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Microbiology > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

chemotherapy

A

the use of any chemical/drug to treat any disease/condition

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2
Q

chemotherapeutic agent

A

any drug used to treat any condition/disease

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3
Q

antimicrobial agent

A
  • any chemical/drug use to treat infectious diseases
  • either by inhibiting action or by killing pathogens in vivo
  • some antimicrobial agents are antibiotics
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4
Q

drugs used to treat bacterial diseases

A

antibacterial agents

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5
Q

drugs used to treat fungal diseases

A

anti fungal agents

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6
Q

drugs used to treat protozoal diseases

A

antiprotozoal agents

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7
Q

drugs used to treat viral diseases

A

antiviral agents

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8
Q

antibiotic

A
  • a subtended produced by a microorganism that kills or inhibits growth of other microorganisms
  • another microbe creates it
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9
Q

semisynthetic antibiotics

A
  • antibiotics that have been chemically modified to kill a wider variety of pathogens or reduce side effects
  • ex: semisynthetic penicillin like ampicillin and carbenicillin
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10
Q

Alexander flemming

A
  • discovered penicillin and antibiotics
  • had a staph colony growing well in one are of plate and poorly growing in another due to an antibiotic being produced by a colony of mold
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11
Q

characteristics of an ideal antimicrobial agent (6)

A
  • kill or inhibit the growth of pathogens
  • cause no damage to host
  • cause no allergic reactions
  • be stable when stores in liquid or solid form
  • remain in specific tissues in body long enough to be effective
  • kill pathogen before they mutate and become resistant
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12
Q

5 most common mechanisms of action of antimicrobial agents

A
  • inhibition of cell wall synthesis
  • damage to cell membranes
  • inhibition of nucleic acid (DNA or RNA)
  • inhibition of protein synthesis
  • inhibition of enzyme activity
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13
Q

bacteriostatic drugs

A

inhibit growth of bacteria

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14
Q

bactericidal drugs

A

kill bacteria

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15
Q

folic acid

A

some bacteria require folic acid to produce certain essential proteins, without it they will die

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16
Q

sulphonamide drugs

A
  • inhibit production of folic acid in bacteria that require p-aminobenzoic acid (PABA) to synthesize folic acid
  • they are competitive inhibitors
  • bacteriostatic
  • competes the PABA because there is more of sulfa/metabolite
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17
Q

mechanism of action of penicillin

A
  • in most gram + bacteria pen interferes with the synthesis and cross-linking of peptidoglycan (cell wall)
  • pen destroys bacteria by inhibiting cell wall synthesis
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18
Q

narrow spectrum antibiotics

A
  • colistin and nalidixic acid destroy only gram - bacteria

- vancomycin selectively kills gram +

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19
Q

broad spectrum antibiotics

A
  • destructive to both gram + and - bacteria
20
Q

multidrug therapy

A
  • when two or more drugs are used simultaneously

- treatment of TB

21
Q

synergism

A
  • when 2 antimicrobial agents are used together to produce a degree of pathogen killing that is greater than that achieved by either drug alone
22
Q

antagonism

A
  • when 2 drugs work against each other

- extent of pathogen killing is less than that achieved by either drug alone

23
Q

major categories of antibacterial agents

A
  • penicillins - bactericidal
  • cephalosporins - bactericidal
  • tetracyclines - bacteriostatic
  • aminoglycosides - bactericidal
  • macrolides - bacteriostatic at low dose; bactericidal at high dose
  • fluroquinolones - bactericidal
24
Q

major categories of antibacterial agents and their mechanism of action

A
  • penicillins - cell wall synthesis
  • cephalosporins - cell wall synthesis
  • tetracyclines - protein synthesis
  • ahminoglycosides - protein synthesis
  • macrocodes - protein synthesis
  • fluroquinolones - DNA synthesis
25
Q

anti fungal agents 3 possible mechanisms of action

A

1) binding with cell membrane sterols
2) interfering with sterol synthesis
3) blocking mitosis or nucleic acid synthesis

