Microbiology Flashcards
What is being described?
- found in the canals of teeth
- very difficult to destroy
- infect nerve cells: transmissible spongiform encephalopathy, Creuzfeld Jakob disease
- no DNA or RNA
- promotes refolding of native proteins
prions
What are 5 oral factors that affect oral microbiology?
- anatomy - alignment of teeth
- saliva
- gingival crevicular fluid
- microbial factors
- local environment
(moisture, pH, antimicrobial therapy, diet, fluoride)
Which bacteria can be found in deep perio pocketing?
porphyromonas
Which bacteria is the following?
Gram-negative, facultative anaerobe, nonmotile bacterium that is often found in association with localized aggressive periodontitis, a severe infection of the periodontium. It is also suspected to be involved in chronic periodontitis.
aggregatibacter
Which fungi bacteria is especially associated with dentures and is a yeast bacteria?
Candida albicans
Which fungi bacteria is the following?
- only tend to cause problems for immunocompromised patients
filamentous and dimorphic fungi
What are 4 examples of how to get oral specimens?
- aspirate of pus for purulent infection
- deep gingival smear for ANUG
- rise for quantifying oral candida
- paper point samples for periodontal pockets for molecular identification (gene probing using PCR)
What are 3 methods of lab analysis?
- non-cultural methods (microscopy, gene probing)
- cultural methods (cultured cells to grown viruses)
- immunological methods (identify organisms using antibodies)
Why is microbiological sampling not commonly used in dentistry?
- hard to avoid contamination of samples in oral specimens
- infections need to be treated quickly to avoid infection getting worse so therefore cannot wait for results to return
- can be hard for patient with facial swelling to tolerate rubber dam
When should oral microbiological culture be taken?
if antimicrobial resistant infection is suspected
or
sometimes before prescribing co-amoxiclav or clindamycin
What are the 2 methods of susceptibility testing?
- minimum inhibitory concentrations (MIC)
- minimum bactericidal concentration (MBC)
What is the benefit of being able to interpret microbiology report?
evidence to help weight up the risks and benefits of treatment options
Which bacteria is the following?
- thought to be involved with initiation
- responsible for causing caries
- gram positive cocci
- crystal violet entrapped in thick peptidoglycan cell wall
- safranin pink not visible
streptococcus mutans
Which bacteria are the following?
- pioneer organism in advancing form of caries
- thought to be involved with deeper lesions
- some of this bacteria has been associated with cases of dental caries (cavities). Lactic acid can corrode teeth, and the Lactobacillus count in saliva has been used as a “caries test” for many years. Lactobacilli characteristically cause existing carious lesions to progress, especially those in coronal caries
lactobacillus spp
Which bacteria is the following?
- found in plaque
- associated with root caries
- a colonial bacterium which can be found as a commensal in the mouth and tonsillar crypts
actinomyces israelii
Which bacteria is the following?
- found in the bottom of periodontal pockets
- Gram-negative, facultative anaerobe, nonmotile bacterium that is often found in association with localized aggressive periodontitis, a severe infection of the periodontium. It is also suspected to be involved in chronic periodontitis
aggregatibacter actinomycetemcomitans
Which bacteria is the following?
- Gram-negative, rod-shaped, anaerobic, pathogenic bacterium
- it is found in the oral cavity, where it is implicated in periodontal disease
porphyromonas gingivalis
Which bacteria is the following?
- the word planktonic is widely used in microbiology for organisms that are floating in bodies of water
- a Gram-positive round-shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin
staphylococcus aureus - planktonic
What is being described?
- a complex structure adhering to surfaces that are regularly in contact with water, consisting of colonies of bacteria that secrete a mucilaginous protective coating in which they are encased
- examples: inside of fish tank, sink U bend, dental plaque, dental unit water lines
biofilms
How is supra gingival oral biofilm disrupted?
tooth brushing
How is sub gingival oral biofilm disrupted?
ultrasonic debridement
What are the 5 stages of biofilm formation?
- initial attachment
- irreversible attachment
- maturation I
- maturation II
- dispersion
What percentage of dental plaque is made up of organic components?
30%
Which tooth surfaces are more protected from host defences and cleaning?
- occlusal fissures
- contact points
- buccal and palatal smooth surfaces
Which patients are more likely to form plaque more quickly?
- those with reduced salivary flow
- reduced muscular movements
- desquamation - lower rate
What are the 4 stages of biofilm formation?
- pellicle formation
- early colonisers
- late colonisers
- detachment
Which stage of oral biofilm formation is the following?
