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Anaesthetic FRCA Primary - eLFH Pharmacology > eLFH - Antimicrobial agents > Flashcards

eLFH - Antimicrobial agents Flashcards

(115 cards)

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1
Q

Classification of bacteria

A

Gram stain

Morphology (shape)

Relationship with oxygen (aerobes or anaerobes)

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2
Q

Gram positive bacteria features and appearance

A

Retain crystal violet stain in their thicker outer peptidoglycan cell wall

Appear blue / violet

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3
Q

Gram negative bacteria features and appearance

A

Do not have outer peptidoglycan wall so thinner cell wall

Therefore don’t stain with crystal violet

Instead stain with safarin red counter stain and appear red / pink

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4
Q

Bacterial morphology classification

A

Cocci - spheres

Bacilli - rods

Spirilla - spirals

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5
Q

Gram positive bacteria tree

A
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6
Q

Gram negative bacteria tree

A
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7
Q

Bacteria responsible for Diphtheria

A

Corynebacterium

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8
Q

Aerobic bacteria definition

A

Use O2 for metabolism

Obligate anaerobes can only survive if O2 present

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9
Q

Anaerobic bacteria definition

A

Metabolise in absence of O2

Obligate anaerobes cannot survive in presence of O2
(lack enzymes to detoxify O2)

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10
Q

Facultative anaerobic bacteria definition

A

Can survive with or without O2

If given choice, prefer O2 as more efficient metabolism

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11
Q

Obligate anaerobic bacteria examples

A

Bacteroides

Clostridium

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12
Q

Three mechanisms of action of antibacterials

A

Actions on cell wall synthesis

Inhibition of protein synthesis

Inhibition of nucleic acid synthesis

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13
Q

Actions on cell wall synthesis mechanisms

A

Cell wall synthesis inhibitors

Cell wall integrity inhibitors

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14
Q

Cell wall synthesis inhibitor examples

A

Glycopeptides

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15
Q

Cell wall integrity inhibitor examples

A

Beta lactams

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16
Q

Inhibition of protein synthesis mechanisms

A

Ribosome 50s subunit inhibitors

Ribosome 30s subunit inhibitors

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17
Q

Ribosome 50s subunit inhibitor examples

A

Macrolides

Lincosamides

Chloramphenicol

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18
Q

Ribosome 30s subunit inhibitor examples

A

Tetracyclines

Aminoglycosides

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19
Q

Inhibition of nucleic acid synthesis mechanisms

A

DNA synthesis inhibitor

DNA gyrase inhibitor

DNA dependent RNA polymerase inhibitor

Folic acid metabolism inhibitor

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20
Q

DNA synthesis inhibitor examples

A

Nitroimidazoles

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21
Q

DNA gyrase inhibitor examples

A

Quinolones

Aka Fluoroquinolones

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22
Q

DNA dependent RNA polymerase inhibitor examples

A

Rifampicin

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23
Q

Folic acid metabolism inhibitor examples

A

Diaminopyrimidines (e.g. trimethoprim)

