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Infection > Lecture 7 - Antibiotics And Resistance > Flashcards

Lecture 7 - Antibiotics And Resistance Flashcards

1
Q

What are categories of antimicrobials?

A

Anti-bacterials
Anti-fungal
Anti-viral
Anti-protozoals

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2
Q

What does it mean if an Antibacterial is Bactericidal?

A

Completely kills bacteria

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3
Q

What does it mean if an antibiotic is Bacteriostatic?

A

Prevents bacterial replication

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4
Q

What is meant by a broad spectrum antibiotic?

A

Targets lots of different types of bacteria

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5
Q

What are some examples of broad categories that a broad spectrum antibiotic might act on?

A

Gram +
Gram -
Anaerobic

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6
Q

How can antibiotics sensitivity/effectiveness be measured?

A

Paper disc soaked in antibiotic
Disc placed in agar culture of bacteria
Area of clearance measured (diameter)
Larger diameter = more effective

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7
Q

What is MIC (Minimum Inhibitory Concentration)?

A

The minimum concentration of antimicrobial agent which visibly inhibits growth

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8
Q

What are the 4 main mechanisms of action of anti bacterial?

A

Cell wall synthesis Inhibitors
Proteins synthesis inhibitors
Nucleic acid synthesis Inhibitors
Cell membrane function Inhibitors

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9
Q

What type of mechanism of antibacterial action does Penicillin have?

A

Cell wall synthesis inhibitor

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10
Q

How does Penicllin actually act as a cell wall synthesis inhibitor?

A

Prevents formation of cross linkages in cell wall

It binds to the penicillin binding protein which prevents the binding protein forming cross linkages

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11
Q

What are the 2 types of antibiotic resistance?

A

Intrinsic

Acquired

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12
Q

What is intrinsic antibiotic resistance?

A

When a species is naturally resistant to an antibiotic

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13
Q

Why do some bacteria have intrinsic antibiotic resistance?

A

The specific characteristics that the antibiotic targets not on bacteria

Doesn’t have target protein on bacteria surface

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14
Q

What is acquired antibiotic resistance?

A

When new genetic material is acquired or mutation occurs

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15
Q

How does a bacteria get acquired immunity from acquiring new genetic material?

A

Horizontal gene transfer (Plasmid)

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16
Q

What is the process of horizontal gene transfer?

A

Pili between donor and recipient bacteria extend and conjugate with each other
Donor plasmid replicates
Single stranded DNA from plasmid enters into recipient

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17
Q

What is adaptive antibiotic resistance?

A

When the bacteria responds to a stress (like low levels of antibiotic)

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18
Q

What are the mechanisms for antibiotic resistance (acquired)?

A

-Enzyme modification to destroy antibiotics
-Enzyme modification to change the target for antibiotic (cant bind)
-Target for antibiotic mutates and changes (cant bind)

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19
Q

What mechanism of action do Beta-lactams have?

A

Cell wall synthesis inhibition

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20
Q

What antibiotics are in the Beta-lactam family?

A

-Penicillins
-Cephalosporins
-Carbapenems
-Glycopeptides

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21
Q

What are the penicillins?

(Order is most narrow spectrum at the top, most broad spectrum at the bottom)

A

Benzylpenicillin
Penicillin V
Amoxicillin
Flucloxacillin

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22
Q

What is an example of a Cephalosporin?

A

Ceftriaxone

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23
Q

What are some Carbapenems?

A

Meropenem
Imipenem

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24
Q

What IV antibiotic is commonly given as a first line defence to sepsis?

A

Ceftriaxone

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25
Q

What bacteria does penicillin usually work on?

A

Streptococci
(Gram +)

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26
Q

What bacteria does Amoxicillin work on?

A

Gram + and some Gram -

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27
Q

What does Flucloxacillin work against?

A

Staphylococci and Streptococci
(Both gram +)

28
Q

Why do you typically pair cephalosporins with another antibiotic?

A

They have no anaerobe activity

29
Q

What type of infections are Carbapenems used for?

What group of people to you have to be careful using carbapenems like meropenem and imipenem with?

A

Gram negative infections

Normally safe with penicillin allergy but safer to avoid

Very broad spectrum (inc anaerobes)

30
Q

What are 2 glycopeptides?

A

-Vancomycin
-Teicoplanin

31
Q

What bacteria does Vancomycin and Teicoplanin act against?

A

Gram +

32
Q

How is vancomycin usually administered and why?

A

IV antibiotic

Not absorbed into the body in the gut

33
Q

When is Vancomycin delivered orally?
What infection is it used for and why?

