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MLA - Pharmacology Revision > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

What should you think about before initiating antimicrobials?

A
  • Allergies
  • Route
  • Is the antimicrobial going to reach the infection site?\
  • Renal impairment
  • Hepatic impairment
  • Pregnancy or breast feeding?
  • Immunocompromised?
  • MRSA carrier?
  • Duration?
  • Drug interactions
  • Community or hospital acquired infection
    Does P have a collection that can be drained?
    Recent travel Hx
    Contact with pets or other animals
    Could work be a source of infection?
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2
Q

What does NKDA stand for on a drug chart?

A

No known drug allergies

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3
Q

Which organisms are commonly implicated in CAP?

A

Strep pneumoniae
Haemophilius influenza
Klebsiella pneumoniae
S. aureus
Atypicals
Virus (13%)

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4
Q

What clinical investigations would you carry out for CAP?

A

CXR
Serum and urine cultures = for pneumococcal and legionella testing
Sputum sample
Throat swap for viral culture if thinking influence virus

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5
Q

What score is an indicate for the severity of pneumonia?

A

CURB-65
C - Confusion
U - Urea (>7mmol)
R - RR (>30)
B - BP <90 S or <60 D
65 YO

+1 for each of these

0-1 = low risk
2 = intermediate risk
3-5 = high risk (mort >15%)

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6
Q

What is the calculation for ideal body weight?

A

IBW Men = 50kg + (2.3 x every inch over 5ft)
IBW Female = 45.5kg + (2.3 x every inch over 5ft)

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7
Q

How many inches are in a foot?

A

12 inches

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8
Q

When do we use corrected body weight?

A

If the actual body weight is greater than 20% of the ideal body weight

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9
Q

What is the calculation for corrected body weight?

A

CBW = IBW + (0.4 x Extra Body Weight)

Extra Body Weight = Actual Body Weight - Ideal Body Weight

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10
Q

How do we work out Extra Body Weight?

A

Extra Body Weight = Actual Body Weight - Ideal Body Weight

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11
Q

82yo M, 5ft 3in, 94 kg

Calculate

Ideal Body Weight
Extra Body Weight
Corrected Body Weight

A

Ideal Body Weight = 50kg + (2.3 x 3) = 56.9kg

Extra Body Weight = 94kg - 56.9kg = 37.1kg

Corrected Body Weight = 71.74kg

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12
Q

What is the calculation for renal function with creatinine clearance?

A

Men CrCl = (1.23 x (140-age) x IBW ) / Serum Creatinine

Women CrCl = (1.04 x (140-age) x IBW) / Serum Creatinine

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13
Q

What are the risks of gentamicin?

A

Ototoxicity
Nephrotoxicity

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14
Q

What are the two broad types of antibiotics?

A

Bacteriostatic
Bacteriocidal

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15
Q

What type of antibiotic should immunocompromised Ps always have?

A

Bacteriacidal

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16
Q

Why are mycobacteria different to other bacteria?

A

Mycobacteria are a group of bacteria belonging to the genus Mycobacterium. They are characterized by their unique cell wall structure, which contains a high lipid content, particularly mycolic acids. This distinctive cell wall structure gives mycobacteria several unique properties, including resistance to many antibiotics and disinfectants, as well as the ability to survive for long periods in the environment.

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17
Q

What are the four classes of bacteria?

A

Gram +ve
Gram -ve
Anaerobes
Atypicals

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18
Q

How do β lactams work?

A

They prevent cross-linking of peptides in the cell wall of the bacteria -> cell lysis

Uses a β lactam ring to do this.

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19
Q

Which types of ABs are β lactams?

A

Penicillins
Cyclosporins
Carbapenems
Monobactems

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20
Q

How do bacteria start to resist β lactams? How was this overcome?

A

The bacteria developed enzymes which caused hydrolysis of the β lactam ring.

Was overcome by adding clauvanic acid - very similar to the β lactam ring and the enzyme binds to it irreversibly

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21
Q

If a P has an allergy to a β lactam - which group of Abx can be used instead?

A

Macrolides

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22
Q

Which penicillin is resistant to β lactamases?

A

Flucloxacillin
Temocillin

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23
Q

Which is the most broad spectrum penicillin?

A

Amoxicillin
Ampicillin

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24
Q

Which penicillin can be used for pseudmonal infections?

A

Piperacillin
Ticarcillin

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25
Q

Why are pseudomonas bacteria hard to treat?

