Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

P.O.D own flashcards > Antimicrobial chemotherapy > Flashcards

Antimicrobial chemotherapy Flashcards

1
Q

what is MIC

A

minimal inhibitory concentration

the minimum conc of antimicrobial needed to inhibit the growth of a given organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is MBC

A

minimal bacterial conc.

minimum conc. of antimicrobial needed to kill a given organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

sensitive

A

organism is sensitive if it is inhibited or killed by the antimicrobial available at the
site of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

resistant

A

organism is resistant if it is not killed or inhibited by the antimicrobial available at the
site of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

bacteriocidal

A

antimicrobial that
kills bacteria
(penicillins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

bacteriostatic

A

antimicrobial that inhibits growth
of bacteria
(erythromycin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are antibiotics only active against?

A

bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

which 3 areas of metabolic activity may antibiotics act on to inhibit or kill bacteria?

A

inhibition of cell wall synthesis (e.g penicillins and cephalosporins
also glycopeptide antibiotics)

inhibition of nucleic acid synthesis (e.g trimethoprim and ciprofloxacin)

inhibition of protein synthesis (e.g gentamicin and erthromycin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Discuss polyene drugs (antifungal)

A

class of extremely toxic drugs with a wide range of side effects including, renal, hepatic and cardiac toxicity

they bind to ergosterol, which is present in the fungal cell wall and this results in an increase in the permeability of the cell wall

they also bind to other sterols e.g cholesterol in mammalian cell membranes and this is the reason why they are toxic in humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Discuss azole (antifungal) drugs

A 
class of drugs
inhibit ergosterol synthesis so disrupt cell wall.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what do the anti-fungal drugs allylamines do?

A

also suppress ergosterol synthesis, but act at a different stage of the synthesis pathway from azoles

The only allyalmine in common use is terbinafine. This drug is used for fungal infection of skin and nails (ringworm, athlete’s foot etc)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what to the antifungal drugs called echinocandins do?

A

they inhibit the synthesis of glucan polysaccharide in several types of fungi- target cell wall
they are used for serious Candida and Aspergillus infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Antiviral drug types

A

anti-herpes virus drugs
anti-HIV drugs
drugs for chronic Hep B and C
drugs for viral respiratory infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

anti-herpes virus drugs

A

aciclovir is a class of anti-herpes drugs
they are nucleoside analogues ie disrupt nucleic acid synthesis
IV form given to treat severe infections
specific for viral infected cells- as only works once activated by an enzyme coded for by virus genome
-has a very low toxicity for uninfected host cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Antibiotics that inhibit cell wall synthesis

A

penicillins and cephalosporins- these groups contain Beta lactams (rings)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

parenteral route of administration?

A

intra-venously (iv)
or intra-muscularly (im),
occasionally subcutaneously.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

which test allows you to compare the MIC of one antibiotic against another organism?

A

E-test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

examples of polyenes

A

anti-fungal
amphotericin B - serious fungal + yeast infections
Nystatin- topically or in oral suspension- skin and vaginal infections etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

examples of Azoles

A

Fluconazole is used to treat a yeast infection. Not all yeasts are sensitive to flucanazole

voricanazole, itraconazole - fight aspergillosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

examples of echinocandins

A

caspofungin- used in serious candida and aspergillus infection, safe, only given by IV
micafungin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

anti-HIV drugs

A

zidorudine- first ever drug used for this- nucleoside analogue
slows replication but doesn’t kill it
nowadays combination therapy is common in HIV treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Viral respiratory infections: drugs to treat this

A

zanamivir and oseltamivir - treat influenza A or B within 48 hours of onset of symptoms
ribavirin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

who is aciclovir restricted from

A

patients with renal impairment as without excreting it toxicity levels rise so we want to prevent neurological toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are 2 ways to combat Beta-lactamase (produced by bacteria to be resitant to antibiotics)?

