Prevention of Hospital Infection

Exogenous infection

Hospital Infection

• Surgical wards

• Operation Theaters

• Surgical Instruments

Surgical wards

• Should be well ventilated and cleaned • The floor should be scrub washed once a

week• Preop. Pts should not be mixed with

postop. Pts.• Severely infected cases should be

isolated • Immuno suppressed pts also isolated

Operation Theaters• Adjacent to ICU• Height – 3M. Floor area 10 sqM.• Anaesthetic room -10 Sqm.• Minimise bacterial contamination The concept Site – away from the wards of

zones : a) outer zone – reception area. b) clean zone – between the reception and OR. C) asceptic zone – OR . D) dirty zone – disposal area and space for cleaning of instruments

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Air flow of OR

•Filtered air – directed vertically or horizontally

• Ideal – laminar flow•Restrict entry of

nonessential personnel & their movements

•Temperature – 20 - 22°C

Other Measures

• Wearing of disposable nonwoven fabric• Masks• Head & beard cover• Preparation of the surgical team• Preparation of the patient Preoperative hospitalisation

minimised Skin infection treated Hair removal Skin preparation, Drapes

Disinfection

The process that reduces the no. of viable microorganisms, but does not affect the spores

Disinfection

Three levels of disinfection 1. Low: reduces the overall no. of

vegetative microorganisms. Does not destroy TB bacilli or bacterial spores .Application – environmental surfaces

2. Intermediate : kills TB bacilli, most viruses,and some fungi but only some spores. Application – horizontal surfaces,floors

3. High: kills most forms of microbial life including TB bacilli but not some spores. Application – flexible endoscopes

Disinfection

• Heat disinfection 1) Pasteurization 2) Boiling 3) Low temperature steam

disinfection

Chemical disinfection

• Chemical disinfectants are used to reduce the pathogenic microbes of inanimate objects, which are heavily contaminated.

• Alcohols, aldehydes, halogens, phenolics and quaternary ammonium compounds

Chemical disinfectants

• Alcohol – isopropyl alcohol & ethyl alcohol – kills most vegetative bacteria in less than 30 seconds , relatively inactive against spores and fungi. 70% alcohol is usually used.

• Aldehydes – glutaraldehyde & formaldehyde – good activity against spores, bacteria, virus and fungi . 2% glutaraldehyde rapidly inactivates HIV and hepatitis B after exposure for 10 minutes.

Chemical disinfection

• Diguanides – e.g. chlorhexidine – good activity against gm + ve organisms , moderate activity against gm- ve organisms, poor activity > TB bacilli, spores , fungi & viruses . Used as an antiseptic for skin & mucous memb.

• Halogens e.g. hypochlorites and chlorine – active against bacteria including spores ,fungi, hepatitis B & HIV virus

Chemical disinfection• Iodophores -1% available Iodine

mixed with alcohol excellent skin preparation

• Phenolics – e.g phenol &chlorxylenol surface cleaning – Hexachlorophene – preparation of surgeon's hands

• Quaternary ammonium compounds – good detergent properties – savlon when mixed with chlorhexidine

Sterilization

• Complete removal of all microbes including spores

• Methods : Heat method – dry or moist

Ionization radiation

Ethylene oxide gas

Heat Methods

• Dry heat – Hot air ovens which have controlled cycles, such as 160°C for 1 hour – suitable for killing bacteria on materials which are not penetrable by steam e.g. glassware, powder such as talc, oils & petroleum jelly.

• Moist heat – Steam under pressure – simplest is domestic pressure

• High pressure vacuum autoclaves• Low temp. steam(73°C) & formaldehyde –

suitable for heat sensitive materials and equipment with plastic component

Ionising Radiation

• Gamma rays – lethal, noncharged, ultrashort, wavelength rays with great penetrating power from a radioactive isotope such asCobalt-60 e.g.Disposable syringes, sutures and rubber gloves

• The radiation dose 2.5 mrad – kills bacteria by ionising their DNA.

EthyleneOxide

• It should be used with suitable humidity at the correct temp. for sufficient time

• CO2 is mixed with ethylene oxide to reduce Highly toxic inflammable gas – kills all types of microbes including spores.

• the risk of explosion• It diffuses well through items such

as plastic materials, swabs and paper.