- selective binding of salivary glycoproteins to tooth surface
- within minutes of cleaning - protects teeth from acids
pellicle formation
Which stage of oral biofilm formation is the following?
- eg. streptococcus spp
- net adhesion - balance of van Der Waals forces and electrostatic repulsion
- irreversible adhesion - polymer bridging between organisms and pellicle
- link to caries
early colonisers
Which stage of oral biofilm formation is the following?
- eg. actinomyces israelii, P. gingivalis
- coaggregation - new bacteria attach to early colonisers
- complexity of biofilm increases with time - climax community
- link to periodontal pathogens
late colonisers
Which stage of oral biofilm formation is the following?
- bacteria can become planktonic and spread to new sites
detachment
What 2 components make up extracellular matrix?
- salivary glycoproteins
- microbial polysaccharides
Which 2 bacterias form lactic acid bacteria?
streptococci spp
and
lactobacilli spp
What is the main source of nutrients for oral bacteria?
saliva
The following bacteria are associated with what?
- mainly gram positive cocci
- streptococcus sanguis
- streptococcus oralis
- actinomyces naeslundi
- actinomyces viscous
- veillonella spp (gram negative anaerobic cocci)
periodontal health
What are the 3 phases of plaque-associated gingivitis?
- initial lesion - develops within 4 days of plaque accumulation
- early lesion - within 7 days
- established lesion - continuation
Which phase of plaque induced gingivitis is the following?
- acute inflammatory reaction > vasculitis, perivascular collagen destruction, increase in crevicular fluid and PMN leucocytosis in the junctional epithelium and crevice
initial lesion
Which phase of plaque induced gingivitis is the following?
- dense infiltration of lymphocytes (75%) with macrophages and plasma cells
- areas of local collagen destruction
- polymorph infiltration of sulcus - peaks 7-12 days
early lesion
Which phase of plaque induced gingivitis is the following?
- changes in the gingival crevice support predominantly anaerobic flora
- to reverse the disease, need to clean in the deepest part of the crevice
established lesion
The following bacteria are mainly associated with what?
- 55% gram positive with occasional spirochaetes and motile rods
- Streptococcus sanguinis
- Streptococcus milleri
- Actinomyces israelii
- Actinomyces naeslundi
- Capnocytophaga spp
- Fusobacterium nucleatum
- Veillonella spp
gingivitis
The following bacteria are mainly associated with what?
- ~75% Gram negative of which 90% anaerobic. Motile rods and spirochaetes
- Porphyromonas gingivalis
- Prevotella intermedia
- Fusobacterium nucleatum
- Tannerella forsythia
- Aggregatibacter actinomycetemcomitans
- Selenomonas spp
- Capnocytophaga spp
- Spirochaetes
- Viruses may be linked but no conclusive data
chronic periodontitis
The pathogenesis of which disease is the following?
- sub gingival plaque spreads apically
- junction epithelium separates from the tooth surface
- inflammatory tissue reactions results in destruction of gingival connective tissue and alveolar bone
chronic periodontitis
The following bacteria are mainly associated with what?
- 65-70% Gram-negative bacilli. Few spirochaetes or motile rods.
- Aggregatibacter actinomycetemcomitans
- Capnocytophaga spp
- Porphyromonas gingivalis
- Prevotella intermedia
- May be associated with cellular immunity or genetic defects
aggressive periodontitis
Which oral disease is the following?
- acutely inflamed, red, shiny and bleeding gingivae
- irregularly shaped ulcers on the interdental papillae
- painful condition - pseudomembranous slough - offensive smell
- linked to poor OH, stress, smoking, malnutrition, immunosuppression
- anaerobic, polymicrobial infection
- fusobacterium nucleatum
- spirochaetes
necrotising ulcerative gingivitis
Which condition is the following?
- a rapidly and frequently fatal progressive gangrenous cellulitis and oedema of the soft tissues of the neck and floor of the mouth. It originates in the region of the submandibular gland with elevation and displacement of the tongue
- bacteria from dental infections or poor oral hygiene are the cause of this skin infection
- can develop if you get a cavity or tooth abscess – often in your second and third molars – or you get periodontitis or gingivitis.
Ludwig’s angina
Which bacterial infection of the mouth is the following?
- salivary gland infections - may be bacterial or viral
sialadenitis
Which bacterial infection of the mouth is the following?
- treponema pallidum
- transmission via direct contact with lesions
- Hutchinson’s incisors/mulberry molars
syphilis
Which bacterial infection of the mouth is the following?
- granulomatous disease from mycobacterium tuberculosis
tuberculosis
Which bacterial infection of the mouth is the following?
