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Infection > Antimicrobial Chemotherapy > Flashcards

Antimicrobial Chemotherapy Flashcards

1
Q

List some antibiotics that increase the risk of C diff contraction

A

Cephalosporin

Ciprofloxacin

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2
Q

List some causes of increased pathogenicity of MRSA when exposed to Quinolones and other antibiotics?

A 
Biofilm formation
Small colony variants
Efflux
Hypermutation
Skin/RT colonization -> transmissibility 
Fibrinonectin-binding protein
etc
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3
Q

What is the current overall trend in total use of antibiotics in Scotland since 2012?

A

Decreasing usage (but increasing in acute hospitals)

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4
Q

What is the IVOST policy?

A

IV to Oral Switch Therapy - the consideration of switching to oral antibiotics after 48 hours if the patient is improving clinically and able to tolerate oral meds.

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5
Q

What are the inidications for use of antimicrobials?

A

-As therapy (empirical/directed)
-As prophylaxis
(Primary (anti-malarial, pre-operative, post-exposure) vs Secondary)

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6
Q

What are some patient characteristics that should be considered when prescribing antibiotics?

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

What should be considered with antimicrobial selection?

A
  • Guideline or “individualised” therapy
  • ? likely organism(s)
  • empirical therapy or result-based therapy
  • bactericidal vs. bacteriostatic drug
  • single agent or combination
  • potential adverse effects
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8
Q

List some likely causative bacteria of a soft tissue infection?

A
  • Streptococcus pyogenes
  • Staphylococcus aureus
  • Streptococcus group C or G
  • E. coli
  • Pseudomonas aeruginosa
  • Clostridium species
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9
Q

List some likely causative bacteria of a pneumonia infection?

A
  • Streptococcus pneumonia
  • Haemophilus influenzae
  • Staphylococcus aureus
  • Klebsiella pneumonia
  • Moraxella catarrhalis
  • Mycoplasma pneumonia
  • Legionella pneumonia
  • Chlamydia pneumonia
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10
Q

What are the properties of bactericidal antibiotics?

A

Bactericidal

e. g.. beta-lactams
- act on cell wall
- kill organisms
- indications include neutropenia, meningitis and endocarditis

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11
Q

What are the properties of bacteriostatic antibiotics?

A

Bacteriostatic

e. g.. macrolides
- inhibit protein synthesis
- prevent colony growth
- require host immune system to “mop up” residual infection
- useful in toxin-mediated illness

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12
Q

Why might single antibiotic therapy be useful?

A
  • simpler
  • fewer side effects
  • fewer drug interactions
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13
Q

When might combination antibiotic therapy be useful?

A
  • HIV and TB therapy
  • severe sepsis (febrile neutropenia)
  • mixed organisms (faecal peritonitis)
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14
Q

When should antibiotics be given orally?

A
  • If not vomiting
  • Normal GI Function
  • No shock, no organ dysfunction
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15
Q

When should IV antibiotics be given ?

A

-For severe/deep-seated infection, and when oral route is not available

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16
Q

Give an example of an immediate hypersensitivity reaction in antibiotics?

A

Anaphylactic shock

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17
Q

Give an example of an delayed hypersensitivity reaction in antibiotics?

A

Rash, drug fever, serum sickness, erythema nodosum, Stevens-Johnson syndrome

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18
Q

Which antibiotics are more likely to result in candida (thrush) infection?

A

Broad spectrum penicillins, cephalosporins

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19
Q

Which antibiotics are more likely to result in adverse renal effects?

A

Gentimicin, vancomycin

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20
Q

Which antibiotics are more likely to result in adverse neurological effects?

A

Ototoxicity - gentamicin, vancomycin

Optic neuropathy - ethambutol (TB)

Convulsions, encephalopathy - penicillins, cephalosporin

Peripheral neuropathy - isoniazid (TB), metronidazole

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21
Q

What are the ‘4 C’s’ associated with C Diff?

A
  • Cefitriaxone
  • Co-amoxiclav
  • Climdamycin
  • Ciprofloxacin
22
Q

List some antimicrobial classes

A 
Penicillins (β-lactams)
Cephalosporins (β-lactams)
Aminoglycosides
Macrolides
Quinolones
Glycopeptides
Others
Antifungals
Antivirals
23
Q

What classes of antimicrobials act by inhibiting cell wall synthesis?

A
  • Beta-lactams: penicillins and cephalosporins

- Glycopeptides: vancomycin, teicoplanin

24
Q

What classes of antimicrobials act by inhibiting protein synthesis?

A
  • Aminoglycosides: gentamicin
  • Macrolides: clarithromycin
  • Tetracyclines: doxycycline
  • Oxazolidinones: linezolid
25
Q

What classes of antimicrobials act by inhibiting nucleic acid synthesis?

