Question book 5 Flashcards

1
Q

21 year old from Colombia, 21 weeks pregnant
Presents with morbilliform rash, conjunctivitis, fever
develops pneumonitis

Which therapy is advocated for this patient?

ribavirin
aciclovir
paliziumab 
measles specific IgG
human normal immunoglobulin
A

human normal immunoglobulin

suggestive of measles - and may be unvaccinated

HNIG can attenuate disease if given early to immunocompromised, pregnant, or infants <9 months (who will be unvaccinated)

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2
Q

26 year old, 16 weeks pregnant, has fever nad URTI
Influenza A confirmed
Started on oseltamivir

What is mechanism of action of oseltamivir?

inhibits neuraminidase cleavage of budding virions
inhibits haemagglutinin binding to epithelial sialic acid
inhibits dissociation of viral ribonuclearproteins
inhibits neuraminidase preventing virion epithelial entry
inhibits epithelial endosome fusion with the viral membrane

A

inhibits neuraminidase cleavage of budding virions

influenza binds to sialic acid on host epithelial cells through haemagluttinin, and then gains access through endosome fusion.
Neuraminidase normally cleaves sialic acid, to allow new virions to bud from cell

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3
Q

which of the following is not used for treatment against the specified virus

lamividuine HIV
lamivudine and HBV
amantadine and influenza B
ribavirin and RSV
aciclovir and HSV
A

amantadine and influenza B

amantadine inhibits with M2 ion channel in influenza A, preventing uncoating.
influenza B has different structure of M2, so oseltamivir is ineffective

lamivudine inhibits reverse transcriptase - HBV/ HIV
aciclovir inhibits thymidine kinase thereby inhibiting DNA polymerase of herpes viruses

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4
Q

What is mechanism of action of fusidic acid

binding to ribosomes and dissociation of peptide-tRNA
inhibition of topoisomerase IV
inhibition of protein synthesis at 30S subunit
interference with pencillin binding protein activity
binding with elongation factor G and interference with protein synthesis

A

binding with elongation factor G and interference with protein synthesis

fusidic acid only effective on gram pos bacteria
fusidic acid is bacteriostatic

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5
Q

Discharging wound grows Staph aureus

Antibiogram shows resistance to penicillin, fusidic acid and gentamicin

What is the main mechanism whereby staphylococcal gains resistance to aminoglycoside therapy

ribosomal binding site alteration
aminoglycoside degrading enzyme production
loss of porin channels
up-escalation of efflux mechanisms
alteration of cell wall d-ala-d-ala cross linkage

A

aminoglycoside degrading enzyme production

3 types of aminoglycoside resistance:

  • reduced uptake/ reduced cell permeability - common in Pseudomonas and other gram negatives
  • alterations to ribosomal binding site - uncommon as ribosome has multiple binding sites, so needs multiple mutations
  • production of aminoglycoside modifying enzymes (most common) - enzymes usually found on plasmids or transposons
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6
Q

What is mechanism of aminoglycoside post-dose effect

prevention of cross-linking of peptide chains
inhibition of cell wall synthesis
binding to protein G and inhibition of protein synthesis
inhibition of ribosomal function
inhibition of topoisomerase IV

A

inhibition of ribosomal function

aminoglycosides damage cell membrane, and bind to 30S subunit of ribsome
need once a day dosing, as there post-dose effect is to block ribosomes from functioning

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7
Q

Plan to use amoxicillin in pregnant patient who has LRTI/

Which pregnancy safety category is amoxicillin classed under

Category A
Category B
Category C
Category D
Category X
A

Category B

FDA guidelines

Cat A - randomised controlled trial shows it is safe
No RCT in pregnant women, but penicillin known to be safe

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8
Q

Patient with CNS TB

Which drug is best for crossing BBB

rifampicin 
isoniazid
ethambutol
streptomycin
pyrazinamide
A

isoniazid

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9
Q

34 year old with drug-susceptible TB, commenced on quadruple therapy.
Remains smear positive at 2 months

