Microbes Flashcards
define infectivity
organism’s ability to infect a host
results in carriage or symptomatic disease
define pathogenicity
organism’s ability to cause disease
depends on host-pathogen interactions
considers specificity to species, whether opportunistic pathogen
define virulence
organism’s ability to multiply
– degree of pathology caused by organism as reflected by ability to multiple within host
a primary pathogen is
infectious, pathogenic, virulent
bacteria may be classified according to whether? (7)
gram positive or negative gram stainable vs non stainable shape- cocci vs rods aerobic vs anaerobic extra vs intracellular culturable vs non culturable fermenters vs non fermenters
fungi may be classified by?
yeast vs mould vs dimorphic fungi
site and mode of infection (subcut, cutaneous, systemic)
yeasts usually endogenous
moulds usually exogenous
very few fungi are primary pathogens
viruses may be classified by?
acute vs chronic vs latent
dna vs rna
blood borne vs not
predominant form of manifestation- resp, gastro, rash etc
parasites are classified by?
ectoparasites= on skin/hair eg scabies, lice endoparasites= on mucusal surfaces/tissues
endoparasites include:
- protozoa- single cell, eg malaria
- helminths- worms, eg tape worm
do they have a nuclear membrane?
virus bacteria fungi protozoa helminths
no- virus no- bacteria yes- fungi yes-protozoa yes- helminths
do they have an external cell wall (made of)
virus bacteria fungi protozoa helminths
no- virus yes, peptidoglycan- bacteria yes, chitin- fungi no- protozoa no- helminths
how do they replicate
virus bacteria fungi protozoa helminths
virus- within host cells
bacteria- in&out of host cells, binary fission
fungi- in&out host cells, binary fission, sexually
protozoa- in&out host cells, binary fission, sexually
helminths- out of host cells, sexually
a virus consists of? features?
consist of a protein, +/- a lipid coat, surrounding a core of genetic material- either RNA or DNA
genome may be single or double stranded
can only replicate inside living cell, so obligate intracellular parasite
family -viridae
