Medical Microbiology

Enterobacteriaceae,Overview 281

Antigenstructure.ThemostimportantantigensoftheEnterobacteriaceae

are:

&Oantigens.Specificpolysaccharidechainsinthelipopolysaccharidecom-

plexoftheoutermembrane(p. 1 56).

&Hantigens.Flagellarantigensconsistingofprotein.

&Kantigens.Linearpolymersoftheoutermembranebuiltupofarepeated

seriesofcarbohydrateunits(sometimesproteinsaswell).Theycancoverthe

celldenselyandrenderthemOinagglutinable(p. 1 55).

&Fantigens.Antigensofproteinattachmentfimbriae.

Escherichiacoli

Fig.4. 17 aGramstainingofaurine

sediment preparation: rounded

gram-negativerods,somecoccoid.

Clinicaldiagnosis:acutecystitis.

bCultureonendoagar,acombined

selective/indicatormedium.Thered

colorofthecolonyandagarindi-

catesthelactosebreakdownpro-

cess.

4

Kayser, Medical Microbiology © 2005 Thieme