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Case 4 - antibiotics Flashcards

1
Q

what does The Gram stain appearance depend on?

A

cell wall structure of the bacteria

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2
Q

what colour do gram positives and gram negatives show with under the microscope?

A

Gram Positives look Purple under the microscope.
Gram nEgatives look rEd under the microscope

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3
Q

what is cocci and bacilli/rods?

A

cocci (round)
bacilli/rods (rod-shaped)

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4
Q

examples of cocci bacteria that are gram positive?

A

Staphylococci
Staphylococcus aureus
Other staphylococci

Streptococci
Streptococcus pyogenes (Group A)
Streptococcus pneumoniae

Enterococci

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5
Q

examples of cocci bacteria that are gram negative?

A

Neisseria meningitidis
(meningococcus)

Neisseria gonorrheae
(gonococcus)

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6
Q

examples of bacilli bacteria that are gram positive?

A

Clostridium difficile
Listeria sp

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7
Q

examples of bacilli bacteria that are gram negative?

A

E. coli
Klebsiella
Pseudomonas

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8
Q

what does Staphylococci cause?

A

Staphylococcus aureus - a virulent pathogen which causes skin and soft tissue
infections, cellulitis/wound infections, deep abscesses, vertebral discitis, osteomyelitis and endocarditis in intravenous drug users.

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9
Q

what is usual treatment of Staphylococcus aureus?

A

Usual treatment is flucloxacillin. If patient is resistant to flucloxacillin, that means the patient has a strain of bacteria called Methicillin-resistant Staphylococcus aureus (MRSA)

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10
Q

what does Streptococcus pyogenes (Group A strep) cause?

A

Streptococcus pyogenes (Group A strep) is a very dangerous pathogen and causes cellulitis, wound
infections, bacterial tonsillitis, scarlet fever, necrotising fasciitis, puerperal fever

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11
Q

what does Enterococci cause?

A

Enterococci causes UTI and is also associated with bowel sepsis.

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12
Q

what does Clostridium difficile cause?

A

Clostridium difficile causes antibiotic-associated diarrhoea

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13
Q

what does Listeria cause?

A

Listeria is a cause of meningitis in neonates, immunocompromised and elderly people. It can also infect women in pregnancy.

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14
Q

what does Neisseria meningitidis (meningococcus) cause?

A

sepsis and meningitis

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15
Q

what does Neisseria gonorrheae (gonococcus) cause?

A

gonorrhoea

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16
Q

what does E.coli cause?

A

common cause of UTI, urinary sepsis and abdominal sepsis.

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17
Q

where does Pseudomonas live?

A

Pseudomonas - This is an environmental organism which like to live in damp places like taps, mop buckets etc

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18
Q

what does Pseudomonas cause?

A

It’s an opportunistic pathogen so doesn’t normally cause infection in healthy people,
but it can cause serious sepsis in immunocompromised/critical care patients.

can also cause hospital acquired pneumonia

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19
Q

Example antibiotics of the Beta-lactams antibiotic class

A

Penicillin, Flucloxacillin, Co-amoxiclav (Augmentin®),
Piperacillin-tazobactam (Tazocin®), cephalosporins, carbapenems