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24
Q

Mechanism by which beta lactams reduce cell wall integrity

A

Inhibit enzymes which cross link the peptidoglycan chains of the cell wall

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25
Beta lactam abx examples
Penicillins Cephalosporins Carbapenems Monobactems
26
Mechanism by which glycopeptides inhibit cell wall synthesis
Bind to terminal residues of growing peptidoglycan chains - prevents formation of cross links
27
Glycopeptide abx examples
Vancomycin Teicoplanin
28
Which abx classes are bacteriostatic rather than bactericidal
All abx which inhibit protein synthesis Trimethoprim
29
Macrolides specific mechanism of action
Bind to 50s ribosome subunit and inhibits peptide chain translocation
30
Macrolide abx examples
Erythromycin Clarithromycin Azithromycin
31
Lincosamide specific mechanism of action
Disrupts 50s subunit to inhibit protein synthesis
32
Lincosamide abx examples
Clindamycin
33
Chloramphenicol specific mechanism of action
Inhibits peptidyl transferase activity of 50s subunit
34
Tetracycline specific mechanism of action
Binds to 30s subunit Inhibits binding of aminoacyl-tRNA
35
Tetracycline abx examples
Doxycycline Lymecycline
36
Aminoglycoside specific mechanism of action
Binds to 30s subunit Causes misreading of mRNA
37
Aminoglycoside abx examples
Gentamicin Amikacin Neomycin Streptomycin
38
Diaminopyrimidines specific mechanism of action
Inhibitor of dihydrofolate reductase Needed for purine / pyrimidine synthesis
39
Diaminopyrimidine abx examples
Trimethoprim
40
Quinolones specific mechanism of action
Inhibits DNA gyrase This enzyme usually compresses DNA into super coils
41
Quinolone abx examples
Ciprofloxacin Levofloxacin
42
Nitroimidazoles specific mechanism of action
Inhibits and damages DNA synthesis Exact mechanism is unclear
43
Nitroimidazole abx examples
Metronidazole
44
Rifampicin specific mechanism of action
Inhibits DNA dependent RNA polymerase Prevents RNA transcription
45
Only clinical situation where choice of a bactericidal abx should be used rather than bacteriostatic abx
Immunocompromised patient Otherwise bacteriostatic vs bactericidal is irrelevant clinically
46
Categories of penicillin abx
Narrow spectrum Broad spectrum Antipseudomonal Beta lactamase resistant
47
Narrow spectrum penicillin examples
Benzylpenicillin Flucloxacillin
48
Broad spectrum penicillin examples
Amoxicillin Piperacillin Ampicillin
49
Antipseudomonal penicillin examples
Piperacillin (hence use of Tazocin) Ticarcillin
50
Beta lactamase resistant penicillin examples
Flucloxacillin
51
Features of narrow spectrum penicillins
Little Gram negative activity Gram negative bacteria have outer phospholipid membrane hindering access of penicillins to cell wall beneath
52
Features of broad spectrum penicillins
Hydrophobic - pass through phospholipid membrane pores Therefore have more Gram negative activity More inactivated by beta lactamases Overcome this by combining broad spectrum penicillin with beta lactamase inhibitor
53
Beta lactamase inhibitor examples
Clavulanic acid Tazobactam
54
Features of antipseudomonal penicillins
Particularly broad spectrum - gram negative, gram positive, anaerobes Beta lactamase sensitive Therefore presented with beta lactamase inhibitor
55
Organisms which commonly produce penicillinase (a beta lactamase)
Staphylococci Hence flucloxacillin use as it is penicillinase resistant
56
MRSA mechanism of resistance
Increased resistance via changes in its penicillin binding proteins Therefore different class of antibiotic needed
57
Penicillin pharmacokinetics
Short half life Renal excretion Good tissue penetration but meninges must be inflamed to cross blood brain barrier
58
Side effects of penicillins
Encephalopathy Diarrhoea Low toxicity
59
Cephalosporin features compared to penicillins
Similar structure to penicillins but broader spectrum Beta lactam ring is less susceptible to beta lactamases
60
Cephalosporin pharmacokinetics
Most excreted unchanged in urine Exceptions of Cefotaxime and Ceftriaxone
61
Cefotaxime pharmacokinetics
50% metabolised in the liver
62
Ceftriaxone pharmacokinetics
Highly protein bound (95%) Long half life so given once daily
63
Cephalosporin indications
Pneumonia Septicaemia Meningitis Surgical prophylaxis
64
Cephalosporin classification and relevance
First generation Second generation Third generation With each successive generation, gram positive cover maintained while gram negative cover increases
65
First generation cephalosporin examples
Cefradine
66
First generation cephalosporin uses
Surgical prophylaxis with gram positive organisms E.g. orthopaedic
67
Second generation cephalosporin examples
Cefuroxime
68
Second generation cephalosporin uses
More stable beta lactam ring and more gran negative cover Prophylaxis in bowel surgery but lacks sufficient anaerobic cover so metronidazole often added
69
Third generation cephalosporin examples
Cefotaxime Ceftriaxone Ceftazidime
70
Disadvantages of third generation cephalosporins
Highly broad spectrum which can encourage superinfection
71
Carbapenem abx examples
Meropenem Imipenem
72
Carbapenem spectrum
Covers gram positive, gram negative, aerobic and anaerobic bacteria Highly beta lactamase resistant
73
Organisms against which carbapenems are ineffective
MRSA E faecalis Some pseudomonas strains
74
