Antimicrobial chemotherapy Flashcards

1
Q

Where can antibiotics act on bacteria?

A
Cell wall synthesis
Folic acid metabolism
Cytoplasmic membrane structure
DNA gyrase
RNA elongation
DNA-directed RNA polymerase
Protein synthesis
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2
Q

What are examples of penicillins?

A
Benzylpenicilin
Amoxicillin
Flucloxacillin
Co-amoxiclav
Piperacillin/tazobactam
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3
Q

What bacteria do benzylpenicillin act on?

A

Streptococci
Neisseria
Spirochetes

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4
Q

What infections are benzylpenicillin used for?

A
Soft tissue infection
Pneumococcal infection
Meningococcal infection
Gonorrhoea
Syphillis
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5
Q

What is the activity of amoxicillin?

A

Broad spectrum but resistance is common

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6
Q

What is amoxicillin generally used for?

A

UTI

Resp tract infection

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7
Q

What is the activity of flucloxacillin?

A

Staphylococci

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8
Q

What is the main use for flucloxacillin?

A

Staph aureus

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9
Q

What is the activity of co-amoxiclav?

A

Broad spectrum including anaerobes

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10
Q

What is co-amoxiclav used for?

A

UTI
Resp tract infection
Soft tissue infection
Surgical wound infection

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11
Q

What is the activity of piperacillin?

A

Broad spectrum including pseudomonas and anaerobes

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12
Q

What is the main use for piperacillin?

A

Neutropenic sepsis

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13
Q

What are different cephalosporin generations?

A

First to fourth generation = narrow to broad spectrum

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14
Q

What are examples of cephalosporins?

A
Cefradine - 1st gen
Cefuroxime - 2nd gen
Ceftriaxone - 3rd gen
Ceftazidime - 3rd gen
Ceftaroline - 4th gen
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15
Q

What is the activity of ceftradine?

A

Broad spectrum - resistance is more common

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16
Q

What is the main use for ceftradine?

A

UTI

Soft tissue infection

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17
Q

What is the activity of cefuroxime?

A

Broad spectrum

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18
Q

What are the main uses for cefuroxime?

A

UTI
Resp tract infection
Surgical prophylaxis

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19
Q

What is the activity of ceftriaxone?

A

Broad spectrum especially good against gram negative bacilli

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20
Q

What is the main use of ceftriaxone?

A

Hospital infections ie bacteraemia

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21
Q

What is the activity of ceftrazidime?

A

Broad spectrum and effective against pseudomonas

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22
Q

What is the main use of ceftrazidime?

A

Pseudomonal infections in hospital

Cystic fibrosis

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23
Q

What is the activity of ceftaroline?

A

Broad spectrum, less gram negative cover, anti MRSA

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24
Q

What is the use of ceftaroline?

A

Skin and soft tissue infection

Endocarditis resistant to other treatment

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25
Q

What is the main example of an aminoglycoside?

A

Gentamicin

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26
Q

What is the activity of gentamicin?

A

Gram negative bacilli

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27
Q

What is the use of gentamicin?

A

Serious gram-negative infections

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28
Q

What are examples of macrolides?

A

Clarithromycin
Erythromycin
Axithromycin

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29
Q

What is the activity of clarithromycin and erythromycin?

A
Streptococci
Staphylococci
Mycoplasma
Chlamydia
Legionella
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30
Q

What are the main uses for clarithromycin and erythromycin?

A

Resp infection
Soft tissue infection if penicillin allergic
STD

31
Q

What is activity of azithromycin?

A

Good for gram negative

32
Q

What is the main use of azithromycin?

A

Chlamydia

33
Q

What are examples of quinolones?

A

Ciprofloxacin

Levofloxacin

34
Q

What is the activity of ciprofloxacin?

A

Gram negative bacilli
Pseudomonas
Some activity against strep and staph

35
Q

What are the main uses of ciprofloxacin?

A

Complicated UTI
Complicated hospital acquired infection
Some GI infections

36
Q

What is the activity of levofloxacin?

A
Enhanced activity againts staph and strep
Less effective against pseudomonas
Effective against pneumococcus
Mycoplasma
Chlamydia
Legionella
37
Q

What is the main use for levofloxacin?

A

2nd or 3rd line agent for pneumonia

38
Q

What is the main example of a glycopeptide?

A

Vancomycin

39
Q

What is the activity of vancomycin?

A

Gram-positive only

40
Q

What is the main use for vancomycin?

A

MRSA
Penicillin allergy
C. Diff

41
Q

What is trimethoprim used for?

