Antimicrobial Chemotherapy Flashcards

1
Q

What are the 7 principles for prescribing antimicrobials?

A
  1. Indications for antimicrobials
  2. Making a clinical diagnosis
  3. Patient characteristics
  4. Antimicrobial selection
  5. Regimen selection
  6. Liasion with laboratory
  7. Antimicrobial stewardship
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2
Q

What is empiric therapy?

A

Treating without microbiology results

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3
Q

What is directed therapy?

A

Treatment based on microbiology results

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4
Q

What are the two types of prophylaxis?

A

Primary, e.g. antimalarials, pre-op antibiotics etc.

Secondary (to prevent a second episode)

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5
Q

What may involved in assessing the severity of an infection?

A

qSOFA, ?septic shock

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6
Q

What patient characteristics may influence antimicrobial choice?

A
  • Age
  • Renal function
  • Liver function
  • Immunocompromised
  • Pregnancy
    Known allergies
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7
Q

What should antibiotic selection be based on?

A

The known or most likly causative organism(s)

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8
Q

What is the difference between bactericial and bacteriostatic drugs?

A

Bactericidal - kills

Bacteriostatic - prevents replication

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9
Q

What features must you consider when selecting an appropriate regimen?

A
  • Route of administration
  • Dose
  • Adverse events
  • Duration
  • IV to oral switch therapy
  • Inpatient/outpatient therapy (OPAT)
  • Therapeutic drug monitoring
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10
Q

What is involved in antimicrobial stewardship?

A

Making the best use of our current antibiotics

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11
Q

Describe the empirical Rx of cellulitis

A

Cellulitis most likely to be strep pyogenes so chose antibiotic effective against that

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12
Q

Describe the empirical Rx of pneumonia

A

Most likely to be strep pneumonia (then H. influenzae, staph aureus…)

If have COPD - moraxella catarrhalis

If been in contact with contaminated water - legionella most common

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13
Q

Give an example of a bactericical

A

Beta-lactams

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14
Q

How do bactericidals work?

A

Act on cell wall

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15
Q

What are the indications for bactericidals?

A
  • Neutropenia
  • Meningitis
  • Endocarditis
  • Lifethreatening infections
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16
Q

Give an example of a bacteriostatic

A

Macrolides

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17
Q

How do bacteriostatic drugs work?

A

Inhibit protein synthesis and prevent colony growth

Require host to mop up residual infection

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18
Q

When are bacteriostatic drugs most useful?

A

In treating toxin mediated illness as they are able to switch off the proteins that the bacteria use to make toxins

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19
Q

Name 2 conditions that require combination antimicrobials

A

HIV and TB

Others: sepsis, mixed organisms

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20
Q
A
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21
Q

When should you give oral route for antimicrobials?

A

IT is preferred whereever possible if no vomiting, normal GI function, no shock, no organ dysfunction

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22
Q

When should you give IV route for antimicrobials?

A

Severe, deep seated infection and when oral route not reliable

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23
Q

What are some of the allergic reactions that can occur due to antibiotics?

A

Immediate hypersensitivity (anaphylaxis)

Delayed hypersensitivity (rash, fever, serum sickness, erythema nodosum, SJS)

GI, e.g nausea, vomiting, diarrhoea, C. diff infection

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24
Q

Which antibiotics shouldn’t be used in those with renal damage?

A

Vancomycin and gentamicin

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25
Q

What antimicrobials are cytotoxic?

A

Gentamicin and vancomycin

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26
Q

What antimicrobial can cause optic neuropathy?

A

Ethambutol

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27
Q

What antimicrobials can cause convulsions and encephalopathy?

A

Penicillins and cephalosporins

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28
Q

What antimicrobials can cause peripheral neuropathy?

A

Isonazid, metronidazole

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29
Q

What antimicrobial can cause megoblastic anaemia and how?

A

Co-trimaxazole

Poisons DNA synthesis via interrupting foltate metabolism

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30
Q

‘Reduce the 4 C’s and reduce C. diff’

What are the 4 C’s?

A

Ceftriaxone, co-amoxiclav, clindamycin ciprofloxacin

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31
Q

What are the classes of antimicrobial?

A
  • Penicillins (beta-lactams)
  • Cephalosporins (beta-lactams)
  • Aminoglycosides
  • Macrolides
  • Quinolones
  • Glycopeptides
  • Others
  • Antifungals
  • Anti-virals
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32
Q

Which antimicrobials work by inhibiting cell wall synthesis?

A

Beta-lactams (peincillins and cephalosporins)

Glycopeptides (vancomycin and teicoplanin)

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33
Q

Which antimicrobials work by inhibiting protein synthesis?

A

Aminoglycosides (gentamicin)

Macrolides (clarithromycin)

Tetracyclines (doxycycline)

Oxazolidnones (linezolid)

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34
Q

Which antimicrobials work by inhibiting nucleic acid synthesis?

A

Trimethoprim

Sulfonamides (sulfamethoxazole)

Quinolones (ciprofloxacin)

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35
Q

How is benzyl penicillin administered?

