Microbiology Flashcards
(145 cards)
1
Q
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
A
prions
2
Q
What are 5 oral factors that affect oral microbiology?
A
- anatomy - alignment of teeth
- saliva
- gingival crevicular fluid
- microbial factors
- local environment
(moisture, pH, antimicrobial therapy, diet, fluoride)
3
Q
Which bacteria can be found in deep perio pocketing?
A
porphyromonas
4
Q
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.
A
aggregatibacter
5
Q
Which fungi bacteria is especially associated with dentures and is a yeast bacteria?
A
Candida albicans
6
Q
Which fungi bacteria is the following?
- only tend to cause problems for immunocompromised patients
A
filamentous and dimorphic fungi
7
Q
What are 4 examples of how to get oral specimens?
A
- 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)
8
Q
What are 3 methods of lab analysis?
A
- non-cultural methods (microscopy, gene probing)
- cultural methods (cultured cells to grown viruses)
- immunological methods (identify organisms using antibodies)
9
Q
Why is microbiological sampling not commonly used in dentistry?
A
- 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
10
Q
When should oral microbiological culture be taken?
A
if antimicrobial resistant infection is suspected
or
sometimes before prescribing co-amoxiclav or clindamycin
11
Q
What are the 2 methods of susceptibility testing?
A
- minimum inhibitory concentrations (MIC)
- minimum bactericidal concentration (MBC)
12
Q
What is the benefit of being able to interpret microbiology report?
A
evidence to help weight up the risks and benefits of treatment options
13
Q
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
A
streptococcus mutans
14
Q
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
A
lactobacillus spp
15
Q
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
A
actinomyces israelii
16
Q
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
A
aggregatibacter actinomycetemcomitans
17
Q
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
A
porphyromonas gingivalis
18
Q
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
A
staphylococcus aureus - planktonic
19
Q
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
A
biofilms
20
Q
How is supra gingival oral biofilm disrupted?
A
tooth brushing
21
Q
How is sub gingival oral biofilm disrupted?
A
ultrasonic debridement
22
Q
What are the 5 stages of biofilm formation?
A
- initial attachment
- irreversible attachment
- maturation I
- maturation II
- dispersion
23
Q
What percentage of dental plaque is made up of organic components?
A
30%
24
Q
Which tooth surfaces are more protected from host defences and cleaning?
A
- occlusal fissures
- contact points
- buccal and palatal smooth surfaces
25
Which patients are more likely to form plaque more quickly?
- those with reduced salivary flow
- reduced muscular movements
- desquamation - lower rate
26
What are the 4 stages of biofilm formation?
1. pellicle formation
2. early colonisers
3. late colonisers
4. detachment
27
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
28
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
29
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
30
Which stage of oral biofilm formation is the following?
| - bacteria can become planktonic and spread to new sites
detachment
31
What 2 components make up extracellular matrix?
- salivary glycoproteins
| - microbial polysaccharides
32
Which 2 bacterias form lactic acid bacteria?
streptococci spp
and
lactobacilli spp
33
What is the main source of nutrients for oral bacteria?
saliva
34
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
35
What are the 3 phases of plaque-associated gingivitis?
1. initial lesion - develops within 4 days of plaque accumulation
2. early lesion - within 7 days
3. established lesion - continuation
36
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
37
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
38
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
39
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
40
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
41
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
42
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
43
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
44
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
45
Which bacterial infection of the mouth is the following?
| - salivary gland infections - may be bacterial or viral
sialadenitis
46
Which bacterial infection of the mouth is the following?
- treponema pallidum
- transmission via direct contact with lesions
- Hutchinson's incisors/mulberry molars
syphilis
47
Which bacterial infection of the mouth is the following?
| - granulomatous disease from mycobacterium tuberculosis
tuberculosis
48
Which bacterial infection of the mouth is the following?
- mycobacterium leprae
- atrophy of the anterior nasal spine, saddle nose
leprosy
49
Which oral fungal infections are the following?
- pseudomembranous - wipes off
- erythematous
- hyperplastic
oral candidiasis
50
Which oral fungal infections are the following?
