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types of cell wall synthesis inhibitors

beta-lactam antibiotics, cephalosporins, other drugs


types of protein synthesis inhibitors

tetracyclines, macrocodes and other drugs


types of folic acid synthesis inhibitors

sulfonamides, trimethoprim


Types of DNA synthesis inhibitors



principles of antibiotic therapy

harm the parasite and not the host, mechanism of action affects processes unique to bacteria, processes common to bacteria and the host cell (more affinity for bacteria), type of bacteria (gram +, gram -, anaerobic, aerobic)


beta-lactam antibiotics (penicillin) characteristics

unstable in acidic pH and susceptible to destruction by beta-lactamase (when antibiotic is killed there is a risk of super infection), inhibit bacterial growth by impeding cell wall synthesis


super infection

caused by the antibiotic being killed, bacteria multiply out of control causing major infection and diarrhea


what does penicillin treat

streptococcous, meningococcous, anthrax, clostridium etc


penicillin side effects

non-toxic, serious effect due to hypersensitivity (anaphylactic shock), diarrhea (superinfection), yeast infection, resistance (90% of staph are beta-lactamase producers)


types of semi-synthetic penecilin

ampicillin, amoxicillin, methicillin


drug therapy guidelines

importance of correct doses, important to take the dose at correct time because drugs are only effective if there are enough in the blood


beta-lactam antibiotics (cephalosporins)

similar to penicillin (chemically, mechanism of action and toxicity), more stable to bacterial beat-lactamase, may cross blood-brain barrier, can be used in cases of penicillin sensitivity but are also sensitizing, given PO/IM/IV


what creates triple antibiotic therapy

bacitracin, polymyxin and neomycin


tetracycline characteristics

broad spectrum, accumulates inside the bacterial cell, binds to ribosomes, impeding formation of new protein, chelates calcium and other divalent cations, given PO or IV,


What type of horses should not have tetracyclines

young horses or pregnant mares because it binds to calcium,all drugs are only effective if they are free in the blood stream. oxytetracycline may be given to foals with contracted tendons so the calcium becomes bound and the tendons relax



prevent bacterial protein synthesis, examples are erythromycin, clarithromycin, azythromycin, erythromycin is used in conjunction with rimfampin to treat pneumonia in foals, may cause diarrhea and light sensitivity (foals need ti be kept inside), fever, can be fatal in adult horses. used in young horses being treated for lawsonia


other protein synthesis inhibitors

aminiglycosides: streptomycin, neomycin, gentamycin (only given IV by vet), amikacin and trobramycin. used against enteric bacteria, extremely ototoxic (damage hearing) and nephrotoxic (damage kidney. Not very used in horses except in ointments


sulfonamide characteristics

some microbes need extracellular PABA to form folic acid. sulfas are structurally similar to PABA (so bacteria grab sulfa instead of PABA), sulfa reversibly blocks folic acid synthesis, bacteriostatic, not very used by itself anymore



generally used in conjunction with sulfamethoxazole (SMZ), works with sulfa to give a stronger reaction (synergism), sulfa and trimethoprim together are bactericidal


how many antibacterials are generally given at one time?

one so they don't prevent each other from working, which may cause endotoxemia


fluoroquinolones (floxacins)

newest antibiotic, broad spectrum, generally the last drug to be used tp help prevent resistance and killing the normal flora of the horse, have great activity against gram -, useful against e. coli