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Chapter 10A Microbilogy

Terms in this set (23)

Selective toxicity
_____must cause significantly greater harm to the pathogen than to the host being treated.
Selective toxicity
this requires the targeting of features of the pathogen that differ from the host's cells
Selective toxicity
bacteria have several such targets such as the cell wall & ribosomes
Selective toxicity
viruses and eukaryotic pathogens are much more challenging to treat since they have less features that can be safely targeted
chemotherapeutic index
the higher the ___________, the safer the drug...
toxic dose
?
Chemotherapeudic= ----------------------------------
therapeutic dose
spectrun
The range of pathogens targeted by a specific antibiotic is referred to as its _______, which can be "broad" or "narrow"
Broad-spectrum antibiotics
•usually refers to drugs effective against more that one general category of pathogens
•e.g., Gram - & Gram + bacteria
Narrow-spectrum antibiotics
•usually refers to drugs effective against only one general category of pathogens
•e.g., Gram + bacteria, or mycobacteria
narrow spectrum
isoniazid & polymyxin are examples of ___.
broad spectrum
tetracycline & erythromycin are examples of ___
broad spectrum drugs
______ are not necessarily preferable due to their effects on the normal microbiota
Resistance genes
enzymes
pumps
barriers
molecular changes
enzymes
degrade the antibiotic
pumps
rapidly expel the antibiotic
molecular changes
_____prevent binding of the antibiotic to the target site
Antimicrobial Testing
Kirby-Bauer test
Etest
Etest
strip with antibiotic gradient on agar reveals minimum inhibitory concentration (MIC
Kirby-Bauer test
•antibiotic discs placed on lawn of bacteria on special agar
•zone of inhibition size indicates susceptibility or resistance (based on chart)
Minimal inhibitory concentration
MIC
Natural penicillin
produced by fungi
narrow spectrum
subject to degradation
synthetic penicillin
side chain only is synthetic
broader spectrum
resistant to degradation
penicillinases
some bacteria can avoid the effects of penicillin by the production of _______
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