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27 Cards in this Set
- Front
- Back
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What is an antibiotic?
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Substance made by microbes that inhibit growth of other microbes (can include semi-synthetic and fully synthetic cmpds)
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What is an antimicrobial?
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Any cmpd, synthetic or biological, that inhibits microbe growth
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What is an antibacterial?
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A cmpd that is specific for growth inhibition of bacteria
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What was the first antibiotic?
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Penicillin (1940's)
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What is the leading cause of death worldwide?
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Infectious Disease
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What are the top 3 diseases that cause death from infection?
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Acute respiratory, diarrhea, TB
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How does death from ID rank for U.S. compared to other causes?
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4th
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What 4 categories of organisms cause infection?
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Bacteria, Viruses, Fungi, Protozoans
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Describe Gram+ bacteria?
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One membrane surrounded by thick peptidoglycan layer
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Describe Gram- bacteria?
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2 membranes with thin peptidoglycan layer in between. Outer membrane attached to peptidoglycan via braun lipoprotein and deep to this is periplasmic space
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What category of bacteria are susceptible to aminoglycosides?
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Aerobic
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Why are rickettsial spp. and chylamidia hard to treat?
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They are intracellular pathogens
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What makes viruses difficult to treat?
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They are so closely intertwined with the machinery of the host cell
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Are penicillin and streptomycin bacteriostatic or bacteriocidal?
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Bacteriocidal; however, streptomycin does not kill via lysing, hence cell turbidity is not affected
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Is chloramphenicol bacteriostatic?
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Yes
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Why would using a bacteriostatic/cidal combo be antagonistic?
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Cidal drugs usually require actively dividing cells which cannot grow in the presence of static drugs
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What are the classes of bactericidal drugs?
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Concentration dependent (aminoglycoside/quinolone) - more effective with higher concentration. Time dependent (b-lactam/vancomycin) - no added benefit from higher dose
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What is the postantibiotic effect?
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Time to return to log growth after removal of antimicrobial agent. This allows for once-daily dosing which helps against resistance
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What role do phagocytes play in helping antibiotic therapy?
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Ultimate pathogen destruction occurs via phagocytes and Ab's. Necrotic WBC's in pus hinders antimicrobial efficacy
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What are superinfections?
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Indigenous, drug-resistant pathogens emerge after antimicrobial therapy wipes out other spp. that kept them in check. Occur with broad spectrum antibiotics. E.g. C. diff colitis
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What defines if 2 antibiotics are synergistic?
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If the minimum inhibitory concentration for each drug is lower when in combination
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What are some diseases that could limit the effectiveness of antimicrobial therapy?
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Agranulocytosis, leukemia, agammaglobulinemia, MM, chronic lympathic leukemia, uremia, DM, and therapies like radiation, corticosteroids, and nitrogen mustards
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What are some organ pathologies that would affect drug efficacy?
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GI tract pathology (absorption), gastric acidity (penicillin degradation), liver pathology (metabolism), renal pathology (excretion)
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What are 3 ways that drug resistance can arise in microbes?
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Mutation and selective pressures, plasmid transfer (most common), chromosomal DNA uptake and recombination
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What are the components of a plasmid?
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The RTF (resistance transfer factor) which helps transfer the plasmid during conjugation and the R determinant which codes for the resistance
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What spp. are known for chromosomal DNA uptake resistance?
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Neisseria, Strep, Haemophilus
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What are the mechanisms of resistance?
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Increased metabolism, decreased activation by microbes into active form, formation of altered receptor that drug cannot affect, decreased uptake
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