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FPGOP > Pharmaceutical microbiology > Flashcards

Pharmaceutical microbiology Flashcards

1
Q

What type of micro organisms are fungi?

A

They are eukaryotic

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2
Q

Common targets of antifungal agents are

A

Plasma membrane and cell wall

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3
Q

What is ergosterol

A

It is a lipid responsible for the fluidity and permeability of the membrane
It is also used for the function if fungal integral membrane proteins

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4
Q

Types of antifungals include

A

Azoles-fluconazole,cotrimazole,
Polyenes-Nystatin, Amphotericin B
Allylamines-Terbinafine ,naftifine
Nucleosides-5-flucytocine
Echinocandins-caspofungin, micafungin

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5
Q

Moa of Azoles

A

They inhibit ergosterol biosynthesis via the cytochrome p450 enzyme 14 alpha demethylase.
It catalyzes the conversion of lanosterol to ergosterol
Azoles alter the morphology and inhibit the growth of fungal membranes.

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6
Q

Moa of polyenes

A

They bind to ergosterol to form a complex that is capable of disrupting the membrane and leading to leakage monovalent ions
It is also involved in an oxidation reaction and interaction with lipoproteins which impairs membrane permeability through the release of free radicals

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7
Q

Moa of Allylamines

A

They inhibit the enzyme squalene epoxidase by inhibiting the early steps of ergosterol biosynthesis,which leads to accumulation of squalene

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8
Q

Allylamines are highly effective against what type of fungal infection

A

Dermatophytes because it accumulates in the skin and nail beds relative to the blood

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9
Q

What does fungal cell wall comprise of.

A

Glucans,glycoproteins, mannans,chitin

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10
Q

Function of the fungal cell wall is

A

for adhesion and fungal pathogenesis
it also serves as a protective barrier

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11
Q

which of the following is not an example of echinocandins?

A

A)neomycin
b)caspofungin
c)micafungins
d)anidulafungins

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12
Q

moa of echinocandins

A

they target the protein complex responsible for the synthesis of beta 1,3 glucans by blocking the enzyme glucan synthase

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13
Q

which antifungal agents target chitin synthase?

A

Nikkomycin and polyoxins

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14
Q

role of chitin synthase

A

the enzyme is responsible for the elongation of the chitin chain

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15
Q

moa of 5-flucytosine

A

it inhibits nucleic acid synthesis which stops the conversion to5-fluororacil by the enzyme cytosine deaminase and then the conversion to 5-fluroroudylic acid by UMP pyrophosphorylase.

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16
Q

moa of Griseofulvin

A

it interferes with intracellular synthesis and the production of microtubles thus inhibiting fungal mitosis.

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17
Q

5-FC in combination with AmB or azoles shows synergistic effect against the treatment of what condition?

A

crytococcal meningitis

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18
Q

sensitivity of organisms to antimicrobials can be measured using?

A

MIC-minimum concentration needed to inhibit their growth and
MBC-minimum concentration needed to kill the bacteria.

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19
Q

antimicribial resistance can be measured by

A

monitoring the MICs and MBCs.

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20
Q

Natural resistance means

A

it is the resistance that is chromosomally mediated and predictable.

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21
Q

mutational or secondary resistance means

A

secondary occurs after therapy with the antimicrobial
mutational resistance is pre existing.

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22
Q

Induction resistance is when

A

the organism(bacteria) is initially sensitive but because of the damaging effect of the drug, the bacteria no longer takes up the drug. hence the conc of the drug should be maintained at high levels such as when using aminoglycosides.

23
Q

Transferrable resistance is when

A

extrachromosomal DNA containing code for the mechanism of resistance is transferred from one organism to another.

24
Q

What are the ways by which resistance can be transferred from one organism to another?

A

1)conjugation
2)Bacteriophage mediated transduction
3)transposons

25
Q

what is meant by conjugation

A

this is when resistance is transferred to several drugs at once. it is common against gram negative organisms

26
Q

what is Bacteriophage mediated transduction?

A

it is when molecular biologists transfer genetic material in both plant and animal genetic research eg in gram possitive(staphylococci)

27
Q

what is transporons?

A

these are minute pieces of DNA that can be part of plasmids which can be translocated into other plasmids or into the normal genome of the bacteria

28
Q

what is drug inactivation in biochemical mechanism of resistance

A

1)Drug inactivation- this involves the enzymatic hydrolysis of the beta lactam ring of penicillins and cephalosporins and the addition of substituents to certain sites on the aminoglycoside antibiotics.

29
Q

what is decreased accumulation/increased efflux

A

in this mechanism, organisms develop the ability to transport drugs out of their cytoplasm which leads to insufficient conc inside the cell to be effective eg of this is tetracyclines. eg of decreased penetration is seen in gonococci and penicillin G.

30
Q

what is decreased affinity/binding

A

it is when there is changes to the enzymes or receptors which leads to decreased affinity for the drug.

31
Q

what is metabolic by pass?

A

it is when organisms synthesize new dihydrofolate reductase hence there is overproduction of the affected enzyme

32
Q

empiric therapy means

A

administering broad spectrum antibiotics to cover infection caused by several organisms

33
Q

the term anti-infective refers to

A

antibacterial,antifungal,antiviral and anti parasitic.

34
Q

antibiotics generally refers to?

A

antibacterial agents obtained from natural sources.

35
Q

Beta lactam antibiotics includes

A

penicillins eg penicillin G and V
Cephalosporins eg cephalexin

36
Q

macrolides

A

eg erythromycins

37
Q

what bonds are found in aminoglycosides?

A

Glycosidic bonds eg gentamycin, neomycin

38
Q

what bonds are found in polypeptides

A

peptide bonds eg vancomycin

39
Q

inhibition of cell wall synthesis

A

this is a characteristic of beta lactams and vancomycin

40
Q

moa of aminoglycosides

A

Irreversibly inhibits protein synthesis

41
Q

moa of quinolones

A

they inhibit nucleic acid synthesis by inhibiting DNA topoisomerases

42
Q

moa of sulfanamides

A

they inhibit nucleic acid synthesis by inhibiting de novo synthesis of purine bases

43
Q

Broad spectrum antibiotics is when

A

the drugs have no predlection for gram positive or negative and may even act against other antimicrobials.

44
Q

Narrow spectrum is when

A

the drugs act specific to the type of bacteria eg penicillin G is effective against gram positive while Gentamicin against gram negative

45
Q

Drugs used to treat HIV are called

A

Antiretrovirals

46
Q

Antiviral drugs are aimed to

A

target and identify viral proteins or their parts.

47
Q

Drugs used to restrict the developement of viral proteins include

A

-Amantadine and rimantadine act on the penetration and uncoating of viral RNA
-reverse transcriptase inhibitors, integrase splice the syntheiszed DNA into the host cell genome

48
Q

Goals of treatment using antiretroviral therapy

A
  • prolong survival of patient
    -improve CD4+ T cell count
    -reduce viral load
    -improve quality of life
    -reduce risk of transmission to others
49
Q

what is the rationale for using combination antiretroviral therapy?

A

it aims to target different steps of the HIV life cycle which provides a synergistic effect and leads to suppresion of viral replication.

50
Q

What are antibacterial drugs?

A

they are small molecules which may be synthetic,semi-synthetic or natural occurring.

51
Q

what are the consequences of resistant microorganisms

A

it leads to the use of last result ,older antibiotics that were abandoned due to toxicity for regular use.
The resistant microorganisms have become stronger than they once were

52
Q

disruption of normal microbial flora

A
53
Q
A

FPGOP (8 decks)

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