chapter 10 study questions Flashcards
which type of chemotherapy involves the use of chemotherapeutic drugs to control infection and diseases caused by many types of microorganisms
antimicrobial chemotherapy
natural agents used only against bacterial infections
antibiotics
three factors that should be considered before beginning antimicrobial therapy are:
the nature of the microbe causing infection, its degree of sensitivity to various drugs, and the overall medical condition of the patient
one reason why antimicrobial sensitivity testing would be performed
is the pathogen commonly shows resistance to the antibiotic
drug susceptibility testing for fungal infections is generally not performed b/c why
antifungals target all fungi
the general term for the use of drugs to control infection is _______.
antimicrobial chemotherapy
what is the minimum inhibitory concentration?
it is the highest DILUTION of a drug where it visibly inhibits growth of particular microbe
the therapeutic index is the ratio of the _____ dose to the __________ dose that is used to assess the safety and reliability of a drug
toxic
therapeutic
true or false
it is essential to perform a drug sensitivity test for all micros
false
drugs that are selectively toxic should kill which cells?
microbial cells
general mechanisms of antimicrobial drug actions
inhibiting protein synthesis
inhibiting nucleic acid structure or function
inhibiting cell wall synthesis
interference of cell membrane structure and function
list two sites in the cell that are not primary sites of action of antimicrobial drugs in bacteria
mitochondria
golgi body
of which of the following, which antibiotic is an inhibitor of protein synthesis?
a. quinolones
b. isoniazid
c. streptomycin
d. trimethoprim
streptomycin
which of the following antibiotics is an inhibitor of cell wall synthesis?
a. polymyxin
b. rifampin
c. penicillin
d. tetracycline
penicillin
which of the following semisynthetic penicillins are useful in treating infections caused by penicillinase-producing bacteria?
a. penicillin G
b. erythromycin
c. cloxacillin
d. nafcillin
e. streptomycin
nafcillin
cloxacillin
penicillins G and V (penicillins)
used to tx gram + cocci, some gram - bacteria
ampicillin, amoxicillin, and carbenicillin (penicillins)
broader spectrum of action, semisynthetic, use against gram neg enteric rods
Clavulanic acid
penicillins
inhibits beta-lactamase enzymes; added to penicillins to increase effectiveness in presence of penicillinase-producing bacteria
which bacterial enzyme makes a cell wall inhibitor ineffective?
penicillinase
which of the following antibiotics is an inhibitor of protein synthesis?
a. tetracycline
b. rifampin
c. penicillin (cell wall)
d. polymyxin (cell membrane)
tetracycline
most drugs that inhibit protein synthesis block the action of
ribosome
which of the following antibiotics is an inhibitor of cell wall synthesis?
a. streptomycin (inhibit protein synthesis)
b. quinolones (inhibit rep and transcription)
c. trimethoprim (prevent folic acid synthesis in cytoplasm)
d. cephalosporin
d. rifampin (inhibition of RNA polymerase)
d. cephalosporin
which of the following antibiotics inhibits translocation of the ribosome subunit during translation?
a. penicillin (blocks cell wall production)
b. erythromycin (protein synth inhibitor on 50S subunit)
c. tetracycline
d. streptomycin
erythromycin
not tetra b/c: while it does stop protein synthesis, it blocks attachment of new amino acids, not movement of the ribosome on the mRNA
not strepto: results in abnormal proteins, but does not block production of proteins
by blocking enzymes required for the synthesis of tetrahydrofolate, _________ interfere with folate metabolism
sulfonamides
to treat Pneumocystis infections in _________ patients,
__________ is used in combination with sulfamethoxazole
AIDS/HIV
trimethoprim
antibiotics that affect nucleic acid synthesis specifically affect the processes of replication and __________
transcription
which antibiotic specifically inserts on sites of the 30S subunit of prokaryotic ribosomes causing the misleading of mRNA and thus inhibit translation?
aminoglycosides
trimethoprim and sulfamethoxazole are often given in combo because of ___________ effect together
synergistic
polymyxins work by interacting with what component of the cell membrane causing leakage
phospholipids
cephalosporins are broad or narrow
broad
erythromycin inhibits __________ of the ribosomal subunit during translation
translocation
antibiotic that specifically inserts on the sites of 30S subunit of prokaryotic ribos causing misreading og mRNA and inhibits TRANSLATION
aminoglycosides (streptomycin)
cephalosporins have the same effect as
penicillins
used by patients who are allergic to pencillin
Aztreonam
biofilm bacteria are not affect in the same way as their free-living counterparts because the biofilm bacteria express different
genes
tetracyclines inhibit protein synthesis by blocking attach of _______ on the A receptor site
tRNA
drugs that are effective against fungi are likely to be toxic to _______ because they are both eukaryotes
humans
glycylcyclines are newer derivatives of
tetracyclines
quinine is a drug used to treat
protozoal infections; extracted from bark; MALARIA
Ivermectin and praziquantel are never drugs used for tx of
helminthic infections
identify three major modes of action an antiviral drugs
preventing virus maturation
barring virus penetration into host cell
blocking virus transcription and translation
OG drug used for malaria
quinine
adaptive response in which microorganisms begin to tolerate an amount of a drug that would ordinarily be inhibitory is called
drug resistance
drug resistance arises when
an organism gains the genetic info for resistance from another organism
spontaneous mutation occurs in the organisms DNA code
bacterial cells described as persisters are resistant to antibiotics b/c they
can slow or stop their metabolism in the presence of a drug
in some fungi, a small regulatory RNA know as interfering RNA can temporarily silence a gene. When this gene encodes ___________, the fungus is transiently resistant to the antibiotic
the target of the antibiotic
epigenetic mechanisms of antibiotic resistance in fungi are
reversible
***think interfering RNA: temporary
drug resistance genes found on the bacterial chromosome usually result from
spontaneous mutation
An ______ factor is a type of plasmid that confers antibiotic resistance
R
horizontal transfer originates from plasmids called resistance R factors that are transferred through
conjugation, transformation, or transduction
mechanisms of drug resistance
new enzymes are synthesized, inactivating the drug
permeability or uptake of the drug into the bacterium is decreased
drug is immediately eliminated (acquisition of new genes)
binding sites for drugs are decreased in number or affinity
an affected metabolic pathway is shut down or an alternative pathway is used
a concerning development is the identification of the mcr-1 gene which renders bacteria resistant to the last-resort antibiotic __________
polymyxin
CRISPR has been used to tx antibiotic-resistant infections by directing specific gene cuts to
the antibiotic resistant genes
preparations of live microbes used as a preventative or therapeutic measure to displace or compete with potential pathogens are called
probiotics
categories of major drug side effects
normal flora disruption
toxicity to tissues
allergic reactions
mcr-1 gene
resistant to polymyxin
BAD- threat
bacterial system that can be used to cause very specific cuts is genes is termed
CRISPR
a drug _____ occurs when a drug acts as an antigen and stimulates an immune response
allergy
antimicrobial drug damage can be
permanent or reversible
problems that have led to the worldwide problem of managing antimicrobial drugs
shot gun approach by doctors
increase in superinfection
development of resistance in “bystander” microbes
t or f
most tissues can be affected by adverse effects caused by use of antimicrobial therapy
TRUE
gastro, cardiovascular, nervous, resp, skin, and bones can all be affected
the human _____ is the sum total of al microbes found on and in a normal human
microbiome
some microbes associated with the body that can be rapidly lost, for example when hand washing, are termed
transients