Therapeutic drug monitoring showed low levels of some of anti-mycobacterials
Genetic testing showed that he was a fast acetylator

Which drug is affected by this genetic mechanism

isoniazid
rifampicin
pyrazinamide
ethambutol
moxifloxacin
A

isoniazid

N-acetyletransferase is an enzyme involved in isoniazid clearance, and genetic variation (fast acetylators) can lead to fast clearance of isoniazid

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10
Q

What is mechanism whereby Streptococcus pneumoniae can display phenotypic resistance to both erythromycin and clindamicin

efflux pump
enzymatic degradation
porin loss
target alteration
impermeability
A

target alteration

macrolide erythromycin and lincosamides clindamicin insert into 23S subunit of 50S ribosome - blocking protein assembly
This is bactericidal for S.pneumoniae

mutation in ermB gene encodes resistance to both drugs - and alters target site at ribosome

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11
Q

At which site do the fluoroquinolone class of antimicrobials act

cell wall synthesis
DNA-dependent RNA polymerase
RNA-dependent DNA polymerase
Topoisomerase IV
ribosomal protein synthesis
A

Topoisomerase IV

Quinolones act on:
DNA gyrase of gram negative bacteria
topoisomerase for gram pos bacteria

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12
Q

What is the mechanism of action of rifampicin

cell wall inhibitor
DNA gyrase inhibitor
DNA-dependent RNA polymerase inhibitor
DNA-dependent DNA polymerase inhibitor
Folate inhibition
A

DNA-dependent RNA polymerase inhibitor

resistance caused by alteration of rpoB gene which encodes part of ribosome subunit

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13
Q

What is main side effect of rifampicin therapy

eighth nerve toxicity 
optic neuritis
hepatitis
dental discolouration 
pulmonary fibrosis
A

hepatitis

optic neuropathy caused by ethambutol or linezolid
peripheral neuropathy caused by isoniazid or linezolid

eighth nerve toxicity caused by aminoglycosides
dental discolouration caused by tetracyclines
pulmonary fibrosis caused by nitrofurantoin

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14
Q

23 year old with enteritis and Campylobacter jejuni detected in stools by PCR
what is suitable antimicrobial therapy

amoxicillin
ciprofloxacin
tetracycline
azithromycin
ceftriaxone
A

azithromycin

most cases do not require antibiotics
if severe infection - e.g fever/ hypotension or immunosuppressed, then may require treatment

22% rate of fluoroquinolone resistance UK. Even higher if campylobacter imported by traveller

C. jejuni causes 90% UK infections
C. coli causes other 10%

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15
Q

65 year old diagnosed with paucibacilliary leprosy
What is an essential component of the treatment regime?

isoniazid
moxifloxacin
dapsone
clarithromycin
clofazimine
A

dapsone

Paucibacilliary - ( lepromatous) one or more hypopigmented macules
Treatment is dapsone + rifampicin for 6 months

Multibacilliary (tuberculoid) - symmetrical skin nodules with thickened dermis
Treatment is dapsone + rifampicin + clofazimine for 24 months

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16
Q

65 year old with paucibacilliary leprosy - commenced on dapsone and rifampicin. Develops rash and eosinophilia

What is most likely diagnosis

agranulocytosis
allergic dermatitis
stevens-johnson syndrome
toxic epidermal necrolysis
dapsone syndrome
A

dapsone syndrome

On spectrum of DRESS (Drug relation eosinophilia with systemic symptoms)

presents with rash, fever, eosinophilia

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17
Q

Patient commenced on linezolid

What monitoring should be undertaken

therapeutic drug levels
FBC
colour vision
LFTs
clotting
A

FBC

use over 14 days can lead to myelosuppression
use over 28 days can also lead to optic neuropathy

