1. Second year Nutrition
1433- 1434 A.H. / 2012- 2013
Microbiology Practical (Course I)
• By:
Hibah A. W. Abusulaiman

2. Once upon a time…
Please don’t sleep

3. Fashionable friends

4. Abrar’s…

5. Sara started the preparation early

6. She got a luxurious manicure and
padicure plus…

7. An elegant evening gown

8. Lubna started the preparation 2 days
before the wedding

9. She got an elegant evening gown,
but…

10. A poor manicure and padicure

11. Both attended the wedding in…

12. After 45 days, Lubna was suffering
from…

13. Diagnosed as Hepatitis Patient

14. After discussion with the Doctor, she
knew it’s because of the poor hygienic
manicure and pedicure

15. Good hygiene Poor hygiene

16. Destruction of Microorganisms

17. So, do you think we are in a war
with…?!

18. Simply because they are the
agents of…
Contamination, infection and decay

19. Early civilization

20. In the 1800s
Aseptic techniques invented to
prevent contamination of surgical
wounds

21. Many organizations classified infection
control systems and substances into:
• Physical methods.
• Chemical methods.
Referred broadly as Germicides

22. Germicidal systems fall into three
categories:
1. Decontamination.
2. Disinfection.
3. Sterilization.

23. 1. Decontamination:
• Reduction of pathogenic microorganisms to be
safe to handle without protective attire.
• The Lowest level of control.
• Includes physical cleaning with soap and
detergents and removing of most organic and
inorganic materials.
• It is the critical step toward disinfection and
steilisation.

24. 2. Disinfection:
• Disinfectants are liquid chemical agents that
kill targeted pathogens but not spores . It can
also be solid or gaseous.
• It is the next level of control.

25. 3. Sterilization
• The complete elimination of viable organisms
including spores.
• The highest level of control

26. Factors influencing disinfection
• Number of microorganisms.
• Species and type of microorganism.
• Temperature.

27. Physical Chemical
Antimicrobial Antimicrobial
Agents agents
Destruction of
Microorganisms

28. Physical Antimicrobial Agents
• Physical environmental
agents can destroy large
concentrations of
microorganisms in lab
cultures or a clinical
specimen.

29. Physical Antimicrobial Agents
Dry heat
Moist heat Radiation
Physical
sterilization
Incineration Filtration
Osmotic
pressure

30. Radiation
UV Light
To inactivate microorganisms on
surfaces

31. Filtration
•Filtration is used to
remove bacteria, fungi
and their endospores
from air or solutions.

32. Osmotic Pressure
• Extremely hypertonic conditions can cause
plasmolysis.

33. Incineration

34. Autoclave
Moist heat- Steam sterilization
121OC for 15 min

35. Dry heat
160OC for 2 hours OR 170OC for an hour

36. Chemical Antimicrobial Agents
• In considering their application to patient
care, two general classes:
1. Those destroying pathogenic microorganisms in
the environment (disinfectants) or on skin
(antiseptics).
2. Those administered to patients for treatment of
infectious diseases (antimicrobial agents, often
called antibiotics).

37. Desinfectants
Disinfectant Bctericidal Sporicidal Fungicidal Viricidal
Ethyl and Good Poor Good good
isopropyl
alcohols
Chlorine Good Good Good Good
Disinfectants
Formaldehyde Good Good Good Good
and
Glutaraldehyde
Hydrogen Good Good Good Good
peroxide
Iodophors Good Poor Good Good

38. Evaluating a disinfectant
• Direct spray method.
• Testing the quality of disinfectant from
different brands.

39. Testing Disinfectant from Different
Brands
0.5 mL
5 mL Bacterial 5 mL Clorox 5 mL DAC 5 mL Gento 5 mL Dettol
Suspension in Nutrient
Broth (Control)

40. Testing Disinfectant from Different
Brands
Water Bath
Bacterial Suspension in Nutrient Bacteria in DAC Bacteria in Gento Bacteria in Dettol
Broth (Control) Bacteria in Clorox

41. Testing Disinfectant from Different
Brands
2 Loopfulls
48 hrs
Water Bath Incubation
in the 37O C
After 5min After 10 min in After 20 min in
Bacterial Suspension in in Water Bath Water Bath Water Bath
Nutrient Broth (Control)

42. Observe the bacterial growth

43. If not preserving food, you will end up
with…

44. Spoiled Food

45. What is food spoilage?!
• Noticeable damage; compromise quality
which renders food undesirable to eat or
inedible.
• Spoiled food detected by:
– Sight: appearance and color
– Taste
– Odor
– Texture: squishy, no longer firm.

46. Types of Spoilage
1. Physical spoilage
2. Spoilage due to insects or rodents
3. Chemical and enzyme spoilage
4. Microbial spoilage

47. Microbial spoilage

48. What do microorganisms do to fruits
and vegetables?!
Positive effect Negative effect
• Influencing the taste • Rotten food
• Increasing the shelf-life • Ex.:
• Ex.: – Turning milk to sour and
curdled.
– Lactic acid bacteria to make
cheese and yogurt from milk. – Putrid smell of meat.
– Yeast in making beer and
bread

49. Eating rotten food can cause
Food contamination Food poisining
• Occurs when a person • Occurs when the food is
consumes a large number of containing the poisonous
living micro-organisms in a waste products secreted by
meal. the bacteria.
• Disturb the digestive • Heating the food does not
system. help in this case: the
• can be prevented by bacteria will be killed, but
sufficient heating, it will kill the poisonous waste will
the micro-organisms. remain unharmed.

50. Preservation methods
• Heating
• Cold
• Fermentation: sugar
• Reduce the moisture: drying and smoking
• Chemical preservation: Sodium benzoate, nitrites
• Oxygen exclusion: canning in glass or metal, air tight
wraps.
• Ultra high pressure.
• Irradiation: change texture and taste, public fear
• Packaging: protection of food from contamination after
processing

51. Objectives
• Some infection control terms.
• Factors influencing disinfectants.
• Physical destruction of microorganisms.
• Chemical destruction of microorganisms.
• Methods of evaluating disinfectants.

52. Thank you for listening
Any questions?!

53. Thank you for paying attention 
Any questions?!