lec 9-sterilisation & disinfection.ppt

7/23/2019 lec 9-STERILISATION & DISINFECTION.ppt

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PRINCIPLES OF STERILISATION ANDDISINFECTION



OBJECTIVES

The objectives of this lecture reto

Defne Sterilization, Disinection andAntisepsis.

Describe the physical and chemical methodso sterilization and disinection commonly usedin the microbiology laboratory and the hospital.

Explain the importance o Quality control.



INTROD!CTION

Microorganisms cause contamination, inectionand decay, it becomes necessary to remoe ordestroy them rom materials or rom areas. !hisis the ob"ect o Sterilization.

STERILI"ATION#$

Sterilization is defne as the process by #hichan article, surace or medium is ree o all liingmicroorganisms either in the egetatie or sporestate.



DISINFECTION#$

Disinection means the destruction or remoal o allpathogenic organisms or organisms capable ogiing rise to inection. Disinection can be done bychemicals.

ANTISEPSIS#$ $eduction o or inhibition omicrobes ound on liing tissue.

ANTISEPTICS#$

%hemical disinectants #hich can be saely appliedto the s&in or mucous membrane and are used topreent inection by inhibiting the gro#th o bacteria

are called antiseptics.



DIFFERENCES BET%EEN ANTISEPTICSAND DISINFECTION

ANTISEPTICSANTISEPTICS DISINFECTIONDISINFECTION

'.'. All antiseptics areAll antiseptics aredisinectants.disinectants. All disinectants are notAll disinectants are notantiseptics.antiseptics.

(.(. )t can be apply on the)t can be apply on the

lie tissues.lie tissues.)t can be applied on)t can be applied on

inanimate ob"ect.inanimate ob"ect.

*.*. E&#$

E&#$ S&in or mucousS&in or mucous

membrane.membrane.E&#$

E&#$ Surace, lab #or&ingSurace, lab #or&ing

tables, +oor or material.tables, +oor or material.



'ET(ODS OF STERILISATION AND

DISINFECTION

!he ollo#ing methods are commonly used inthe microbiology laboratory and hospital.

)I* P(+SICAL 'ET(ODSunlight, Drying,

Dr, het# $ed heat, laming, )ncineration, (ot irove-.

'oist het# -asteurization, oiling, Autoclve /Steamunder pressure0.

iltration and $adiation etc.)II* C(E'ICAL 'ET(OD

Alcohols, Aldehydes, 1alogens /)odine, %hlorine etc0,

-henols, 2ases and Surace 3 actie agents /soap,detergent0 etc.



(OT AIR OVEN !his is the most #idely used method o

Sterilization by Dr, het.

A holding period o /012C for o-e hour isused to sterilize glass#are, orceps, all3glass

syringes, s#abs etc.

2lass#are should be perectly dry beore being

placed in the oen. !est tubes and +as&s shouldbe #rapped in paper.

!he material should arranged so as to allo# ree

circulation o air in bet#een the ob"ects.



(ot ir ove- co-ti-ue3…..

)t should not be oerloaded.

)t must be ftted #ith a an to ensure eendistribution o air.

!he oen is usually heated by electricity #ithheating elements in the #all o the chamber.

!he oen must be allo#ed to cool slo#ly orabout t#o hours beore the door is opened,since the glass#are may crac& due to sudden or

uneen cooling.



(OT AIR OVEN



STERILI"ATION B+ 'OIST (EAT

'oist (et is 3ivi3e3 i-to 4 5etho3s6

'0 !emperature bello# '445%

E&# Psteuristio- of 5il7.

(0 !emperature at '445%

E&# Boili-& of 8ter.

*0 !emperature aboe '445% /Steam underpressure0

E&# Autoclve.



A!TOCLAVE)n its simplest orm, the laboratory autoclae consists o a

ertical or horizontal cylinder o gunmetal or stainlesssteel.

!he lid or door is made airtight.

!he autoclae has on its lid or upper side a discharge tap

or air and a saety ale that can be set to blo# o6 at anydesired pressure.

1eating is by gas or electricity.

Su7cient #ater is put in the cylinder, the material to besterilized is placed on the tray and the autoclae isheated.

!he lid is scre#ed tight.



Autoclve co-ti-ue3 …..

!he steam pressure rises inside and #hen it reaches the desiredset leel, the saety ale opens and the excess steam escapes.

rom this point, the holding period is calculated. !he holdingperiod is /9/2 C t /: ;ou-3 ;ressure for /: 5i-utes.

8hen the holding period is oer, the heater is turned o6 and theautoclae allo#ed to cool till the pressure inside is e9ual to theatmospheric pressure.

!he discharge tap is opened slo#ly and air is let into the

autoclae.

!he domestic pressure coo&er seres as a miniature autoclaeand may be used or sterilizing small articles in clinics.



