Ch. 12 Anti-infective Drugs Flashcards by Dana Dyches

What is the goal of antimicrobial tx?

to render the microbe helpless (either by killing them or inhibiting their replication) and not hurt the animal being treated

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What is an antimicrobial?

a chemical substance that has the capacity, in diluted solutions, to kill (biocidal activity) or inhibit the growth (biostatic activity) of microbes

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Classifications of antimicrobials

Antibiotics
Antifungals
Antivirals
Antiprotozoals
Antiparasitics

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Pathogenic microorganisms can be classified as

local or systemic

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A localized infection may involve _ or an _ _ and may progress into a systemic infections

skin; internal organ

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A systemic infection involves the whole animal and is more _ than a local infection

serious

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Antibiotics work only on _ and are described by their spectrum of action (range of _ for which the agent is effective)

bacteria

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Narrow-spectrum antibiotics only work on _ or _ bacteria. (Not both)

gram-postive or gram-negative

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Broad-spectrum antibiotics work on

both gram-positive and gram-negative bacteria (but not necessarily all)

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Antibiotics can be classified as _ or _

bactericidal or bacteriostatic

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Bactericidals do what

kill the bacteria

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Bacteriostatics do what

inhibit the growth or replication of bacteria

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What does antibiotic resistance mean

that the bacteria survive and continue to multiply after administration of the antibiotic

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What can develop through the following:
-bacterial mutation
-bacteria acquiring genes that code for resistance

antibiotic resistance

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What is an antibiotic residue

the presence of a chemical or its metabolites in animal tissue or food products

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What can antibiotic residues cause

allergic reactions in humans or produce resistant bacteria that can be transferred to people who consume these products

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Withdrawal times for antibiotics are aimed at eliminating:

antibiotic residues in food-producing animals

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Penicillins have - structure that interferes with bacterial cell wall synthesis

beta-lactam

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Penicillin G and V are _-spectrum gram positive antibiotics

narrow

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Penicillin G is given _

parenterally

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Penicillin V is given _

orally

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Broader-spectrum penicillins are -

semi-synthetic

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Examples of broader spectrum penicillins

-AmoxiCILLIN
-AmpiCILLIN
-CarbeniCILLIN
-TicarCILLIN
-MethiCILLIN

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Examples of beta-lactamase resistant penicillins

-methicillin
-oxacillin
-dicloxacillin
-cloxacillin
-floxacillin

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Potentiated penicillins are chemically combined with _ _ to enhance effects of both

another drug

example of a potentiated penicillin

amoxicillin and clavulanic acid (which binds to beta-lactamase to prevent the beta-lactam ring from being destroyed)

What are cephalosporins

-semi-synthetic, broad-spectrum antibiotics that are structurally related to the penicillins -have the beta-lactam ring

How can cephalosporins be identified

ceph- or cef- prefix in the drug name

Cephalosporins are classified into four generations. as the number of the generation increases, the spectrum of activity broadens (but becomes less ___)

effective against gram-positive bacteria

Clinical uses for cephalosporins

skin infections, soft tissue infections, bovine mastitis, shipping fever

What group of drug is described? -Interfere with the production of protein in bacterial cells -Are specialized group of antibiotics with a broad spectrum of activity used for gram-negative bacteria -Are not absorbed well from GI tract, so are given parenterally -May be recognized by -micin or -mycin ending in drug name (not only group using these suffixes)

Aminoglycosides

Aminoglycosides are _ derived

sugar

Side effects of aminoglycosides

nephrotoxicity and ototoxicity

Examples of aminoglycosides

-GENTAMICIN -NEOMYCIN -AMIKACIN -tobramycin -dihydrostreptomycin

Aminoglycosides are inactive against what

most fungal organisms, viruses, and anaerobic bacteria

What group of drug is described? -Interfere with the production of protein in bacterial cells -Considered to be bacteriostatic -Group of antibiotics with a broad spectrum of activity, including respiratory infections and rickettsial agents -Can bind to calcium and be deposited in growing bones and teeth, or bind components of antacids and other mineral-containing compounds -Recognized by cyclone ending in drug name

Tetracyclines

Side effects of tetracylines

teeth staining in young animals

Examples of tetracylines

-tetracyline -oxytetracycline -doxycycline -minocycline -chlortetracycline

What group of drug is described? -interfere w/ production of protein in bacterial cells -are broad spectrum antibiotics that have a large molecular structure -used to tx penicillin-resistant infections or in animals that have allergic reactions to penicillins

Macrolides

Examples of macrolides

-erythromycin -tylosin -tilmicosin

What drug group is described? -Interfere w/ production of protein in bacterial cells -Narrow spectrum, gram-positive antibiotics -SE: GI problems

Lincosamides

Examples of lincosamides

-clindamycin -lincomycin -pirlimycin

What drug group is described? -Are broad-spectrum antibiotics that inhibit the synthesis of folic acid (needed for growth of many bacteria) -Some are designed to stay in GI tract; some are absorbed by GI tract and penetrate tissues -SE: crystalluria, KCS, skin rashes -May be potentiated with trimethoprim or ormetoprim

