L2

Question 1

Way to control microorganism growth

Answer 1

Clean
Sanitisation
Disinfection
Sterilazation

Question 2

Sterilisation vs disinfection vs sanitization

Answer 2

Sterile kill all living microorganisms
Disinfection kills most microorganism exclude endospore
Sanitisation reduce numbers of bacteria

Method of killing germs
Sterilisation: heat
e.g. autoclave 121oc high pressure 15min

Disinfection: chemical,
using disinfectant to

Sanitisation: chemical
Use sanitizer to reduce number of microbe number

Question 3

Physical & chemical methods for disinfects

Answer 3

Physical:
heat: dry heat / moist heat
Radiation: x ray, gamma ray, UV light

Chemical
Low: soap
Medial: Alcohol
High: oxidising agent

Question 4

Dry heat vs moist heat & principle

Answer 4

Moist heat better as water penetrates object better
Conduct heat better
Requires lower temperature and shorter time than dry heat sterilization

Moist
98-100C 10min
Heat resistant e.g. endospore requires up to 30min

Question 5

Pasteurization

Answer 5

Reduce number of bacteria in milk or juice
High temperature short time: 75C 15sec
Ultra high temperature pasteurisation: 135C 2-5sec

Question 6

Physical method: irradiation

Answer 6

X ray: bacteria breakage, more penetrating, sterilisation

UV light: bacteria mutation, less penetrating, surface cleaning

Question 7

Chemical: low

Answer 7

Soap: reduce number of microbes, physically rub off the bacteria

Heavy metal: silver, copper,

Question 8

Bacterial growth rate

Answer 8

Lag phase
No major increase of cell number

Log phase
Major increase if cell number

Stationary phase
Cell growth but jot cell number

Decrease phase
Decreasing number of living cells

Question 9

Chemical method: intermediate antimicrobial power

Answer 9

Phenolic

Halogen

70% alcohol

Question 10

Chemical high power antimicrobial

Answer 10

Oxidizing agent

Aldehyde

Question 11

Beneficial effects of microbiota

Answer 11

1. As a barrier to inhibit pathogenic bacteria
2. Stimulate immune response
   ( induce production of immunoglobulins)
3. Improve digestion

Question 12

Interaction between pathogen & human

Answer 12

Pathogen: microorganism that can cause disease in human

Infection: the entry+ development of infectious agent that cause disease

Question 13

Level of infection:

Answer 13

Subclincal: no symptoms

Latent infection: inactive at first, active and produce symptoms later)

Clinical infection: have symptoms, no delay

Question 14

Mechanism of pathogenicity

Answer 14

1. Portal of entry
2. Adhere
3. Defense
4. Invade
5. Damage
6. Portal of exit

Question 15

Details of mechanism of pathogenicity

Answer 15

1. Portal of entry: enter the host through skin
2. Adhere: bind to cell or skin
3. Defence: ability of pathogen to defence the host’s immune system
4. Invade: ability of pathogen penetrating the tissue & spread in the host
5. Damage: damage host’s tissue by
   
   1. Using host’s nutrient
   2. Causing direct damage
   3. Produce toxin
   4. Induce hypersensitivity reaction
6. Portal of exit: way bacteria leaving host
   
   1. Droplet
   2. Coughing
   3. Feaces

Question 16

Exotoxin vs endotoxin

Answer 16

Exotoxin: from both gram+ and gram - bacteria

Being secreted out through exocytosis / after cell lysis

Cause serious disease or death

Endotoxin

Lipopolysaccharide on cell wall of gram- bacteria

Released after cell lysis

Effects: fever, hypotension, septic shock