bacte lec (definition of terms)

Saprophytes

these microorganisms are nonpathogenic; their natural habitat is dead organic matter

parasites

unicellular or metazoan organism living in or on an organism of another species (host) on the expense of the host

commensals

normal inhabitants of skin and mucosa; the normal flora is thus the total ——- population

pathogenic microorganisms

classic disease-causing pathogens

opportunist or facultatively pathogenic microorganisms

can cause disease in immunocompromised individuals given an “oportune” situation; theseare frequently germs of the normal flora or occasionally from the surrounding environment, animals or other germ carriers

pathogenicity

capacity of a pathogen species to cause disease

virulence

sum of the disease-causing properties of a strain of a pathogenic species

incubation period

time between infection and manifestation of disease symptoms; this specific disease characteristic can be measured in hours, days, weeks, or even years

prepatency

a parasitological term; time between infection and first appearance of products of sexual re-production of the pathogen (e.g., worm eggs in stool of a host with helminthosis)

infection spectrum

the totality of host species “susceptible” to infection by a given pathogen

minimum infective dose

smallest number of pathogens sufficient to cause an infection

mode of infection

method or pathway used by pathogen to invade

contamination

microbiological presence of microorganisms on objects, in the environment, or in samples for analysis

colonization

presence of microorganisms on skin or mucosa; no penetration into tissues; typical of normal flora; pathogenic microorganisms occasionally also show colonization behavior

infection

invasion of a host organism by microorganisms, proliferation of the invading organisms, and host reaction

inapparent (or sub clinical) infection

infection without outbreak of clinical symptoms

infectious disease (or clinical infection)

infection with outbreak of clinical symptoms

probability of manifestation

frequency of clinical manifestation of an infection in disposed individuals

endogenous infection

infection arising from the colonizing flora

exogenous infection

infection arising from invasion of host by microorganisms from sources external to it

nosocomial infection

infection acquired during hosptalization

local infection

infection that remains restricted to the portal of entry and surrounding area

generalized infection

lymphogenous and/or hematogenous spread of invading pathogen starting from the portal of entry; infection of organs to which pathogen shows a specific affinity

sepsis

systematic disease caused by microorganisms and/or their toxic products; there is often a localized focus of infection from which pathogens or toxic products enter the blood stream continuously or in intermittent phases

transitory bacteremia/viremia/parasitemia

brief presence of microorganisms in the bloodstream

superinfection

occurrence of a second infection in the course of a first infection

relapses

series of infections by the same pathogen

reinfection

series of infections by different pathogens