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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
Why are pseudomonas bacteria hard to treat?
They are gram negative rods
26
What type of drugs are ticarcillin and piperacillin?
Extended spectrum penicillins (β lactam Abx)
27
What type of drug is cephalexin?
Cephalosporin (β lactam Abx)
28
What type of drug is meropenem?
Carbapenem (β lactam Abx)
29
What are glycopeptides used for?
Serious Gram +VE which produce β-lactamases or not responding to other Abx.
30
Which drug is used to treat C Diff infection?
Vancomycin
31
What are the important side effects of glycopeptides?
Are nephrotoxic
32
What are the important side effects of Vancomycin?
Nephrotoxic Ototoxic Also narrow therapeutic window - dose by drug levels in blood
33
Which drug can be used to Rx resistant strains of MRSA?
Vancomycin
34
What type of bacteria are affected by vancomycin?
Gram positive
35
Which ribosomes do bacteria use for protein synthesis?
50S and 30S
36
Erythromycin Clarithromycin Azithromycin are all examples of what type of Abx?
Macrolides
37
Which bacteria are targeted by macrolides?
Gram +ves Gram -ves Cell wall deficient bacteria Are broad spectrum
38
Give an example of a cell wall deficient bacteria.
Chlamydia
39
How is vancomycin metabolised? How is it excreted?
It isn't. Excreted in the urine
40
How is clarithromycin metabolised? How is it excreted?
Hepatic Metabolites excreted in bileWh
41
What are the adverse effects of clarithromycin?
N&D Arrhythmias (alters cardiac conduction)
42
What is amoxicillin used for?
Sore throat & skin infection - S pyrogenes Respiratory tract - Pneumococcal UTI - Coliform infection
43
What illness is clarithromycin used for?
Similar to amoxicillin Sore throat & skin infection - S pyrogenes Resp tract - pneumococcus UTI - coliform Chlamydia
44
What type of drug is Gentamicin?
Aminoglycoside
45
How does Gentamicin have to be given?
Direct to the blood - is not active orally
46
What are the adverse effects of gentamicin?
Nephrotoxicity Ototoxicity
47
What type of drug is Doxycycline and Minocycline?
Tetracyclines
48
Are tetracyclines bactericidal or bacteriostatic?
Bacteriostatic
49
Are aminoglycosides bactericidal or bacteriostatic?
Bactericidal
50
What are the AEs are tetracyclines?
Phototoxicity Chelation of metal ions -> deposition in teeth Bone growth inhibition
51
What type of Abx are Ciprofloxacin, Nalidixic acid, Norfloxacin and Ofloxacin?
Quinolones
52
How do Quinolones work?
Inhibit DNA gyrases in bacteria - prevent DNA replication = rapid cell death
53
Which types of bacteria do Quinolones work on?
Lots - G+ve, G-ve, Mycoplasma, anaerobes, chlamydia.
54
What illnesses are Quinolones used for?
UTI Pseudomonal infection GI infections Prostatitis STDs
55
What are the adverse effects of Quinolones?
Lots of interactions with other meds Caution in children poss inc resistant bacteria
56
Are quinolones bacteriostatic or bacteriocidal?
Bacteriocidal
57
Is metronidazole bacteriostatic or bacteriocidal?
Bacteriocidal
58
How does metronidazole work?
Metabolites are toxic to DNA of bacteria
59
What are the AEs of metronidazole?
Potentially mutagenic Carcinogenic Teratogenic = use for 10 days only.
60
Is Rifampicin bacteriostatic or bacteriocidal?
Bacteriocidal
61
Which bacteria is rifampicin used for?
Mycobacteria - M. tuberculosis - M. leprae
62
How does Rifampicin work?
Binds to RNA polymerase - inhibits RNA synthesis
63
What do you need to remember about Rifampicin?
Strong inducer of CP450 - beware other drugs that can be affected. (esp contraceptive pill) Also - can turn saliva, tears and sweat orange.
64
Which Abx affect the bacterial cell wall?
β lactams Glycopeptides
65
Which Abx affect protein synthesis?
Macrolides Aminoglycosides Tetracyclines
66
Which Abx affect DNA replication?
Quinolones Metronidazole
67
Which Abx affects RNA synthesis?
Rifampicin
68
Which ABx are anti-metabolites?
Trimethoprim Sulphonamides
69
Are sulphonamides and trimethoprim bactericidal or bacteriostatic?
Bacteriostatic
70
How do sulphonamides and trimethoprim work?
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
What is the AE of trimethoprim?
May cause folate deficiency if given for a long time.
72
Which bacteria have resistance?
MRSA Vancomycin resistant enterococcus (VRE) Extended spectrum β lactase producing organisms (ESBL/AMPC) TB Acinetobacter
73
What affects the penetration by Abx into the CSF?
Lipid solubility Molecular weight Protein binding Susceptibility to transporters or efflux pumps
74
What are the RF for ABx resistant infections?
75
What is the organisational or healthcare system wide approach to promoting good use of antimicrobials to preserve their future effectiveness called?
Antimicrobial stewardship
76
In primary care - when should you prescribe Abx
If there is clear clinical benefit. Not for acute self-limiting URTIs. Avoid prescribing over phone Avoid broad-spectrum Abx
77
When should you prescribe Abx in secondary care?
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
When should you review Abx in secondary care?
