(exam 3) ch 20 Antimicrobial drugs Flashcards
what is selective toxicity?
selectively finding and destroying pathogens without damaging the host
___________ is the use of chemicals to treat a disease (not just used for cancer treatment)
chemotherapy
__________ is a substance produced by a microbe that in small amounts, inhibits another microbe. There are limited sources of these with human relevance.
Antibiotics
__________ are synthetic substances that interfere with the growth of microbes.
Antimicrobial drugs
which type of pathogen is the easiest to treat with antimicrobial drugs?
bacteria
what are drugs with a narrow spectrum of microbial activity?
drugs that affect a limited range of microbial drugs and are usually used after the pathogen has been identified
what are drugs with broad spectrum antibiotics?
affect a broad range of gram + and gram - bacteria and are often used for initial treatment to slow or kill whatever is growing
One disadvantage to using broad-spectrum antibiotics is that they ?
destroy normal microbiota
A _________ is the overgrowth of normal microbiota and overgrowth of pathogens that have developed antibiotic resistance.
superinfection
A __________ is bacteria that are resistant to large numbers of antibiotics.
superbug
If an antibiotic prevents bacteria from growing, then its action is termed?
bacteriostatic
If an antibiotic kills microbes directly, it’s action is termed?
bactericidal
Penicillin works by inhibiting ________ synthesis.
cell wall
what structure in penicillin prevents the synthesis of peptidoglycan?
B-lactam ring
Polypeptide antibiotics work by inhibiting ______ synthesis.
cell wall
how do drugs work to inhibit protein synthesis?
selective toxicity which targets bacterial 70S ribosomes
Eukaryotes have 80S ribosomes, whereas prokaryotes have ________ ribosomes.
70S
The mode of action of chloramphenicol is to?
inhibit protein synthesis
Aminoglycosides work by inhibiting _______ synthesis.
protein
Tetracyclines work by inhibiting _______ synthesis.
protein
The mode of action of lipopeptides is to?
injure the plasma membrane
Antifungals which injure the plasma membrane target what?
sterols
Rifamycin works by inhibiting _______ synthesis.
nucleic acid
Inhibiting nucleic acid synthesis does what to the pathogen?
interferes with DNA replication and transcription which prevents the microbe from growing and kills it
Sulfanilamide works by inhibiting _______ synthesis?
essential metabolites
inhibiting essential metabolite synthesis does what to the pathogen?
stops synthesis of folic acid which is needed for nucleic acid and protein synthesis so the cell can not grow and dies
___________ are inhibitors that block host cell receptors and block fusion of virus and cell so there is no access to the host cell.
entry and fusion inhibitors
what two steps of viral replication are affected by entry and fusion inhibitors?
attachment and entry
_______________ are inhibitors that prevent viral uncaring, inhibit viral DNA integration into host genome, and nucleoside analogs inhibit RNA and DNA synthesis.
Uncoating, genome integration and nucleic acid synthesis inhibitors
what two steps of viral replication are affected by entry and fusion inhibitors?
uncoating and biosynthesis
Nucleoside analogs affect steps in _________ because they resemble DNA or RNA but cause termination of expanding chains.
virus replication (biosynthesis)
__________ are a type of assembly and exit inhibitors that block cleavage of protein precursors.
protease inhibitors
__________ are a type of assembly and exit inhibitors that inhibit neuraminidase, an enzyme that is needed for some viruses to bud deem the host.
exit inhibitors
which two steps of viral replication are affected by assembly and exit inhibitors ?
maturation and release
__________ are produced by viral infected host cells to inhibit further spread of the infection.
interferons
_________ promotes interferon production.
imiquimod
in order to provide good treatment, we need to know what about pathogens?
pathogen sensitivities
_________ tests the effectiveness of chemotherapeutic agents by using paper disks with a chemotherapeutic ager on a container of agar containing the organism.
Disk diffusion method (aka. Kirby-Bauer test)
what do we look for to indicate the sensitivity of an organism to an antibiotic in a disk diffusion test?
the zone of inhibition
what does a large zone of inhibition indicate?
that a pathogen is sensitive to a certain antibiotic
_________ is a test used to determine the minimal inhibitory concentration (MIC) by using a plastic strip containing an antibiotic at varying concentrations.
E test (epsilometer)
what is minimal inhibitory concentration (MIC)?
lowest antibiotic concentration that prevents bacterial growth
________ is a test used to determine BOTH MIC and minimal bactericidal concentration (MBC) of an antimicrobial drug.
Broth dilution tests
what is minimal bactericidal concentration (MBC) ?
lowest antibiotic concentration that kills bacteria
what does the broth dilution test give valuable information about?
provides information that is used to prevent the overture or misuse of antibiotics by determining safe dosing
________ reports on the susceptibility of organisms encountered clinically.
Antibiograms
_________ are microbes with genetic characteristics allowing for their survival when exposed to an antibiotic; Vertical transmission of survival genes through reproduction.
persister cells
how are resistance genes typically spread?
horizontally among bacteria on plasmids or transposons via conjugation or transduction
_________ are bacteria that are resistant to large numbers of antibiotics (such as MRSA)
superbugs
what are four mechanisms of resistance?
1) prevention of penetration to the target site within the microbe
2) enzymatic destruction or inactivation of the drug
3) alteration of the drug target site
4) rapid efflux (ejection) of the antibiotic before it reaches a high concentration in the cell