18
Q

Patient commenced on linezolid. Which medication significantly interacts with linezolid

venlafaxine
propranolol
salbutamol
nifedipine
sodium valproate
A

venlafaxine

linezolid is weak inhibitor of monoamine oxidase A and B

Avoid SSRI - citalopram, fluoxetine, venlafaxine, sertraline

19
Q

6 day old has meningitis
What is most frequent adverse event from chloramphenicol usage

optic neuritis
isolated thrombocytopenia
agranulocytosis
gray baby syndrome
apalstic anaemia
A

gray baby syndrome

chloramphenicol binds to 50S ribosomal subunit, preventing peptide elongation

side effects include bone marrow suppression - requires FBC monitoring

in neonates, immature liver means chloramphenicol not metabolised fully. Un-metabolised chloramphenicol can cause hypotension and cyanosis

20
Q

6 day old has meningitis.
Mother has anaphylaxis to pencillin.
What is empiric therapy for neonate

ceftriaxone
benzylpenicillin
chloramphenicol
amoxicillin
vancomycin
A

benzylpenicillin

maternal history of allergy has no predictive value in neonatal allergy

21
Q

6 day old has meningitis.
Blood culture grows E.coli
What is best empiric therapy for neonate

Ceftriaxone
Cefotaxime
Amoxicillin
Meropenem
Benzylpenicillin
A

Cefotaxime

Avoid ceftriaxone in neonates because it competes with bilirubin in binding to serum albumin, which can cause hyperbilirubinaemia
No concerns with cefotaxime

Amoxicillin used in listeria
Benzylpenicillin initial empirical therapy, particularly for GBS

22
Q

54 year old with methicillin susceptible Staph aureus batceraemia

What is the treatment regime

Flucloxacillin
Flucloxacillin and rifampicin
Flucloxacillin and gentamicin
Vancomycin
Vancomycin and rifampicin
A

Flucloxacillin

bacteraemia with no focus can have monotherapy

23
Q

54 year old with methicillin susceptible Staph aureus prosthetic valve endocarditis

What is the treatment regime

Flucloxacillin
Flucloxacillin and rifampicin
Flucloxacillin, rifampicin and gentamicin
Vancomycin and rifampicin
Vancomycin, rifampicin and gentamicin
A

Flucloxacillin, rifampicin and gentamicin
Because it is a prosthetic valve. Gent has synergistic effect with flucloxacillin. Rifampicin reduces biofilms on valve

flucloxacillin monotherapy suitable for native valve endocarditis

24
Q

Which drug is most likely to significantly interact with rifampicin

penicillin
ibuprofen
lansoprazole
furosemide
warfarin
A

warfarin

significant interactions with rifampicin:
warfarin
oral contraceptive
statins
tacrolimus
azole antifungals, ARVs
25
Q

75 year old with urosepsis prescribed an aminoglycoside therapy

What is mode of action of aminoglycoside

disruption of cytoplasmic membrane function
inhibition of cell wall synthesis
inhibition of DNA gyrase
inhibition of tRNA binding at ribosomal active site
interference with bacterial folic acid metabolism

A

disruption of cytoplasmic membrane function

aminoglycosides have two mechanisms of action:

  • bind to 30S ribosome subunit - provides post-dose effect
  • cell membrane dysfunction

tetracyclines - inhibition of tRNA binding at ribosomal active site

Note gentamicin ends in “micin” as developed from a bacteria. Neomycin/ streptomycin developed from Streptomycin species, so keep “mycin” suffix

26
Q

What is most frequent adverse event from aminoglycoside therapy

low frequency hearing loss
high frequency hearing loss
interstitial tubular nephritis
focal segmental glomerulonephritis
nephrotic syndrome
A

high frequency hearing loss

27
Q

patient commenced on daptomycin therapy

What monitoring must be undetaken

creatinine clearance
creatine phosphokinase
platelet count
ALT
ALP
A

creatine phosphokinase - check baseline, then weekly monitoring

not to be used for gram pos pneumonia as it is inactivated by lung surfactant

28
Q

14 year old with cerebral palsy diagnosed with sepsis secondary to ESBL E.coli in urinary tract
meropenem commenced