A

With C.difficile
Stays in the lumen of the gut since it can’t be absorbed

34
Q

What are the major side effects/concerns with cephalosporins?

A

C.difficile infection

35
Q

When is Teicoplanin usually given instead of Vancomycin?

A

When patient no longer in hospital (IV is more difficult)

36
Q

When is a Tetracycline e.g Doxycycline used?

A

Penicillin allergy
Gram + bacteria But is Broad spectrum

37
Q

How are tetracyclines (doxycycline) always given?

A

Oral

38
Q

Who should never receive tetracyclines like doxycycline and why?

A

Children younger than 12yrs
Pregnant or Breastfeeding women

Causes staining of developing bones and teeth

39
Q

What mechanism of action do tetracyclines act by?

A

Protein synthesis inhibition

40
Q

What are 3 groups of antibiotics that act via the protein synthesis inhibition mechanism?

A

-Aminoglycosides
-Tetracyclines
-Macrolides

ATM
Go to the ATM because protein is expensive AF

41
Q

What is the most common Aminoglycoside?

What is the mechanism of action of this antibiotic?

A

Gentamicin

Protein synthesis inhibition

42
Q

When are Amino-glycosides mainly used/reserved for?

A

Severe Gram negative sepsis

Good against gram negative bacteria

43
Q

Why are Aminoglycosides like gentamicin reserved for severe gram negative sepsis?

A

Potentially nephrotoxic so requires constant monitoring since its easy to reach toxic levels

44
Q

What is an example of a Macrolides?

What is the mechanism of action of this antibiotic?

A

Erythromycin

Protein synthesis inhibition

45
Q

What ribosome subunit do tetracyclines and Aminoglycosides target?

A

30s

46
Q

What subunit do Macrolides and Linezolids target?

A

50s

47
Q

What are 3 groups of Nucleic acid synthesis inhibitors (DNA or RNA)?

A

-Quinolones
-Trimethoprim
-Rifampicin

48
Q

What is the most common Quinolone?

What is this antibiotics method of action?

A

Ciprofloxacin

Nucleic acid synthesis inhibition

49
Q

What are the risks surrounding use of Quinolones like Ciprofloxacin?

A

Risk of Tendinitis and rupture (Achilles tendon)
Aortic dissection (tearing of aorta)
C.difficile

50
Q

How do Trimethoprim and sulphonamides inhibit DNA synthesis in a bacteria?

A

Inhibits folic acid synthesis

51
Q

What is Co-trimoxazole?

A

Trimethoprim + sulphamethoxazole

52
Q

What microorganism is Co-trimoxazole used to treat?
What disease does this microbe usually cause?

When is this infection commonly seen?

A

Pneumocystis jirovecii (PJP)
A fungal pneumonia

Causes Pneumocystis pneumonia

Pneumocystis pneumonia commonly seen in patients with HIV infection (immunocompromised)

53
Q

What disease does the organism Pneumocystis jirovecii cause?

A

PCP (Pneumocystis pneumonia)

54
Q

What is PCP and who are more prone to developing it?

A

A fungal pneumonia caused by the fungus Pneumocytis jirovecii

People with HIV/AIDS

55
Q

What are the 2 categories of Antifungals?

A

-Azoles
-Polyenes

56
Q

What is the mechanism of action of Azoles?

What category of anti-microbial are they?

A

Inhibit cell-membrane synthesis

Anti-fungal

57
Q

What are the most common Azoles?

A

Fluconazole
Itra/Vori/posaconazole

58
Q

What does Fluconazole treat?

A

Candida (thrush)

59
Q

What Itra/vori/posaconazole used to treat?

A

Aspergillus

60
Q

What are 2 polyenes?

What broad category of anti-microbial are these a part of?

A

Nystatin
Amphotericin

Anti-fungal

61
Q

What is nystatin used for?

A

Topical treatment of Candida

62
Q

What is Amphotericin used to treat?

What category of anti-microbial is it?

A

Systemic fungal infections (Aspergillus) via IV

Anti-fungal

63
Q

What are 2 Antivirals?

A

Acyclovir
Oseltamivir

64
Q

What does Acyclovir treat?

A

Herpes simplex (genital herpes + encephalitis)
Varicella zoster - chicken pox and shingles

65
Q

What does Oseltamivir treat?

A

Influenza A and B

66
Q

What microbes does Metronidazole work against?

A

Its an:
Antibacterial (anaerobic)
Antiprotozoal

67
Q

What Protozoa is Metronidazole effective against?

A

Amoebae (dysentery and systemic)
Giardia (diarrhoea)
Trichomonas vaginalis (vaginitis)

Infection (21 decks)

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