Chapter 14 Flashcards
what are antimicrobial drugs used for?
to kill microorganisms or suppress their growth
what do biocidal agents do?
kills microbes
what do biostatic agents do?
inhibit growth or reproduction
antibiotic drugs
a chemical substance that has the capacity to kill or inhibit the growth of bacteria
spectrum of activity
the range of bacteria that an antibiotic or antimicrobial will eradicate
what test is used to test microbial cultures and antimicrobial susceptibility?
agar diffusion test
what are the results a bacteria can get from an agar diffusion test?
resistant, sensitive, intermediate
breakpoint
a chosen concentration of antibiotic drug used to determine a bacteria’s resistance and sensitivity
how do antimicrobial drugs work?
inhibition of cell wall synthesis, damage to cell membrane, inhibition of protein synthesis, interference with metabolism, impairment of nucleic acid production
time-dependent antibiotics
drug concentration has to stay above MIC of pathogen, long-acting formulations, multiple dose per day
concentration-dependent antibiotics
drug concentration needs to be multiple times higher than MIC of pathogen, significant post-antibiotic effect, larger doses less often
antibiotic drug resistance
condition in which the bacteria continue to multiply despite administration of a antibiotic
plasmid transfer
transfer of nonchromosomal DNA material from a resistant bacterium to a nonresistant bacterium
first-line drug
first drug of choice, historically been safe and effective
second-line drug
possible greater risk of serious adverse effects, more expensive, unapproved for vet use
what antibiotics are cell wall agents?
penicillins, cephalosporins, bacitracin, vancomycin, carbapenems, monobactams
what types of penicillin are there?
natural, broad-spectrum, beta-lactamase-resistant, potentiated
what are penicillins active against?
gram-positive bacteria and gram-negative cocci (spheres) and bacilli (rods)
what are adverse effects of penicillin?
anorexia, vomiting, diarrhea (oral admin), hypersensitivity reactions (parental admin)
what are some important things about cephalosporins?
has a beta-lactam ring, semisynthetic, potentially neurotoxic, extra-label use in food animals is prohibited, has 5 generations
what generations of cephalosporin is used in vet med?
first and third generations
what is bacitracin effective against?
gram-positive bacteria, beta-lactamase producing bacteria
what are some things to know about baciracin?
it’s a polypeptide antibiotic drug, nephrotoxic when administered systemically, topical or ophthalmologic, poorly absorbed by the GI tract
what are vancomycins effective against?
gram-positive bacteria and anaerobes
what adverse effects are caused by vancomycin?
ototoxicity and nephrotoxicity
what are things to know about vancomycins?
not first-line treatment, given IV, treats resistant strains of bacteria, treats Clostridium sp. when given orally
what are carbapenems used for?
serious infections that can’t be treated with first-line treatment drugs
what are the adverse effects of carbapenem?
GI upset, pain on injection, induction of seizures
what is carbapenem effective against?
gram-positive bacteria, gram-negative bacteria, anaerobic bacteria, beta-lactame production bacteria
what are monobactams effective against?
gram-negative bacteria, beta-lactame producing gram-negative bacteria
what are the adverse effects of monobactams?
GI upset, pain/swelling following IM injection, phlebitis after IV injection
what is there to know about monobactams?
bacteriocidal, good penetration into most tissues, low toxicity risk, reserved for treating serious infections only
what are things to be aware of for cell membrane agents?
more potential for toxicity problems, polypeptide antibiotic drugs, nephrotoxic when administered systemically, not absorbed orally or topically
what are cell membrane agents effective against?
gram-negative bacteria
how do protein synthesis-inhibiting agents work?
they interfere with the formation of the 30S and 50S ribosomal units and inhibit production of necessary proteins
what drug is a cell membrane agent?
polymyxin B
what drugs are protein synthesis-inhibiting agents?
aminoglycosides, tetracyclines, phenicols, macrolides, lincosamides, aminocoumarins, tiamulin
how do nucleic acid agents work?
interference with the bacterial nucleic acid function
