Microbiology Flashcards
how is angular cheilitis sampled
sample with sterile swab and moistened with sterile water
what type of agar plate should be used when sampling angular cheilitis
non-selective agar - blood agar
name three oral diseases that the bacteria staphylococus aureus can be attributed to
angular cheilisi
mucositis
bone infections
how can staph aureus be transmitted
hands
fomites
what is a non-selective agar
blood agar
how can bacterial infections be identified
growth on selective agar
colony morphology
gram stain
what is an example of selective agar for staph aureus
manitol salt sugar
what is the difference between selective and non-selective agar
non-selective will grow everything - can give overall appearance of pathogens present
selective agar only grows a specific pathogen
what is the typical gram stain appearance of staph aureus
grape-like appearance
why is there a colour change in the mannitol salt sugar agar if staph aureus is present
staph aureus ferments mannitol which lowers the pH - there is a pH indicator in the mannitol which is what causes the colour change
what colour does staph aureus turn mannitol agar
yellow
name three identifiable features of staph aureus’ colony morphology
round
convex
1-4mm in diameter with sharp border
what is the coagulation test
adding the suspected staph aureus to a test which then clumps
is staph aureus coagulase positive or negative
positive
what is the common microbe used that will not cause colour change on mannitol agar and is coagulase negative
staph. epidermitis
what are the two antibiotic susceptibility tests
discs on an agar plate
e-test strip - minimum inhibitory conc = 0.5mg/L
what are the difference between prokaryotes and eukaryotes
prokaryotes = bacteria
eukaroytes = our cells
name key anatomical features of a bacterial cell
outer capsule
cell envelop
bacteria flagellum
circular stranded DNA and ribosomes
Pili (fimbriae)
what aids attachment of bacteria to oral surfaces
pili (fimbriae)
name virulence factors of pili (fimbriae)
adhesion
name virulence factor of flagella
chemotaxis and penetration of mucus
what is the general rule for when metronidazole is used
gum infections because it targets anaerobes
what is the general rule for when PenV is used
teeth because specific for staph/ strep
what occurs in type B vacuum type sterilisers
pretreatment - air sucked out
sterilisation
posttreatment - drying by releasing the air
name the stages of gram stain reaction
flood with crystal violet - all cells take up dye]
flood with iodine - all cells appear blue- black
decolourise with acetone - gram +ve cells retain dye and gram -ve cells are decolourised
counterstain with red dye - gram +ve appear blue/black and -ve appears red
what colour are gram -ve cells after gram stain
red
what colour are gram +ve cells after gram stain
blue/ black
what does the crystal violet stick to in gram +ve cells
peptidoglycan layer in the cell wall
what is present in the peptidoglycan layer in gram +ve cells
penicillin binding proteins - penicillin antibiotic can bind here and stops further cross linking
how does the exotoxin leukocidin cause an inflamamtory reaction
secreted from staph aureus
assemble on polymorphonuclear white cell membranes (PMN)
cause PMN lysis
lysed PMNs cause inflammatory response and eventually tissue necrosis
what is an example of an endotoxin
LPS - lipopolysaccharide
name the links of the chain of infection in the correct order
infectious agent
reservoir
portal of exit
mode of transmission
portal of entry
susceptible host
explain the infectious agent
micro-organism that can cause infection
explain the reservoir
where the infectious agent lives and thrives
name actions we can use to break chain of infection
standard infection control precautions (SICPs)
when should SICPs be used
all staff in all healthcare settings whether infection is known to be present or not
name the SICPs most relevant to dentistry
hand hygiene
PPE
respiratory and cough hygiene
safe management of blood and body fluid spillages
safe disposal of waste
safe management of care environment
safe management of care equipment
occupational safety - prevention and exposure management
how should blood and body fluid spillages be managed
PPE worn
organic matter removed with disposable absorbent towel
apply sodium hypochlorite granules
remove granules with disposable scoop
clean using water and general purpose detergent
dispose of waste
perform hand hygiene
name the agents used when dealing with a spillage
sodium hypochlorite
dichloroisocyanrate
what is the contact time for chlorine releasing agents
3 minutes
according to manufacturer’s instructions
at what concentrations should these granules be used
10, 000 ppm available chlorine
give examples of waste disposed of in the orange waste stream
apron
gloves
mask
visor
gauze
give examples of waste that goes into the black waste stream
hand hygiene paper towels
instrument wrapping that is uncontaminated
when should the temporary closure mechanism used on a sharps box
when the container is left unattended or not in use
