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31 Cards in this Set

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What are Anti-infective Drugs?

Drugs used to combat infections caused by micro-organisms

How are anti-infective drugs identified?

- Culture and sensitivity of the organism




- Differential staining of the organism

Organisms to be identified

- viruses


- chlamydia


- rickettsia


- bacteria


- fungi

Define antibiotics

Agents that act against bacteria

Antibiotic classifications

- Identification through staining


Gram "-" or Gram "+"




- Identification through oxygen requirements


Aerobes (need 02) or Anaerobes (no 02 requirements)



What color do Gram Positive stain?

blue or purple

What color do Gram Negative stain?

pink or red

Why use classifications?

Classifications help to characterize the spectrum of action of an antibiotic

Mechanism of action for antibiotics

- bactericidal




- bacteriostatic




* can be both depending on dosing

action of bactericidal antibiotics

Kills bacteria outright

action of bacteriostatic antibiotics

Inhibits growth and slows reproduction of


bacteria

Define Resistance

Mutation of a bacteria, making it lose susceptibility to a given antibiotic; I.E. super-bug

Define Susceptibility

- In Vitro: Kirby Bauer procedure & Broth dilution (Lab)




- In Vivo: Actual effects in patients - how well the antibiotic counteracts the bacteria




* Effects are not always the same in vivo as in vitro

Considerations prior to antibiotic use

- do not use for mild infections
- use only in individuals at risk for severe infection
- asepsis technique
- culture and sensitivity
- fulfill therapeutic dosing (against hardier organisms)
- maintain safety of food supply (including withdrawal time in food supply animals)

Classes of Antibiotics

- Beta-Lactams (Penicillins, Cephalosporins, Carbapenems)


- Tetracyclines


- Aminocyclitols


- Quinolones


- Macrolides/Lincosamides


- Sulfonamides


- Chloramphenicol/Florfenicol


- Polypeptides (topical)


- Nitrofurans (topical)


- Metronidazole (oral, IV)



Classes of Antibiotics (Others)

- Nitrofurantoin


- Rifampin


- Novobiocin


- Potassium Iodide

Beta Lactams

- Bactericidal


- Have Beta Lactam ring in chemical structure


- Penicillin: first modern antibiotic by Alexander Fleming

Many generations of Penicillins differing in

- administration forms


- duration of action


- spectrum (gram +/-)


- resistance to B-lactamase

What is B-lactamase?

An enzyme produced by some bacteria that renders the antibiotic ineffective

Penicillin - Pharmacokinetics

- variable absorption through the GI tract (primarily stomach and small intestines




- rapid distribution when injected (IM)




- excreted via kidneys

Penicillin - Pharmacodynamics

- bind to cell wall, increasing osmotic pressure and causing bacteria to burst




- inactivated by B-lactamase (penicillinase - bacterial enzyme)

What is the spectrum of Penicillins?

Spectrum is variable

Penicillin spectrum ranges

- narrow


- broad spectrum


- potentiated


- probenecid


- B-lactamase resistant

Narrow Spectrum Penicillins

Pen-G, Pen-V (no use in birds, small animals, or food animals; not given SQ)

Broad Spectrum Penicillins

- Ampicillin (inj.)


- Amoxicillin (tab. or reconstituted liq.) - TX lyme


- Carbenicillin

Potentiated

- Amoxicillin and Clavulonic Acid


- Ticarcillin and Clavuloate

Probenecid

Inhibits tubular secretions of penicillins




(Given with penicillins to decrease the concentration in body tissues)

Beta-Lactamase Resistant

- Ampicillin/Sublactam


- Methicillin


- Cloxacillin


- Dicloxacillin


- Floxacillin


- Oxacillin

Adverse side effects of penicillin

- vomiting and diarrhea


- urticaria / hives


- Anaphylactic shock (with inj.)


- Neurotoxicity with extended use




ALLERGIC REACTION to any penicillins = reaction to ALL penicillins and cephalosporins

Considerations with penicillin use

- Acts synergistically with aminoglycosides (can give 2 abx that improve the effects of each other)




- Pre-slaughter withdrawal times




- Allergic risks to technicians

Carbapenems

- Beta-Lactam antibiotics


- Inhibit bacterial cell wall synthesis (wide range of activity)


- Act as bactericidal


- Used in equine and small animal [Imipenam]


{Cilastatin}