Antimicrobials

drugs that kill or inhibit reproduction of microbes

antibiotics, antifungal, antiparasitics, antivirals

kills bacteria

slows growth of bacterial reproduction

most common method in bacterial identification

resist decolorizing, show up purple

stain red

get both Gram + and Gram - and aerobic/anaerobic bacteria

restricted to getting a certain bacteria

gives prohibitive drugs on food producing animals and gives withdrawal/discard time of approved drugs

bactericidal, inhibition of cell wall synthesis

bactericidal, alter cell membrane permeability

bactericidal or bacteriostatic, inhibition of protein synthesis

bacteriostatic, interfere with metabolism

bactericidal, nucleic acid impairment

- B- lactam antibiotics: includes penicillins and cephalosporins; bind to penicillin-binding proteins; makes bacteria osmotically unstable

• - penetration of the cell wall (easier to get into a gram + due to thinner outer coat)
• - binding of target PBPs where they exert their effect
• - production of B-lactamases (enzymes produced by bacteria; hydrolyzes breaking down B-lactam ring and render the drug ineffective)

• - natural penicillins*
• - aminopenicillins*
• - penicillinase-resistant penicillins
• - extended-spectrum penicillins
• - potentiated penicillins*

*most commonly used in vet med

• - includes penicillin G
• - narrow-spectrum against non-B-lactamase producing gram +, but also a few gram - and many anaerobes
• - bactericidal
• - usually restricted to by injection
• - dosed in units
• - large animal mostly

• - broad-spectrum or ampicillin penicillins
• - great for UTIs
• - include ampicillin (capsule and injectable, dental procedures) and amoxicillin (most common, comes as liquid for suspension, tablet in dogs, and injection, refrigerated for 14 days only)
• - still susceptible to inactivation by B-lactamases
• - usually dosed orally (not in ruminants)

• - B-lactamase inhibitor (added)
• - clavulanate (clavulanic acid) and amoxicillin
• - clavamox: oral suspension
• - broad-spectrum drug great for skin infections and UTIs

• - generally a safe drug
• - may develop blood disorders, swollen lymph nodes, fever
• - hypersensitivity
• - not used in rodents or rabbits
• - GI distress (give drug with food)
• - never IV unless formulated as so
• - procaine penicillins not used in race horse b.c. will test as lidocaine which is illegal

• - bactericidal
• - B-lactam antibiotics
• - based on spectrum of activity and when they were synthesized (broken down by generations)
• - high therapeutic index but cross-sensitivity with penicillins
• - may cause GI distress
• - pain on injection
• - antibiotic associative diarrhea or superinfections
• - ceph or cef
• - excreted in urine

• - first generation
• - oral administration to dogs and cats
• - treat soft tissue infection, UTIs and upper respiratory tract infections
• - come in tablet or in suspension
• - human generic and cephalexin for larger animals and lower cost

• - first generation
• - vet approved for intramammary infusion
• - treat mastitis caused by staph or strep
• - Cefa-Lak for lactating cows and Cefa-dry for cows in dry period
• - consider milk discard time
• - OTC

-gram positive and most active of cephalosporins used in vet med against gram -

• - dry powder ready for reconstitution
• - most common use in horses; effect for strangles
• - broad spectrum
• - given by injection
• - excellent antibiotic in cattle with shipping fever and in swine
• - gets gram + and - infections

• - broad spectrum (gram -/+; B-lactamase enzyme producing bacteria)
• - single injection last 7 days
• - primarily in cattle
• can be used in goats and sheep
• - used for resp. tract infection; shipping fever
• - may be injected SQ in ear
• - no side effects
• - do not inject in artery --> death

• - SQ injectable antibiotic
• - single injection; high efficacy
• - sting at injection site
• - once reconstituted will only last 28 days
• - multidose vial in sterile water or saline
• - used to treat bacterial skin infections

• - tablet (once/day)
• - approved for dogs to treat skin infections
• - oral prodrug that can withstand the acid stomach

• - nephrotoxic if injected
• - only topical use
• - polypeptide antibiotic that inhibits cell wal synthesis
• - narrow spectrum (only gram +)
• - not absorbed orally
• - often combined with other antibiotic agents in topical form (otic and opthalmic preparations)