A

IV/IM only

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36
Q

What is the activity of benzyl penicillin against?

A

Streptococci, Neisseria, spirochetes

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37
Q

What is benzyl penicillin mostly used to Rx?

A

Soft tissue, pneumococcal, meningococcal, gonorrhoea, syphilis infections

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38
Q

What is the activity of amoxicillin against?

A

Broad spectrum

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39
Q

What is amoxicillin mostly used to Rx?

A

UTI, RTI

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40
Q

What is flucloxacillin mostly used to Rx?

A

S. aureus infections

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41
Q

What is co-amoxiclav mostly used to Rx?

A

UTI, RTI, soft tissue infections, surgical wound infections

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42
Q

What is piperacillin/tazobactam mostly used to Rx?

A

Neutropenic sepsis

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43
Q

What is cefradine mostly used to Rx?

A

UTI, soft tissue infection

44
Q

What is cefuroxime mostly used to Rx?

A

UTI, RTI, surgical prophylaxis

45
Q

What is ceftriazone/cefotaxime mostly used to Rx?

A

Hospital infections, e.g. bacteraemia, pneumonia, abdo sepsis

46
Q

What is cefazidine mostly used to Rx?

A

Pseudomonal infections in hospital and in CF

47
Q

What are gentamicin/amikacin mostly used to Rx?

A

Serious gram -ve infections, e.g. bacteraemia, endocarditis, neutropenic sepsis

48
Q

What are clarithromycin/erythromycin mostly used to treat?

A

Respiratory infections, soft tissue infection (if penicillin allergic), STF

49
Q

What is azithromycin mainly used to treat?

A

Chlamydia

50
Q

What is the main use of ciprofloxacin?

A

Complicated UTI, complicated HAI, pneumonia, some GI infections

51
Q

What is the main use of levofloxacin/moxifloxacin?

A

2nd/3rd line for pneumonia

52
Q

What are vancomycin/teicoplanin mostly used for?

A

MRSA, patients allergic to penicllin, C. diff

53
Q

What is the main use of trimethoprim?

A

UTI, respiratory infection, MRSA

54
Q

What is the main use of co-trimaxazole?

A

Respiratory infection, PCP

55
Q

What is the main use of clindamycin?

A

Soft tissue infection gangrene

56
Q

What is the main use of tetracycline/doxycyline?

A

Q fever, brucellosis, chlamydia, atypical pneumonia, MRSA

57
Q

What is the main use of rifampicin?

A

TB, MRSA, meningococcal prophylaxis, complicated staph infections

58
Q

What is the main use of meropenem?

A

2nd/3rd line for hospital infections

59
Q

What is the main use of linezolid/daptomycin?

A

2nd line agent for MSSA, MRSA, VRE

60
Q

What is the main use of tigecycline?

A

2nd line intra-abdominal sepsis, soft tissue infections (last resort)

61
Q

What bacteria does co-amoxiclav have activity against?

A

Broad spectrum, incl anaerobes

62
Q

What bacteria does piperacillin/tazobactam have activity against?

A

Broad spectrum, incl anaerobes and pseudomonas

63
Q

What bacteria do the cephalosporins have activity against?

A

Broad spectrum

64
Q

What bacteria do aminoglycosides have activity against?

A

Gram negatives

65
Q

What bacteria does clarithromycin/erythromycin have activity against?

A

Strep, staph, myocplasma, chlamydia, legionella

66
Q

What bacteria does azithromycin have activity against?

A

Better for gram -ves (incl haemophilus, chlamydia)

67
Q

What bacteria does ciprofloxacin have activity against?

A

Gram -ve bacilli incl. pseudomonas w. some activity against staph/strep

68
Q

What bacteria does levofloxacin/moxifloxacin have activity against?

A

Enhanced against staph/strep

Active against pneumococcus, mycoplasma, chlamydia, legionella

69
Q

What bacteria do glycopeptides have activity against?

A

Gram +ve only (staph, strep)

70
Q

What bacteria does trimethoprim have activity against?

A

Gram -ve bacilli, some activity against strep and staph

71
Q

What bacteria does co-trimoxazole have activity against?

A

Broad spectrum, PJP

72
Q

What bacteria does clindamycin have activity against?

A

Strep, staph, anaerobes

73
Q

What bacteria does tetracycline/doxcycline have activity against?

A

Strep, staph, chlamydia, ricketassiae, brucella

74
Q

What bacteria does rifampicin have activity against?

A

Mycobacteria, meningococcus, staph

75
Q

What bacteria does meropenem have activity against?

A

Broad spectrum antibiotics incl anaerobes, pseudomonas

76
Q

What bacteria does metronidazole have activity against?

A

Anaerobes, protozoa

77
Q

What bacteria does linezolid/daptomycin have activity against?

A

Gram +ve bacterial only

78
Q

What bacteria does tigecycline have activity against?

A

V broad spectrum, e.g. MRSA, ESBL

79
Q

What is the main use of metronidazole?