A

They are gram negative rods

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26
Q

What type of drugs are ticarcillin and piperacillin?

A

Extended spectrum penicillins (β lactam Abx)

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27
Q

What type of drug is cephalexin?

A

Cephalosporin (β lactam Abx)

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28
Q

What type of drug is meropenem?

A

Carbapenem (β lactam Abx)

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29
Q

What are glycopeptides used for?

A

Serious Gram +VE which produce β-lactamases or not responding to other Abx.

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30
Q

Which drug is used to treat C Diff infection?

A

Vancomycin

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31
Q

What are the important side effects of glycopeptides?

A

Are nephrotoxic

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32
Q

What are the important side effects of Vancomycin?

A

Nephrotoxic
Ototoxic

Also narrow therapeutic window - dose by drug levels in blood

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33
Q

Which drug can be used to Rx resistant strains of MRSA?

A

Vancomycin

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34
Q

What type of bacteria are affected by vancomycin?

A

Gram positive

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35
Q

Which ribosomes do bacteria use for protein synthesis?

A

50S and 30S

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36
Q

Erythromycin
Clarithromycin
Azithromycin

are all examples of what type of Abx?

A

Macrolides

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37
Q

Which bacteria are targeted by macrolides?

A

Gram +ves
Gram -ves
Cell wall deficient bacteria

Are broad spectrum

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38
Q

Give an example of a cell wall deficient bacteria.

A

Chlamydia

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39
Q

How is vancomycin metabolised?
How is it excreted?

A

It isn’t.
Excreted in the urine

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40
Q

How is clarithromycin metabolised?
How is it excreted?

A

Hepatic
Metabolites excreted in bileWh

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41
Q

What are the adverse effects of clarithromycin?

A

N&D
Arrhythmias (alters cardiac conduction)

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42
Q

What is amoxicillin used for?

A

Sore throat & skin infection - S pyrogenes
Respiratory tract - Pneumococcal
UTI - Coliform infection

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43
Q

What illness is clarithromycin used for?

A

Similar to amoxicillin

Sore throat & skin infection - S pyrogenes
Resp tract - pneumococcus
UTI - coliform
Chlamydia

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44
Q

What type of drug is Gentamicin?

A

Aminoglycoside

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45
Q

How does Gentamicin have to be given?

A

Direct to the blood - is not active orally

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46
Q

What are the adverse effects of gentamicin?

A

Nephrotoxicity
Ototoxicity

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47
Q

What type of drug is Doxycycline and Minocycline?

A

Tetracyclines

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48
Q

Are tetracyclines bactericidal or bacteriostatic?

A

Bacteriostatic

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49
Q

Are aminoglycosides bactericidal or bacteriostatic?

A

Bactericidal

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50
Q

What are the AEs are tetracyclines?

A

Phototoxicity
Chelation of metal ions -> deposition in teeth
Bone growth inhibition

51
Q

What type of Abx are Ciprofloxacin, Nalidixic acid, Norfloxacin and Ofloxacin?

A

Quinolones

52
Q

How do Quinolones work?

A

Inhibit DNA gyrases in bacteria - prevent DNA replication = rapid cell death

53
Q

Which types of bacteria do Quinolones work on?

A

Lots - G+ve, G-ve, Mycoplasma, anaerobes, chlamydia.

54
Q

What illnesses are Quinolones used for?

A

UTI
Pseudomonal infection
GI infections
Prostatitis
STDs

55
Q

What are the adverse effects of Quinolones?

A

Lots of interactions with other meds
Caution in children
poss inc resistant bacteria

56
Q

Are quinolones bacteriostatic or bacteriocidal?

A

Bacteriocidal

57
Q

Is metronidazole bacteriostatic or bacteriocidal?

A

Bacteriocidal

58
Q

How does metronidazole work?

A

Metabolites are toxic to DNA of bacteria

59
Q

What are the AEs of metronidazole?

A

Potentially mutagenic
Carcinogenic
Teratogenic
= use for 10 days only.

60
Q

Is Rifampicin bacteriostatic or bacteriocidal?

A

Bacteriocidal

61
Q

Which bacteria is rifampicin used for?

A

Mycobacteria
- M. tuberculosis
- M. leprae

62
Q

How does Rifampicin work?

A

Binds to RNA polymerase - inhibits RNA synthesis

63
Q

What do you need to remember about Rifampicin?

A

Strong inducer of CP450 - beware other drugs that can be affected. (esp contraceptive pill)

Also - can turn saliva, tears and sweat orange.

