M3 Flashcards
what is Koch’s postulate?
the microorganism is present in every case of the disease but absent from healthy organisms
suspected organism must be isolated and grown in a pure culture
define mutalistic
relationship, where host and organism gain mutual value
define parasitic
live on or in living creatures causing harm/damage to the host
benefits of mutualism?
- organisms can produce nutrients or vitamins
- can exclude access/colonisation by pathogen (colonisation resistance)
where is lactobacillus spp. present in oral cavity?
ONLY aproximal (majority is approximal and subgingival)
where is fusobacterium spp.present in the oral cavity?
approximal and subgingival
spirochaetes spp.?
subgingival
define pathogen
A microbe capable of causing host damage.
define virulence factor
a component of a pathogen that damages the host. this can include components essential for viability
Virulence factor - Adhesin
enables binding of the organism to host tissue
VF - invasin cell/ tissue
enables the organism to invade a host
VF -impedin
enables organism to avoid host defense mechanisms
VF - aggressin
causes damage to the host directly
VF - modulin
induces damage to the host indirectly
how can one be protected against Kochs postulates?
antibodies directed against the gene product protect the host
what are the limitations for carrying out Kochs postulate?
- organisms cannot be cultured
- organism is a human pathogen
what pathogens must cause disease for transmission?
obligate pathogens
which pathogens do not have to cause disease for transmission?
opportunistic
which pathogen hinders disease or prevents transmission?
accidental pathogens
define epidemiology?
the study of the occurrence, spread and control of disease
consider for any organism
- infective dose
- virulence of the organism
- hosts status (resistance)
define prevalence (epidemiology)
proportion of population affected
define sporadic
occurs at irregular intervals or only in a few places
define endemic
restricted to a certain place ie africa
define epidemic
widespread ocurrence of infectious disease at a particular time
define pandemic
outbreak of disease over the whole world
