Human Microbiome and Infection Control

Question 1

What is not found in a prokaryotic cell?

Answer 1

Membrane bound nucleus, mitochondria and other organelles.

Question 2

Bacillus

Answer 2

Rod

Question 3

Coccus

Answer 3

Spherical

Question 4

What is the cell wall of a prokaryotic cell made up of?

Answer 4

Peptidoglycan

Question 5

What is a heterotroph?

Answer 5

A heterotroph is an organism that cannot manufacture its own food by carbon fixation and therefore derives its intake of nutrition from other sources of organic carbon, mainly plant or animal matter.

Question 6

Define commensalism.

Answer 6

Living in a relationship in which one organism derives food or other benefits from another organism without hurting or helping it.

Question 7

Commensal Flora

Answer 7

Found on all epithelial surfaces of the body.

Generally do not harm the host and are protective and beneficial.

May be associated with non-infectious diseases such as inflammatory bowel disease and obesity.

Question 8

What disrupts commensal flora?

Answer 8

Antibiotics.

Question 9

What are the main bacteria of the skin?

Answer 9

Staphylococcus epidermis
Cutibacterium acnes
Corynebacterium

Question 10

What does skin bacteria break sweat down into?

Answer 10

Odoriferous amines and steroids.

Question 11

How does deodorant work?

Answer 11

Deodorants contain aluminium salts to prevent sweating and antiseptics to inhibit bacterial growth.

Question 12

Outline the appearance of staphylococcus epidermis

Answer 12

Staphy = clustered
Coccus = round 
Epidermis = found on the skin

Question 13

Is staphylococcus epidermis gram negative or positive?

Answer 13

Gram Positive

Question 14

When does staphylococcus epidermis cause problems?

Answer 14

When it enters the blood of newborns and immune compromised individuals.
It can also contaminate indwelling medical devices e.g intravenous catheters.

Question 15

What can bacteremia lead to?

Answer 15

Sepsis
Pneumonia
Meningitis
Ineffective endocarditis
Septic arthritis

Question 16

What is the treatment for staphylococcus epidermis?

Answer 16

Vancomyocin (antibiotic) and replacing intravenous catheters with new ones (especially in newborns).

Question 17

Where are lactobacilli found?

Answer 17

Lining the vagina

Question 18

What do lactobacilli do?

Answer 18

Lactobacilli break down glycogen in the vagina into lactic acid helping maintain the acidic pH of the vagina protecting it from pathogens.

Question 19

What is the negative effect of antibiotics on commensals?

• effect on women?

Answer 19

Antibiotics can kill commensal bacteria allowing pathogens to take their place.
In women administering antibiotics can lead to development of thrush in this way.

Question 20

What does C difficile cause?

Answer 20

Diarrhoea

Question 21

Is C difficile gram positive of negative?

Answer 21

Gram Positive

Question 22

What are the signs and symptoms of someone infected with C difficile?

Answer 22

Lower abdominal pain
Fever 
Diarrhoea
Leucocytosis
Occurs 5-10 days after administration of antibiotics.

Question 23

What is an opportunistic infection?

Answer 23

Where a pathogen takes advantage of a situation not normally available to it e.g a host with a weakened immune system.

Question 24

What is used to treat C difficile?

Answer 24

Vancomyocin and ideally stopping any other current antibiotic treatments.

Question 25

Clostridium difficile is a gram (positive/negative) bacillus?

Answer 25

Clostridium difficile is a gram positive bacillus.

Question 26

How is Clostridium difficile infection diagnosed?

Answer 26

Clostridium difficile infection is diagnosed by detecting toxins in stool by polymerase chain reaction.