A
  1. introduce 2nd component to the antibiotic (B-lactamase inhibitor) protecting the antibiotic from enzymatic degradation
  2. modify antibiotic side chain producing new antibiotic resistant to actions of B-lactamase (flucloxicillin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

inherent or intrinsic resistance

A

bacteria’s natural ability to resist antibiotics due to its inherent structural or functional characteristics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

acquired resistance

A

via spontaneous mutation or spread of resistance by plasmid -genetic transfer or by transposons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the major current issue relating to bacterial resistance

A

widespread use of antibiotics causes selective pressure and encourages new resistant organisms to outgrow sensitive strains
bacteria are becoming more and more resistant to everyday antibiotics and soon we won’t be able to fight many diseases/infections that would normally be treatable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

common antibiotics that inhibit cell wall synthesis

A

penicillins, cephalospoirins, vancomysin, teicoplanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

common antibiotics that inhibit protein synthesis

A

gentamicin, erythromicin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

common antibiotics that inhibit DNA synthesis

A

trimethoprim, sulphamethoxazole, ciprofloxacin

31
Q

How do drugs inhibit cell wall synthesis?

A

they inhibit kill the bacteria by disrupting peptidoglycan from cross-lining the carbohydrate chains. They do this by inhibiting the enzymes responsible for this.
peptidoglycan layer is important for cell wall structural integrity in bacteria however more so in gram positive as it is in the outer membrane.
Gram negative have peptidoglycan in it’s 3rd membrane in so is less sensitive to this kind of inhibition

32
Q

Why are humans not affected by antibiotics that inhibit C.W synthesis?

A

eukayrotic cells do not have a cell wall

33
Q

How do bacteria grow resistance to penicillin/ cephalosporins?

A

bacteria can synthesise a Beta-lactamase, an enzyme that attacks the beta lactam ring- which is essential in the effectiveness of the antbiotic

34
Q

vancomycin and teicoplanin?

A

only able to penetrate the gram +ve cell wall due to being hydrophilic
they are not absorbed by the GI tract and so are only given parenterally (IV etc)
they act on a different stage of C.W synthesis than Beta lactamase
they inhibit the assembly of peptidoglycan precursor

35
Q

what does inhibition of protein synthesis entail?

A

interruption of translation of messenger mRNA at the ribosome

36
Q

gentamicin antibiotic

A

an aminoglycoside (class)
it’s toxic
targets mRNA by disrupting the way a specific codon of mRNA is read by RNA polymerase
insert a different amino acid into the sequence so the protein doesn’t work
useful for gram -ve treatment

37
Q

why are humans not affected by gentamicin?

A

it only attacks bacterial ribosomes as they are different to human ones

38
Q

erythromicin antibiotic

A 
part of macrolides class
inhibits protein synthesis by preventing the peptide bond from being created along amino acids 
useful alternative for patients who are allergic to penicillin
39
Q

what does inhibition of nucleic acid synthesis entail?

A

wide range of antibiotics inhibit DNA synthesis either directly, or indirectly by interrupting the supply of precursors for DNA synthesis
or inhibition of different steps in purine synthesis A+G bases

40
Q

Trimethoprim and sulphamethoxazole antibiotics

A

used in combined form in the drug ‘co-trimoxazole’
trimethoprim inhibits purine synthesis ie A+G bases on DNA won’t be in DNA so they’re no longer there in translation of RNA so not in the protein as a result- DNA structure no longer has correct amount of purine needed (need the same A-T and G-C)
bacteria will die as they can no longer replicate

41
Q

ciprofloxacin antibiotic

A 
fluoroquinolones class
inhibit DNA synthesis more directly as it interrupts/inhibits function of DNA gryase (an enzyme that can wrap/unwrap DNA) so by inhibiting it and keeping DNA wrapped up there is no access to the DNA molecule for DNA replication to occur 
CAN'T BE USED IN CHILDREN
42
Q

which common infections do penicillins treat?

A

chest infections
skin infections
UTI’s

43
Q

which common infections does gentamicin treat?

A

staph. aureus
endocarditis
UTI’s
pneumonia

44
Q

which common infections does erythromicin treat?

A

it treats respiratory tract infections ie bronchitis, whooping cough,

45
Q

what does trimethoprim treat on its own? and what does it treat combined with sulfamethoxazole?