- denture stomatitis
- angular cheilitis
- median rhomboid glossitis
candida-associated infections
51
Which bacteria is responsible for >90% of human candida infections?
Candida albicans
52
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
53
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
54
What illnesses are associated with coxsackieviruses (group A) - papulovesicular lesions?
- hand, foot and mouth disease
| - herpangina
55
What illness is associated with paramyxovirus?
mumps - enlargement of one or more parotid glands
56
What are 6 oral manifestations of HIV?
- xerostomia
- enlargement of major salivary glands
- candidiasis
- hairy leukoplakia
- kaposis sarcoma
- necrotising periodontitis
57
What does bactericidal mean?
kills bacteria
58
What does bacteriostatic mean?
keeps bacteria in the stationary phase of growth
59
What are 3 examples of bactericidal antibiotics?
- penicillins
- cephalosporins
- metronidazole
60
What are 4 examples of bacteriostatic antibiotics?
- macrolides
- lincosamides
- tetracyclines
- fusidic acid
61
What is a contraindication of penicillin?
interaction with methotrexate - can be fatal
62
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
63
Which penicillin antibiotic is the following?
- broad spectrum - mixed infections
- dental abscesses, also otitis media, bronchitis, pneumonia, UTI, gonorrhoea
amoxicillin
64
Which penicillin antibiotic is the following?
- narrow spectrum
- as amoxicillin but dose QDS (4x daily) on empty stomach
phenoxymethylpenicillin (pen v)
65
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
66
Which penicillin antibiotic is the following?
- narrow spectrum - bone and joint infections
- BUT - MRSA emerging widely
flucloxacillin
67
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)
68
What is an adverse reaction of metronidazole?
disulfiram like reaction - acute sensitivity to ethanol
immediate feeling of hangover
Warning: no alcohol
69
Which drugs interact with metronidazole?
interacts with coumarin anticoagulants eg. warfarin
70
What is metronidazole used for?
used to treat dental abscess and ANUG
| also used to treat pseudomembranous colitis - C. Diff
71
What are 2 adverse reactions of macrolides?
- GI disturbances common and unpleasant
| - lots of drug interferences
72
What are macrolide antibiotics used for?
if patient allergic to penicillin and metronidazole can't be used
73
What are adverse reactions of clindamycin?
- mild diarrhoea - common
| - pseudomembranous colitis - rare but fatal (C diff)
74
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
75
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
76
What are the clinical uses of fusidic acid?
- good against staphylococcus aureus
| - topical sodium fusidate cream for angular cheilitis
77
What is the only antiviral in the dental practitioners formulary?
aciclovir
78
What are the 3 stages of mechanism action of aciclovir?
1. aciclovir triphosphate blocks herpes viral DNA polymerase
2. aciclovir is initially converted by viral thymidine kinase to aciclovir monophosphate
3. aciclovir monophosphate converted by host kinases to aciclovir triphosphate
79
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
80
What are 2 azole anti fungal drugs?
- miconazole
| - fluconazole
81
What is a polyene anti fungal drug?
nystatin
82
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
83
What are the clinical uses of nystatin?
- used to prevent or treat mucosal candidiasis
- too toxic for systemic use
- not absorbed by alimentary canal
84
Which type of antiseptic/disinfectant?
- skin antisepsis - ethyl alcohol or propyl alcohol (70%) in water
- hard surface disinfection - alcohol/aldehyde combination
alcohols
85
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
86
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
87
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
88
What are 3 limitations of antimicrobial use?
1. antimicrobial resistance
2. secondary effects (side effects)
3. medication incompatibilities (drug interactions)
89
What are two patient groups who are the most vulnerable to infections due to being immunocompromised?
- cancer patients
| - transplant patients
90
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
91
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
92
What are the 3 reasons bacteria resist antibiotics?
1. degradation - enzymes break it down
2. alteration - enzymes deactivate it
3. efflux - proteins pump it out
93
How do bacteria become resistant? (4 points)
- mutation
- conjugation
- transformation
- transduction
94
How do bacteria get new DNA?
- mutation
| - acquired from another bacterium
95
What are some adverse drug reactions to antibiotics?