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20
Q

Example antibiotics of the Tetracyclines antibiotic class

A

Doxycycline, Tetracycline

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21
Q

Example antibiotics of the Glycopeptides antibiotic class

A

Vancomycin, Teicoplanin

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22
Q

Example antibiotics of the Macrolides antibiotic class

A

Clarithromycin, azithromycin, erythromycin

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23
Q

Example antibiotics of the Quinolones antibiotic class

A

Ciprofloxacin

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24
Q

Example antibiotics of the Aminoglycosides antibiotic class

A

Gentamicin, amikacin

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25
Penicillin V (oral) or benzylpenicillin (i.v.) are used for which bacteria
Narrow spectrum but still useful for streptococci including Streptococcus pneumoniae and Streptococcus pyogenes.
26
give examples of Beta lactam antibiotics
Penicillins, Flucloxacillin, Amoxycillin, Cephalosporins (e.g. cefuroxime, cefotaxime, ceftriaxone), Carbapenems (e.g. meropenem, imipenem), Beta-lactamase inhibitor combinations (e.g. co-amoxiclav (Augmentin®), piperacillin-tazobactam (Tazocin®))
27
Penicillin V (oral) or benzylpenicillin (i.v.) used for which infections?
used for tonsillitis and skin infections.
28
what is Flucloxacillin used for?
Narrow spectrum. Agent of choice for Staphylococcus aureus infections.
29
what is Amoxycillin used for?
(Amoxycillin has a broader spectrum than flucloxacillin and penicillin) Amoxycillin is useful for enterococci or streptococci. Amoxycillin can be effective against E.coli but 50% of E.coli is now resistant.
30
what's a first line treatment for bacterial meningitis?
Ceftriaxone, is a type of Cephalosporins
31
how do some bacteria become resistant to beta lactams?
Some bacteria become resistant to beta-lactams by producing beta lactamase enzymes which destroy the antibiotics.
32
what is Carbapenems used for?
Very broad spectrum. Reserved for critical care/ immunocompromised patients
33
what can inhibit the beta lactamase enzymes?
Inhibitors can inhibit these enzymes and can be combined with a beta-lactam antibiotic to protect the antibiotic. Augmentin® and Tazocin® are examples of such combinations.
34
what can doxycycline be used for?
Doxycycline can be used for chest infections, where the most important pathogen is Streptococcus pneumoniae (Gram positive). It also covers ‘atypical’ pneumonia organisms such as Mycoplasma
35
how are Glycopeptides usually taken?
Glycopeptides are generally given intravenously as they can’t really be absorbed by the GI tract. however, oral vancomycin (a type of Glycopeptide) which is used for C.difficile infections is given orally/absorbed by the gut because the C.difficile infection is in the gut
36
when are macrolides used?
Macrolides- used in GPs for staphylococcus and streptococcus infections when the pt is allergic to penicillin, such as being used for tonsilitis and minor skin infections
37
what are Quinolones used for
Quinolones – used for Pseudomonas bacterial infection, Quinolones are the only oral antibiotics effective/active against Pseudomonas
38
why did we stop using Aminoglycosides and then start using them again?
We stopped using Aminoglycosides so much when cephalosporins became available but now Aminoglycosides are being used again more because of the perceived greater risk of C.difficile infections with cephalosporins
39
what are Aminoglycosides used for?
Aminoglycosides – usually reserved for serious gram negative sepsis and given intravenously only
40
why do we need to measure serum levels of Aminoglycosides when they're in the correct range?
Aminoglycosides are Ototoxic (hearing loss) and nephrotoxic (poisonous/damaging to the kidney) so have to measure serum levels to ensure they are in the correct range.
41
what is Metronidazole used for?
Anaerobes
42
our 3 steps in choosing an antibiotic
1. What is the likely source of infection? (clinical assessment) KNOW YOUR PATIENT 2. What organisms are likely to cause infection in that source? KNOW YOUR ENEMY (basic knowledge of microbiology) 3. What antimicrobials are needed for those organisms? -in general choose a narrow spectrum agent where possible. UNDERSTAND ANTIBIOTIC SPECTRA
