Microbiology

Question 1

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

Answer 1

Gram +ve = purple
Gram -ve = pink

Question 2

Why does gram +ve stain purple and not pink?

Answer 2

because contains thick layer of peptidoglycans in cell wall

Question 3

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

Answer 3

Staphylococci and Streptococci

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

Question 4

How can you distinguish Streptococci?

Answer 4

Haemolysis test - grow on blood agar

Question 5

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

Answer 5

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

Question 6

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

Answer 6

Strep. pneumoniae

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

Question 7

How is beta haemolytic strep differentiated?

Answer 7

Lancefield grouping

Question 8

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

Answer 8

Streptococcus pyogenes

Question 9

How does Staph. aureus appear on blood agar?

Answer 9

Gold colonies

Question 10

How do you differentiate between types of Staph bacteria?

Answer 10

Coagulase test

Question 11

How do you distinguish Gram -ve bacteria?

Answer 11

1. MacConkey / XLD / CLED agar

Question 12

What are the big boy lactose fermenters?

Answer 12

Klebsiella pneumoniae and E. Coli

Question 13

How do you distinguish non-lactose fermenters?

Answer 13

Oxidase test!
Pseudomonas is oxidase +ve

Question 14

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

Answer 14

Neisseria Meningitidis

Question 15

What unusual organism can cause infective endocarditis?

Answer 15

Coxiella burnetti

Question 16

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

Answer 16

IV benzylpenicillin + gentamycin

Question 17

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

Answer 17

IV flucloxacillin + gentamycin

Question 18

What is the most common cause of CAP?

Answer 18

Streptococcus pneumoniae

Question 19

Other common causes of CAP

Answer 19

Staph. aureus, viruses

Question 20

Atypical causes of CAP

Answer 20

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

Question 21

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

Answer 21

Urinary Ag

Question 22

First line for legionella CAP?

Answer 22

Clarithromycin

Question 23

First line for strep. pneumoniae CAP?

Answer 23

Amoxicillin

Question 24

Causes of HAP

Answer 24

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

Question 25

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

Answer 25

Vancomycin - broad spectrum Abx

Question 26

Big boi cause for COPD exacerbations

Answer 26

H. influenzae

Question 27

Agar for growing H. influenzae colonies

Answer 27

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

Question 28

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

Answer 28

Hib vaccine

Question 29

Most common cause and other causes of TB

Answer 29

**Mycobacterium tuberculosis Mycobacterium bovis/africanum/microti

Question 30

How is mycobacteria different from normal bacteria?

Answer 30

Intracellular

Question 31

TB : test for rifampicin resistance?

Answer 31

PCR Xpert

Question 32

When is the mantoux test positive?

Answer 32

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

Question 33

Alongside RIPE, what should you give?

Answer 33

Vit B6 bc isoniazid depletes Vit B6 - causes peripheral neuropathy

Question 34

Causes of osteomyelitis : haematogenous spread

Answer 34

Staph. Aureus

Question 35

Causes of osteomyelitis : exogenous/local spread

Answer 35

Staph. Epidermis, pseudomonas aeruginosa

Question 36

How does treatment vary between Osteomyelitis TB and pulmonary TB?

Answer 36

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

Question 37

Cause of septic arthritis

Answer 37

Prosthetic joint gram +ve bacteria (mostly staph - Staph epidermis) In children, staph aureus, group A strep, gram -ve bacilli

Question 38

Main bacteria in skin infections

Answer 38

Gram +ve bacteria Staph. Aureus, Strep pyogenes

Question 39

What MUST you distinguish cellulitis from?

Answer 39

DVT

Question 40

What is given to treat cellulitis and why?

Answer 40

Penicillin V (phenoxymethylpenicillin) + **flucoxacillin** Flucloxacillin bc covers both strep and staph

Question 41

Types of necrotising fasciitis

Answer 41

TYPE 1 : Polymicrobial - mix of anaerobic (clostridium perfringens) + aerobic bacteria TYPE 2 : Single bacteria (esp. Group A strep)

Question 42

1st line antibiotic for staphylococcus aureus infection?

Answer 42

Flucloxacillin

Question 43

Name common organisms of meningitis

Answer 43

Neisseria meningitidis Strep pneumoniae Group B streptococcus

Question 44

Common causes of UTI

Answer 44

**E. coli Klebsiella Enterococci

Question 45

Name 2 anti-fungal treatments

Answer 45

Clotrimazole, fluconazole

Question 46

micro tbd

Answer 46

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