Lecture notes for medical students

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2. infection

3. infection
Diseases caused by microorganisms
– Bacteria
– Viruses
– Fungi
– Parasites
– Prions

4. Sterilization
Introduction & History.

5. Sterilization
Introduction & History.
• Problems of Surgery:
– Pain
– Hemorrhage
– Shock
– Infection

6. Sterilization
Introduction & History.
• Semelweis and Holmes
• Pasteur
• Lister
• Asepsis

7. Sterilization
Some terms

8. Sterilization
Some terms
• Infection
• Sterilization
• Asepsis
• Disinfection
• Decontamination
• Degerming
• Antiseptics

9. Sterilization
•

10. Sterilization
• Sterilization: killing all microorganisms
i.e..
– Bacteria
– Spores
– Viruses
– Fungi
– Parasites

11. Sterilization
• Asepsis:
– Preventing access of microorganism into an
operative wound.
By-
– Scrubbing
– Donning
– Sterile supply
– Laminar airflow

12. Sterilization
• Disinfection:
Killing of pathogenic microorganisms (not
all) on inanimate objects through the use of
chemical agents.
instruments and equipments
Floors
Excreta

13. Sterilization
• High level Disinfection:
– only few endospores are spared.

14. Sterilization
• Decontamination:
Thorough mechanical cleansing with soap or
detergent and water to remove all traces of
– blood
– pus
– protein
– mucus
• Ultrasonic washer for delicate instruments.
• Enzymes

15. Sterilization
• Degerming
• Antiseptics
Chemical substances used to kill
pathogenic microorganisms from skin
of Operative site or operating hands.

16. Sterilization Methods

17. Sterilization Methods
• Physical
– Heat
– Radiation
– Filtration
• Chemical
– Alcohols
– Aldehydes
– Dyes
– Halogens
– Phenols
– Metallic salts
– Gases- ETO, Hyrogen Peroxide Plasma
– Peracetic acid

18. Sterilization Methods
• Heat
– Dry heat
• Flaming
• Incineration
• Hot air
– Moist heat
• Boiling
• Autoclaving

19. Autoclaving:

20. Autoclaving:
• Most efficient method of Sterilization
• For heat resistant articles.
• Steam under pressure
• Attention to details is important
• Must exhaust all air at the beginning.
• Newer models have vacuum pump..

21. Sterilization by boiling

22. Sterilization by boiling
• Disinfection rather than sterilization
i.e.. Spores are not killed.
• Metallic and glass articles
• Boil for 30 to 40 minutes.

23. Sterilization By dry heat

24. Sterilization By dry heat
• Hot air Oven
• For glassware, sharps
• For materials that resist penetration by
steam- talc Vaseline, fats and oils
@121oC---6hours
@170oC---1hours
More useful in pathology lab.

25. Sterilization By dry heat
• Flaming
Trays, surfaces, steel instruments

26. Sterilization By dry heat
Incineration:
Hospital waste

27. Colour coding of Hospital waste

28. Colour coding of Hospital waste
• Red : Infectious Non bio degradable
• Yellow:Infectious biodegradable
• White : Sharps
• Blue :Non Infectious Non biodegradable
• Green Non Infectious biodegradable
• Black: Unused expired medicines

29. Colour coding of Hospital Waste
Transfer out if COVID-19 negative
Discharge: afebrile for 48 hours; normal vital signs
(pulse, respiration and BP

30. Sterilization by radiation

31. Sterilization by radiation
• Two types of Radiation are used:
-Ionizing radiation :gamma rays
-high energy electrons
• Used commercially for:
–Plastic disposables
–Sutures

32. Sterilization by radiation
• Ultraviolet
• Used for disinfection of air of OT
-UV lamps in OT
- UV lamps +fan in air
sterilizer
-inside OT’s AC
• Harmful to the eyes.