You need to review the clinical diagnosis and whether Abx are needed to continue within 48 hours of the first dose
79
Which of the following are considered broad or narrow spectrum? β lactams glycopeptides macrolides aminoglycosides tetracyclines quinolones metronidazole rifampicin trimethoprim sulphonamides
Broad: β lactams macrolides aminoglycosides tetracyclines quinolones rifampicin Glycopeptides (Vanc) = narrow Metronidazole - primarily anaerobes Trimethoprim & sulphonamides = narrow -> broad
80
What are the most common causative pathogens of acute pyelonephritis?
Gram negative bacteria! E coli (60-80%) Klebsiella Proteus mirablis Psuedomonas Enterobacter
81
What patient factors may impact on Abx prescribing?
Immune system Renal and hepatic function Perfusion Age Pregnancy
82
Which is the first choice oral Abx for acute pyelonephritis?
Cefalexin Co-amox - if culture results available and shows susceptibility Ciprofloxacin
83
What is the first line IV Abx for acute pyelonephritis?
Co-amox (if culture results available and susceptible) Cefuroxime Ceftrixaone Gentamicin
84
Which is the first oral ABx if the patient is pregnant?
Cefalexin Cefuroxime
85
What type of Abx is Cefalexin?
Cyclosporin (β lactam)
86
What is the MOA of Cefalexin?
Inhibits bacterial cell wall synthesis
87
Which generation of cephalosporins in cefalexin?
First generation
88
Which bacteria is cefalexin effective against?
G+ve cocci - S. aureus - S. epidermidis - Strep. pneumoniae - Strep. pyrogens - Anaerobic streptococci G-ve rods - E. coli - Kliebsella pneumoniae - Proteus mirablis
89
What illnesses can Cefalexin be used for?
Acute pyelonephritis Lower UTI HAP Infections if susceptible - RTI, otitis media skin and bone infections
90
What are the AEs of Cephalexin?
Allergy Abdo pain Diarrhoea Leucopenia
91
What are the drug interactions to be wary of with Cephalexin?
Can be nephrotoxic with gentamicin, ibuprofen and celecoxib
92
Is Cefalexin harmful in breastfeeding or pregancy?
No
93
Which are the Abx of choice in breastfeeding women?
94
What are the most common causative bacteria of cellulitis?
Strep pyogenes (G+ve) Staph aureus (G+ve cocci) also Strep pneumoniae Haemophilus influenzae (both G -ve anaerobes)
95
What is the first choice ABx for cellulitis?
Flucloxacillin If allergy - Clarithromycin, Erythromycin. Doxycycline If MRSA resistant = Vancomycin
96
If flucloxacillin broad or narrow spectrum?
Broad
97
What illnesses is fluclox used for?
Sore throat & skin - S. pyogenes Resp tract - pneumococcus UTI - Coliform
98
What is the MOA of Fluclox?
Inhibits bacterial cell wall synthesis
99
What are the AEs of Fluclox?
Allergy Diarrhoea Skin reactions GI disturbance Opportunistic infections - Candida albicans
100
What interactions can Fluclox have?
Can inc levels of other protein bound drugs
101
In ribosome subunits - which subunit does Chloramphenicol and Macrolides bind to? Which do tetracyclines bind to?
Chloramphenicol and macrolide - bind to 50S Tetracyclines - bind to 30S
102
When is Vancoymycin given by oral route? Why?
Given by oral route for Rx of C Diff - Not otherwise given orally as not absorbed
103
What interactions does clarithromycin have?
Inhibits the P450 enzyme system
104
What are the indications for use of Clarithromycin?
Cellulitis Mild diabetic foot infection CAP HAP H-Pylori eradication
105
Is Chloramphenicol broad or narrow spectrum?
Broad spectrum
106
Is chloramphenicol bacteriostatic or bacteriacidal?
Bacteriostatic mostly Does kill H influenzae
107
What is the MOA of Chloramphenicol?
Inhibits protein synthesis - binds to 50S subunit.
108
What are the adverse effects of chloramphenicol?
Pancytopenia Gray baby syndrome (mort 40%) - beware use in newborms
109
What interactions does chloramphenicol have?
Inhibits CYP3A4 and CYP2C19 preventing metabolism of certain drugs
110
What organisms is Doxycycline effective against?
Broad spectrum - G+ve - G-ve Protozoa Mycobacteria
111
What is the MOA of Doxycycline?
Binds to 30S ribosome subunit - this inhibits protein synthesis.
112
What interactions can Doxycycline have?
Competes for protein binding Can enhance the anticoagulant effect of warfarin - likely due to competitive interaction for albumin binding.
113
Why is gentamicin given as IV?
Is not absorbed from the gut
114
Is Gentamicin broad or narrow spectrum?
Broad spectrum - however inactive against anaerobes. Poor against haemolytic strep & pneumococci.
115
What is the MOA of Gentamicin?
Binds to the 30S ribosome and inhibits protein synthesis
116
117
118
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
119
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
120
Which atypicals is Ciprofloxacin active against?
Chlamydia Legionella Mycoplasma
121
What interactions does Ciprofloxacin have?
Prolongs QT interval Inhibits CYP1A2 and poss CYP3A4 metabolism Avoid with dairy products
122
What is the MOA of Ciprofloxacin?
Inhibits DNA gyrases - prevents bacterial DNA replication. Rapid cell death.
123
What are the AEs of Ciprofloxacin?
N&V Headache & dizziness Tendinitis, tendon rupture Peripheral neuropathy CNS - hallucination, anxiety, insomnia, confusion and seizures Phototoxicity
124

MLA - Pharmacology Revision (17 decks)

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