A!TOCLAVE



FILTRATIONMembrane flters are #idely used #hich is made o

cellulose esters or other polymers. !heir aerage pore

diameters /A-D0 is 4.(( mm size.

iltration helps to remoe bacteria rom li9uids such assera and solutions o sugars or antibiotics used or

preparation o culture media.MembraneMembranefltersflters



RADIATION!#o types o radiation are used or Sterilization – :onionizing ; )onizing.

IONISIN<RADIATION Infrared andUltraviolet rays are ofthe nonionizing lowenergy type.

Applications:-

Clean surfaces likeinoculation hoods,microbiology & otherlaboratories, hospital

wards and operation

!rays, "amma rays &

Cosmic rays are highlylethal to all cells includingbacteria.

#hey have very highpenetrative power. #heydamage $% by variousmechanisms.

Applications:-Commercial plants usegamma radiation forsterilization of disposable

items such as plastics

NONIONISIN<NONIONISIN<

RADIATIONRADIATION



)II* C(E'ICAL A<ENTSSeeral chemical agents are used as antiseptics and

disinectants used in the microbiology laboratory and hospital.1o#eer little is &no#n about the mechanism o action o

many o these agents.A- i3el -tise;tic or 3isi-fect-t shoul3 be#$

1ae a #ide spectrum o actiity and must be e6ectieagainst all microorganisms, that is, bacteria including spores,iruses, protozoa and ungi<

1ae speedy action< 1ae high penetrating po#er< e stable.

:ot corrode metals< :ot cause local irritation or sensitization<

:ot interere #ith healing< :ot be toxic i absorbed intocirculation<

e cheap and easily aailable< e sae and easy to use.



ALCO(OLS

Ethyl alcohol /ethanol0, )sopropyl alcohol and Methyl alcoholare the most re9uently used.

!hey are used as Disinectants ; antiseptics. !heir mode oaction is denaturing bacterial proteins.

Methyl alcohol is e6ectie against ungal spores and is usedor treating cabinets and incubators a6ected by them.

ALDE(+DESormaldehyde is actie against the amino group in protein

molecule.

)t is used to presere anatomical specimens.

Suraces #hich hae disinected by this agent may gie o6an irritant apour or some time ater disinection.



(ALO<ENSIODINE

)odine is #idely used as a s&in disinectant /antiseptic0.

)t is actie against bacteria, ungi and iruses etc.or eg= etadine.

C(LORINE

%hlorine is used as disinectants in microbiologylaboratories, hospital, #ater supplies ; s#immingpools etc.

%hlorine is commonly used as hypochlorites.

%hlorine and hypochlorites are mar&edly bactericidal.

!hey hae a #ide spectrum o action against iruses.



P(ENOL -henol /carbolic acid0 is a po#erul and good generaldisinectants.

-henol is #idely used as disinectants or ariouspurposes in microbiology laboratories ; hospitals. >ysoland cresol are actie against a #ide range o organisms.

<ASES

FOR'ALDE(+DE <AS

!his is #idely employed or umigation o operation

theatres and other rooms. Ater sealing the #indo#s andother outlets, ormaldehyde gas is generated and letunopened or ?@ hours.



Co55o-l, use3 Che5icl A&e-ts i-

'icrobiolo&, lbortor, -3 (os;itl ALCO(OLALCO(OL FOR'ALDE(+DEFOR'ALDE(+DE

IODINEIODINE P(ENOLP(ENOL C(LORINEC(LORINE

DETER<ENTSDETER<ENTSL+SOLL+SOL

I f li l



I5;ort-ce of =ulit, co-trolco-ti-ue3>.E?5;le of @ulit, co-trol#$

Sterilitio- co-trol for (ot ir ove-

• !he spores o Clostridium tetani are used as test odry heat e7ciency.

• -aper strips impregnated #ith spores are placedin enelopes and inserted into suitable pac&s.

• Ater sterilization, the strips are remoed and

inoculated into thioglycollate or coo&ed meat mediaand incubated or sterility test under strictanaerobic conditions or fe days at *5%. ) there isno gro#th in the culture media, the hot air oen

#or&s properly.



LEARNIN< O!TCO'ES

At the e-3 of the lecture stu3e-t shoul3 be

ble to#

Defne Sterilization, Disinection and Antisepsis.

Describe the arious methods o physical andchemical methods o sterilization.

Select the ideal method o sterilization or di6erenttypes o culture media, laboratory e9uipments andsurgical instruments.

Explain #ith suitable examples the importance o9uality control or sterilization and disinection.



BOOS FOR REFERENCES

Te?t boo7 of 'icrobiolo&, b,A--th-r,- -3 P-i7ers.

A Te?t boo7 of 'icrobiolo&, b,

P.Ch7rbort,.

'e3icl 'icrobiolo&, b, J8et

'el-ic7 A3elber&s.

'e3icl 'icrobiolo&, b, 'urr,.

lec 9-sterilisation & disinfection.ppt

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