Animal Health 12

Antimicrobial substances produced by living organisms

A mold called P. chrysogenum

Acts at last stage of bacterial cell wall synthesis; defective cell wall = cell lysis
2. bacteriocidal

*Only actively growing & dividing bacteria
1. Gram +'s primarily
2. At high doses, Gram -'s

1. Degraded by gastric acids (not administered orally)
2. Inactivated by B-lactamase made by Gram -'s and Staphylococci (Staph)

1. Overcomes some of the disadvantages of Pen/G
2. Broader spectrum of targets

1. Aminopenicillins
2. Carboxypenicillins
3. Ureidopenicillin
4. 6-methoxypenicillin

1. ampicillin
2. amoxicillin
3. hetacillin

1. carbenicllin
2. ticarcillin

1. Toxic to guinea pigs & hamsters
2. Dogs, cats, horses are hypersensitive

IM, sub Q, IV, Orally, topically (depending upon class)

Semisynthetic derivatives of a compound produced by a fungus

1. Inhibit synthesis of a bacterial cell wall component
2. bacteriocidal

1. similar, but broader than penicillin
2. Gram +'s and Gram -'s
3. Less susceptible to B-lactamase

1. cephalexin (keflex)
2. cephazolin (kefzol)
3. cephapirin (cefadyl)

Bacterial infections of the respiratory, urinary and genital tracts, soft tissues, bones, joints, and skin

Minimally toxic, can cause vomitiong, diarrhea when used orally

Interferes with bacterial protein synthesis by causing misreading of the genetic code of mRNA

Certain gram +'s and Gram -'s

1. streptomycin
2. dihydrostreptomycin
3. neomycin
4. kanamycin

amikacin and gentamicin

1. poorly absorbed from GI tract
2. Administered parenterally

High degree of toxicity
1. nephrotoxicity
2. ototoxicity

1. inhibit bacterial protein synthesis
2. bacteriostatic

1. Broad
2. Certain aerobic, anaerobic, Gram +, Gram - bacteria, spirochetes, mycoplasmas, rickettsiae, chlamydia, and protozoa

1. Tetracyclines (Panmycin, Achromycin, Tetracyn)
2. Oxytetracycline (terramycin)
3. Chlortetracyclin (aureomycin)

1. development of resistant bacteria
2. toxicities: GI disturbances such as vomiting and diarrhea due to altered gut flora, Nephrotoxicity, and Anaphylaxis
3. Staining of teeth

1. becomes fixed in growing osseous structures
2. may stain teeth of puppies & kittens if administered to bitch or queen during last 2-3 weeks of gestation or if given to the neonate in 1st months of life

Streptomyces erythreus (macrolides)

1. inhibits RNA dependent bacterial cell protein synthesis
2. bacteriostatic

1. Primarily against Gram +'s
2. Strep, Staph, Borrelia, Erysipelothrix, Clostridium Legionella

Increasing bacterial resistance

1. Relatively low
2. Nausea, vomiting, diarrhea

Primarily orally

Chemical derivatives of 5-nitrofuraldehyde

1. cause bacterial DNA strand to break
2. Interfere w/many bacterial cellular enzymes
3. Bacteriocidal or static (depends on susceptibility of organism and amount of drug at infection site)

Broad spectrum

Rarely

Blood and pus; this allows them to be used as a topical wound ointment

Used most commonly to treat urinary tract infections when other drugs have failed

May cause vomiting and diarrhea when given orally

Interferes w/an enzyme necessary for the formation of normal nucleic acids

Inhibits bacterial synthesis of dihydrofolic acid

Result is synergistic and results in a bacteriocidal drug

Primarily in treatment of respiratory and urinary tract infections

1. Relatively non-toxic
2. Especially effective for low does, long term therapy of urinary tract infections (SMZ/TMP; Tribrissen)

1. Organism should be susceptible or sensitive to the drug
2. Drug must distribute to site of infection in adequate concentrations
3. Environmental conditions at site of infection (pH, abscesses, blood supply, etc)
4. THe patient must be considered (age, condition, economics, etc)

1. Wrong drug
2. Wrong dosage
3. Wrong administration
4. Bacterial resistance