43
choosing an antibiotic
* Spectrum of activity * Penetration into site of infection– eg brain/bone * Side-effects eg antibiotic–associated diarrhoea * allergies * Drug interactions * intravenous vs oral route (Some achieve blood/tissue concentrations orally equivalent to intravenous eg metronidazole) * Pregnancy/lactation * Guidelines/local policies * Cost
44
what do beta lactams act on?
cell wall synthesis
45
what do Glycopeptides act on?
cell wall synthesis
46
what do aminoglycosides act on?
ribosomes
47
what do Tetracyclines act on?
ribosomes
48
what do macrolides act on?
ribosomes
49
what do Quinolones act on?
DNA gyrase
50
what do Folate inhibitors act on?
Folate synthesis
51
name the beta lactams - penicillins, and their spectrums and what bacteria they're used for
* Penicillin– Narrow spectrum – good for streptococci * Flucloxacillin– Narrow spectrum - for Staphylococcus aureus * Ampicillin/amoxycillin– A broader spectrum penicillin - good for streptococci and enterococci
52
Penicillins combined with beta-lactamase inhibitors
* Amoxycillin +/- clavulanate*– ‘Co-amoxiclav’ (Augmentin®)– Gives broader cover including anaerobes, Gram negatives * Piperacillin +/- tazobactam* – ‘Piptazo-bactam’ (Tazocin®)– gives broader cover including anaerobes and Pseudomonas aeruginosa (PSA)
53
ICUs/bone marrow transplant/chemotherapy units now very reliant on what?
Beta-lactams: carbapenems
54
common side effects of beta lactams
rash, gastrointestinal upset
55
rare side effect of beta lactams
Rarely, can cause bone-marrow suppression (reversible)
56
spectrum of glycopeptides
Spectrum: Gram-positive cover only and they cover nearly all Gram-positives
57
do you need to measure blood levels for beta lactams antibiotics
no
58
are beta lactams generally safe
yes
59
do you need to measure blood levels for glycopeptides antibiotics
yes, to ensure adequate dosing while avoiding toxicity
60
common uses of glycopeptides
critical care
61
Toxicity of glycopeptides
kidney toxicity
62
do you need to measure blood levels for Aminoglycosides antibiotics
yes, need to measure blood levels to avoid toxicity
63
Toxicity of Aminoglycosides
Toxicity: kidneys and inner ear hair cells (nephrotoxic and ototoxic)
64
spectrum of Aminoglycosides
Spectrum: usually used for Gram-negatives
65
what antibiotics cover anaerobes
* Metronidazole covers all anaerobes * Beta-lactams: co-amoxiclav, piperacillin tazobactam and carbapenems cover most anaerobes
66
what are atypical pathogens
‘Atypical’ pathogens do not generally have a cell wall, or have unusual cell walls, and hence do not respond to beta-lactams. Eg: Legionella sp Mycoplasma sp Chlamydia Coxiella (Q fever)
67
what antibiotic should we use for atypical pathogens
In first instance use: * Macrolides (eg clarithromycin, azithromycin) * Tetracyclines (eg doxycycline) is the 1st choice for Chlamydia trachomatis (STI)
68
In what common clinical scenarios are atypical organisms important?
STI * Chlamydia trachomatis Pneumonia * Chlamydia pneumoniae * Mycoplasma * Chlamydia psittaci * Q fever (Coxiella) * Legionella
69
Likely organisms of cellulitis?
– Group A streptococci – Staphylococcus aureus
70
likely organisms to cover for pneumonia
– Streptococcus pneumoniae – ‘Atypicals’ (Legionella, Mycoplasma, Chlamydophila, Coxiella)
71
Likely organisms of bowel sepsis
– E. coli and other Enterobacterales – enterococci – anaerobes
72
Some possible organisms of Ventilator acquired pneumonia (VAP)
* Pseudomonas * Enterobacterales like E. coli and Klebsiella (likely to be resistant) * S. aureus
73
treatment of Ventilator acquired pneumonia (VAP)
Suitable antibiotics will be broad spectrum, enter lung tissue and cover Pseudomonas aeruginosa, e.g. * Piperacillin-tazobactam * carbapenem
74
how to measure C-Reactive Protein (CRP)?
Blood test that measures the amount of C-reactive protein. [Does not replace clinical judgement, but is a tool to aid diagnosis]
75
C-Reactive Protein (CRP) levels in the blood reflect what?
CRP reflects levels of inflammation in the body. High levels are caused by infections and many long-term diseases.
76
high levels of CRP are caused by what
High levels are caused by infections and many long-term diseases.

Case 4 (10 decks)

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