64
Q

Which Abx affect the bacterial cell wall?

A

β lactams
Glycopeptides

65
Q

Which Abx affect protein synthesis?

A

Macrolides
Aminoglycosides
Tetracyclines

66
Q

Which Abx affect DNA replication?

A

Quinolones
Metronidazole

67
Q

Which Abx affects RNA synthesis?

A

Rifampicin

68
Q

Which ABx are anti-metabolites?

A

Trimethoprim
Sulphonamides

69
Q

Are sulphonamides and trimethoprim bactericidal or bacteriostatic?

A

Bacteriostatic

70
Q

How do sulphonamides and trimethoprim work?

A

They are chemically similar to bacterial metabolites and interfere with normal metabolic pathways - inhibit synthesis of purines, prevent tetrahydrofolate being made = no production of RNA.

71
Q

What is the AE of trimethoprim?

A

May cause folate deficiency if given for a long time.

72
Q

Which bacteria have resistance?

A

MRSA
Vancomycin resistant enterococcus (VRE)
Extended spectrum β lactase producing organisms (ESBL/AMPC)
TB
Acinetobacter

73
Q

What affects the penetration by Abx into the CSF?

A

Lipid solubility
Molecular weight
Protein binding
Susceptibility to transporters or efflux pumps

74
Q

What are the RF for ABx resistant infections?

A
75
Q

What is the organisational or healthcare system wide approach to promoting good use of antimicrobials to preserve their future effectiveness called?

A

Antimicrobial stewardship

76
Q

In primary care - when should you prescribe Abx

A

If there is clear clinical benefit.

Not for acute self-limiting URTIs.

Avoid prescribing over phone

Avoid broad-spectrum Abx

77
Q

When should you prescribe Abx in secondary care?

A

No evidence of infection clinically = NO ABX

Use guidelines, obtain cultures

Can give single dose prophylaxis if ABx have been shown to be effective.

78
Q

When should you review Abx in secondary care?

A

You need to review the clinical diagnosis and whether Abx are needed to continue within 48 hours of the first dose

79
Q

Which of the following are considered broad or narrow spectrum?

β lactams
glycopeptides
macrolides
aminoglycosides
tetracyclines
quinolones
metronidazole
rifampicin
trimethoprim
sulphonamides

A

Broad:
β lactams
macrolides
aminoglycosides
tetracyclines
quinolones
rifampicin

Glycopeptides (Vanc) = narrow
Metronidazole - primarily anaerobes
Trimethoprim & sulphonamides = narrow -> broad

80
Q

What are the most common causative pathogens of acute pyelonephritis?

A

Gram negative bacteria!

E coli (60-80%)
Klebsiella
Proteus mirablis
Psuedomonas
Enterobacter

81
Q

What patient factors may impact on Abx prescribing?

A

Immune system
Renal and hepatic function
Perfusion
Age
Pregnancy

82
Q

Which is the first choice oral Abx for acute pyelonephritis?

A

Cefalexin
Co-amox - if culture results available and shows susceptibility
Ciprofloxacin

83
Q

What is the first line IV Abx for acute pyelonephritis?

A

Co-amox (if culture results available and susceptible)
Cefuroxime
Ceftrixaone
Gentamicin

84
Q

Which is the first oral ABx if the patient is pregnant?

A

Cefalexin
Cefuroxime

85
Q

What type of Abx is Cefalexin?

A

Cyclosporin (β lactam)

86
Q

What is the MOA of Cefalexin?

A

Inhibits bacterial cell wall synthesis

87
Q

Which generation of cephalosporins in cefalexin?

A

First generation

88
Q

Which bacteria is cefalexin effective against?

A

G+ve cocci
- S. aureus
- S. epidermidis
- Strep. pneumoniae
- Strep. pyrogens
- Anaerobic streptococci

G-ve rods
- E. coli
- Kliebsella pneumoniae
- Proteus mirablis

89
Q

What illnesses can Cefalexin be used for?

A

Acute pyelonephritis
Lower UTI
HAP
Infections if susceptible - RTI, otitis media skin and bone infections

90
Q

What are the AEs of Cephalexin?

A

Allergy
Abdo pain
Diarrhoea
Leucopenia

91
Q

What are the drug interactions to be wary of with Cephalexin?

A

Can be nephrotoxic with gentamicin, ibuprofen and celecoxib

92
Q

Is Cefalexin harmful in breastfeeding or pregancy?

