ASEPTIC & ANTISEPIC TECHNIQUES Begashaw M (MD)

DEFINITIONS  Aseptic technique: prevention of microbial contamination of tissues & sterile materials by excluding, removing or killing microorganisms  Disinfection: killing or removal of sufficient microbes to render an inanimate object safe for its intended purpose  Antiseptics: Chemicals which can be applied to living tissues to kill or inhibit the growth of microbes

CHOICE OF ANTISEPTIC  Ideal antiseptic: a. spectrum of activity broad b. resistant to inactivation by organic materials  blood & feces c. no toxicity or allergic reaction, non – staining d. inexpensive

Source of infection patient Staff operation room instruments

Route of infection Personal contact Airborne

Preventative Measures-patient Preventative Measures-patient Short hospital stay preoperatively Shower a day before surgery Treatment of any infectious site before surgery Aseptic methods Special preparations - bowel preparation for colonic surgery use of antiseptic solution Prophylactic antibiotics

Operating Theater  Staff Wear clean clothes, shoes or covers, mask & cap Scrubbing for at least 5 min dry with sterile towel & apply 70% alcohol Put on sterile gloves & gowns

Scrubbing & gowning

Gloving

Gowning

Gloving

Patient  Clean the operation field with antiseptic - Chlorohexidine & 2.5% Iodine for adults - 70% alcohol for children - Povidone Iodine for all ages if available  cover with sterile drapes

Draping

Operating Room number of personnel reduced adequate ventilation windows should be open to allow ingress of fresh outside air & escape of anesthetic gases Keep all doors closed except as needed for passage of equipment & personnel Clean operating rooms between operations

Instruments  Sterilization: - is a process by which inanimate objects are made free of all microorganisms

Sterilize: Chemical High-pressure steam Dry heat 17 Decontaminate Clean Dry/Cool and Store High-Level Disinfect: Boil Steam Chemical Aseptic Instrument Processing Instrument Processing

Effectiveness of Methods for Processing Instruments MethodEffectiveness (kill or remove microorganisms) End Point DecontaminationKills HBV and HIV and most microorganisms 10-minute soak Cleaning (water only)Up to 50%Until visibly clean Cleaning (water and soap) Up to 80%Until visibly clean Sterilization100%High-pressure steam, dry heat, or chemical High-Level Disinfection 95% (does not inactivate some endospores) Boiling, steaming, or chemical for 20 min

Autoclaving  preferred method  uses steam at a pressure of 750 mmHg above atmospheric pressure & temperature of 120 degree Celcius for mins  steam is helpful for penetration even into spores  Appropriate indicators needed

Dry heat poor alternative suitable for metal instruments uses a temperature of 170 degree celcius for 2 hrs

Alcohols ethyl, isopropyl Acts by denaturing proteins Broad spectrum- gram-positive & gram-negative rapid action  short acting moderately expensive most active against bacteria at 70% concentration Is bactericidal Also fungicidal & virucidal

Chlorhexidine Good activity against staphylococci & streptococci moderate activity against gram negative bacteria persistent action-up to 6 hrs moderately expensive non-toxic unpleasant taste

Iodine Lugol’s solution Broad spectrum Cheap Stains Hypersensitive

Povidone iodine Broad spectrum - spore forming organisms -both gram-positive & gram-negative moderately expensive some hypersensitivity skin rapid inactivation by blood