Microbiology Flashcards
what colour does gram positive stain
black/purple
what colour does gram negative bacteria stain
do not retain the stain so remain red
compare the structure of ram negative and positive bacteria and relate to the gram stain
+ve = 1 membrane with a thick layer of peptidoglycan (murien) cell wall
-ve = 2 membranes separated by a thin layer of peptidoglycan cel wall. Outer membrane has lipopolysaccharide component
gram negatives very thin cell wall doesnt retain the purple crystals used in the gram stian so do not stain
what are kochs consulates
The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.
The microorganism must be isolated from a diseased organism and grown in pure culture.
The cultured microorganism should cause disease when introduced into a healthy organism.
The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
why can most diseases not be researched with kochs constulates
kochs consulates refers to a single microbe causing the problem e.g. TB or HIV
most dental problems are polymicrobial so we cannot isolate the ‘single’ microbe and the addition of that ‘single’ microbe wouldn’t necessary cause disease in a healthy patient
what type of bacteria do we find in established plauqe
gram positive aerobes attached at the pellicle
gran negative anaerobes on overlying plauqe
why is it difficult to examine deep gingival bacteria
to get to deep gingival bacteria we must go through the supragingival bacteria. very hard to isolate the deeper microbes
what is P.Gingivalis classed as and why
keystone pathogen
in mouse models, introduction of P.Gingivlais shifts the Whole population from non-pathogenic to pathogenic community
what is the function of P.Gingivlas and is it found in high numbers
shifts the population from non-pathogenic to pathogenic
keystone pathogen
usually found in low numbers
Releases gingapins that cause pain and tissue loss
what are three major bacteria found in periodontal disease and what type of bacteria are they
P.Gingivlis
T.Denticola
Ta.Forsythia
red complex bacteria
what complex causes necrotising gingviits
fuso-spirochaetal complex
what causes necrotising gingivitis
deep invasion of fuso-spirochaetal complex
depression of host response by smoking, malnutrition, stress
depression of blood supply to teeth and soft tissues causing necrosis
how do Streptococci move through dentine and how could we prevent their movement
attach to collagen I through antigen protein I/II in dentinal tubules
slowly move along dentinal tubules by fluid flow and growth
remove of protein I/II
which bacteria are common in enamel caries
Strep. Mutans
Lactobacilli
what bacteria are prominent in necrotic pulp
Strep. Mutans Fusobacterium Black-Pigmented Anaerobes P.gingivalis P.Endodontalis
