Microbiology And Antimicrobials Flashcards
What type of bacteria is Streptococcus Angiosus?
Gram Positive Cocci
Give an example of a gram positive cocci bacteria:
Streptococcus Anginosus
What type of bacteria is Veillonella Species?
Gram Negative Cocci
What is an example of a gram negative cocci bacteria?
Veillonella Species
What type of bacteria is Actinomyces Israeli?
Gram Positive Bacilli
What is an example of a Gram Positive Bacilli bacteria?
Actinomyces Israelii
What is an example of a Gram Negative Bacilli bacteria?
Prevotella Intermedia
What type of bacteria is Prevotella Intermediate?
Gram Negative Bacilli
What type of bacteria is Prevotella Intermediate?
Gram Negative Bacilli
What is the meaning of an Aerobic Growth condition?
Growth in the presence of Oxygen
What is the meaning of a Capnophilic growth condition?
Growth in the presence of Carbon Dioxide
What is the meaning of a facultative growth condition?
With and Without oxygen
What is the meaning of Strictly Anaerobic growth conditions?
Without oxygen
Which growth condition for bacteria does metronidazole have effect?
Strictly Anaerobic
Which growth condition for bacteria does metronidazole have effect?
Strictly Anaerobic
What is the definition of Antimicrobial Resistance?
Occurs when microorganisms such as bacteria, viruses, fungi and parasites change in ways that render the medications used to cure the infections they cause ineffective
What is the definition of Antimicrobial Resistance?
Occurs when microorganisms such as bacteria, viruses, fungi and parasites change in ways that render the medications used to cure the infections they cause ineffective
What are the two types of resistance?
Intrinsic and Acquired
What are two examples of acquired resistance?
Mutation and Acquisition of new DNA
What is an example of resistance by altered target site?
S.mitis
Penicillin resistance due to modified penicillin binding proteins
What is an example of antibiotic resistance?
Enzymatic Inactivation
What two species of bacteria demonstrate resistance by enzyme inactivation?
Prevotella and Fusobacterium
Define: Endogenous Infection
The infectious agent is derived from the host flora
What is the ideal specimen for a dental abscess?
Pus Aspirate
Why is a pus aspirate the ideal sample for a dental abscess?
Prevents contamination with saliva
What are the treatment principles for a localised infection?
Establish a diagnosis and document it
Remove the source of infection
Which two bacterias are commonly associated with dental abscesses?
Streptococcus Anginosus
Prevotella Intermedia
Which two bacterias are commonly associated with Periodontal Abscesses?
Anaerobic Streptococci
Prevotella Intermedia
Which bacterias are associated with Pericoronitis?
Mixed oral Anaerobes (P Intermedia)
S Anginosus group
Which bacterias are associated with Pericoronitis?
Mixed oral Anaerobes (P Intermedia)
S Anginosus group
What is the recommended antibiotic for systemic pericoronitis?
Metronidazole
What type of bacteria is associated with localised alveolar osteitis?
Mixed oral flora
What is Osteomyelitis of the Jaws predisposed by? (5)
Bisphosphonate therapy
Impaired vascularity of the bone (radiotherapy, Paget’s disease)
Foreign bodies (implants)
Compound fractures
Impaired host defences (diabetes)
What types of bacteria are associated with Osteomyelitis of the Jaw (4)?
Anaerobic gram negative rods
Anaerobic streptococci
Streptococcus Anginosus
Staphylococcus Aureus
What bacterias are associated with M/BRONJ? (3)
S. Anginosus
Mixed anaerobes
Actinomyces Israelii
What two bacterias are associated with Salivary Gland infection?
S. Aureus
Mixed Anaerobes
What is the treatment for Salivary Gland infection?
Drainage
Flucloxacillin and Metronidazole
What are the four stages of Documentation when administering antibiotics?
- Document diagnosis
- Document Ab choice, dose, route and duration
- Document a review date
- Document deviation from guidance
What does SOI stand for?
Severe Odontogenic Infection
What is the definition of Ludwig’s Angina?
Bilateral infection of the submandibular space
Which three bacterias are commonly associated with Ludwigs Angina?
Anaerobic gram negative bacilli
Streptococcus Anginosus
Anaerobic Streptococci
What is the definition of sepsis?