A

Surgical infections, giardiasis, amoebiasis, trichomonal infections

80
Q

Which antibiotics are in the penicillins group?

A
  • Benzylpenicillin penicillin V
  • Amoxicillin
  • Flucloxacillin
  • Co-amoxiclav
  • Piperacillin/tazobactam
81
Q

What antibiotics are in the cephalosporin group?

A
  • Cefradine (1st)
  • Cefuroxime (2nd)
  • Ceftriazone/cefotaxime (3rd)
  • Cefazidine
82
Q

What antibiotics are aminoglycosides?

A
  • Gentamicin
  • Amikacin
83
Q

What antibiotics are macrolides?

A
  • Clarithromycin
  • Erythromycin
  • Azithromycin
84
Q

What antibiotics are quinolones?

A
  • Ciprofloxacin
  • Levofloxacin/moxifloxacin
85
Q

What antibiotics are glycopeptides?

A
  • Vancomycin
  • Teicoplanin
86
Q

What are the four types of antifungal therapy?

A

Azoles

Polyenes

Echinocandins

Terbinafine

87
Q

What are the azole drugs and what fungi are they active against?

A
  • Fluconazole: candida, some resistance
  • Itraconazole: candida, aspergillus
  • Voriconazole: candida, aspergillus
88
Q

What are the polyenes and what are the active against?

A
  • Amphotericin: candida, aspergillus
  • Nystatin: candida
89
Q

What are the endocandins and what are the active against?

A

Caspofungin, anidulafungin, micafungin: candida, aspergillus

90
Q

What is terbafine mostly used for?

A

Tinea or fungal nail infections

91
Q

Delete as appropriate:

All antivirals are viruostatic/virucidal

A

Viruostatic

Viruses require host cell enzymes to replicate & therefore antivirals target viral proteins that do this

92
Q

How do most antivirals work?

A

Most are nucleoside analogues

They work by inhibiting nucleic acid synthesis

93
Q

What is a big problem with antivirals?

A

Toxicity to the host cell may lead to side effects

Only used in minority of cases because of this

94
Q

What are the types of antiviral treatment?

A
  • Prophylaxis (preventing infection)
  • Pre-emptive (evidence of infection detected but before symptoms apparent)
  • Overt disease
  • Suppressive therapy (keep viral replication below rate that causes tissue damage in asymptomatic infected patients, e.g. antiretrovirals
95
Q

When are antivirals indicated in herpes infections?

A
  • Mucocutaneous: oral, genital, eye, skin
  • Encephalitis
  • Immunocompromised
96
Q

What antivirals can used to treat herpes infection?

A

Aciclovir, famciclovir, ganciclovir

Usually use foscarnet if aciclovir resistant

97
Q

What antivirals can be used to treat HCV?

A

Pegylated nterferon alpha (s/c)/ribavirin + protease inhibitor (e.g. telaprevir/boceprevir)

98
Q

When are antivirals indicated for chickenpox?

A
  • In those at increased risk of complications
  • Neonates
  • Immunocompromised
  • Pregnant
  • Immunocomponent adult (only if begun within 24 hours of onset of rash)
99
Q

The treatment of shingles with antivirals only decreases the risk of ___________ in the immuncompetent if begun within ___hours of onset of symptoms

A

post-herpetic neuralgia

72

100
Q

What is the mode of action of aciclovir?

A

Acyclovir is converted by viral thymidine kinase to AVCMP

ACVMP then converted by host cell kinases to ACV-TP via phosphorylation

ACV-TP (aciclovir triphosphate) competes for the viral DNA polymerase, becomes incorporated into the viral DNA chain and inhibits further DNA polymerase activity

Aciclovir lacks a 3’-hydroxyl group on its acyclic side-chain, and therefore cannot form a phosphodiester bond with the next nucleotide due to be added to the growing herpes DNA chain, which is terminated prematurely

This prevents further viral DNA synthesis without affecting normal cellular processes

101
Q

What antiviral may be used in the treatment of respiratory syntical virus?

A

Ribavirin (rarely indicated)

102
Q

What are the two ways to test for resistance to antivirals?

A
  • Phenotypic – can virus grow in presence of compound
  • Genotypic – sequence genome and identify resistance-associated mutations
103
Q

What 3 points are included in the UK 5 Year Antimicrobial Resistance Strategy?

A
  • Improve knowledge and understanding of AMR
  • Converse and steward the effectiveness of existing treatments
  • Stimulate the development of new antibiotics, diagnostics and novel therapies
104
Q

What is the role of the Scottish Antimicrobial Prescribing Group (SAPG)?

A

Coordinates and delivers a national framework for antimicrobial stewardship to enhance the quality of antimicrobial prescribing and management in Scotland

105
Q

What is IVOST?

A

IV to Oral Switch Therapy

Consider switching patients from IV to oral antibiotics after 48 hours, provided that patient improving clinically & able to tolerate oral formulation (can swallow, normal vital signs etc.)