A

on it’s own: UTI’s

combined: chest infections

46
Q

which common infections does cephalosporins treat?

A

septicaemia
pneumonia
meningitis
UTI’s

47
Q

antibacterial resistance can be 2 things?

A

inherent or intrinsic

acquired

48
Q

inherent or intrinsic resistance- explain

A

bacteria’s natural ability to resist antibiotics due to it’s inherent structural or functional characteristics
STREPTOCOCCI are always resistant to aminoglycosides
gram -ve always resistant to vancomycin as it is unable to pass through lipopolysaccharide outer membrane so can’t kill it effectively/exert its action

49
Q

acquired resistance

A

via spontaneous mutation or spread of resistance by plasmid- genetic transfer or by transposons

50
Q

which common bacteria is resistant to penicillin and why?

A

staph. aureus as it can produce Beta lactamase which inactivates penicillin by hydrolysing the beta lactam ring

51
Q

what are two ways to combat Beta lactamase

A

introduce a second component to the antibiotic (Beta lactamase inhibitor) protectinng the antibiotic from enzymatic degradation
or
modify antibiotic side chain producing new antibiotic resistance to actions of Beta lactamase

52
Q

can an infection be caused by a patients own microbiological flora?

A

yes for example in a UTI, E.coli from the gut causes infection

53
Q

what types of diseases are TB, leprosy and syphilis?

A

granulomatous diseases

54
Q

what are 2 common resistant mechanisms of staph aureus

A

Producing Beta lactamase
MRSA- has a gene that codes for Penicillin binding protein (PBP)- changes the active site of the antibiotic- not inhibited by beta lactam

55
Q

which drug is the drug of choice treating MRSA?

A

Vancomycin (very toxic- careful with administration)- acts on CW synthesis at stage prior to beta lactamase
or paptomycin

56
Q

What does MRSA stand for?

A

(meticillin)-resistant S. aureus (MRSA)

57
Q

once you detect MRSA infection in a patient what happens?

A

isolate patient
treat with antibiotics
attempt treatment in different way- different combinations/ modify side chain

58
Q

Which antibiotic is not inactivated by beta lactamase and should be used to treat infections caused by penicillin-resistant staphylococci?

A

flucloxacillin

59
Q

drugs for chronic Hep B and C

A

Interferon alpha

lamivudine

60
Q

what is nitrofurantoin?

A

an antibiotic used to treat bladder infections and UTIs

61
Q

benzylpenicillin treatment for what?

A

pneumococcus or meningococcus bacteria- once you find this without meningitis use this antibiotic via IV

62
Q

in culture what visual changes help determine between streptococci species?

A

haemolysis
if alpha haemolytic = partial haemolysis (green colour)
beta haemolytic- full haemolysis
non haemolytic = no difference

63
Q

alpha haemolytic examples

A

strep viridans

strep pneumoniae

64
Q

beta haemolytic examples

A

strep pyogenes

strep agalactiae

65
Q

non-haemolytic bacteria example

A

enterococcus

66
Q

how are vancomycin and teicoplanin administered

A

only given parenterally ie IV or intramuscular

67
Q

Ototoxicity

A

toxicity to ear

hearing impairment

68
Q

what are macrolides like erythromicin and clarithromicin useful in treating

A

gram negative bacteria that can’t be treated by penicillins

69
Q

Linezolid what is it

A

new class of protein synthesis inhibitors in common use.
It has good activity against MRSA and can be
given orally- usually held in reserve for serious infection

70
Q

co-trimoxazole used to treat what now and why?

A

chest infection since it Is less likely than other broad spectrum agents to cause Clostridium difficile infections.

71
Q

VRE

A

vancomycin resistant enterococci
the peptidoglycan precursor to which vancomycin
normally binds has an altered structure

72
Q

Nalidixic acid used to treat which one infection

A

UTI

73
Q

Clostridium difficile infection (CDI)

A

is an important side effect of antibiotic therapy- causes diarrhea

74
Q

piperacillin

A

has an extended spectrum and is active against

Pseudomonas species

P.O.D own flashcards (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions