Inhibits growth and replication of bacteria

-Not good for immunosuppressed patients

1. Target the cell wall

2. Target the cell membrane

3. Target protein synthesis

4. Target nucleic acid

-Molecule contains β-lactam ring that interferes with peptidoglycan cross-linking during cell wall formation in bacteria; Safe for mammalian cells because they lack a cell wall

-Bactericidal: Cell wall is weakened and cell bursts

-Concentration-Dependent: Keep 2-4 times above MIC during treatment

-Most effective against actively growing bacteria

-Most effective against Gram + bacteria; Gram - bacteria have outer coat surrounding cell wall so drugs have harder time acting on cell wall synthesis; Ineffective against bacteria without a cell wall (Mycoplasma)

Penicillin G

aka

Benzylpeniciliin

-β lactam drug

-Produced by fungus

-Combined with procaine local anesthetic or benzathine to delay absorption from IM or SQ injection site

-Combined with potassium (K) to stabilize; Can give IV

-Tubular secretion/renal excretion

Enzyme produced by some bacteria that degrades the β lactam ring of β lactam drugs to prevent them from working against cell wall synthesis

1. Add a molecule to the drug that makes it bigger so β-lactamase can't reach the β-lactam ring to degrade it

2. Add a molecule to the drug that inhibits β-lactamase

Bactericidal β-lactam drugs that act on cell wall synthesis

Later generation drugs become more effective against

Gram - bacteria, but may lose some efficacy against Gram + bacteria compared to older generations 

Secreted from renal tubules → Reach high concentration in urinary tract so good for UTI

Good access to bone → Good for orthopedic surgery patients 

3rd generation cephalosporin drug

Effective against Gram - bacteria but slightly less effective against Gram + bacteria

Can be given IV, Sub-Q or IM

3rd generation cephalosporin 

Given orally

Cephalosporin drug combined with β-lactamase inhibitor 

Very broad spectrum

β lactam drugs taht aren't susceptible to β lactamase

Act on cell wall synthesis - Bactericidal

Broad Spectrum

Polypeptide drug that interferes with bacterial cell wall synthesis (bactericidal) but has no β lactam ring so β lactamase is ineffective against it

Nephrotoxic - Mostly used topically

Effective against Gram + bacteria

Glycopeptide drug that acts against cell wall synthesis (bactericidal)

Toxic

Bactericidal drugs that target bacterial cell membranes (less selective toxicity)

Most effective against Gram - bacteria → Able to bind and neutralize endotoxin

Poor oral absorption

Renal excretion

Combination of:

Polymixin B (for Gram - bacteria)

Bacitracin (for Gram + bacteria)

Neomycin

Bacteriostatic protein synthesis inhibitors

High affinity for calcium and is inactivated when it binds calcium (more problematic with older tetracyclines)

Very broad spectrum: Gram -/Gram + bacteria and protozoa

Renal excretion

Anti-inflammatory effects

Bacteriostatic protein synthesis inhibitor

High lipid solubility

Renal and GI excretion so better for kidney patients than other tetracyclines

IV form should not be used in horses

Bacteriostatic protein synthesis inhibitor

Commonly used in large animal medicine

Bacteriostatic protein synthesis inhibitor

Very lipid soluble

Very broad spectrum - Good for anaerobes 

Eliminated via glucuronidation (can be toxic to cats)

Inhibits p450 enzymes (be careful if coadministering with drugs that are metabolized by p450)

Can cause irreversible aplastic anemia in primates - DO NOT USE IN FOOD PRODUCING ANIMALS

Bacteriostatic protein synthesis inhibitor

Very similar to chloramphenicol, but doesn't cause aplastic anemia in primates so approved for food animals

Bacteriostatic protein synthesis inhibitors

Can cause severe, possibly fatal colitis in horses

Inhibit P450 enzymes so can interfere with metabolism of other drugs - Possible Toxicity

Older macrolide that targets Gram + bacteria

Binds motilin receptors in stomach/upper GI tract at subantibacterial doses - Can be used to treat gastric atony

Newer macrolides that are broader spectrum against Gram + and Gram - bacteria

Good access to respiratory tissues

Bacteriostatic inhibitors or protein synthesis

Good for Gram + infections

Upsets GI flora in horses and causes potentially fatal colitis

Clindamycin

(AKA Antirobe)

Broader spectrum lincosamide that is good for Gram + bacteria, anaerobes, and some protozoa (Toxoplasma and Neospora)

