Medical Microbiology

LaboratoryDiagnosis 215

&Chemicalcharacteristicshavelongbeeninusetoidentifybacteria,e.g.,

indetectionofantigenstructures.Moleculargeneticmethods(seebelow)

willplayanincreasingroleinthefuture.

Table3. 8 CharacteristicsUsefulinIdentificationofBacteria

Morphologicalcharacteristics

Form(sphere,rod,spiral)

Size;pseudogroupings(clusters,chains,diplococci)

Staining(Gram-positive,Gram-negative);flagella(presence,arrangement);

capsule(yes,no);spores(form,withincellformation)

Physiologicalcharacteristics

Respiratorychainenzymes(oxidases,catalases)

Enzymesthatbreakdowncarbohydrates,alcohols,glycosides

(e.g.,betagalactosidase)

Proteinmetabolismenzymes(e.g.,gelatinase,collagenase)

Aminoacidmetabolismenzymes(e.g.,decarboxylases,deaminases,urease)

Otherenzymes:hemolysins,lipases,lecithinases,DNases,etc.

Endproductsofmetabolism(e.g.,organicacidsdetectedbygaschromatography)

Resistance/sensitivitytochemicalnoxae

Characteristicsofanabolicmetabolism(e.g.,citrateassolesourceofC)

Chemicalcharacteristics

DNAstructure(basesequences)

Structureofcellwallmurein

Antigenstructure:finestructuresdetectablewithantibodies

(e.g.,flagellarproteinorpolysaccharidesofthecellwallorcapsule)

Fattyacidsinmembranesandcellwall;analysisusingdifferentchromatographic

methods

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Kayser, Medical Microbiology © 2005 Thieme