- mycobacterium leprae
- atrophy of the anterior nasal spine, saddle nose
leprosy
Which oral fungal infections are the following?
- pseudomembranous - wipes off
- erythematous
- hyperplastic
oral candidiasis
Which oral fungal infections are the following?
- denture stomatitis
- angular cheilitis
- median rhomboid glossitis
candida-associated infections
Which bacteria is responsible for >90% of human candida infections?
Candida albicans
What are 5 predisposing factors for candida infections?
- ill fitting or poor hygiene of oral appliance
- disturbed oral ecology eg. xerostomia or antibiotic therapy
- immunological or endocrine disorder eg diabetes
- malignant or chronic disease
- heavy smoking
What are the following?
- HHV1; primary infection - herpetic gingivostomatitis
secondary - herpes labialis (cold sore)
- HHV2 (genital infections)
- HHV3; Varicella zoster primary infection - chicken pox, secondary infection - shingles
- HHV4; epstein-barr virus, infective mononucleosis (glandular fever), hairy leukoplakia (associated with HIV)
- HHV8; Kaposis sarcoma (associated with HIV)
herpes viruses
What illnesses are associated with coxsackieviruses (group A) - papulovesicular lesions?
- hand, foot and mouth disease
- herpangina
What illness is associated with paramyxovirus?
mumps - enlargement of one or more parotid glands
What are 6 oral manifestations of HIV?
- xerostomia
- enlargement of major salivary glands
- candidiasis
- hairy leukoplakia
- kaposis sarcoma
- necrotising periodontitis
What does bactericidal mean?
kills bacteria
What does bacteriostatic mean?
keeps bacteria in the stationary phase of growth
What are 3 examples of bactericidal antibiotics?
- penicillins
- cephalosporins
- metronidazole
What are 4 examples of bacteriostatic antibiotics?
- macrolides
- lincosamides
- tetracyclines
- fusidic acid
What is a contraindication of penicillin?
interaction with methotrexate - can be fatal
What is the mechanism of action of beta lactam antibiotics?
by binding to penicillin-binding proteins (PBPs) and disrupting peptidoglycan cross-linking during cell wall synthesis, resulting in bacterial lysis and cell death
Which penicillin antibiotic is the following?
- broad spectrum - mixed infections
- dental abscesses, also otitis media, bronchitis, pneumonia, UTI, gonorrhoea
amoxicillin
Which penicillin antibiotic is the following?
- narrow spectrum
- as amoxicillin but dose QDS (4x daily) on empty stomach
phenoxymethylpenicillin (pen v)
Which penicillin antibiotic is the following?
- as amoxicillin but reduced resistance as clavulanic acid inhibits B-lactamase enzyme
- risk of C. Diff
- only use after consultation with secondary care
co-amoxiclav
Which penicillin antibiotic is the following?
- narrow spectrum - bone and joint infections
- BUT - MRSA emerging widely
flucloxacillin
Which penicillin antibiotic is the following?
- administered IV or IM
- used in secondary care
- works more quickly than oral doses
- moderate to severe infections - meningitis or Ludwig’s angina
benzylpenicillin (pen g)
What is an adverse reaction of metronidazole?
disulfiram like reaction - acute sensitivity to ethanol
immediate feeling of hangover
Warning: no alcohol
Which drugs interact with metronidazole?
interacts with coumarin anticoagulants eg. warfarin
What is metronidazole used for?
used to treat dental abscess and ANUG
also used to treat pseudomembranous colitis - C. Diff
What are 2 adverse reactions of macrolides?
- GI disturbances common and unpleasant
- lots of drug interferences
What are macrolide antibiotics used for?
if patient allergic to penicillin and metronidazole can’t be used
What are adverse reactions of clindamycin?
- mild diarrhoea - common
- pseudomembranous colitis - rare but fatal (C diff)
What is clindamycin used for?
- currently being questioned whether it is appropriate as a pre-surgery dose for before implants
- effective at penetrating poorly vascularised bone and connective tissue
What are adverse reactions of tetracyclines?
chelate calcium ions - so are deposited in growing bones and teeth
- do not give to pregnant/nursing mothers or to children under 9
What are the clinical uses of fusidic acid?
- good against staphylococcus aureus
- topical sodium fusidate cream for angular cheilitis
What is the only antiviral in the dental practitioners formulary?
aciclovir
What are the 3 stages of mechanism action of aciclovir?
- aciclovir triphosphate blocks herpes viral DNA polymerase
- aciclovir is initially converted by viral thymidine kinase to aciclovir monophosphate
- aciclovir monophosphate converted by host kinases to aciclovir triphosphate
What are the clinical uses of aciclovir?
