients site of infection
- the bacteria may be currently exhibiting exponential growth e.g. beta lactams work better against rapidly dividing bacteria
- the bacteria may not be under the same conditions as the laboratory-adpated isolate e.g. decreased O2 in poorly vascularised compartments- gentamicin works better in normal O2 conditions.
What are the 5 antibiotics that can not be used in milk or meat production
Which 1 of these can be used in meat production
1- Chloramphenicol 2- Enrofloxacin (or any fluroquinolone) 3- Gentamicin 4- Metronidazole 5- Tilmicosin
Tilmicosin can be used in meat production but has a 28d WHP
Why can’t Enroflaxacin be used?
- there is no MRL set by the APVMA and MRLs are used to set WHP.
