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Microbiology 1 Flashcards

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1
Q

What infections are associated with broad antibiotic spectrum use?

A

Candida

C.diff

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2
Q

What antibiotic has activity against gram positive and gram negative bacteria?

A

Meropenem

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3
Q

What does Benzyl-penicillin have activity against?

A

Streptococci

Neisseria

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4
Q

What are the three different types of antibiotic therapy?

A

Guided therapy
Empirical therapy
Prophylactic therapy

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5
Q

Beta-lactam antibiotics can be separated into four groups. What are they?

A
  1. Penicillin
  2. Cephalosporins
  3. Carbapenems
  4. Monobactams
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6
Q

Give three examples of penicillins

A
  1. Benzylpenicillin
  2. Flucloxacillin
  3. Amoxicillin
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7
Q

Give an example of a cephalosporin antibiotic

A

Ceftriaxone

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8
Q

Give an example of a cabapenem antibiotic

A

Meropenem

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9
Q

Give an example of a monobactem antibiotic

A

Aztreonam

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10
Q

What makes up Augmentin?

A

Amoxicillin + clavulanic acid

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11
Q

What makes up Tazocin?

A

Piperacillin + tazobactam

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12
Q

What is the MoA of beta-lactam antibiotics?

A

inhibit cross-linking of the cell wall peptidoglycan
Causes lysis of the bacteria
Bactericidal

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13
Q

Describe beta-lactamases

A

Enzymes that lyse and inactivate the beta-lactam drugs by lysis of the beta-lactam ring

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14
Q

What bacteria commonly secrete beta-lactamases?

A

Gram negatives

S.aureus

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15
Q

How are beta-lactam antibiotics excreted?

A

Unchanged in urine and bile

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16
Q

Why do beta-lactam antibiotics often need to be given IV?

A

Poorly absorbed via GI tract

Can cause vomiting which limits dose

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17
Q

What GI toxicity is associated with beta-lactam antibiotics?

A

Nausea and vomiting
Diarrhoea
Cholestasis - abnormal LFTs

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18
Q

What hypersensitivity reactions can occur following beta-lactam antibiotic use?

A

Stage 1 - urticaria, anaphylaxis

Stage 4 - Stephen-Johnson syndrome and toxic epidermal necrolysis

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19
Q

What infections are associated with beta-lactam antibiotic use?

A

Candidiasis - oral, vulvovaginal

C.diff

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20
Q

What are rare reactions associated with beta-lactam antibiotics?

A

Seizures
Haemolysis
Leukopenia

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21
Q

What is the first choice Abx for a serious streptococci infection such as erysipelas?

A

Benzylpenicillin

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22
Q

How should Benzylpenicillin be administered?

A

IV

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23
Q

What does amoxicillin have activity against?

A

Gram negative bacteria (streptococcus, enterococcus, Neisseria, haemophilus, clostidium)

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24
Q

What does flucloxacillin have activity against?