how is the temporary closure mechanism engaged
press the lid down until you hear one click
two clicks for permanent closure
what waste should be disposed of in orange sharps box stream
k files
needles
matrix bands
what waste should be disposed of in blue topped sharps box stream
local anaesthetic cartridges that aren’t empty
who is responsible for the disposal of sharps
the user/ operator
who is responsible for carrying out a risk assessment following a sharps injury
supervising clinician
clinician
DN team leader
named nurse
what action should be taken if you receive a sharps injury and your patient refuses consent for bloods to be taken
same protocol is observed whether patient gets bloods taken or not
contact occupational health and get your own bloods taken once risk assessment carried out
what procedure must be followed if you receive a sharps injury while treating a patient
stop what you’re doing
inform the patient
make the sharp safe
first aid - encourage bleeding
notify supervising clinician
risk assessment carried out by appropriate person
contact occupational health
consent patient for bloods
paperwork
datix
name the online system used for recording accidents/ incidents or near misses within the GDH
DATIX
what happens to patient’s risk assessment paperwork after a sharps injury
must be destroyed after occupational health have been called
must not be written in the patient’s notes
what are the five WHO moments of hand hygiene
before you touch a patient
before clean/ aseptic procedure
after procedure or body fluid exposure risk
after you touch a patient
after touching a patient’s surrounding
what goes into the red top white bottom waste stream
amalgam capsules
extracted teeth with amalgam
left over amalgam
what goes into the red top yellow bottom waste stream
extracted teeth with no amalgam restorations
what is antimicrobial resistance
antimicrobials become ineffective as the organisms you are trying to kill go through genetic changes leading to resistance
how do bacteria grow
by horizontal gene transfer
name three issues with antimicrobial resistance
causes deaths
simple infections become difficult to treat
stagnant development of new antibiotics
who does antimicrobial resistance affect
anyone needing routine operations (they will be given prophylactic antibiotics to reduce risk of post-op infections)
immunocompromised people
can effect anyone potentially
name four ways of tackling antimicrobial resistance
drug development
alternative therapies
prevention
prescribing
name a gram positive cocci and a disease it causes
strep. mutans
dental caries
name a gram positive bacilli and a disease it causes
c. tetani
tetanus
name a gram negative cocci and a disease it causes
N meningitidis
meningitis
what shape of bacteria is associated with ulcerative gingivitis
spiral
name gram negative bacilli and a disease it causes
prevotella intermedia
periodontal disease
name three general properties of viruses
small size
they have RNA or DNA genome
metabolically inert
what is a virion
complete virus particle
what is the viral structure
envelope - lipid membrane
capsid - protein shell
name the 6 key stages in viral replication
attachment
penetration
uncoating
synthesis of viral components
assembly
release
what are the effects of virus on cells
cell death (HSV I)
transformation (HPV)
latent infection (HSV I)
examples of virus transmission
inhalation via respiratory tract
ingestion via GIT
inoculation
sexually
name types of specimens you can take for viral investigation
swabs
faeces
aspirates
plasma
CSF
urine
what antibody is produced first in the acute phase of infection
IgM
what antibody appears later in viral infection (2 weeks into infection)
IgG
what type of viruses are influenza
RNA viruses
what is antigenic drift
minor change
point mutations
causes epidemics
what is antigenic shift
a major change in antigen structure
can result in pandemics
only A type influenza is subject to this
what are prion diseases
transmissible spongiform encephalopathies - fatal neurological disease
accumulation of abnormal form of the prion protein - no immune response
what is rare about prions and why may it be harder to sterilise
it is devoid of nucleic acid
what are the three types of prion disease
infectious
genetic
sporadic
what is CJD
Creutzfeldt Jackob’s disease
why is vCJD relevant to dentistry
prion protein difficult to clean from instruments
residual infectivity can survive steam sterilisation
has an incubation period of decades
what should happen to instruments used on a patient with CJD for a dental procedures
as dental procedures are considered low risk, the instruments are put through the regular disinfection and sterilisation regime and re-used
name surface associated virulence factors of bacteria
pili - used in adhesion and can be antiphagocytotic
what colour will staph aureus turn the mannitol agar plate if present
yellow
what severe clinical complication is the endotoxin LPS associated with
sepsis
what are the five cardinal signs of infection/ inflammation
redness, swelling, pain, heat, loss of function