- allergic reactions
- antibiotic associated diarrhoea
- opportunistic candida infections
- Steven johnson syndrome
- toxic epidermal necrolysis (TEN)
96
Which antibiotics may result in Steven Johnson syndrome and toxic epidermal necrolysis?
pencillins
and
cephalosporins
97
Which antibiotic can have the following side effects?
| - rash, diarrhoea, abdo pain, nausea/vomiting, drug fever, allergic reactions
(penicillins)
| amoxicillin
98
Which antibiotic can have the following side effects?
| - abdo pain, diarrhoea, anorexia, nausea/vomiting, taste alterations
(macrolides)
azithromycin
and
clarithromycin (taste alterations)
99
Which antibiotics can have the following side effects?
| - nausea/vomiting, dizziness, headache, vaginal candidiasis, metallic taste
metronidazole
100
WHO advises against giving any antibiotics within 3 days of patients having which vaccine?
typhoid
101
Any drugs ending in 'azole' can have possible interactions with which drugs?
warfarin
102
Which microbes live in balance with the host?
commensal microbes
103
Which microbes take advantage of host with reduced defences?
opportunist microbes
104
Which microbes are capable of causing disease?
pathogenic microbes
105
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
106
What are the 3 routes of transmission of infectious diseases?
1. inhalation - via airborne spread
2. inoculation - via contaminated sharps
3. ingestion - via direct contact
107
What is the term used for the following?
| - the ability of a pathogen to produce injurious substances that damage the host
toxigenicity
108
What are 4 complications of C.Diff?
- toxic mega colon
- perforation of the colon
- sepsis
- death
109
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
110
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
111
What does subclinical mean?
no symptoms but patient is infectious
112
What is the definition of sterilisation?
process that kills or removes all organisms (and their spores) in something
113
What is the definition of disinfection?
process that kills or removes pathogenic organisms (but not spores) so that they pose no threat of infection
114
What is the definition of antisepsis?
application of a chemical agent on a live surface to destroy organisms or inhibit their growth
115
Which disinfectant has been shown to bind blood and protein to stainless steel and therefore should be avoided?
alcohol
116
What is the term used for quaternary ammonium compound disinfectants?
quats
117
Which viruses are non alcohol based disinfectants ineffective against?
TB bacteria and non-enveloped viruses such as polio
118
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
119
How long should dental unit water lines be flushed out at the beginning and end of the day and after lunch breaks?
2 minutes
120
How long should dental unit water lines be flushed out in between patients?
20-30 seconds
121
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
122
What are the symptoms of legionnaires disease?
mild influenza to severe pneumonia with mental confusion
123
What is the causative bacteria of legionnaires disease?
legionella pneumophilia
124
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
125
What is the causative bacteria of tuberculosis?
mycobacterium tuberculosis
126
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
127
What is the route of transmission of mycobacterium tuberculosis?
droplet spread (coughing)
128
How is tuberculosis prevented?
BCG vaccination
129
Which cardiovascular condition is the following?
| - inflammation of the endocardium of the heart valves resulting from an infection
infective endocarditis
130
What is meant by the term bacteremia?
bacteria in the blood from toothbrushing, chewing etc
131
Which bacteria is linked to acute infective endocarditis?
S. aureus
and
S. pyogenes
132
Which bacteria is linked to chronic infective endocarditis?
viridian's streptococci
133
What are 5 symptoms of infective endocarditis?
- night sweats
- muscle and joint pain
- petechiae
- heart murmurs
- fatigue
134
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
135
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
136
What is an oral manifestation of scarlet fever?
strawberry tongue
137
Which bacteria is responsible for staph infections?
S. aureus
138
What are 2 viral infections of relevance to dentistry?
- HIV
| - Hep B
139
Which virus is associated with oropharyngeal cancer?
HPV
140
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
141
Which condition is the picture attached?
candidiasis
142
Which condition is the picture attached?
kaposi sarcoma
143
Which condition is the picture attached?
hairy leukoplakia
144
Where does Hep B virus concentrate intraorally?
gingival sulcus
145
What are 2 prion infections relevant to dentistry?
- transmissible spongiform encephalopathy
| - creuzfeld jakob disease
