Microbiology Flashcards
forms of oral candidosis
pseudomembraneous
= thrush
erythematous
- atrophic, denture
hyperplastic
= leukoplakia
angular cheilitis
what is the mode of action of azoles
inhibits fungal enzymes
inhibits ergosterol synthesis which is a vital component of fungal cells
makes less effective at regulating ion/molecule transport, disrupts essential cellular processes, compromised cell viability
class of antifungals commonly used to treat pt with recurrent oral candidosis
azoles
resistance mechanisms of candida that render it resistant to azoles
alters target site, reducing binding affinity of azoles to the enzymes and makes it resistance
efflux pump regulations to pump the drug outwith the cell meaning it cannot work and reduce concentration
biosynthesis pathway alterations
upregulation of stress responses
name one species resistant to azoles
candida glabrata
how to differentiate candida albicans and glabrata
albicans can form hyphae, glabrata cannot
characteristics of biofilm extracellular matrix that confers resistance from antimicrobial agents
physical barrier
slowed diffusion
chemical sequestration
altered environment [pH]
gene transfer
efflux pumps
name important bacteria clearly implicated in periodontal disease, based on Socranksys red disease complex
p.gingivalis
t.forsythia
t.denticola
name bacteria associated with caries development
s.mutans
actinomyces
lactobacilus
what key features enable carcinogenic organisms to stick to enamel surfaces and autoggregate and to survive within an acidic envrionment
adhesion
production of EPS which allow sticking
biofilm formation
glucan production
acid tolerance and production
name systemic diseases that are associated with periodontal biofilms
CVD
diabetes
cystic fibrosis
rheumatoid arthritis
alzheimers
pancreatic cancer
what term can be used to describe the collective group of microorganisms within the oral cavity
AND
what are they referred to when they are attached to a surface
oral microbiome
oral biofilms
list the key microbial stages of caries plaque formation
formation of pellicle which is a thin protein film which covers tooth surface in contact with saliva
early colonisation where s.mutan etc adhere to this layer and metabolise dietary sugars into acids, leading to enamel demineralisation and initiation of carious lesions
biofilm maturation where bacterial populations grow and form biofilm structure known as plaque
environment becomes increasingly acidic, dissolution of hydroxyapatite, demineralisation and progression of plaque formation
name bacterium associated with secondary endodontic infections
p.endodontalis
virulence factors used by s.mutans to influence enamel dissolution
acid production
extracellular polysaccharide production [adhesion]
acid tolerance
what is the key virulence factor of p.endodontalis
production of endotoxins - induces inflammation, triggers immune response, contributes to periapical tissue destruction
[LPS]
proteolytic enzymes - tissue destruction, affects host defense
why is it difficult to determine causality from a specific bacteria in endodontic infections
polymicrobial nature
biofilm formation
sampling tissue
host response variability
what culture independent technique cold be used to assess changes in oral microbial populations following antibiotic exposure
16s rRNA gene sequencing
limitations of 16S rRNA gene sequencing
cannot reliably differentiate between closely related species or strains
PCR bias
what antimicrobial is primarily used to disinfect the root canal
NAOCl
sodium hypochlorite
factors which cause candidosis
immunocompromised, immunosuppressive drugs, advanced HIV, intra-abdominal surgery, central venous catheter, broad spectrum antibiotics, diabetes, trauma pt, burn unit, long term corticosteroid use
name the organism and virulence factor which causes candidosis
candida albicans
hyphae, adhesions, hydrolytic enzymes
biofilm formation
antifungal resistance
key stages in biofilm formation
adhesion
colonisation
maturation
complex community
dispersal
EPS production
how would you test for candida albicans and suggest a lab identification method
take a swab and culture on Sobourads agar
if present - white, creamy, yeast colonies
germ tube formation