A
  • Trimethoprim
  • Sulfonamides: sulfamethoxazole
  • Quinolones: ciprofloxacin
26
Q

Are antiviral medications virustatic or virucidal?

A

All are virustatic

27
Q

What may antiviral treatment be used for?

A
  • Prophylaxis (Prevent infection)
  • Pre-emptive therapy (Before symptoms)
  • Overt disease
  • Suppressive therapy
28
Q

When would antivirals be used in herpes simplex?

A

Mucocutaneous: oral, genital, eye, skin Encephalitis Immunocompromised: any site

29
Q

When would antivirals be used in chickenpox?

A

in those at increased risk of complications…

  • neonate
  • immunocompromised
  • pregnant
  • immunocompetent adult…only if begun within 24 hours of onset of rash
30
Q

When would antivirals be used in shingles?

A

Decreases post-herpetic neuralgia in the immunocompetent host if begun within 72 hours of onset of symptoms

31
Q

What antivirals would be used in HSV and VZV?

A
  • Aciclovir (oral, IV, eye ointment, cream)
  • Valaciclovir (oral)
  • Famciclovir (oral)
  • Foscarnet (IV)
32
Q

Where does the Aciclovir Triphosphate derived from aciclovir have its mode of action?

A

Viral DNA polymerase

33
Q

When would antivirals be used to treat CMV?

A
  • Life or sight threatening CMV infections
  • HIV patients: CMV retinitis, coitis
  • Tranplant recipients: penumonitis
  • Also neonates with symptomatic congenital CMV infection
34
Q

What antivirals may be used to treat CMV infection?

A
  • Ganciclovir (IV, ocular implant)
  • Valganciclovir (oral)
  • Cidofovir (IV)
  • Foscarnet (IV)
35
Q

What antivirals may be used to treat chronic hepatits B infection?

A
  • Tenofovir
  • Adefovir
  • Entecavir
  • Lamivudine
  • Emtricitabine
  • Telbivudine
36
Q

What antivirals may be used to treat chronic hepatits C infection?

A

Currently…
Pegylated interferon alpha (subcut.) & ribavirin (oral)
As above, PLUS protease inhibitor (telaprevir or boceprevir)

New directly-acting antivirals, in combination
-Daclatasvir
-Sofosbuvir
-Simeprevir
Rapidly evolving field !
37
Q

What antivirals may be used in Influenza A or B?

A

Oseltamivir, zanamivir

Treatment and prophylaxis

38
Q

What antivirals may be used in Respiratory Syncytial Virus?

A

Ribavirin

39
Q

What method can be used for antibacterial sensitivity testing?

A

Etesting

40
Q

What are the four main mechanisms of antibacterial resistance?

A
  • Enzymatic inactivation
  • Modified targets for drugs
  • Reduced permeability to drug
  • Efflux of drug
41
Q

How can antibacterial resistance be acquired?

A
  • Chromosomal Mediated or

- Plasmid Mediated

42
Q

What does VRE stand for?

A

Vancomycin resistant enterococci

43
Q

What factors influence antibiotic resistance?

A

Widespread antibiotic use encouraging selective pressure (i.e surviving bacteria develop resistance)

Antibiotic use by medical professions, veterinary practices, farming

Patients surviving longer with more medical conditions and hospital contact

More invasive procedures and prosthetic devices eg dialysis patients

In UK increased bed pressure encourages spread of resistant organisms

44
Q

What is a type 1 hypersensitivity reaction to antibiotics?

A
  • IgE mediated specific immunoglobulin, stimulates pro-inflammatory release resulting in urticarial, laryngeal oedema, bronchospasm/circulatory collapse
  • Anaphylaxis occurs in 4 to 15 of every 100,000 penicillin treatment courses
45
Q

What is a type 2 hypersensitivity reaction to antibiotics?

A

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

46
Q

What is a type 3 hypersensitivity reaction to antibiotics?

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

47
Q

What is a type 4 hypersensitivity reaction to antibiotics?

A

Not antibody mediated but T-cell recognises antigen leading to localised inflammation eg contact dermatitis

48
Q

List some reasons for failure of antibiotic therapy, other than resistance

A
  • Inadequate dose of antibiotic
  • Inappropriate route
  • Non-compliance with antibiotic
  • Bacteria walled off in abscess cavity
  • Foreign bodies eg surgical implants/prosthesis
  • Poor penetration of drug to site of infection
49
Q

List some antibiotics with good biofilm activity

A
  • Rifampicin
  • Daptomycin
  • Ceftobiprole
50
Q

What percentage of patients give history of beta-lactam allergy?

A

5-20%

51
Q

What percentage of patients that give history of beta-lactam allergy will have Type 1 sensitivity?

A

Less than 1%

Infection (7 decks)

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