Life threatening organ dysfunction caused by a dysregulated host response to infection
What are the two components of a sepsis diagnosis?
SIRS and suspected/confirmed infection
What does SIRS stand for?
Systemic Inflammatory Response Syndrome
What are the four features of SIRS?
Temperature <36 or >38
Pulse >90/min
Respiratory rate >20/min
White Cell Count <4 or >12
How many people die from sepsis per year in Scotland?
3,500
What are the treatment principles of Severe Odontogenic Infections?
Diagnose
Seek advice/help
What are the 4 factors to consider in Severe Odontogenic Infection diagnosis?
Patient looks unwell
Family or carer is very concerned
There is ongoing deterioration
Physiology is abnormal for this patient (check HR, Oxygen Saturation and Blood Pressure)
What are the eight red flags in Severe Odontogenic Infection diagnosis?
New deterioration in Glasgow Coma Scale/ AVPU
Systolic SP <= 90mmHg (or >=40 below normal)
Heart rate >= 130 per minute
Respiratory rate >= 25 per minute
Needs oxygen to keep SpO2 92% (88% in COPD)
Non-blanching rash or mottled/ashen/cyanotic
Not passed urine in last 18 hours
Recent chemotherapy (within 6 weeks)
What are the sepsis six?
Give high flow oxygen
Take blood cultures
Give IV antibiotics
Give a fluid challenge
Measure lactate
Measure urine output
What does S stand for in microbiology results?
Susceptible at a standard dose
What does I stand for in microbiology results?
Susceptible at increased exposure/dose
What does R stand for in microbiology results?
Resistant, even with increased exposure/dose
What is the definition of a breakpoint?
A chosen concentration (mg/L) of an antibiotic which defines whether a species of bacteria is susceptible or resistant to the antibiotic
What is the definition of clinical resistance?
When infection is highly unlikely to respond even to maximum doses of antibiotics
What are the laboratory confounding variables of resistance testing?
Inoculum size
Planktonic phase
PH
Atmosphere
Biofilm
What are the clinical confounding variables of resistance testing?
Co-morbidities
Pus collections
Foreign bodies
Site of infection
Biofilm
What is exposure a function of?
Mode of administration
Dose, dosing interval, infusion time
Distribution/excretion of the antibiotic
Interactions with bacteria at site of infection
What is the aim of antimicrobial stewardship?
To preserve antimicrobial medicines by taking measures to promote their control
What are the five strategic objectives of Antimicrobial Stewardship?
Improve awareness and understanding
Strengthen the knowledge through surveillance and research
Reduce the incidence of infection
Optimise the use of antimicrobial medicines
Ensure sustainable investment
What is the definition of antimicrobial stewardship?
A coherent set of actions which promote using antimicrobials responsibly
What is the role of the Scottish Antimicrobial Prescribing Group (SAPG)?
Coordinates the national antimicrobial stewardship programme in humans
What is Penicilin V most active against?
Oral streptococci
Anaerobes
Selected gram negative cocci
What is amoxicilllin most active against?
Oral streptococci
Anaerobes
Gram negative cocci
Members of the enterobacteriaceae family
What antimicrobials is anginosus streptococci invariably sensitive to?
Penicillin V
Amoxicillin
What is the first line antimicrobial for dental infection?
Phenoxymethylpenicillin (penicillin V)
What is the recommended dose of penicillin V?
500mg every 6 hours for 5 days
What are four factors that cause candidosis?
Poor denture hygiene
Hospitalisation
Immunocompromised
Poor oral hygiene
HIV
What are the 3 features of Candida albicans?
Hyphae
Hydrolytic enzymes
Adhesions
What are the 3 features of Candida albicans?
Hyphae
Hydrolytic enzymes
Adhesions
What type of fungus is candida?
A dimorphic fungus present both as yeast (blastosporic) and filamentous (hyphae)
What is the size of a yeast cell in comparison to a bacteria?
Yeast cells are 25-50x bacteria cells
What are the risk factors of candidiasis?
Immunocompromised patients
Advanced HIV infection
Central venous catheter
Broad spectrum antibiotics
Colonisation at a sterile site
Trauma patient
Immunosuppressive drugs
Intra-abdominal surgery
Parenteral nutrition
Dialysis
Burn unit victim
Long term corticosteroid use
What is the classification of oral candidiosis?
