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Chapter 20
micro chapter 20
62
Microbiology
Undergraduate 1
04/03/2011

Additional Microbiology Flashcards

 


 

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Term
antibiotic
Definition
substance produced by a microbe, then in small amounts, inhibits another microbe
Term
selective toxicity
Definition
a drug that kills harmful microbes without damaging the host. more difficult in eukaryotic pathogens because they are more like the host
Term
paul ehrlich
Definition
developed the concept of chemotherapy
Term
chermotherapeutic agents
Definition
kill pathogens without harming the host
Term
gerhard domagk
Definition
developed sulfa drugs, which came into prominence in the 1930s during WW2
Term
alexander fleming
Definition
discovered first antibiotic, penicillin in 1929
Term
narrow-spectrum drugs
Definition
affect only a small group of microbes
Term
broad-spectrum antibiotics
Definition
affect a more diverse range of microbes. disadvantage to them is that they can harm normal flora
Term
super infections
Definition
when you kill all of the normal flora, so it is easy or another microbes to take their place
Term
bactericidal
Definition
directly killing microorganisms
Term
bacteriostatic
Definition
inhibiting thier growth
Term
actions of antimicrobial drugs
Definition
inhibition of cell wall synthesis, of protein synthesis (inhibits 70s ribosomes), nucleic acid replication (RNA polymerase has diff structure in eukaryotes), injury to plasma membrane, and inhibition of essential metabolites (folic acid)
Term
ß-lactam ring
Definition
all penicillins contain this
Term
natural penicillins
Definition
produced by penicillum and effective against gram positive cocci and spirochetes
Term
penicillin G
Definition
requires injections because it is destroyed in stomach acid
Term
penicillin V
Definition
can be taken orally
Term
penicillinases (ß-lactamases)
Definition
bacterial enzymes that destroy natural penicillins by cleaving the ß-lactam ring
Term
semi-synthetic penicillins
Definition
mad ein the lab by adding different side chains on the the ß-lactam ring
Term
oxacillin
Definition
narrow spectrum (only gram pos but resistant to penicillinase)
Term
ampicillin
Definition
extended spectrum so many gram negatives
Term
methacillin
Definition
penicllinase-resistant penicillins
Term
cephalosporins
Definition
inhibit cell wall synthesis and are used against penicillin resistant strains. 1-4 generations and each has a progressively wider spectrum. 4th is oral while others are injected.
Term
bacteracin
Definition
inhibit cell wall synthesis primarily in gram positive bacteria
Term
vancomyacin
Definition
inhibits cell wall synthesis. It is a last line against S. aureus and are penicillinase resisant
Term
isoniazid and ethambutol
Definition
inhibit cell wall synthesis in mycobacteria by effecting the mycolic acid in their cell membranes
Term
chloramphenicol
Definition
broad spectrum, potentially toxic. binds to the 50s and inhibits peptide bond formation
Term
aminoglycosides
Definition
streptomyacin, neomyacin (in neosporin) and gentramyacin. broad spectrum, can cause hearing loss, changes shape of 30s subunit
Term
tetracyclines
Definition
broad spectrum, interferes with tRNA attachment
Term
macrolides (erythromyacin)
Definition
against gram positives, used as an alternative to penicillin, binds to 50s and prevents translocation
Term
streptogramins
Definition
against gram pos, binds to 50s subunit and inhibits translation
Term
synercid
Definition
combo of two streptogramins that act as different steps in protein synthesis (to reduce possibility of resistance and to be more effective)
Term
oxazolidinones
Definition
linezolid= totally synthetic, against gram pos, binds to 50s subunit and prevents formation of 70s ribosome
Term
polymyxin B
Definition
damages cell membranes
Term
bacitracin
Definition
inhibits cell wall synthesis
Term
neomycin
Definition
inhibits cell wall synthesis
Term
rifamycin
Definition
inhibts RNA synthesis; it is used to treat TB
Term
quinolones and fluoroquinolones
Definition
inhibit DNA gyrase for treating UT infections
Term
ciprofloxacin
Definition
used against anthrax infections
Term
sulfonamides
Definition
competitively inhibit folic acid synthesis by competing with the intermediate PABA to bind to the enzyme
Term
sulfamethoxazole
Definition
(SMZ)- inhibts PABA
Term
trimethoprim
Definition
TMP inhibitsdihydrolic acid to going to tetrahydrofolic acid
Term
ergosterols
Definition
in plasma membrane
Term
miconazole
Definition
targets sterols in plasma membrane, for treatment of athlete's foot and vaginal infections
Term
ß-glucans
Definition
in cell wall
Term
fluctosine
Definition
antimetabolite of cytosine/cytosine analog that interferes with RNA synthesis. Enzyme converts flucytosine to 5-fluorouracil that's incorporated into mRNA
Term
griseofluvin
Definition
interferes with eukaryotic cell division and is ed orimary to treat skin infections caused by fungi. binds selectively to keratin (in skin) then inhibits microtubule production in the fungi on the skin
Term
acyclovir
Definition
nucloside that looks like guanine and used to treate herpes virus infections (chicken pox, shingles, genital); phosphate binds to the fals nucleoside thus inhibiting DNA synthesis
Term
zidovudine
Definition
inhibit DNA or RNA synthesis
Term
fusion inhibitors
Definition
fusion is required to enter the cell
Term
reverse transcriptase inhibitors
Definition
inhibit replication of nucleic acids
Term
protease inhibitors
Definition
inhibit the viral DNA from being cutting up, so remains long
Term
Disk diffusion test
Definition
filter paper disks with chemotherapeutic agenst are overlaid on the culture and the diameter of the zone if inhibition is used to determine whether the organism is sensitive, intermediate or resistant to a drug
Term
MIC
Definition
minimal inhibitory concentration, the lowest concentration of drug capable of preventing microbial growth
Term
E test
Definition
plastic strip with varying concentrations to help determine MIC
Term
Broth Dilution tests
Definition
microorganism is grown in liquid media with different concentrations to determine the MIC
Term
MBC
Definition
minimal bactericidal concentration, lowest concentrations of a chemotherapeutic agent the kills bacteria
Term
Drug resistance factors
Definition
carried by plasmids and transposons, resistant mutants develop and replace the sensitive strains
Term
enzymatic destruction
Definition
have enzymes that inhibit the antibiotic
Term
prevention of penetration
Definition
drug can't penetrate the outer membrane
Term
cellular or metabolic changes at target sites
Definition
bacteria changes the shape of the ribosomal proteins so now the antibiotic can't bind to the ribosome to inhibit it
Term
Rapid efflux of the antibiotic
Definition
ex: tetracycline is pumped out of the cell
Term
misuse of antibiotics
Definition
using them for the common cold, in animal feed, failure to complete prescription, using outdated antibiotics, using someone else's leftover medication
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