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Microbiology > Lecture 10 > Flashcards

Lecture 10 Flashcards

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Biology 101 flashcards
1
Q

What is the goal of antimicrobial chemotherapy?

A

administer a drug to an infected person that destroys the infective agent without harming the host’s cells (selective toxicity)

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2
Q

Chemotherapeutic drug

A

any chemical used in the treatment, relief, or prophylaxis of a diease

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3
Q

Prophylaxis

A

the use of a drug to prevent imminent infection of a person at risk

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4
Q

Antimicrobials

A

all inclusive term for any antimicrobial drug no matter its origin

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5
Q

Antibiotics

A

substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms

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6
Q

semisynthetic durgs

A

natural resources that are chemically modified in the lab

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7
Q

synthetic drugs

A

drugs produced by chemical reactions

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8
Q

Why are antibiotics produced and what are they derived from?

A
  • are common metabolic products of aerobic bacteria and fungi
  • produced to inhibit the growth of competing microbes in the same habitat

Derived from
bacteria in the genera Streptomyces and Bacillus

molds in the genera Penicillium and Cephalosporium

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9
Q

What is the kirby-baurer techinque testing for drug susceptibility?

A

surface of an agar plate is spread with bacteria

small discs containing a prepared amount of antibiotic are placed on the plate

zone of inhibition surrounding the discs is measured and compared with a standard for each drug

antibiogram provides data for drug selection

this method is less effective for anaerobic, fastidious, or slow-growing bacteria

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10
Q

What is the tube dilution test for testing for drug susceptibility?

A

more sensitive and quantitative than the Kirby- Bauer test

antimicrobial is diluted serially in tubes of broth

each tube is inoculated with a small uniform sample of pure culture

useful in determining the effective dosage and providing a comparative index against other antimicrobials

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11
Q

What is the therapeutic index?

A

-the ratio of the dose of the drug that is toxic to humans as compared to its minimum effective (therapeutic) dose

-the smaller the ratio, the greater the potential for drug reactions
Toxic dose ÷ MIC
The closer this is to 1, the more toxic it is.

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12
Q

What are the goals of antimicrobial drugs?

A

disrupt cell processes or structures of bacteria, fungi, or protozoa

inhibit virus replication

interfere with the function of enzymes required to synthesize or assemble macromolecules

destroy structures already formed in the cell

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13
Q

What is selectively toxic?

A

kill or inhibit the actions or synthesis of molecules in microorganisms but not vertebrate cells

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14
Q

What do drugs with excellent selective toxicity do?

A

block the synthesis of the bacterial cell wall (penicillins)

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15
Q

What drugs are most toxic to humans?

A

drugs that act upon a structure common to both the infective agent and the host cell (cell membrane)

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16
Q

What is minimum inhibitory concentration (MIC)?

A

the smallest concentration (highest dilution) of drug that visibly inhibits growth

17
Q

What are the goals of chemotherapy?

A

identifying structural and metabolic needs of a living cell and removing, disrupting, or interfering with these requirements

18
Q

What are the antimicrobial drug categories?

A

inhibition of cell wall synthesis

inhibition of nucleic acid structure and function

inhibition of protein synthesis

interference with cell membrane structure and function

inhibition of folic acid synthesis

19
Q

facts about penicilins

A

original penicillin was narrow-spectrum and susceptible to microbial counterattacks

molecule has been altered and improved upon over the years

later penicillins overcome the limitations of the original molecule

20
Q

Are Biofilms unaffected or affected by the same antimicrobials that work against them when they are free living?

A

unaffected

21
Q

What are the stragies for treating biofilm infections?

A

interrupting quorum sensing signals

adding DNase to antibiotics helps with penetration

impregnating devices with antibiotics

22
Q

What is quinine?

A

principal treatment of malaria for hundreds of years

has been replaced by synthesized quinolones, chloroquine and primaquine

several species of Plasmodium and many stages in its life cycle means that no drug is universally effective

23
Q

What is metronidazole?

A

widely used amoebicide
treats intestinal infections and hepatic disease caused by Entamoeba histolytica

also treats Giardia lamblia and
Trichomonas vaginalis

24
Q

What are the challenges of antihelminthic drug therapy?

A

flukes, tapeworms, and roundworms are larger parasites

their physiology is much more similar to humans

blocking reproduction does not affect adult worms

most effective drugs immobilize, disintegrate, or inhibit the metabolism of all stages of the life cycle

25
Q

What are the unique challenges of antiviral chemotherapeutic agents?

A

infectious agent relies on a host cell for the vast majority of its metabolic functions

disrupting viral metabolism requires disruption of cellular metabolism

measles, mumps, and hepatitis are prevented through the use of vaccines

AIDS, influenza, and the common cold attest to the need for more effective medications for the treatment of viral infection

26
Q

What are the modes of action of antiviral agents?

A

barring penetration of the virus into the host cell

blocking transcription and translation of viral molecules

preventing maturation of viral particles

27
Q

What is drug resistance?

A

an adaptive response in which microorganisms begin to tolerate an amount of drug that would normally be inhibitory

due to the genetic versatility and adaptability of microbial populations

can be intrinsic as well as acquired

28
Q

When do microbes become newly resistant to a drug?

A

pontaneous mutations in critical chromosomal genes

acquisition of entire new genes or sets of genes via horizontal transfer from another species

29
Q

What was the original wonder drug and how was it formed?

A

pencilin and by fungus

30
Q

What is chromosomal drug resistance and what does it result from?

A

usually results from spontaneous random mutation

slight changes in drug sensitivity can be overcome with larger doses of drug

can be the result of a phenotypic, rather than a genotypic change; slowing or stopping of metabolism so that the microbe can’t be harmed by the antibiotic

Microbiology (12 decks)

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