Pseudomembranous- thrush
Erythematous- atrophied (HIV-related), denture related
Hyperplastic- candida leukoplakia
Angular cheilitis
What are the three Newton’s type for denture induced stomatitis?
Newtons Type 1: localised inflammation
Newtons Type 2: diffuse inflammation
Newtons Type 3: granular inflammation
What are the two main species of candida?
Candida albicans
Candida glabrata
What are the 4 features of Candida albicans?
Adhesion and colonisation
Hyphal penetration and invasion
Vascular dissemination
Endothelial colonisation and penetration
What do hydrolytic enzymes do?
Catalyse the hydrolysis of a substrate through the addition of water
What do phospholipases do?
Lipids that allow host cell penetration
What do haemolysins do?
RBCs
Facilitates hyphal invasion
What do proteinases do?
Protein
Adhesion to epithelial cells
What are five methods of collection for laboratory diagnosis?
Smear
Oral rinse
Swab
Foam pad
Biopsy
What are the three types of antifungal?
Echinocandins: active against biofilms
Azoles: ineffective against biofilm
Polyenes: active against biofilms
What are three examples of echinocandins?
Caspofungin
Micafungin
Aniduafungin
What are three examples of azoles?
Fluconazole
Voriconazole
Pocaconazole
What are three examples of polyenes?
Nystatin
Amphoteicin B
Liposomal AmB
What antifungals are Candida albicans sensitive against?
Fluconazole and Metaconazole
What antifungal is candida glabrata sensitive to?
Nystatin
Which microbes are associated with periodontitis?
P. Gingivalis
T. Denticola
T. Forsythia
Which microorganisms are associated with gingivitis?
Actinomyces
Prevotella intermedia
Bacteriodes
Fusobacterium nucleatum
What are the influences on microflora?
Host factors
Diet
Saliva
Gingival crevicular fluid
Microbial interactions
Gaseous environment
What is the preferred clinical specimen for oral biofilm infections?
Swab for wound/lesion taken chair side
Cultured on agar plate for incubation
What is the preferred clinical sample for an abscess?
Pus
What are the six features of the chain of infection?
Infectious agent
Reservoir
Portal of exit
Portal of entry
Mode of transmission
Susceptible host
What microorganisms are associated with endodontic infections?
Bacteriodes
Streptococcus
Fusobacterium nucleatum
Prevotella
Clostridium
Lactobacillus
Porpphyomonas endodontalis
What microbe is associated with 4-40% of endodontic infections?
Enterococcus faecal is
What are examples of virulence factors?
Endotoxins
Adhesions
Collagenases
Hyalurnates
Immune evasion
What are bacterial detection methods associated with microbial culture?
Agar medium
Isolate bacteria
Identify by characterisation of enzyme activities
Sugar fermentation tests
What are bacterial detection methods associated with molecular biology?
DNA probes
PCR
How can we identify anaerobes?
They have a sensitivity to metronidazole
What are the advantages of culture methods?
Yields bacterial isolates for future testing and study
What are the disadvantages of culture methods?
Required viable cells
Insensitive
Only a small number analysed at once
Inconclusive results
Labour intensive
What are the 3 stages of PCR?
Denature (94-95C)
Annealing (50-56C)
Extension (72)
What are the advantages of PCR?
Less time consuming than culturing
Very sensitive
Can directly detect bacterial DNA within clinical samples
Does not require viable cells
Can detect uncultivable species
What are the disadvantages of PCR?
May detect dead cells
Detects only pre-selected species
What are the disadvantages of PCR?
May detect dead cells
Detects only pre-selected species
How does a restriction enzyme analysis work?
Digests whole enzyme with restriction enzymes
What are the molecular (genetic) typing methods?
Restriction enzyme analysis
Gene probe typing
Ribotyping
How does ribotyping work?
Use E-coli rRNA as a DNA probe following restriction enzyme analysis (REA)
rRNA operon present in multiple copies in bacterial genomes
What is the mode of action of azole antifungals?
