Medical Microbiology

250 4 BacteriaasHumanPathogens

mustbeadministeredtoseverelyinjuredpersonswithinsufficientvaccina-

tionprotectionorifthebasicimmunizationhistoryisuncertain.

Clostridiumbotulinum(Botulism)....................

Foodbornebotulismisnotaninfection,butratheranintoxication,thatis,the

toxinisingestedwithfood.Infantbotulisminvolvesingestionofsporesand

woundbotulismresultsfrominfectionofawound.

Toxin.Theverystrongbotulinumneurotoxinisaheat-labileprotein.Seven

toxigenictypesaredifferentiated,eachofwhichproducesanimmunologi-

callydistinctformofbotulinumtoxin.TypesA,B,andEcausepoisoning

inhumans.Thetoxinisametalloproteasethatcatalyzestheproteolysisof

componentsoftheneuroexocytosisapparatusinthemotorendplates,result-

inginflaccidparalysisofthemusculature.

Pathogenesisandclinicalpicture.Classicbotulismresultsfromeating

spoiledfoodsinwhichthetoxinhasbeenproducedunderanaerobiccondi-

tionsbyC.botulinum.Thetoxinisabsorbedinthegastrointestinaltract,and

thentransportedtotheperipheralnervoussysteminthebloodstream.

Withinamatterofhoursordaysparalysissymptomsoccur,especiallyin

thenervesofthehead.Frequentsymptomsincludeseeingdouble,difficulty

swallowingandspeaking,constipation,anddrymucosa.Lethalityratesrange

from 25 – 70 %,dependingontheamountoftoxiningested.Deathusuallyre-

sultsfromrespiratoryparalysis.Woundbotulismresultsfromwoundinfec-

tionbyC.botulinumandisveryrare.Infantbotulism,firstdescribedin 197 6,

resultsfromingestionofsporeswithfood(e.g.,honey).Probablyduetothe

conditionsprevailingintheintestinesofinfantsuptotheageofsixmonths,

thesporesareabletoproliferatethereandproducethetoxin.Thelethalityof

infantbotulismislow(< 1 %).

Diagnosis.Basedontoxindetectionbymeansofthemouseneutralization

test.

Therapy.Urgentadministrationofapolyvalentantitoxin.

Epidemiologyandprevention.Botulismisararedisease.Exposuretothe

toxinisafoodhygieneproblemthatcanbeavoidedbytakingappropriate

precautionsduringfoodproduction.Aerosolizedbotulinumtoxinhasbeen

usedexperimentallyasabioweapon.

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Kayser, Medical Microbiology © 2005 Thieme