A 
Staphylococcus aureus (not MRSA)
Streptococci
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25
Beta-lactamase inhibitors greatly broaden the activity of penicillins against which bacteria?
Gram negative | S.aureus
26
What bacteria do Cephalosporins have good activity against?
Gram positive | Gram negative
27
When is Ceftriaxone prescribed?
Bacterial meningitis
28
What type of beta-lactam antibiotics can be given to patients with a penicillin allergy?
Monobactems
29
How should monobactem antibiotics be administered?
IV - no oral absorption
30
What is the MoA of Vancomycin?
Inhibits cell wall formation in gram positive bacteria
31
For what type of infection is Vancomycin first line, and why?
MRSA | Not dependent upon penicillin binding proteins (PBP)
32
When should Vancomycin be given orally?
For treatment of C.diff
33
What toxicity is associated with Vancomycin?
Nephrotoxicity Red Man Syndrome (give over 2-3 hours) Ototoxicity
34
What 3 classes of antibiotics target the 50S subunit of bacterial ribosomes?
1. Macrolides 2. Clindamycin 3. Chloramphenicol
35
What are three examples of macrolide antibiotics?
1. Erythromycin 2. Chlarithromycin 3. Azithromycin
36
What 2 classes of antibiotics target the 30S subunit of bacterial ribosomes?
1. Aminoglycosides | 2. Tetracycline
37
Give an example of an aminioglycoside
Gentamicin
38
Give an example of a tetracylcine
Doxycycline
39
What activity do macrolides have?
Gram positive Respiratory gram negatives Atypicals (chlamdyia, legionella, mycoplasma)
40
How should macrolides be administered?
Orally (unless patient is severely unwell - vomiting or poorly perfused GIT)
41
What can clarithromycin be used against?
``` Streptococcus Staphylococcus Neisseria Haemophilus Enterococcus Atypicals ```
42
For what specific type of infection is clarithromycin useful for?
Respiratory tract infections
43
What are the adverse effects of macrolides?
D&V | QT prolongation
44
What drug interactions are associated with macrolides?
Simvastatin Atorvastatin Warfarin
45
What is the principle action of clindamycin?
Gram positives
46
What is clindamycin particularly good at doing?
Stopping exotoxin production
47
In what infections should clindamycin be given?
Toxic Shock Syndrome | Necrotizing fasciitis
48
Why should clindamycin not be given to patients who are more vulnerable at developing C.diff infections?
Very broad anaerobe activity Disrupt gut flora Increase risk of C.diff
49
How long can it take for the gut flora to recover its diversity following antibiotic use?
6-9 months
50
What are the 4 c.differgic antibiotics?
1. Clindamycin 2. Co-amoxiclav 3. Cephalosporins 4. Ciprofloxacin
51
What is the MoA of chloramphenicol?
Inhibits 50S ribosomal subunit
52
What are the toxic effects of chloramphenicol?
Bone marrow suppression Aplastic anaemia Optic neuritis
53
What are the uses of chloramphenicol?
Topic therapy to eyes | Bacterial meningitis with beta-lactam allergy
54
Aminoglycosides have activity against what type of bacteria?
Gram negative
55
What are the bacteriostatic and bactericidal effects of aminoglycosides?
Bacteriostatic - reversibly binds to 30S subunit Bactericidal - affects cell membrane at high concentrations
56
What toxicity is associated with aminoglycosides?
Nephrotoxicity Ototoxicity Neuromuscular blockade - myasthenia gravis
57
Describe the dosing that should be used for aminoglycosides?
High initial dose - rapid killing Long dosing interval (24-48h) - minimise toxicity Measure trough level 3 days only
58
Tetracyclines have activity against what type of bacteria?
``` Streptococcus Staphylococcus Neisseria Haemophilus Enterococcus ```
59
Who should not be given tetracyclines and why?
Pregnant women Children Bone abnormalities Tooth discolouration
60
What are the types of antibiotics which target DNA repair and replication?
Quinolones | Rifampicin
61
Give two examples of quinolones
Ciprofloxacin | Levofloxacin
62
Which quinolone has stronger activity against gram negative bacteria?
Ciprofloxacin
63
Which quinolone has stronger activity against gram positive bacteria?
Levofloxacin
64
For what type of infections is ciprofloxacin commonly used for?
UTI | Abdominal infection
65
What type of infection is levofloxacin commonly used for?
Respiratory tract infections
66
What toxicity is associated with quinolones?
GI toxicity QT prolongation Tendonitis
67
What is rifampicin particulary useful against?
Biofilms
68
What are the interactions associated with rifampicin?
Potent CYP450 inducer Most drugs that undergo hepatic metabolism OCP is ineffective
69
What is the mechanism of action of trimethoprim?
Inhibits folate synthesis
70
When should trimethoprim be used?
Uncomplicated UTI
71
What toxicity is associated with trimethoprim?
Elevation of serum creatinine (action on PCT) Elevation of serum K (potassium sparing diuretic) Rash and GI disturbances - uncommon
72
What toxicity is associated with co-trimoxazole?
Bone marrow suppression | Steven Johnson syndrome
73
What antibiotic causes an unpleasant reaction with alcohol?
Metrondiazole
74
What is the mechanism of action of metrondiazole?
Enters the bacteria by passive diffusion | Produces free radicals
75
What is metrondiazole effective against?
Anaerobic bacteria
76
What is associated with long term use of metrondiazole?
Peripheral neuropathy
77
In 80% of young women with cystitis, what is the causative bacteria?
E.coli
78
What is the first line antibiotic for uncomplicated UTI?
Trimethoprim
79
Apart from trimethoprim, what other antibiotic is useful for UTI infections?
Nitrofuratoin
80
When should nitrofuratoin be avoided?
In renal failure
81
What antibiotic should be used in complicated UTI (fever, flank pain but no sepsis)?
Ciprofloxacin (oral)
82
What antibiotic should be used in UTI with sepsis?
Gentamicin (lots of activity against E.coli but requires monitoring) IV
83
What antibiotics are not safe for use during pregnancy?
1. Tetracyclines - bone/tooth abnormalities 2. Trimethoprim - neural tube defect (1st trimester) 3. Nitrofurantoin - haemolytic anaemia (3rd trimester) 4. Aminoglycosides - ototoxicity (2/3rd trimester) 5. Quinolones - bone/joint abnormalities

MBChB (14 decks)

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