- primary and secondary herpes infections
- topical 5% cream - recurrent herpetic ulcers
- oral tablets - for severe herpetic stomatitis or herpes zoster
- either can be used for gingivostomatitis
What are 2 azole anti fungal drugs?
- miconazole
- fluconazole
What is a polyene anti fungal drug?
nystatin
What are the clinical uses for azole antifungals?
- miconazole is bacteriostatic against S. aureus
- Miconazole oromucosa gel good for angular cheilitis
- Fluconazole tablets good for preventing candida infections in HIV patients
What are the clinical uses of nystatin?
- used to prevent or treat mucosal candidiasis
- too toxic for systemic use
- not absorbed by alimentary canal
Which type of antiseptic/disinfectant?
- skin antisepsis - ethyl alcohol or propyl alcohol (70%) in water
- hard surface disinfection - alcohol/aldehyde combination
alcohols
Which type of antiseptic/disinfectant?
- two positive charges at its polar end
- Chlorhexidine highly active against bacteria and candida but not M.tuberculosis
- 0.4% solution = hibiscrub for surgical scrub
- 0.2% aqueous solution = antiplaque mouthwash
- 2% can be used as a denture disinfectant
bisguanides
Which type of antiseptic/disinfectant?
- hypochlorites and povidone-iodine are oxidising agents which release halide ions
- readily corrode metal and quickly inactivated by organic matter
- sodium hypochlorite gold standard for disinfecting root canals
halogen compounds
Which type of antiseptic/disinfectant?
- phenolic disinfectants for gross decontamination but poorly viricidal and sporicidal
- chloroxylenol antiseptic limited to domestic disinfection as poor activity against many bacteria
phenolics eg. stericol, clearsol, dettol
What are 3 limitations of antimicrobial use?
- antimicrobial resistance
- secondary effects (side effects)
- medication incompatibilities (drug interactions)
What are two patient groups who are the most vulnerable to infections due to being immunocompromised?
- cancer patients
- transplant patients
Which resistant strain of bacteria is the following?
- found on skin and in nose
- causes poor wound healing, septicaemia and endocarditis
- associated with hospital care due to:
- point of entry through skin
- density of ‘at risk’ population
- elderly and immune-compromised
MRSA
Which resistant strain of bacteria is the following?
- found in GI tract
- causes colitis
- associated with over 65s
- associated with the use of ‘4Cs’
- co-amoxiclav
- clindamycin
- cephalosporins
- ciprofloxacin
C.Diff
What are the 3 reasons bacteria resist antibiotics?
- degradation - enzymes break it down
- alteration - enzymes deactivate it
- efflux - proteins pump it out
How do bacteria become resistant? (4 points)
- mutation
- conjugation
- transformation
- transduction
How do bacteria get new DNA?
- mutation
- acquired from another bacterium
What are some adverse drug reactions to antibiotics?
- allergic reactions
- antibiotic associated diarrhoea
- opportunistic candida infections
- Steven johnson syndrome
- toxic epidermal necrolysis (TEN)
Which antibiotics may result in Steven Johnson syndrome and toxic epidermal necrolysis?
pencillins
and
cephalosporins
Which antibiotic can have the following side effects?
- rash, diarrhoea, abdo pain, nausea/vomiting, drug fever, allergic reactions
(penicillins)
amoxicillin
Which antibiotic can have the following side effects?
- abdo pain, diarrhoea, anorexia, nausea/vomiting, taste alterations
(macrolides)
azithromycin
and
clarithromycin (taste alterations)
Which antibiotics can have the following side effects?
- nausea/vomiting, dizziness, headache, vaginal candidiasis, metallic taste
metronidazole
WHO advises against giving any antibiotics within 3 days of patients having which vaccine?
typhoid
Any drugs ending in ‘azole’ can have possible interactions with which drugs?
warfarin
Which microbes live in balance with the host?
commensal microbes
Which microbes take advantage of host with reduced defences?
opportunist microbes
Which microbes are capable of causing disease?
pathogenic microbes
What are the 4 stages of infectious disease presentation?
- incubation period (time from acquisition to symptoms)
- prodromal period (non-specific symptoms eg, fever and malaise)
- acute specific illness (characteristic signs and symptoms)
- recovery period
What are the 3 routes of transmission of infectious diseases?
- inhalation - via airborne spread
- inoculation - via contaminated sharps
- ingestion - via direct contact
What is the term used for the following?
- the ability of a pathogen to produce injurious substances that damage the host
toxigenicity
What are 4 complications of C.Diff?