Which medication might this antimicrobial significantly interact with

levetiracetam
baclofen
valproate
phenytoin
gabapentin
A

valproate

beta-lactams, carbapenems, and particularly quinolones reduce the seizure threshold
meropenem directly reduces levels of sodium valproate

29
Q

45 year old has sputum which grows Pseudomonas
Phenotypically resistant to ceftazidime, tazocin, meropenem

which drug is most likely to be effective as treatment for this patient

ceftobiprole
ceftraroline
ceftolozane-tazobactam
ceftazidime-avibactam
cefotaxime
A

ceftolozane-tazobactam

loss of ceftazidime susceptibility is due to combination of upregulation of AmpC betalactamase production and increased efflux
Pseudomonas usually remains susceptible to ceftolozane-tazobactam combination

ceftaroline is 5th generation cephalosporin - primarily for gram pos eg MRSA

30
Q

Which agent must rifampicin not be co-prescribed with

fusidic acid
flucloxacillin
voriconazole
acivlovir
ciprofloxacin
A

voriconazole

rifampicin is potent enzyme inducer, and greatly affects metabolism of azoles

31
Q

Which antifungal requires therapeutic drug monitoring

amphotericine B
micafungin
flucytosine
caspofungin
anidulofungin
A

flucytosine

anti-fungal drugs requiring monitoring:
flucytosine
itraconazole
posaconazole
voriconazole
32
Q

15 year old diagnosed with tinea capitis and Microsporum spp grown

Which antifungal treatment is appropriate for fungal infection of hair shaft

topical terbinafine
topical ketoconazole
oral ketoconaozle
oral voriconazole
oral griseofulvin
A

oral griseofulvin

invade hair shaft - so topical treatment is ineffective

33
Q

37 year old neutropenic patient is on ward, and there is building work on oging in next ward.
Which antifungal is not indicated for prophylaxis

liposomal amphotericin B
amphotericin B deoxycholate
posaconazole
voriconazole
fluconazole
A

fluconazole

building work suggests risk of aspergillus.
Fluconazole is only drug here that does not have activity against aspergillus

34
Q

Which antifungal is not effective against PCP

caspofungin
voriconazole
pentamidine
dapsone
co-trimoxazole
A

voriconazole

Treatments for PCP:
co-trimoxazole
primaquine + clindamicin
pentamidine
dapsone + trimethoprim
atovaquone
caspofungin - rarely used, but some effect on PCP
35
Q
Small company designing alternative to traditional antibiotics which work to increase the expression of anti-inflammatory chemokines and cytokines and reduce expression of pro-inflamamtory cytokines
in which class of anti-infective would this agent be described
antimicrobial peptide
innate defence peptide
engineered bacteriophage
probiotic
metal chelation
A

innate defence peptide

36
Q

What drug must fusidic acid not be co-prescribed with

A

fusidic acid and statins have risk of myotoxicity

37
Q

What is mechanism of action of dapsone?

A

inhibits synthesis of dihydrofolic acid

38
Q

What are indications for dapsone?

A

leprosy - essential treatment
PCP
toxoplasmosis

also used for anti-inflammatory effects such as acne, and other skin conditions

39
Q

What are indications for dapsone?

A

leprosy - essential treatment
PCP
toxoplasmosis

also used for anti-inflammatory effects such as acne, and other skin conditions

40
Q

75 year old with CAP and pencillin allergy prescribed doxycycline

What is mode of action of tetracyclines

disruption of cytoplasmic membrane function
inhibition of cell wall synthesis
inhibition of DNA gyrase
inhibition of tRNA binding at ribosomal active site
interference with bacterial folic acid metabolism

A

inhibition of tRNA binding at ribosomal active site