Good prophylactic for dental patients

Doesn't eliminate protozoal infections so must be given long term (possibly for life)

-Bactericidal protein synthesis inhibitors 

-Especially good against Gram - aerobes; Work against Gram + aerobes

-Ineffective against anaerobes - Anaerobes lack pump that allows drug to enter cell

-Water soluble - Not great tissue access

-No hepatic metabolism

-Nephrotoxic if they accumulate in proximal convoluted tubules during renal excretion (dose-dependent)

-Ototoxic (vestibular and hearing problems)

-High doses can cause weakness and paralysis

Aminoglycoside often found in ear medications

Good against pseudomonas

Bactericidal: Products of bacterial metabolism cause DNA strands to break 

(Because DNA breakage can potentially be mutagenic/teratogenic/oncogenic, these drugs can't be used in food animals)

Good for anaerobic infections (abscesses, periodontal disease) - Combined with other antimicrobials to increase aerobic spectrum

Effective against protozoa Giardia and Trichomonas so often used for diarrhea

Hepatic metabolism - Give lower dose with liver disease to prevent neurotoxicity

Bactericidal antibacterial drugs that inhibit RNA polymerase to prevent mRNA synthesis

Antimycobacterial - Used for tuberculosis

Useful for intracellular infections (Rhodococcus equi, Listeria)

Effective against Gram + but not Gram - bacteria

Never use alone to prevent resistance - Give with erythromycin, clarithromycin, etc.

Bacteriostatic inhibitors of nucleic acid synthesis Competitive inhibitors of PABA which prevents folic acid synthesis needed for nucleic acid synthesis

Broad spectrum - Most effective against Gram + bacteria

Also works against protozoa - Coccidia

Lipid soluble and great tissue access

Diaminopyrimidines are combined with sulfa drugs to create a sequential blockade of bacterial enzymes involved in folic acid synthesis resulting in bactericidal effects

Diaminopyrimidines: Trimethoprim, methoprim, ormetoprim, aditoprim, pyrimethamine

Bactericidal: Inhibits DNA gyrase needed for breaking and mending DNA strands in bacteria

Broad spectrum - Most effective against Gram - aerobes

Newer drugs have increased efficacy against Gram +

Lipid soluble - Excellent tissue penetration

Antifungal drug that inhibits β-glycogen synthesis in the fungal cell wall

Rarely used because it is so expensive

IV antifungal drug that affects fungal cell membrane permeability by poking holes in ergosterol

Nephrotoxic

Antifungal drugs that inhibit ergosterol synthesis in fungal cell membranes

Requires long-term therapy because fungi grow so slowly

Newer azoles have better tissue penetration

Monitor liver enzymes while treating

Azole drug that inhibits fungal membrane ergosterol synthesis

Requires acidic stomach pH for absorption so give with food to stimulate stomach acid

p450 enzyme inhibitors - Potential for drug toxicity 

Antifungal drug that binds to spindle microtubules and causes mitotic arrest in metaphase

Used for ringworm treatment

Teratogenic - Stops mitosis in fetus

Anemia - Slows RBC turnover/mitosis of progenitors 

Antifungal drug that is incorporated into nucleic acid and affects fungal protein synthesis

Enters fungal cells through the cytosine pump

Oral paste that interferes with protozoal intermediary metabolism

Used to treat Equine Protozoal Myeloencephalitis (Sarcocystis neurona)

Used to treat coccidiosis in dogs

Competes with thiamine uptake in protozoa and inhibits energy metabolism

Used against Coccidia - More effective prophylactically 

Give with thiamine to avoid thiamine deficiency/neurotoxicity in patient

Antiprotozoal ionophore antibiotic used against coccidia

Forms complexes with Na+ or K+ ions, and the complexes block K+ transport into mitochondria which inhibits substrate oxidation and ATP metabolism in the mitochondria

Cardiac toxicity in horses

Interferes with electron transfer in aerobic metabolism of protozoa

Used to treat Cryptosporidium infections in immunocompromised people in which normal symptomatic therapy (fluids) isn't enough

Organic arsenical used to treat heartworm infections

Arsenic disrupts adult worm metabolism and causes slow death

Injected IM

Doxycycline is given with it to elimate Wolbachia

Heartworm preventive given orally once a month

Active against heartworm larvae

Heartgard Plus includes pyrantel for increased spectrum

Heartworm preventive active against larvae

Also affects intestinal worms