A

No

93
Q

Which are the Abx of choice in breastfeeding women?

A
94
Q

What are the most common causative bacteria of cellulitis?

A

Strep pyogenes (G+ve)
Staph aureus (G+ve cocci)

also
Strep pneumoniae
Haemophilus influenzae
(both G -ve anaerobes)

95
Q

What is the first choice ABx for cellulitis?

A

Flucloxacillin
If allergy - Clarithromycin, Erythromycin. Doxycycline

If MRSA resistant = Vancomycin

96
Q

If flucloxacillin broad or narrow spectrum?

A

Broad

97
Q

What illnesses is fluclox used for?

A

Sore throat & skin - S. pyogenes
Resp tract - pneumococcus
UTI - Coliform

98
Q

What is the MOA of Fluclox?

A

Inhibits bacterial cell wall synthesis

99
Q

What are the AEs of Fluclox?

A

Allergy
Diarrhoea
Skin reactions
GI disturbance
Opportunistic infections - Candida albicans

100
Q

What interactions can Fluclox have?

A

Can inc levels of other protein bound drugs

101
Q

In ribosome subunits - which subunit does Chloramphenicol and Macrolides bind to?

Which do tetracyclines bind to?

A

Chloramphenicol and macrolide - bind to 50S

Tetracyclines - bind to 30S

102
Q

When is Vancoymycin given by oral route? Why?

A

Given by oral route for Rx of C Diff

  • Not otherwise given orally as not absorbed
103
Q

What interactions does clarithromycin have?

A

Inhibits the P450 enzyme system

104
Q

What are the indications for use of Clarithromycin?

A

Cellulitis
Mild diabetic foot infection
CAP
HAP
H-Pylori eradication

105
Q

Is Chloramphenicol broad or narrow spectrum?

A

Broad spectrum

106
Q

Is chloramphenicol bacteriostatic or bacteriacidal?

A

Bacteriostatic mostly
Does kill H influenzae

107
Q

What is the MOA of Chloramphenicol?

A

Inhibits protein synthesis - binds to 50S subunit.

108
Q

What are the adverse effects of chloramphenicol?

A

Pancytopenia

Gray baby syndrome (mort 40%) - beware use in newborms

109
Q

What interactions does chloramphenicol have?

A

Inhibits CYP3A4 and CYP2C19 preventing metabolism of certain drugs

110
Q

What organisms is Doxycycline effective against?

A

Broad spectrum
- G+ve
- G-ve
Protozoa
Mycobacteria

111
Q

What is the MOA of Doxycycline?

A

Binds to 30S ribosome subunit - this inhibits protein synthesis.

112
Q

What interactions can Doxycycline have?

A

Competes for protein binding

Can enhance the anticoagulant effect of warfarin - likely due to competitive interaction for albumin binding.

113
Q

Why is gentamicin given as IV?

A

Is not absorbed from the gut

114
Q

Is Gentamicin broad or narrow spectrum?

A

Broad spectrum - however inactive against anaerobes.

Poor against haemolytic strep & pneumococci.

115
Q

What is the MOA of Gentamicin?

A

Binds to the 30S ribosome and inhibits protein synthesis

116
Q
A
117
Q
A
118
Q

Which of the following ABx should not be given to children less than 8 due to its deposition in bone and teeth?
A - Clarithromycin
B - Doxycycline
C - Vancomycin
D - Amoxicillin

A
119
Q

A 26 yo marathon runner reports to the clinic with acute Achilles tendon rupture. They recently took an Abx. Which of the following may have contributed to tendon rupture?
- Co-Amox
- Cefalexin
- Ciprofloxacin
- Minocycline

A
120
Q

Which atypicals is Ciprofloxacin active against?

A

Chlamydia
Legionella
Mycoplasma

121
Q

What interactions does Ciprofloxacin have?

A

Prolongs QT interval

Inhibits CYP1A2 and poss CYP3A4 metabolism

Avoid with dairy products

122
Q

What is the MOA of Ciprofloxacin?

A

Inhibits DNA gyrases - prevents bacterial DNA replication. Rapid cell death.

123
Q

What are the AEs of Ciprofloxacin?

A

N&V
Headache & dizziness
Tendinitis, tendon rupture
Peripheral neuropathy
CNS - hallucination, anxiety, insomnia, confusion and seizures
Phototoxicity

124
Q
A

MLA - Pharmacology Revision (17 decks)

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