Microbiology

Question 1

What is the definition of colonisation

Answer 1

Presence of a microbe in the human body without an inflammatory response

Question 2

What is the definition of infection

Answer 2

Inflammation due to a microbe

Question 3

What is the definition of bacteraemia

Answer 3

Presence of viable bacteria in the blood

Question 4

Define sepsis

Answer 4

Systemic inflammatory response to infection

Question 5

What type of bugs do phagocytes target

Answer 5

Bacteria and fungi

Question 6

what type of bugs do T lymphocytes target?

Answer 6

Viruses, fungi, protozoa

Question 7

what type of bugs do antibody and B lymphocytes target target?

Answer 7

Viruses and bacteria

Question 8

What type of bug do eosinophils target?

Answer 8

fungi
protozoa
worms

Question 9

what type of bugs do mast cells target?

Answer 9

worms

Question 10

what type of bugs complement target?

Answer 10

Bacteria

Question 11

What investigations are done to diagnose infection

Answer 11

Lab features
- microbiology
- WCC
- CRP
- platelets, clotting
Microbiology
- blood, stool, Urine, wound, tissue cultures
Microscopy
- stool, urine, sputum
Serology
Antigen detection
PCR

Question 12

Name some bacteraemia sources in community and hospital

Answer 12

Community

• E.Coli (urine and abdo)
• S.Pneumoniae (respiratory)
• S.Aureus (Skin)

Hospital

• E.Coli (catheter related or abdo)
• S.aureus (MRSA line/wound)
• CNS (line/prosthesis)
• Enterococci (urine. would, line)
• Klebsiella (urine and wound)
• Pseudomonas

Question 13

What gram positive organisms can cause upper resp tract infections?

Answer 13

Strep pneumoniae
Strep pyogenes
Stahylococcus aureus

Question 14

What gram negative organisms can cause upper resp tract infections?

Answer 14

H. influenzae

Moraxella catarrhalis

Question 15

How can you tell apart gram negative and positive bacteria

Answer 15

Gram staining

• Positive stains purple
• Negative stains pink

Question 16

Causative organisms of community acquired pneumonia

Answer 16

Strep pneumonia (70%)
Atypicals/viruses (20%)
H influenzae
Staph aureus

Question 17

How to diagnose community acquired pneumonia

Answer 17

sputum culture
viral PCR
Serology
Blood cultures

Question 18

Risk factors for community acquired pneumonia

Answer 18

Increasing age
Immunocompromised
smoking

Question 19

what are the normal flora of the mouth

Answer 19

Strep viridans (Neisseria, anaerobes)
Candida, staphylococci

Question 20

Signs of a S. aureus infection

Answer 20

rash
folliculitis 
abscess
carbuncle
impetigo
scalded skin syndrome

Question 21

What group do haemolysis and surface proteins classify as in streptococcus pyogenes

Answer 21

Group A

Question 22

give some features of streptococci pyogenes

Answer 22

Gram positive
chains
catalase negative
Beta haemolysis (complete)

Question 23

What kind of skin infections do streptococcus pyogenes cause

Answer 23

Impetigo
cellulitis
necrotising fasciitis

Question 24

Causes of a sore throat?

Answer 24

Bacterial

• Group A strep
• Group C, G strep
• Neisseria gonorrhoea

Viral

• rhinovirus
• coronavirus
• adenovirus
• Parainfluenza
• Influenza A and B
• herpes simplex
• EBV, CMV, HIV

Atypical agents

• mycoplasma pneumoniae
• Chlamydophila pneumoniae

Question 25

What are the different types of haemolysis on blood agar?

Answer 25

Beta - complete haemolysis, clear zones around the colonies Alpha - partial haemolysis, green surrounding colonies Gamma - no haemolysis

Question 26

What is the most common bacteria causing middle ear infections (otitis media)? How can they be treatment?

Answer 26

H. influenzae strep. pneumoniae strep. pyogenes Usually self resolving first line - amoxicillin seconds line - erythromycin

Question 27

Most common organisms causing acute sinusitis? What is treatment?

Answer 27

H. influenzae strep pneumoniae strep pyogenes# First line - phenoxymethylpenicillin Second line - doxycycline (but not in kids)

Question 28

Common organisms causing bacterial conjunctivitis?

Answer 28

staph aureus strep pneumoniae H influenzae (mainly kids)

Question 29

Investigations and management of bacterial conjunctivitis

Answer 29

``` Swabs Topical antibiotic (chloramphenical) ```

Question 30

what is a complication of giving too high a dose of chloramphenicol in a baby

Answer 30

grey baby | - neonate cannot process the drug as the liver is too immature and can cause hypotension

Question 31

What is viral conjunctivitis most commonly caused by?

Answer 31

adenovirus herpes simplex herpes zoster

Question 32

Presentation of orbital cellulitis, investigations?

Answer 32

painful eye movements proptosis paranasal sinusitis pyrexial Emergency CT scan

Question 33

Common organisms in sexually transmitted infections (bacterial, viral, parasites)

Answer 33

Bacterial - chlamydia trachomatis - Neisseria gonorrhoea - Treponema pallidum (syphilis) Viral - HPV (genital warts) - herpes simplex (genital herpes) - Hepatitis and HIV Parasites - Trichomonas vaginalis - phthirus pubis (lice) - scabies

Question 34

common cause of candida

Answer 34

C. albicans

Question 35

What is acute bacterial prostatitis and what are common organisms associated, management?

Answer 35

Rare complication of UTI in men causing penile pain and tender prostate E.coli, enterococcus, STI (gonorrhoea and chlamydia) Ciprofloxacin for 28 days Trimethoprim if high C. diff risk (those taking antibiotics/immunosuppressed)

Question 36

Normal vaginal flora

Answer 36

``` - Lactobacillus spp. (produces lactic acid to suppress growth) (also produces hydrogen peroxide) - Strep viridans - Group B beta haemolytic streptococcus - Candida spp. ```

Question 37

What is the normal pH of the vagina

Answer 37

4 - 4.5 | raised in bacterial vaginosis