Alexander Fleming 3.ppt

7/25/2019 Alexander Fleming 3.ppt

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Alexander Fleming and Penicillin:

The Accidental Discovery?





The Discovery o! $yso)yme

• n *+,, Fleming describedlyso)yme

• $yso)ymes are en)ymes

present in diverse materialssuch as tears" mucous" eggwhites etc that cause

bacteria to lyse

• -is lyso)yme research grew

out o! his interest inshowing the ine!!ectivenesso! chemical antiseptics totreat in!ection



Fleming Disagrees

• .ased on $ister&s theory" physicians o! the time

generally believed that i! antiseptics 'illed germs

they were there!ore use!ul in treating woundin!ections

• Fleming strongly disagreed with this idea

• Fleming and his mentor" /right" argued that the

best way to treat wound in!ections was to enhance

the body&s natural immune response



A 0evolutionary Approach to

/ound 1are• Fleming noted that"

although antiseptics 'ill

bacteria" they also 'ill

leu'ocytes o! the immune

system more rapidly than

they 'ill invading bacteria

• They recommended using

saline solution to cleansewounds instead o!

antiseptic solutions



$yso)yme 0esearch

• Few accepted Fleming&s recommendation !or woundcare

• This re2ection !ueled Fleming&s search !orantibacterial agents and particularly his interest inlyso)yme

• $i'e leu'ocytes" lyso)yme was an endogenous way

to treat in!ections• Fleming believed that the best way to treat woundin!ections was to enhance the body&s naturalimmune response



$yso)yme continued• n *+,, Fleming described

lyso)yme when he notedthat lyso)yme(containingmaterial would inter!ere

with the growth o! bacterial cultures

• Fleming !ound that aculture o! his own nasalmucous inhibited thegrowth o! staph cultured!rom that same mucous



$yso)ymes continued

• Fleming was !ortunate in that the strain o!

bacteria he was culturing was particularly

sensitive to lyso)yme

• -owever" Fleming was disappointed in that

the bacteria most susceptible to lyso)yme

were those that aren&t as in!ectious inhumans



Discovery 3 3 3

• n *+,4 a!ter returning to his lab !ollowing a twowee' vacation Fleming encountered the place in itsusual disarray

• Fleming had a inoculated a number o! petri disheswith staphylococci prior to leaving on vacation

• -e hadn&t placed them in an incubator because he'new that the staph would su!!iciently multiply overthe long vacation

• $ittle did he 'now that penicillium mold grows wellat room temperature



Fleming&s observation• Fleming returned to his lab to

!ind many o! his culture platescontaminated with !ungus

• -e immediately started

preparing to clean all his plates but it happened that a!ormer member o! his lab wasvisiting that day

• Fleming too' some o! thecontaminated cultures to showhis visitor and that&s when henoticed the inhibition )onearound the !ungus



Fleming&s %bservation cont3

• Fleming was not very

'nowledgeable about

!ungi but 'new thatthe mold in his dish

was a species o!

penicillin

• 5ventually determinedto be Penicillium

notatum



Accidental?

• Fleming&s observation was made under

some accidental circumstances but clearly

made sense in light o! Fleming&s research bac'ground

• Fleming had the sophistication to reali)e

that anti(bacterial agents existed 6 this viewwas really !ueled by his bac'ground in

lyso)yme research



The Power o! Penicillin

• t was obvious to

Fleming that penicillin

was much more power!ul than

lyso)ymes because his

crude extracts could be

diluted *777 times andstill be e!!ective in

'illing bacteria



*+,+ Paper

• n *+,+ Fleming published a paper detailing

his discovery

• This was also a crucial moment because his

ideas reached a large audience

• .ut it wasn&t until ten years later that other

scientists began trying to use penicillin totreat clinical disease



*+,+(*+8*

• Fleming continued to wor' on and o!! with penicillin during this time but was never able to produce it in #uantities necessary !or practicaltesting or applications

• Fleming !ound that many o! his cultures wereunstable and stopped producing mold a!ter eightdays

• nterestingly" Fleming initially conceived o! penicillin as a topical agent and did not thin' o!using it as an in2ectable or ingestible medication



Fleming&s 0esearch• Fleming did in2ect one rabbit and one mouse with

penicillin to ma'e sure there were no ill e!!ects 9therewere none but never in2ected these animals with asimultaneous bacterial strain

• ronically" even though Fleming was an expert atadministering intravenous salvarsan to syphilis patients"he only thought o! penicillin as an external germicide

• Fleming" in his *+,+ article" compares penicillin&s

e!!ects to carbolic acid 9anti(septic !avored by $isterand his !ollowers !or treating wound in!ections



Production Accelerates

• From ;anuary to <ay

*+=8 only =77 million

units o! penicillin had been made

• .y the time the war

ended >S companies

were ma'ing @7 billion units a month



Awards

• Fleming and Florey

were 'nighted in *+==

• 1hain was later'nighted in *+@

• The Bobel Pri)e in

Physiology or

<edicine was awarded

to Fleming" Florey and

1hain in *+=@

Documents

Alexander Fleming 3.ppt