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ALM5 MCQ MasterSheet > Microbiology > Flashcards

Microbiology Flashcards

1
Q

What are three ways which antibiotics work?

A
  • disruption of cell membrane
  • disrupt nucleic acid synthesis
  • disrupt protein synthesis
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2
Q

What are some drivers of antimicrobial resistance?

A
  • human/animal misuse/overuse
  • suboptimal dosing
  • healthcare transmission
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3
Q

Name 3x modes of resistance

A
  • restricted access (impermability or efflux pumps)
  • modification of drug target
  • inactivating enzymes
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4
Q

What are the two types of resistance?

A

Intrinsic/chromosomal (of an entire species)

or
Acquired (through mutation or gene transfer), of a strain

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5
Q

What method of resistance does MRSA use?

A

Acquired, changes to penicillin binding protein (target modification)

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6
Q

What can we use for MRSA?

A

Vancomycin (IV) or other things (but check susceptibility): clindamycin, cotrimoxazole, doxycycline, ciprofloxacin

e.g. send home with oral clindamycin

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7
Q

What can we use for MSSA (normal Staph Aureus?)

A

Flucloxacillin, amox-clav, all cephalosporins + carbapenams

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8
Q

Beta lactamase production is associated with which gram bacteria?

A

Gram negative

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9
Q

How can we target bacteria with B-lactamase production?

A

Clavulanate or tazobactam

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10
Q

How to treat ESBL (extended spectrum) bacteria?

A

e.g. enterobacteria love this

Clavulanate + tazobactam are not reliable, need to use **carbapenam **

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11
Q

Drugs to treat pseudomonas aeruginosa?

A

Piperacillin-tazobactam
Ceftazidime, Cefepime
Meropenem
Ciprofloxacin

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12
Q

What is the virulent component of Staph aureus?

A

Protein A, a component of the cell wall which bings to Fc protion of antibodies, so IgG and complement cannot bind–> impaired phagocytosis

Protein A adheres S. aureus to vWF –> increased infectiousness at skin penetration

Protein A binds to TNFR-1 receptors –> lung inflamation

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13
Q

What does Staph aureus cause?

A

Pneumonia, (IVDU)
Septic arthritis,
Skin infections (cellulitis, impetigo, boils, abscesses)
Bacterial endocarditis (IVDU)
Osteomyelitis

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14
Q

Which heart valve is most implicated in bacterial endocarditis of Staph aureus?

A

Tricuspid

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15
Q

What are the toxin diseases of Staph aureus?

A

Scalded skin syndrome
Toxic shock syndrome
Food-poisoning

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16
Q

What does staph epidermis often cause?

A

Artificial joint, indwelling catheter and valve replacement infections

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17
Q

Where do we see staph saphro?

A

UTI in sexually active females

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18
Q

How do we test for staph epidermis/saphro VS staph aureus?

A

staph epidermis+saphro are coagulase negative

Staph aureus is coagulase positive

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19
Q

1) What does not have anaerobic cover?

Amoxicillin-clavulanate
Metronidazole (only treats anaerobes)
Meropenem
Cefazolin

A

Cefazolin

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20
Q

2) On piptax for HAP. Gets C diff. AKI, WCC 30. lactic acidosis

Treatment?
Oral vancomycin + urgent surgical review
Oral metronidazole
Fecal transplant
Stop antibiotics (not sufficient alone)

A

Oral vancomycin + urgent surgical review

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21
Q

Inpatient for stroke, fever, on review has phlebitic. gram positive cocci!

Remove line and start flucoloxacillin
Start vanco and ceftrizone
Echo as likely has endocarditis
Await coagulase status

A

Remove line and start flucoloxacillin

If they were not feverish/phlebitis, w8 4 coag status b4 treatment.

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22
Q

Elbow surgery -> febrile with mucky wound. Likely cause?

Staph aureus + strep pyogenes
E coli + Pseudomonas aeruginosa
Staph haemolyticus, strept agalactiae ( normal bugs
Candidas albicans, anaerobes

A

Staph aureus + strep pyogenes

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23
Q

What is not a risk factor for leptosporiasis?
Triathalon in lake
Abbatoir worker
Working in rat infested shop
Eating raw chicken

A

Eating raw chicken

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24
Q

How does toxoplamosis present in an immunocompromised person?