Sulfonamides

Clinical uses for sulfonamides

UTI, URI, Coccidiosis

Examples of sulfonamides

-sulfadiazine/trimethoprim -sulfadimethoxine -sulfadimethoxine/ormetotprim

What drug group is described? -are antibiotics w/ fluorine bound to the quinolone base, which increases the drug's potency, spectrum of activity and absorption -are broad spectrum antibiotics -can be recognized by -floxacin ending in drug name

fluoroquinolones

Side effects of fluoroquinolones

development of bubble-like cartilage lesions in growing dogs, and crystalluria

Examples of fluoroquinolones

-ENROFLOXACIN -CIPROFLOXACIN -orbifloxacin -difloxacin -marbofloxacin -sarafloxacin

What are nitrofurans?

broad-spectrum antibiotics that include furazolidone, nitrofurazone, and nitrofurantoin

What are nitrofurans used to tx?

wounds and urinary tract infections

What are nitrimiazoles?

Have antibacterial and antiprotozoal activity; work by disrupting DNA and nucleic acid synthesis

An example of a nitromiazole is

metronidazole, which is considered by some the drug of choice for canine diarrhea

What drug group is described? -Interferes with the production of protein in bacterial cells -Is a synthetic, broad-spectrum antibiotic -SE: local tissue reaction (possible loss of tissue at slaughter), inappetence, decreased water consumption, and diarrhea -Used to tx Bovine resp. Disease Complex (nuflor)

Florfenicol

What is the only drug in the florfenicol category?

florfenicol

What is rifampin and what does it do?

-Is a broad-spectrum; used in conjunction w/ other antibiotics -Disrupts RNA synthesis

What drug group is described? -Interferes with the production of protein in bacterial cells -Broad-spectrum antibiotic that penetrates tissues and fluids well (including the eyes and CNS) -Has toxic side effects (bone marrow depression) that extremely limit use -Use caution when handling

Chloramphenicol

What is the only drug in the chloramphenicol category

chloramphenicol

What does bacitracin do?

Disrupts the bacterial cell wall and is effective against gram-positive bacteria

How is bacitracin used?

topically (skin, MM, eyes) and as a feed additive

Vancomycin is effect against many gram-positive bacteria; used for _ infections

resistant

How does polymyxin B work

by attacking the cell membrane of bacteria (remember that animal cells have cell membranes too)

How is polymyxin B used

as an ointment (eye) or wet dressing; not absorbed when taken orally or applied topically

Polymyxin B is a _-spectrum

narrow

Antifungals are chemicals used to tx diseases caused by

fungi (mold or yeast)

Some fungal diseases are _ (ringworm); others are _ (blastomycosis)

superficial; systemic

Categories of antifungal agents

-Polyene agents -Imidazole agents -Antimetabolic agents -Superficial agents

Polyene antifungals work by

binding to the fungal cell membrane

Examples of polyene antifungals

-Nystatin (used orally for Candida albicans infections) -Amphotericin B (used IV for systemic mycoses)

Cautions for Amphotericin B

extremely nephrotoxic, light sensitive, can precipitate out of solution

Imadazole antifungals work by

causing leakage of the fungal cell membrane

Examples of imidazole antifungals

-Ketoconazole (for superficial infections) -Miconazole (for superficial infections) -Itraconazole (for superficial and systemic infections) -Fluconazole (for systemic and sometimes superficial infections)

Antimetabolic antifungals work by interfering with

the metabolism of RNA and proteins

Example of an antimetabolic antifungal

flucytosine (usually used in combo with other antifungals)

Superficial antifungals work by

disrupting fungal cell division

an example of a superficial anti fungal

griseofulvin, an oral medication used to tx dermatophyte infections

What is lufenuron used to tx in cats?

ringworm

_ _ is used topically to tx ringworm

Lyme sulfur

_ are intracellular invaders that alter the host cell's metabolic pathways

viruses

Antiviral drugs act by

preventing viral penetration of the host cell or by inhibiting the virus's production of RNA and DNA

Antiviral drugs used in veterinary practices

-Acyclovir, used to tx ocular feline herpes virus infections -interferon, used to tx ocular feline herpes infection and FeLV

Asepsis

an environment or procedure that is free of contamination by pathogens

Sterilization is

the removal of destruction of all microbes

Disinfection is suing physical or chemical agents to

reduce the number of pathogens or inanimate objects

Antiseptics kill or inhibit growth of microorganisms on _ objects

animate

Disinfectants kill or inhibit growth of microorganisms on _ objects

inanimate

Phenols (lysol) works by destroying the selective permeability of cell membranes. They are effective against what

gram-positive and gram-negative bacteria, fungi, some enveloped viruses

Quaternary ammonium compounds (Roccal) work by concentration at the cell membrane and dissolving _ in the cell walls and membranes

lipids

Aldehydes work by affecting protein structure. They are effective against

gram-positive and gram negative bacteria, fungi, viruses, bacterial spores

Ethylene oxide us a gas used for _ _

chemical sterilization

Alcohols work by

coagulating proteins and dissolving membrane lipids

Alcohols are effective against

gram positive and gram negative bacteria, fungi, and enveloped viruses

Chlorine kills

bacteria, fungi, viruses, and spores

Iodine kills

most classes of microbes if used at proper concentration and exposure times

hydrogen peroxide damages proteins and is used to kill _ bacteria; can cause tissue damage so use is limited

anaerobic