Medical Microbiology

GeneralEpidemiology 25

nizationresistance.Ontheotherhand,apotentiallyharmfuleffectofthe

normalfloraisthattheycanalsocauseinfectionsinimmunocompromised

individuals.

GeneralEpidemiology

&Withinthecontextofmedicalmicrobiology,epidemiologyisthestudyof

theoccurrence,causality,andpreventionofinfectiousdiseasesinthepopu-

lace.Infectiousdiseasesoccureithersporadically,inepidemicsorpandemics,

Table 1. 7 NormalMicrobialFlorainHumans

Microorganisms Microbiotopes

Skin Oral

cavity

Intes-

tine

Upperre-

spiratory

tract

Genital

tract

Staphylococci +++ + + ++ ++

Enterococci ++ +

a-hemolyticstreptococci + +++ + + +

Anaerobiccocci + + +

Pneumococci + +

Apathogenicneisseriae + + +

Apathogeniccorynebacteria ++ + + + +

Aerobicspore-formingbacteria (+)

Clostridia +++ (+)

Actinomycetes +++ +

Enterobacteriaceae (+) (+) +++ (+) +

Pseudomonas +

Haemophilus + ++ (+)

Gram-neg.anaerobes +++ +++ +++ +++

Spirochetes ++ + (+)

Mycoplasmas ++ + + ++

Fungi(yeast) ++ + + + +

Entamoeba,Giardia,Trichomonas + +

+++=numerous,++=frequent,+=moderatelyfrequent,(+)=occasionaloccurrence

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Kayser, Medical Microbiology © 2005 Thieme