Asymptomatic
Pharyngitis
Encephalitis
Mono-nucleosis like syndrome (this or asymptomatic in NORMAL person)

A

Encephalitis

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25
Q

Bloody diarrhea after going to SE Asia
Likely pathology?
Shigella
Listeria
Giardia
Norovirus

A

Shigella

THE REST CAUSE SMALL BOWEL PRESENTATION - large volume crampy
Shigella most likely LB and travel

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26
Q

Spreading erythema over leg, non fluctuant and no wound. Most likely organism?
Streptococcus pyogenes
Staph aureus
MRSA

A

Streptococcus pyogenes

NON-PURULENT

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27
Q

Dog bite to hand, erythema + pus from wound. Which abx?
Amox-clauv
Fluclox
Cefalexin
Doxyxycline

A

Amox-clauv

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28
Q

Recurrent skin abscesses, previous MRSA. New boil on leg but otherwise well what is most appropriate?
Flucloxacillin
Cefalexin
Co-trimoxazole
Vancomycin

A

Co-trimoxazole

Pencillin + cephlosporins (first two) wont work
Vancomycin is IV drug, not in community
Co-trimoxazole best

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29
Q

IVDU fevers and general malaise , splinter haemorrhage + murmur of Left sternal edge. What next?

Treat with ceftrizone + vancomycin
3 blood cultures and wait for results
Admit to hospital for.6 weeks abx
Start flucloxacillin + organise transosephageal echo.

A

3 blood cultures and wait for results

Patient is not that sick and who knows what bug he has (iV drug user)

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30
Q

10kg loss, changed bowel habit, anaemia + now unwell with fevers and malaise for 2 weeks. Most likely bug?

Strept gallolyticus
Staph aureus
Enterococcus faecalis
Eikenella corrodens

A

Strept gallolyticus

Very specific bug associated with colorectal cancer –> subacute endocarditis
EF could also present like this but the history is key
Eikenella more likely with dental work

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31
Q

Aortic valve replacement. obstructed renal stone, Fever, unwell 2 weeks. BC positive with gram positive cocci endocarditis
What bug?

Enterococcus faecalis
Strep viridans
Staph aureus
Streptococcus pyogenes

A

Enterococcus faecalis

All are gram positive, renal hx - enterococcus faecalis (can commonly colonize the urine)
Viridans - usually to do with mouth e.g. dental

32
Q

Recent dental work, 4/52 unwell. 3x BC grew strep viridans. Most appropriate abx?
Penicillin
Amoxicillin
Vancomycin
Flucloxacillin

A

Penicillin

33
Q

Metastatic melanoma with brain mets. Dexamethasone 8mg for last 7 weeks, SOB + hypoxia.
Most likely organism?
Legionella
Pneumocystic jiroveci
RSV
Pseudomonas aeruginosa

A

Pneumocystic jiroveci

Steroids predispose to this. SOB + hypoxic, bilateral infiltrates CXR is the picture.

34
Q

AML< induction chemo. Neutropenic 20 days. New fever + cough. CT shows nodules with surrounding ground glass ?bug

Aspergillus fumigatus
Candida albicans
Staph aureus
Cryptococcus neoformans

A

Aspergillus fumigatus

35
Q

New HIV, CD4 count 20. Has headache fever meningism. LP high opening pressure.
Bug?
Cryptococcus neoformans
HIV encephalitis
Listeria
Pneumocystis jiroveci

A

Cryptococcus neoformans

36
Q

Multiple abx for recurrent chest infecitions/ Itchy white discharge. Tx?

Fluconazole
Flucytosine
Terbinafine (nails)
Amphotericin B (usually for serious invasive fungal infections)

A

Fluconazole

37
Q

Lung cancer, high dose steroids. Change in taste, pain and difficulty swallowing. White plaques on tongue.

A

Fluconazole orally

Nystatin drops not sufficient

38
Q

Return from Vietnam 1wk ago. High fever, headache, myalgia, rash for 2/7. What test made the diagnosis?

Dengue NSI antigen
Leptospirosis PCR
Blood culture with gram neg bacilli
Ebola PCR

A

Dengue NSI antigen

Typhoid wouldn’t cause myalgia and rash as commonly as dengue

39
Q

Returned from Uganda 2/52 agoo, High fever, malaise, abdo pain, 10% parasites in blood. Treatment?