A

UTI

MRSA

42
Q

What is co-trimoxazole used for?

A

Resp infection

43
Q

What is clindamycin used for?

A

Soft tissue infection

Gangrene

44
Q

What is tetracycline and doxycycline used for?

A

Brucellosis

Atypical pneumonia

45
Q

What is rifampicin used for?

A

TB

46
Q

What is meropenem used for?

A

2nd or 3rd line for hospital infections

47
Q

What is metronidazole used for?

A

Surgical infections

48
Q

What is linezolid used for?

A

2nd line for MRSA

49
Q

What is daptomycin used for?

A

2nd line for MRSA

50
Q

What is tigecycline used for?

A

3rd line for intra-abdominal sepsis

51
Q

What is empiric antimicrobial therapy?

A

Given without microbiology results

52
Q

What is directed antimicrobial therapy?

A

Given based on microbiology results

53
Q

What is primary prophylaxis?

A

Prevent infection

54
Q

What is secondary prophylaxis?

A

Prevent a second episode

55
Q

What are patient characteristics which will impact prescription?

A
Age
Renal function
Liver function
Immunocompromised
Pregnancy
Known allergies
56
Q

How do we choose antimicrobials?

A
Guidelines
Consider likely organisms
Empirical or result based?
Bactericidal vs bacteriostatic
Single agent or combination
Potential adverse effects
57
Q

How can antibiotic resistance be tested?

A

Disk defusion method

58
Q

What are the 4 main mechanisms of antibiotic resistance?

A

Enzymatic inactivation of drug
Modified targets for drugs
Reduced permeability to drug
Efflux of drug

59
Q

What us chromosomally mediated resistance?

A

Mutation in gene coding for drug target or membrane transport system

60
Q

What is plasmid mediated resistance?

A

Bacteria transfer resistance genes to other species of bacteria horizontally

61
Q

What are medically important resistant organisms?

A

Methicillin resistant staph aureus (MRSA)
Vancomycin resistant enterococci (VRE)
Extended spectrum beta lactamase (ESBL) producing enterobacteriaciae
Carbapenem producing enterobacteriacae (CPE)
C diff

62
Q

What makes MRSA resistant?

A

Change in binding site

63
Q

Why is VRE so dangerous?

A

Only susceptible to 1 or 2 antibiotics since enterococci are intrinsically only sensitive to limited number of antibiotics

64
Q

What factors influence antibiotic resistance?

A

Antibiotic use by medical professions, veterinary practice, farming
Patients surviving longer with more medical conditions and hospital contact
More invasive procedures and prosthetic devices
Increased bed pressure

65
Q

What antibiotics can be given for penicillin resistant organisms?

A
Quinolones
Macrolides
Licosamides
Co-trimoxazole
Aminoglycosides
Glycopeptides
Daptomycin
Tetracycline
Tigecycline
Oxazolidinones
66
Q

What is type I hypersensitivity reaction?

A

IgE mediated specific immunoglobulin, stimulates pro-inflammatory release resulting in urticarial, laryngeal oedema, bronchospasm

67
Q

What is type II hypersensitivity reaction?

A

Beta lactam specific IgG or IgM antibodies bind to circulating blood cell resulting in haematological reactions or interstitial nephritis

68
Q

What is type III hypersensitivity reaction?

A

Circulating beta-lactam specific IgG or IgM bind to beta-lactam antigens fixing complement and lodging in tissues resulting in serum sickness and drug related fever

69
Q

What is type IV hypersensitivity reaction?

A

Not antibody mediated, T-cell recognises antigen leading to localised inflammation

70
Q

What is the difference between resistance and failure of therapy?

A

Resistance is inability of antibiotic to kill bacteria, failure is clinical error

71
Q

What can cause failure of therapy?

A
Inadequate dose of antibiotic
Inappropriate route
Non-compliance with antibiotic
Bacteria walled off in abscess cavity
Foreign bodies
Poor penetration of drug to site of infection
72
Q

What antibiotics are effective against biofilms?

A

Rifampicin
Daptomycin
Ceftobiprole

73
Q

When can a patient be considered for switching from IV to oral antibiotics?

A
If all of the criteria are met:
Able to swallow and tolerate fluids
Temp 36-38 for at least 48 hours
Heart rate <100 for previous 12 hours
WCC between 4 and 12
74
Q

When should a patient not be switched from IV to oral?

A

Oral route is compromised
Continuing sepsis
Febrile neutropenia
Hypotension/shock