- toxic mega colon
- perforation of the colon
- sepsis
- death
Which type of inflammation is the following?
- neutrophils predominate
- S. pyogenes
- S. aureus
- S. pnemoniae
- Infections in which pus is produced. A wound, whether surgical or accidental, has a tendency to become infected. Strains of Staphylococcus aureus, which are resistant to many of the available antibiotics, are not uncommon in hospitals.
pyogenic inflammation
Which type of inflammation is the following?
- macrophages and T lymphocytes predominate
- most macrophages kill most of the bacteria but some survive by growing inside the macrophage > granuloma formation
- M. tuberculosis
- a histologic pattern of tissue reaction which appears following cell injury.
- caused by a variety of conditions including infection, autoimmune, toxic, allergic, drug, and neoplastic conditions
granulomatous inflammation
What does subclinical mean?
no symptoms but patient is infectious
What is the definition of sterilisation?
process that kills or removes all organisms (and their spores) in something
What is the definition of disinfection?
process that kills or removes pathogenic organisms (but not spores) so that they pose no threat of infection
What is the definition of antisepsis?
application of a chemical agent on a live surface to destroy organisms or inhibit their growth
Which disinfectant has been shown to bind blood and protein to stainless steel and therefore should be avoided?
alcohol
What is the term used for quaternary ammonium compound disinfectants?
quats
Which viruses are non alcohol based disinfectants ineffective against?
TB bacteria and non-enveloped viruses such as polio
Which type of disinfectant is rapidly bactericidal, also effective against TB, fungi and viruses, virucidal against enveloped viruses such as HIV and hep b and against the non-enveloped viruses, such as poliovirus, rhinoviruses and hep a?
alcohol based disinfectants
How long should dental unit water lines be flushed out at the beginning and end of the day and after lunch breaks?
2 minutes
How long should dental unit water lines be flushed out in between patients?
20-30 seconds
Which 2 main disinfectant agents have been shown to be effective in the removal of biofilm as well as the reduction of micro bacterial contamination?
sodium hypochlorite
and
isopropanol
What are the symptoms of legionnaires disease?
mild influenza to severe pneumonia with mental confusion
What is the causative bacteria of legionnaires disease?
legionella pneumophilia
What are 2 ways of transmission of legionnaires disease?
- water aerosols
- potential link to stagnant water in hot water taps and dental unit water lines
- cannot be eradicated from water as its ubiquitous
What is the causative bacteria of tuberculosis?
mycobacterium tuberculosis
What are the symptoms of tuberculosis?
- caseating granulomas especially of the lungs
- oral cavity is site of secondaries - painless ulcers of long duration, enlargement of lymph nodes
- cough lasting more than 3 weeks
- fever
What is the route of transmission of mycobacterium tuberculosis?
droplet spread (coughing)
How is tuberculosis prevented?
BCG vaccination
Which cardiovascular condition is the following?
- inflammation of the endocardium of the heart valves resulting from an infection
infective endocarditis
What is meant by the term bacteremia?
bacteria in the blood from toothbrushing, chewing etc
Which bacteria is linked to acute infective endocarditis?
S. aureus
and
S. pyogenes
Which bacteria is linked to chronic infective endocarditis?
viridian’s streptococci
What are 5 symptoms of infective endocarditis?
- night sweats
- muscle and joint pain
- petechiae
- heart murmurs
- fatigue
What are the top 3 groups of patients who are at risk of infective endocarditis and should therefore be offered antibiotics prior to treatment?
- infective endocarditis in the past
- structural congenital heart disease
- those with valve replacement
Which genitourinary tract infection has a relevance to dentistry?
syphilis - Hutchinson’s incisors and mulberry molars, sore in the mouth 3 weeks after initial infection
What is an oral manifestation of scarlet fever?
strawberry tongue
Which bacteria is responsible for staph infections?
S. aureus
What are 2 viral infections of relevance to dentistry?
- HIV
- Hep B
Which virus is associated with oropharyngeal cancer?
HPV
What can be the cause of the following?
- CD4 lymphocyte count <200X10 (6)
- oropharyngeal candidiasis
- hairy leukoplakia
- chronic dryness of the mucosa leading to caries, periodontal disease and ascending bacterial sialadenitis
AIDs
Which condition is the picture attached?
candidiasis
Which condition is the picture attached?
kaposi sarcoma
Which condition is the picture attached?
hairy leukoplakia
Where does Hep B virus concentrate intraorally?
gingival sulcus
What are 2 prion infections relevant to dentistry?
- transmissible spongiform encephalopathy
- creuzfeld jakob disease