• - all alter cell membrane permeability by acting as a detergent and disrupting bonds
• - considered bactericidal
• - includes polymyxin B

• - bactericidal; gram - narrow spectrum
• - combined with bacitracin to increase efficacy and make broad spectrum
• - treat coronal ulcers and other opthalamic disorders
• - if injected also nephrotoxin; topical use only

• - interfere with translation and bacterial ribosomal subunits
• - include aminoglycosides, tetracyclines, florfenicol, macrolide and lincomycin
• - either bactericidal or bacteriostatic

• - bactericidal; injection or topical; ototoxic and nephrotoxic
• - inlcude gentomycin (gentocin) and amikacin (amikin) which can combine with bacitracin and polymyxin B
• - narrow spectrum against Gram -
• - inhibit mRNA synthesis
• - in dogs will see nephrotoxicity before ototoxicity and cats will see ototoxicity first; reversible if caught early

• - bacteriostatic
• - broad spectrum; most commonly synthesized
• - treat almost anything
• - do not administer with cations
• - binds to growing bones and teeth (stain)
• - may cause esophageal stricture--> scarring making it hard to swallow
• - never give rapid IV injection
• - expired drugs are nephrotoxic
• - can cause gastric distress; eliminated in urine and feces
• - use for foal to stand upright (tighten tendons and ligaments); use for pink eye in cattle; used for foot rot

most effective in treating eye infections in kittens (zoonotics)

treat lyme disease; if doesnt work use amoxycillin

liquid tetracycline for dogs and cats

• - bacteriostatic
• - related to chloramphenicol (can cause aplastic anemia in humans)
• - used in cattle and swine
• - treat resp. disease and foot rot
• - not used in small animals
• - topical; orally (feed)

• - drugs that interfere with metabolism of bacteria
• - include sulfonamids and potentiated sulfas

• - bacteriostatic
• - interfere with folic acid necessary for bacteria
• - include sulfadimethoxine (Albon): oral sulfa, liquid pill form, add to poultry or cattle feed, used as cocciostat, treat wide variety of injections, cats like its custard flavor)

• - bactericidal
• - are sulforamides with additives
• - broad spectrum
• - trymethoprim/ormethoprim which inhibit enzyme necessary for folic acid synthesis
• - pill form
• - side effects: crystalluria which can cause kidney stones, dry eye (KCS, irreversible), hypothyroidism but reversible, skin disease, blood dyscrasias (anemia)

Tribrissen

Primor

• - bactericidal; inhibit bacterial replication and transcription
• - MA: interfere with DNA gyrase
• - Fluoroquinolones; broad spectrum (gram -/+)
• - UTI, RTI, prostate infection, gets into bone
• - not used in food-producing animals or animals with CNS disease
• - side effects: arthropathy in young animals (disease of cartilage of joints--> lameness) and blindness in cats at high doses
• - ex: Enrofloxacin (Baytril), Orbifloxacin (Orbax), Marbofloxacin (Zeniquen), Ciprofloxacin (Cipro)

• - used for dental problems in dogs and cats
• - osteomyolitis (bone infection)
• - has bacterial ribose and its target
• - used for deep puncture wounds

• - most common fungus is ringworm; topical
• - dermophites (fungus infection of the skin)
• -zoonotic in cattle
• - include: griseofulvin, fluconazole, topicals

• - fungistatic
• - interfere with mitotic spindle leading to mitotic arrest in metaphase which causes cell senescence
• - cannot get in mammalian cells
• - limited spectrum to dermatocytes
• - commonly used, absorbed better with a fatty meal or tuna and oil for cats-- decreases GI side effects
• - known to be teratogenic (causes birth defects)--> contraindicated in pregnant cats
• - used for under nail infection- long term treatment 4-6 months

• - used for systemic mycosis
• - fungal infection that is inhaled to vessel to circulation system to organs
• - fungistatic
• used a lot in avian practices
• - affects sterols in fungal cell wall

• - most common
• - wear gloves when handling
• - OTC: clotrimazole and myconizole
• - cream or liquid
• - treat twice a day
• - for ring worm --> solitary lesions