Doxycycline
IV artesunate
Chloroquine
Artemether-lumafantrine

A

IV artesunate

Falciporim (from Africa), 10% parasites is severe
Art-Lum also treats malaria, but this is for less severe
Doxycycline is a prophylaxis

40
Q

Return from visiting parents in India 2 wks ago. High fever, anorexia, abdo pain last week. Dx?

Malaria
Typhoid
Dengue
Leishmaniasis

A

Typhoid

41
Q

Risk factors for brucella?

Unpasteurized milk
Tick bite
Floodwater exposure
Childcare centres

A

Unpasteurized milk
Tick bite
Floodwater exposure
Childcare centres

Goats + cows predominantly

42
Q

Fever, cervical lymphadenopathy + deranged LFTs. What is unlikely to cause this?
HIV
Toxo
CMV
Influenza

A

Influenza

43
Q

Patient with CAP. Which does not need legionella cover?
Severe pneumonia
Summer season
Winter season
Recent potting mix exposure

A

Winter season

44
Q

Which abx do not provide legionella cover?
Doxycycline
Azithromycin
Amoxicillin
Ciprofloxacin

A

Amoxicillin

Beta lactams do not

45
Q

Fever, cough, SOB + consolidation on CXR. Likely pathogen?
Strep pneumoniae
Strepto pyogenes
Strepto agalactiae
Streptococcus mutans

A

Strep pneumoniae

46
Q

Strep pneumoniae –> meningitis, what to treat with?
Ceftrixone 2g q12h
Ceftriaxone 2g q24h
Amoxicillin 2g q4h
Vancomycin 1.5g q12h

A

Ceftrixone 2g q12h

47
Q

Simple cystitis. ESBL E-coli. What drug to NOT use?
Nitrofuantoin
Trimethoprim
Cefalexin
Meropenem

A

Cefalexin

Cephalosporin! Mero is typical, and the others could work

48
Q

Old lady has fever, confusion and new urinary symptoms. Which drug?
Nitrofuantoin
Flucloxacillin
Meropenem
Ceftrixone

A

Ceftrixone

49
Q

MRSA bacteraemia, multiple brain abscess. Which abx is best?
Vancomycin
Doxycycline
Clindamycin
Flucloxacillin

A

Vancomycin

50
Q

Which is a Macrolide?
Clindamycin
Tobramycin
Gentamicin
Azithromycin

A

Azithromycin

51
Q

UTI. Reg meds methotrexate, aspirin, prednisone, simvastatin, omeprazole. Which drug must be avoided?
Nitrofurantoin
Amoxicillin
Cefalexin
Trimethoprim

A

Trimethoprim

Affects folate pathways - methotrexate –> pancytopenia

52
Q

Man with urethral discharge, recent unprotected sex. Gram neg cocci.
Cause?
Gonorrhea
Chlamdia
Syphillis
Mycoplasma genitalium

Cannot gram stain the rest

A

Gonorrhea

Cannot gram stain the rest

53
Q

Male presents with urinary sx + pelvic pain, Tender prostate on exam. Abx?
Nitrofuantoin
Cotrimoxazole
Gentamycin
Trimethoprim

A

Cotrimoxazole

54
Q

Complicated UTI (prostate) - need systemic so nitro + trimeth off the list. Gentamycin does not enter tissue/abscess, better for bloodstream.

Full STI screen female:
HIV + syphillis serology, oral rectal + vaginal swabs for NAAT
Vag swab for trichomonas + BV
First pass urine chlamydia + gonorrhoea
Tell her doesn’t need testing

A

HIV + syphillis serology, oral rectal + vaginal swabs for NAAT

55
Q

Female with dysuria + frequency. Least likely pathology?
Staph saphrophyticus
E coli
Pseudomonas aeruginosa
Proteus mirabilis

A

Pseudomonas aeruginosa

56
Q

Man with dementia with fractured hip. Urine from catheter –> enterobacter clocae. Action?
Treat with amox-clav
Treat with nitro
Change catheter + resend sample
Do nothing as no sign of infection

A

Do nothing as no sign of infection

57
Q

Man never tested/treated for syphillis before, asymptomatic. Serology EIA reactive, TPPA reactive, RPR 1:64. What should we treat it as?
Primary
Secondary
Early latent
Late latent

A

Late latent

Aymptomatic - must be latent. Cannot say due to unknown duration - treat as late as safer, most rigid treatment.