33. Chemical Sterilization

34. Chemical Sterilization
• Prior decontamination and
subsequent cleansing of equipment
is mandatory

35. Chemical Sterilization
Glutaraldehyde
• 2% aqueous solution is used
• Heat sensitive equipment are immersed for
25 to 45 minutes.
• Sterilant in10 hours.
• Ideal for Endoscopes, Laparoscopes and
accessories,

36. Chemical Sterilization
• Isopropyl alcohol/Ethyl alcohol
(Spirit):
• Used for degerming before:
–Operations
–Injections
–Dressing
–On surgeon’s hands after scrubbing.

37. Isopropyl alcohol/Ethyl alcohol

38. Isopropyl alcohol/Ethyl alcohol
• Can be used for instruments and
endoscopes
• Complete decontamination prior to its
use is a must.
• Doesn’t kill spores.

39. Autoclaving:

40. Autoclaving:
• -
15 psi 121oC 20minutes
30 psi 134oC 3minutes
45 psi 141oC 1minute

41. Steps of Autoclaving
• Loosely pack articles in drum.
• Keep open the holes of drum.
• Fill water in autoclave up to the mark
• Put drums inside the autoclave.
• Close the lid.
• Close all valves.
• Switch on.

42. Steps of Autoclaving
• When pressure reaches 2psi>Open air
release valve.
• When pressure reaches zero>Close air
release valve.
• When pressure reaches 15 psi
whistling starts> Note Time DO NOT
SWITH OFF
• Autoclave maintains pressure &
temperature by releasing small
amounts of steam.
• If autoclave has multiple heating
elements keep only one on.

43. Steps of Autoclaving
• After 20 minutes at this pressure and
temperature i.e. 15 psi, 121oC:-
– 1.Switch off power.
– 2.Open steam release valve
– 3.When all steam has exited> CLOSE
STEAM RELEASE VALVE.
Allow to cool for 10 minutes.
Open the lid and take out drum
Close holes of drum

44. Autoclaving
• Instead of drum articles can be put in
open pots or on the racks.

45. Storage

46. Storage
• Sterile and disinfected articles should
be kept in storage area which should be
clean and dry.
• Remain sterile for one week if lid is
not opened.

47. CSSD

48. CSSD
• Autoclaving is carried out in
CENTRAL STERILE SUPPLY
DEPARTMENT
• From CSSD supplied to OT and
various other wings of the hospital.

49. Sterilization Cycle

50. Sterilization Cycle
• Contamination from patient
Soak in0.5% chlorine
Cleaning
Disinfection Sterilization
Rinsing
Drying Storage

51. Chemical Sterilization

52. Chemical Sterilization
• Lysol
Sharp instruments are kept immersed in it
ready for use.

53. Chemical Sterilization
Formalin
• Used for fumigation of rooms
• For endoscopes, rubber and plastic articles
• Vapor is used in formalin chambers.
• Exposure time 10 to 24 hours.
• Must be wiped away before use.
• Not favooured nowadays

54. Chemical Sterilization
Gas
• E.O./E.T.O.—Ethylene Oxide
• Sterilization is achieved on 3 to 6 hours of
exposure.
• Specially designed chamber is used.
• Gas is highly explosive hence used mixed
with Nitrogen or Carbon Dioxide

55. Gas Sterilization

56. Gas Sterilization
• Useful for
– Endoscopes
– Tubing and plastic parts of heart-lung
machine and respirators
– Prepacked plastic products like syringes,
iv sets
– Blankets, Pillows Mattresses.

57. Gas Sterilization
• Gas is toxic
• Is absorbed by rubber, plastics, Fabric and
leather.
• Gas must be removed from these by
aeration for 24 hours.
• Plastic and metal objects can be used
immediately.

58. Chemical Sterilization

59. Chemical Sterilization
0.5% Chlorine (Sodium Hypochlorite)
• All articles contaminated with body fluids
are immersed for 30 minutes even prior to
handling.
• Surfaces are mopped with.