26
Q

antiprotozoal agents mechanisms of action

A

1) interfering with DNA and RNA synthesis

2) interfering with protozoal metabolism

27
Q

why are antiprotozoal and anti fungal agents more toxic to host

A
  • because the drugs are eukaryotic organisms, like the infected host
  • same structures of own cell
28
Q

antiviral agents

A
  • newest weapon
  • difficult to develop because viruses are produced within host cell
  • some drugs developed to kill certain viral infections
  • work by inhibiting viral replication within cells
29
Q

cocktail drugs

A
  • when several antiviral drugs are administered simultaneously
  • to treat HIV
30
Q

superbugs

A
  • microbes, mostly bacteria, that have become resistant to one or more antimicrobial agents
  • infections are difficult to treat
31
Q

examples of bacterial superbugs (8)

A
  • methicillin-resistant staphylococcus aureus (MRSA)
  • vancomycin-resistant enterococcus (VRE)
  • multidrug-resistant mycobacterium TB (MDRTB)
  • e coli
  • klebsiella
  • salmonella
  • shigella
  • n. gonorrhoeae
32
Q

why do hospitals produce a lot of resistant microbes

A
  • because they are cleaning all the time and a lot of bacteria is introduced into hospitals
33
Q

intrinsic resistance

A
  • bacteria that are naturally resistant because they lack the specific target site for the drug
  • or drug is unable to cross organisms cell wall or membrane and can’t reach site of action
34
Q

acquired resistance

A

when a bacteria was once susceptible to a particular drug becomes resistant

35
Q

acquired resistance involving chromosomal mutations

A
  • causes change in structure of binding site preventing drug from binding to cell
  • causes change in cell membrane permeability preventing the drug from crossing it and entering cell
36
Q

acquired resistance involving acquisition of a gene

A
  • enables bacteria to produce an enzyme that destroys/inactivates drug resulting in drug being destroyed or inactivated by enzyme
  • enables bacteria to produce a multi-drug resistant (MDR) pump that pumps the drug out of the cell before it can act
37
Q

acquisition of a gene to create resistance by…

A
  • transduction, transformation, and conjugation

- most commonly conjugation

38
Q

penicillin resistance

A
  • many bacteria have become resistant to it because they have acquired the gene for penicillinase production
  • penicillinase kills penicillin
39
Q

resistance factor (R-factor)

A
  • a plasmid that contain multiple genes for a drug resistance
40
Q

B-lactam ring

A
  • every penicillin and cephalosporin molecule contain double ringed structure referred to as “house and garage”
  • “garage” is known as B-lactam ring
41
Q

B-lactamases

A
  • some bacteria produce B-lactamases that destroy B-lactam ring
  • when ring is destroyed the drug no longer works
  • drug companies have developed drugs that combine B-lactam antibiotic with B-lactamase inhibitor
42
Q

2 types of b-lactamases

A
  • penicillinases and cephalosporinases
  • some bacteria produce both
  • these enzymes kill the drugs
43
Q

strategies in war against drug resistance (8)

A
  • education of HCP and pts
  • its should stop demanding antibiotics when they are sick
  • physicians should not be pressured to prescribed antibiotics by its
  • clinicians should prescribe narrow-spectrum drug if lab indicates that it kills the pathogen
  • pts should destroy excess/outdated meds
  • antibiotics should not be used prophylactically
  • HCP should practice good infection control
  • pts should take drugs as directed
44
Q

empiric therapy

A
  • when drug therapy is initiated before lab results are available
  • sometimes necessary to save life
  • clinicians make educated guess based on experience
  • multiple factors to consider before prescribing
45
Q

factors to be considered in empiric therapy (11)

A
  • use pocket chart of antimicrobial susceptibility test data if pathogen identity is known
  • pt allergies
  • pt age
  • pregnant pt
  • inpatient or outpatient
  • is drug the hospital formulary
  • where is site of infection
  • other meds of pt
  • pt medical problems
  • pt WBC count or immunocomprimisation
  • cots of drug
46
Q

undesirable effects of antimicrobial agents

A
  • organisms susceptible to agent will die but resistant ones will survive, which is selecting for resistant organisms
  • pt may become allergic to agent
  • many agents are toxic or very toxic to humans
  • broad-spectrum may destroy normal flora resulting in overgrown bacteria known as superinfection with prolonged use

Microbiology (18 decks)

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