Carbapenem pharmacokinetics
Excreted unchanged in kidneys Imipenem is combined with cilastatin to prevent renal metabolism and increase plasma concentration
75
Potential side effect of carbapenems
Can cause convulsions (Imipenem more than Meropenem)
76
Monobactam abx example
Aztreonam This is the only available monobactam
77
Monobactam coverage
Spectrum limited to Gram negative aerobic bacteria
78
Glycopeptide spectrum
Broad Gram positive spectrum Limited Gram negative cover as large polar molecules unable to penetrate outer lipid layer of these bacteria
79
Glycopeptide indications
MRSA Endocarditis
80
Teicoplanin features compared to Vancomycin
Teicoplanin is: More potent with longer duration of action (OD dosing) Better tissue penetration Better tolerated Demonstrates more resistance
81
Glycopeptide pharmacokinetics
Elimination unchanged in urine Minimal systemic absorption absorption from healthy gut
82
Side effects of glycopeptides
Reversible toxicity is common so plasma level monitoring needed: Nephrotoxicity Ototoxicity Thrombocytopenia Neutropenia Red man syndrome with Vancomycin
83
Red man syndrome
Risk with Vancomycin use so must be given slowly IV Caused by phlebitis and histamine release
84
Macrolide spectrum
Similar spectrum to penicillin but broader spectrum (Hence their use in penicillin allergy) Cover Gram positive, Mycoplasma and Legionella
85
Azithromycin use and why
Increased Gram negative cover and longer half life Therefore single dose will treat chlamydial urethritis
86
Macrolide pharmacokinetics
Metabolised and excreted mainly by liver Generally well tolerated
87
Macrolide side effects
Potent cP450 inhibitor - multiple interactions GI upset / Prokinetic Prolong QT interval
88
Aminoglycoside spectrum
Gram negative including pseudomonas Some Gram positive activity
89
Aminoglycoside indications
First line for Gram negative infections Urological surgery prophylaxis - Gram negative organisms predominate
90
Why aminoglycosides work synergistically with penicillins and glycopeptides
Aminoglycosides are large polar molecules that require active transport into the cell Penicillins and glycopeptides break down cell wall allowing the aminoglycosides better cellular access
91
Aminoglycoside pharmacokinetics
Renal excretion Low lipid solubility so IV administration Narrow therapeutic range
92
Side effects of Aminoglycosides
Reversible toxicity to kidneys Permanent toxicity to cranial nerve VIII Prolongs non-depolarising neuromuscular blocker effects
93
How do aminoglycosides prolong effects of non-depolarising neuromuscular blockers
Aminoglycosides impair neuromuscular transmission by decreasing prejunctional release and reducing junctional sensitivity to ACh
94
Quinolone spectrum
Broad Mainly towards gram negatives but some Gram positive cover Levofloxacin has increased pneumococcal cover
95
Quinolone pharmacokinetics
Good oral absorption Widely distributed with excellent CNS penetration Excreted unchanged in urine and faeces
96
Side effects of Quinolones
Risk of C diff / MRSA colonisation Prolonged QT interval Lowers seizure threshold via GABA antagonism GI upset Inhibits cP450
97
Nitroimidazole spectrum
Anaerobes (Bacteroides, gut flora, Clostridia) Protozoa
98
Nitroimidazole pharmacokinetics
Excreted unchanged in urine Distributes widely in CSF, cerebral abscesses, prostate and pleural fluid Well tolerated generally
99
Side effects of Nitroimidazoles
Rash Pancreatitis Peripheral neuropathy
100
Side effects of nitroimidazoles when combined with alcohol
Flushing Hypotension
101
Differences between bacterial cells vs human cells
Single celled organisms Cell walls No nucleus - just loop of DNA in middle Replicate by dividing
102
Why do abx affecting ribosomes not affect human cells
Human ribosomes have different sized subunits
103
Definition of antibiotics
Pharmacological agents which target bacteria without damaging mammalian host cells Act by either killing bacteria of preventing replication which relies on host immune system
104
Minimum inhibitory concentration
Minimum concentration required to prevent ongoing growth of bacteria If peak antibiotic levels fall below this concentration then bacteria will start to grow again
105
Virus definition
Segment of DNA or RNA code surrounded by protein Target host cells infecting them and promoting replication
106
Aciclovir mechanism of action
Inhibits nucleic acid synthesis Only affects infected cells
107
Main subgroups of fungi
Moulds - e.g. aspergillus Yeasts - e.g. candida
108
3 major sub-classes of antifungals
Azoles Polyenes Echinocandins
109
Ergosterol
Predominant component of fungal cell membrane and main target of antifungals
110
Examples of Azoles
Fluconazole Voriconazole Ketoconazole
111
Examples of Polyenes
Amphotericin B Nystatin
112
Examples of Echinocandins
Caspofungin Micafungin
113
Azoles mechanism of action
Inhibit Lanosterol 14 alpha-demethylase enzyme Prevents conversion of Lanosterol to Ergosterol
114
Polyenes mechanism of action
Binds to ergosterol in fungal cell membrane - creates pores disrupting electrochemical gradient and leads to fungal cell death
115
Echinocandins mechanism of action
Inhibit B-1,3-glucan synthase Inhibits B-1,3-glucan synthesis with is required for fungal cell wall integrity

Anaesthetic FRCA Primary - eLFH Pharmacology (11 decks)

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