60. Filtration

61. Filtration
• Filtration is the preferred method of
sterilizing heat sensitive liquid and
gases without exposure to denaturing
heat.
• method of choice for sterilizing
antibiotic solutions, toxic chemicals,
radioisotopes, vaccines, and
carbohydrates, which are all heat-
sensitive.

62. Filtration
• The liquid or gas is passed through a
filter, a device with pores too small for
the passage of microorganisms, but
large enough to allow the passage of
the liquid or gas.

63. Relative size of human cells, bacteria and virus

64. Filtration
•
Materials Name of the filter
Asbestos pad Seitz filter
Diatomaceous earth Berkefeld filter
Procelain Chamberland-Pasteur filter
Sintered glass disks Sintered glass filter
Cellulose Membrane filter
Borosilicate glass fiber HEPA filter
Clay, mud Candle filter

65. Sterilization:
Overview

66. Sterilization:
Overview
Sharps ETO/Cidex/Lysol
Wrapped Autoclaving
Sutures Radiation/Autoclaving
Diathermy
Electrodes
ETO/Radiation
Silicon oil Autoclaving

67. Tests for Sterilization:

68. Tests for Sterilization:
• Indicator tapes.
• Culture
• Test strips for Cidex
• Browne’s tube.

69. Degerming

70. Degerming
• Painting the operative site
• Standard Practice:
– Chlorhexidine scrub
– Remove with sterile swab
– Paint with Povidone Iodine
– Paint with 70% Ethyl alcohol / Isopropyl
alcohol
Recent trend- Paint with povidone Iodine then
allow to dry

71. Antiseptics
• Chlohexidine (Savlon)
• Iodophores: Povidon Iodine
• Ethyl/Isopropyl alcohol
• Eusol
• Chlorooxylonol
• Cetrimide(Cetavlon)

72. Antiseptics
• Chlohexidine (Savlon)
• Iodophores: Povidon Iodine
• Ethyl/Isopropyl alcohol
• Eusol
• Chlorooxylonol
• Cetrimide(Cetavlon)

73. Antiseptics
General principles:
1. To be used on healthy skin not on other
tissues.
2. Tissue debris interferes with action
3. If used on Instruments must be rinsed
prior to use.
4. Avoid using antibiotics as antiseptic

74. Maintaining Sterility in OT

75. Maintaining Sterility in OT
Center For Disease Control (CDC)
guidelines:
1. Surveillance and classification
2. Preparation of patient
3. Preparation of surgical team
4. Ventilation and air quality in OR
5. Cleaning and culturing
6. Operative technique
7. Wound care
8. Prophylactic antibiotics

76. Surveillance and classification

77. Surveillance and classification
All Operations:
• Clean
• Clean contaminated
• Infected
Record Infection rates

78. Preparation of patient
• Preexisting bacterial infection
• Short preop hospital stay
• Nourishment
• Bath night before
• Hair removal
• Painting
• Draping

79. Preparation of surgical team

80. Preparation of surgical team
Wear:
1. Mask
2. Cap/hood
3. Beard must be covered
• Scrubbing
• Sterile gowns and gloves

81. Ventilation and air quality in OR

82. Ventilation and air quality in OR
• Doors kept closed
• Minimum number of personnel allowed
• 25 air exchanges per hour
• Filtered air

83. Cleaning and culturing

84. Cleaning and culturing
OR must be cleaned:
• Between Operations
• Daily
• Weekly
Routine culturing is not recommended
Mats not recommended

85. Operative technique

86. Operative technique
• Gentle tissue handling
• Prevent Bleeding
• Eradicate dead space
• Minimize devitalized tissue and foreign
material in the wound

87. Wound care

88. Wound care
• Dirty and infected wounds should not be
closed primarily
• Drain
• Wash hands before and after
• Gloves
• Change of dressing

89. Prophylactic antibiotics

90. Prophylactic antibiotics
• Parenteral
• 2 hours before (except Cesarean section)
• Oral not recommended
• Colorectal: 24 hours before operation
• Dirty/infected:- therapeutic

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