58
Q

Abscess on thigh in young main. Most likely pathogen?
E coli
Streptococcus pyogenes
Staph aureus
Staph epidermis

A

Staph aureus

59
Q

Smelly urine grew pseudomonas. What do you do?
Treat with IV piperacillin-taxobactam
Ciprofloxacin
Take another urine culture
Do not treat + reassure

A

Do not treat + reassure

Smelly urine is not a symptom. NO dysuria, frequency or systemic symptoms.

60
Q

Abx for MRSA?
Flucloxacillin
Cefazolin
Piperaciillin-tazobactam
Co-trimoxazole

A

Co-trimoxazole

61
Q

HIV lost to follow up. PJP presentation. What is not an AIDS defining infection?
Kaposi sarcoma
Toxoplasmosis encephalitis
Leptospirosis
Cryptosporidium

A

Leptospirosis

62
Q

IV patient, CD4 count 800, VL undetectable. New partner, wants advice on risk.
Partner needs PREP + condoms.
Advise no sex.
Advise not to disclose.
No risk of transmission. Discuss PREP for casual sex, condoms for other STI

A

No risk of transmission. Discuss PREP for casual sex, condoms for other STI

63
Q

New HIV with CD4 180. What is at the least risk of?
TB
CMV retinitis
Oesophageal candidias
Pneumocystitis

A

CMV retinitis

<200 so more infections but… <100 toxo, <50 CMV
TB at any CD4 count.

64
Q

New HIV CD4 count 230. VL 200,000. What will happen once he starts treatment?
Counts wont change
CD4 rise, VL undetectable
Risk in both CD4 count + viral load
Reduction in both CD4 + viral

A

CD4 rise, VL undetectable

65
Q

45M with new RUQ pain, jaundice, fever, Bloods: HBsAg positive, anti HBc IgM positive. What is prognosis?
Risk of fulminant hepatitis is high (50%)
90% chance of progressing to chronic HBV
Likely to recover in 3 months, unlikely to progress to chronic HBV
Reasonable risk of developing hepatocellular carcinoma (25%)

A

Likely to recover in 3 months, unlikely to progress to chronic HBV

New infection of hep B, new onset in an adult will likely go away.
IgM positive means acute infection. Last 6 months.
If get this as a kid, 90% change of progressing to chronic Hep B.

66
Q

Which patient with Hep B are we most likely to treat?
12 asymptomatic, normal LFTS, VL 500000 copies
34F pregnant, HBsAg negative, Anti-HBc Ab positive, negative HBV DNA
50y Male, ALT 300, HBeAg neg, VL 10,000 copies
50y M, ALT 30, HbeAg positive, VL 100000 copies

A

50y M ALT 300, HBeAg positive, VL 100000 copies

HBsAg = surface antigen, currently have the virus, could be acute or chronic

HBeAg = e-protein, similar to above

Anti-HBc Ab = antibody, indicates protection either through vaccine or past infection

anti-HBc or HBcAB = core antibody, means a past or current hep B infection. –> does not provide protection against hep B like above

Would treat the one with LIVER inflammation
Pregnant has PAST Hep B

67
Q

Relapse rate for Maviret with Hep C?
50
1
90
10
Cures pretty much everybody.

A

1

68
Q

Which Hep most worried about in pregnancy for mother?
A
D
C
E

A

E

E big issue in pregnancy.
B would be an issue in pregnancy for vertical transmission.

68
Q
A
69
Q

Latent TB infection
Treatment 95% efficacious
Patients should be treated as they are infectious
Patients have cavities on CXR
80% will eventually develop active TB

A

Treatment 95% efficacious

Latent - non-infectious, generally no cavities, just tiny calcified granulomas. 5-10% progress to active TB lifetime risk.

70
Q

Which vaccine bad for pregnant?
Covid
Varicella
Meningococcal ACWY
Pertussis

A

Varicella

+ MMR

71
Q

Which is not effective against pseudomonas?
Ciprofloxacin
Piperacilin-tazobactam
Ceftriaxone
Ceftazidime

A

Ceftriaxone

72
Q

Newborn baby w/ hearing loss ?CMV. What is best test?
Maternal CMV serology
Urine CMV PCR
Baby CMV IgG
Placental histology

A

Urine CMV PCR

Within 3 weeks. After 3 weeks could’ve been from community
Babies don’t make IgG

73
Q

What mechanism of resistance does ESBL employ?

A

Inactivating enzyme (beta-lactamase)

Resistant to all penicillins and cephalosporins

74
Q
A

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