Microbiology Flashcards

1
Q

What colours are gram +ve and gram -ve bacteria?

A

Gram +ve = purple
Gram -ve = pink

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2
Q

Why does gram +ve stain purple and not pink?

A

because contains thick layer of peptidoglycans in cell wall

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3
Q

What are the two big groups of gram +ve bacteria and how can you distinguish them?

A

Staphylococci and Streptococci

Catalase test
OR under a microscope (strep = chains, staph = clusters)

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4
Q

How can you distinguish Streptococci?

A

Haemolysis test - grow on blood agar

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5
Q

What are the types of Streptococci and how do they appear?

A

Alpha haemolytic - partial/green
Beta haemolytic - full/clear
Gamma haemolytic - none

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6
Q

Name an important alpha haemolytic streptococci and how would you differentiate this from other a-strep ?

A

Strep. pneumoniae

Optochin susceptibility test = strep. pneumoniae
If resistant, strep. viridans

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7
Q

How is beta haemolytic strep differentiated?

A

Lancefield grouping

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8
Q

What organism is in group A of Lancefield grouping that is resistant to optochin?

A

Streptococcus pyogenes

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9
Q

How does Staph. aureus appear on blood agar?

A

Gold colonies

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10
Q

How do you differentiate between types of Staph bacteria?

A

Coagulase test

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11
Q

How do you distinguish Gram -ve bacteria?

A
  1. MacConkey / XLD / CLED agar
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12
Q

What are the big boy lactose fermenters?

A

Klebsiella pneumoniae and E. Coli

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13
Q

How do you distinguish non-lactose fermenters?

A

Oxidase test!
Pseudomonas is oxidase +ve

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14
Q

ESQ -
It is reported that the organism from the sample you sent is a Gram -ve cocci. What organism are you worried about?

A

Neisseria Meningitidis

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15
Q

What unusual organism can cause infective endocarditis?

A

Coxiella burnetti

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16
Q

What Tx is prescribed for a Staph-induced infective endocarditis?

A

IV benzylpenicillin + gentamycin

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17
Q

What Tx is prescribed for a Strep-induced infective endocarditis?

A

IV flucloxacillin + gentamycin

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18
Q

What is the most common cause of CAP?

A

Streptococcus pneumoniae

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19
Q

Other common causes of CAP

A

Staph. aureus, viruses

20
Q

Atypical causes of CAP

A

Chlamydia psittaci
Chlamydia pneumoniae
Coxiella burnetti
Mycoplasma pneumoniae
Legionella pneumophilia (SPAIN, A/C, HOLIDAYS)

21
Q

If legionella is indicated in history for CAP, what do you do?

A

Urinary Ag

22
Q

First line for legionella CAP?

A

Clarithromycin

23
Q

First line for strep. pneumoniae CAP?

A

Amoxicillin

24
Q

Causes of HAP

A

Same as CAP
+
Staph. aureus (and MRSA)
Klebsiella pneumoniae
Pseudomonas aeruginosa

25
Q

What antibiotic might you use if someone has a pneumonia causes by MRSA? Why?

A

Vancomycin - broad spectrum Abx

26
Q

Big boi cause for COPD exacerbations

A

H. influenzae

27
Q

Agar for growing H. influenzae colonies

A

Chocolate agar
(blood agar heated to 80oC, has factors X + V for growth)

28
Q

Why is there a reduction in children getting infections caused by H. influenzae?

A

Hib vaccine

29
Q

Most common cause and other causes of TB

A

**Mycobacterium tuberculosis

Mycobacterium bovis/africanum/microti

30
Q

How is mycobacteria different from normal bacteria?

A

Intracellular

31
Q

TB : test for rifampicin resistance?

A

PCR Xpert

32
Q

When is the mantoux test positive?

A

In Px w/ latent TB and those who have has BCG vaccination

33
Q

Alongside RIPE, what should you give?

A

Vit B6 bc isoniazid depletes Vit B6 - causes peripheral neuropathy

34
Q

Causes of osteomyelitis : haematogenous spread

A

Staph. Aureus

35
Q

Causes of osteomyelitis : exogenous/local spread

A

Staph. Epidermis, pseudomonas aeruginosa

36
Q

How does treatment vary between Osteomyelitis TB and pulmonary TB?

A

Tx for Osteomyelitis TB is longer (12 months instead of 6)

37
Q

Cause of septic arthritis

A

Prosthetic joint
gram +ve bacteria (mostly staph - Staph epidermis)

In children, staph aureus, group A strep, gram -ve bacilli

38
Q

Main bacteria in skin infections

A

Gram +ve bacteria
Staph. Aureus, Strep pyogenes

39
Q

What MUST you distinguish cellulitis from?

A

DVT

40
Q

What is given to treat cellulitis and why?

A

Penicillin V (phenoxymethylpenicillin) + flucoxacillin

Flucloxacillin bc covers both strep and staph

41
Q

Types of necrotising fasciitis

A

TYPE 1 : Polymicrobial - mix of anaerobic (clostridium perfringens) + aerobic bacteria

TYPE 2 : Single bacteria (esp. Group A strep)

42
Q

1st line antibiotic for staphylococcus aureus infection?

A

Flucloxacillin

43
Q

Name common organisms of meningitis

A

Neisseria meningitidis
Strep pneumoniae
Group B streptococcus

44
Q

Common causes of UTI

A

**E. coli
Klebsiella
Enterococci

45
Q

Name 2 anti-fungal treatments

A

Clotrimazole, fluconazole

46
Q

micro tbd

A

Antibiotics: bacteriostatic vs bactericidal, resistance, mechanism of action
Malaria
HIV (know one of each treatment class: e.g. protease inhibitors)
(Tropical diseases)
(Helminths)
Soft tissue infections: impetigo + erysipelas + abscesses (staph. Aureus)
Neurology: rabies, tetanus, botulinism, polio
Resp: URTI, LRTI, influenza
Fungal infections (e.g. aspergillosis)
GI: serological findings of viral hepatitis