Medical Microbiology

Salmonella(Gastroenteritis,TyphoidFever,ParatyphoidFever) 285

Pathogenesisandclinicalpictures.Salmonellaeareclassifiedaseitherty-

phoidorentericregardingtherelevantclinicalpicturesandepidemiologies.

Itisnotknownwhytyphoidsalmonellaeonlycausesystemicdiseaseinhu-

mans,whereasentericsalmonellainfectionsoccurinanimalsaswellandare

usuallyrestrictedtotheintestinaltract.

&Typhoidsalmonelloses.Attachmentoftyphoidsalmonellaetocellsof

thejejunum(Mcells).Invasionbymeansofendocytosis,transfer,andexo-

cytosis.Phagocytosisinthesubserosabymacrophagesandtranslocationinto

themesentericlymphnodes.Proliferationoccurs.Lymphogenousandhema-

togenousdissemination.Secondaryfociinthespleen,liver,bonemarrow,bile

ducts,skin(roseola),Peyer’spatches.

Manifestillnessbeginswithfever,risinginstagesthroughoutthefirstweek

to39/40/4 18 C.Furthersymptoms:stupor(typhos[greek]=fog),leukopenia,

bradycardia,splenicswelling,abdominalroseola,beginninginthethirdweek

diarrhea,sometimeswithintestinalbleedingduetoulcerationofthePeyer’s

patches.

&Entericsalmonelloses.Attachmenttoenterocytesoftheileumandcolon.

Invasionofmucosainducedbyinvasinproteinsonthesurfaceofthesalmo-

nellacells.Persistenceinepithelialcells,possiblyinmacrophagesaswell.

ProductionofSalmonellaenterotoxin.Localinflammation.Manifestillness

usually beginssuddenly withdiarrhea andvomiting,accompaniedin

somecasesbyhighfever.Thesymptomsabateafterseveraldayswithoutspe-

cifictherapy.Incasesofmassivediarrhea,symptomsmaybeobservedthat

resultfromthelossofwaterandelectrolytes(Table4. 8 ).

Diagnosis.Themethodofchoiceisdetectionofthepathogensincultures.

Selectiveindicatormediumsareusedtoisolatesalmonellaeinstool.Identi-

ficationisdoneusingmetabolicpatterns(seeFig.3. 36 ,p. 21 4).Serovarclas-

sificationisdeterminedwithspecificantiseraintheslideagglutinationtest.

Culturingrequiresatleasttwodays.Typhoidsalmonellosescanbediagnosed

indirectlybymeasuringthetiterofagglutinatingantibodiestoOandHanti-

gens(accordingtoGruber-Widal).Toprovideconclusiveproofthetitermust

risebyatleastfourfoldfrombloodsampledatdiseaseonsettoasampletaken

atleastoneweeklater.

Therapy.Typhoidsalmonellosesmustbetreatedwithanti-infectiveagents,

whereassymptomatictreatmentwillsufficeforentericinfections.Sympto-

matictreatmentencompassesslowingdownintestinalactivity(e.g.,with

loperamide)andreplacingfluidandelectrolytelossesorallyasrequired

(WHOformula:3.5gNaCl,2.5gNaHCO 3 , 1 .5gKCl, 20 gglucoseperliterof

water).

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Kayser, Medical Microbiology © 2005 Thieme