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Antibiotic resistance and new antibiotics Flashcards

1
Q

Linezolid

  • coverage
  • MOA
  • what drugs do you have to avoid because of interactions?
A

Gram positiives including hVISA, VISA, MRSA
plus mycobacteria and nocardia

Not strep viridans or milleri

Inhibits protein synthesis

MAO inhibition so avoid SSRIs and Tramadol

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2
Q

Daptomycin

  • coverage
  • MOA
A

Most gram positives; like vanc with VRE coverage
Not good for VISA, VRSA
Inhibited by surfactant so not for pneumonia

Binds cell membrane and inhibits synthesis of DNA, RNA, protein

Bactericidal

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3
Q

Tigecycline

  • coverage
  • MOA
A

For Gram positives
Bacteriostatic for MRSA, MSSA, VISA, VRE
Also lots of gram negatives but NOT pseudomonas

Bacteriostatic

Protein synthesis inhibitor

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4
Q

Ceftaroline

  • coverage
  • MOA
A 
For gram positives
Novel cephalosporin active against MRSA (incl hVISA, VISA)
NOT VRE
Good for gram negatives except ESBLs
Does kill pseudomonas
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5
Q

Colistin

  • coverage
  • MOA
A

Binds and disrupts outer cell membrane–>leakage and death

Very renal and neurotoxic

Works: pseudomonas, acinetobacter, E coli, Klebsiella, salmonella, some enterobacter

Does not work: Burkholderia cepacia, Proteus, Serracia, Proteus, Morganella, gram positives

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6
Q

Fosfomycin

  • coverage
  • MOA
A

Inhibits the MurA enzyme
Bacterocidal

Used for resistant UTIs not pseudomonas

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7
Q

Ertapenem

  • coverage
  • role
A

Newer carbopenem covers ESBLS but not with pseudomonas cover

Once daily IV

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8
Q

Moxifloxacin

coverage

A

Very broad spectrum
Not pseudomonas- go for cipro

Monitor QT

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9
Q

How is pseudomonas resistant to carbapenems?

A

porins –>reduced penetration

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10
Q

How is pneumococcus resistant to macrolides?

A

mef mutation–>efflux

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11
Q

What is the concern with over use of anti-anaerobic antibiotics?

A

Metro or Aug kill anaerobes and are take up by enterococcus –>new resistance VRE

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12
Q

What is conjugation?

A

Where pilus between two cells allows transfer of a mobile plasmid

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13
Q

What is transformation?

A

eg VRE strains

A bacterial cell dies and bursts with fragments of DNA released–>enterococcus takes up and integrates into own DNA

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14
Q

What is transduction?

A

Phages attach and infect and break up and package host DNA then infect new host with new DNA incorporated

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15
Q

What is the new classification for MRSA?

A

No longer community and hospital acquired but

MRSA vs NORSA (non multiply resistant oxacillin resistant staph)

NORSA usually susceptable to bactrim, macrolides, clindamycin, gent

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16
Q

What is the virulence gene for MRSA?

A

Panton Valentine leucocidin

encodes pore forming toxin that punches holes in neutrophils

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17
Q

How is s aureus defined according to reduced vancomycin susceptibility?

A

MRSA/VSSA = MIC under 2 for vanc
VISA when MIC 4-8
VRSA when MIC over 16

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18
Q

What is hVISA

A

the intermediate stage between MRSA and VISA- some colonies of each,
MIC usually 1-2 for vancomycin

Associated with thickened cell wall and more D-ala-D-ala targets for vancomycin- vanc failures common

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19
Q

Treatment for hVISA?

20
Q

VISA- which patients?

A

dialysis patients
infected foreign bodies eg LVAD
similar treatment options to hVISA

21
Q

What is the target of vanc?

A

glycosyltransferase enzyme in the cell membrane that is making new peptidoclycan chains for the cell wall

Also bind d-ala-d-ala monomers

22
Q

What is VRE? I mean which actual bugs?

A

Enterococcus faecalis and faecium

23
Q

What genes give enterococcus the VRE status?

A 
Van A (teicoplanin resistant)
Van B (teicoplanin sensitive)
"vancomycin resistance gene clustering"- change d-ala-d-ala to d-ala-d-lac. Cell also cleaves d-ala-d-ala into single units so that vanc cannot bind
24
Q

How do you treat VRE?

A

Linezolid
Tigecycline
Daptomycin (not if already was on vanc though)
Not teicoplanin as a bit crappy

25
When S pneumoniae is resistant to penicillin?
It's not beta lactamase.... it's altered PBP!!
26
What are the four classes of beta lactamase?
A penicillinases B Metalloenzymes C Cephalosporinases D Oxacillinases
27
What are the ESCAPPM organisms?
Those with class C beta lactamase enzyme due to AMP C If put on cephtriaxone improve initially then the beta lactamase is induced and there is rebound ``` Eg enterobacter serratia citrobacter acinetobacter providencia proteus morganella ```
28
What are ESBLs? - what mutations? - how did this happen?
Extended spectrum beta lactamases - Class A - Mutations in existing beta lactamase genes eg CTX-M most common, alsoTEM, SHV - plasmid mediated transfer Lots in klebsiella, E coli, Proteus Can look sensitive to 3rd gen ceph in vitro Probably linked to fluoroquinolone use
29
ESBL treatment?
Carbapenems Colistin Amikacin
30
What is a metallobetalactamase? - why is it metallo - which bugs - how did the mutation get there - resistant to what
``` zinc dependent class B beta lactamase pseudomonas and acinetobacter plasmid mediated resistant to all carbapenems and all beta lactams except aztreonam ``` an example is new delhi betalactamase
31
Treatment for NDM?
Colistin
32
What is MDR TB?
isoniazid | rifampicin
33
What is EDR TB?
isoniazid rifampicin moxifloxacin at least one injectable agent like amikacin
34
How do you treat a paradoxical TB reaction?
Keep going with treatment Steroids Aspirate/excise where able
35
Is alcohol a risk for reactivation of latent TB?
Yes, but not a strong risk factor
36
What are the components of SMART-COP?
``` SBP under 90 Multilobar CXR Albumin under 35 RR over 25 in under 50, 30 if over 50 tachycardia over 125 confusion new oxygen under 93%/90% age based pH under 7.35 ``` more points for oxygen, pH, BP
37
When would you give metronidazole for aspiration?
``` Terrible gums Foul sputum Alcoholic Cavitating lung lesion Empyema or severe white out ```
38
Where would some one come from to think MERS coronavirus?
Arabian peninsula South Korea DPP4 on nonciliated bronchial ep cells is the binding point
39
How does flu get in?
Sialic acid bound by haemaglutinin | Neuraminidase allows daughter virions to be released from the infected cell
40
What factors give you severe flu?
``` Obese Asthma Immunosupressed Pregnant Low IgG and especially IgG2 ```
41
If someone becomes very sick with MERS can consider...
Ribavirin plus interferon alpha 2b
42
Tight stenosis L main on angiogram....
syphilis! Tertiary
43
Alemtuzumab gives you what types of infections?
Fungal things! HBV, CMV TB
44
In abx terminology, what is MDR?
3 or more drug classes resistance
45
EDR in abx terminology?
2 or fewer classes left

ID (14 decks)

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