Indirectly target the ergosterol in the fungi cell wall by interrupting the activity of the enzyme that produces it: 14-alpha demethylase
Fungistatic effect
What is an example of a polyene anti fungal?
Nystatin
What is the mode of action of polyenes?
Directly targets the ergosterol and causes perforation and leakage of intracellular contents
Fungicidal effect
What is an example of an echinocandin?
Micafungin
What effect do echinocandins have?
Fungicidal
What are the factors of chlorhexidine substantivity?
Adsorption to oral surfaces
Maintainacne of antimicrobial activity
Slow neutralisation of antimicrobial activity
What is the treatment for erythematous candidiasis
Thorough cleaning of denture: milton soak
What is the treatment for pseudomembranous candidiasis?
Nystatin
Topical MW 4x daily
Chlorhexidine adjunct
What is the treatment for hyperplasticity candidiasis?
Systemic antifungals
Fluconazole 50mg or Itraconazole 10-20mg
What is the treatment for angular chelitis?
Chlorhexidine and miconazole crea, (50mg 7 days)
What type of substance is chlorhexidine?
Bisbiguanide
What is the mode of action of chlorhexidine?
Dicationic: 1 cation is dental pellicle, 1 cation is bacterial membrane
How does chlorhexidine perform at a low concentration?
Increases cell permeability
How does chlorhexidine perform at a high concentration?
Causes cytoplasmic and cell death
What is the substantivity of chlorhexidine?
12 hours
What does substantivity mean?
Persistence of action
What is substantivity dependent on?
Absorption to oral surfaces
Maintenance of antimicrobial activity
Slow neutralisation
What are the dosing options for chlorhexidine?
0.2% 10ml 2x day
0.12% 15ml 2x day
What are the virulence factors of candida?
Adhesions
Hyphae
Hydrolytic enzymes
What are the mechanisms of antimicrobial resistance?
Biofilm too thick for penetration
Antimicrobial inactive against non-growing organisms
Antimicrobial broken down and destroyed by enzymes
What are the stages of biofilm development?
Adhesion
Colonisation
Accumulation
Complex Community
Dispersal
What are the key organisms associated with caries?
Streptococcus mutans
Lactobacillus acidophilus
Actinomyces
What are the virulence factors for microorganisms associated with caries?
Binding proteins
Acid tolerance
Adaption
Sugar modifying enzymes
Adhesions
Effluent pumps
What are the features of acid tolerance?
Maintains pH
Alters cell membrane
Protection and repair mechanisms
What are the side effects of chlorhexidine?
Anaphylaxis
Hypersensitivity
Brown staining
Tongue discolouration
Burning gums
Impairs perio healing
What does a biofilm compose of?
Aggregate of micro-organisms whose cells adhere to one another and embed in a surface
The adherent cells become embedded within a self produced matrix of extracellular polymeric substances which allow adherence to a surface
What is a niche?
The role a species plays in its environment and how it meets its need for food and shelter
What is the role of fimbrillar adhesions?
Virulence factors
Help invade membrane vesicles of host cells by binding to cellular integrins
What are lipopolysaccharides?
A distinct cell wall component of gram negative bacteria with the potential structural diversity to mediate specific adherence
What is lipotechoic acid?
A cell wall component of gram-positive bacteria involved in specific or non-specific adherence
What are protein fimbrae?
Filamentous proteins on the surface of bacterial cells that may act as adhesions for specific adherence
What are lectins?
Any proteins that bind to a carbohydrate
What are examples of host receptors?
Glycolipid
Integrins
Glycoproteins
Collagen
What are factors that contribute to successful colonisation?
Adherence, substrate (energy) and a liable environment
Mucosa surface, pellicle, acid rich police proteins, minerals and lectins
Mechanical washing, bacteriocidal enzymes, buffering and secretor IgA
Adhesions, LTA, protease, virulence factors
What bacteria is associated with NUG/NUP?
Anaerobic fusospirochetal bacteria
When are antibiotics not indicated?
When there is no infection associated with systemic signs
What systemic signs provide clear evidence of spreading infection?
Trismus
Lymphadenopathy
Difficulty swallowing
Pyrexia
Tachycardia
What is a risk associated with spreading infections in the canine space?
Potential to cause intracranial bacterial infections
What signs associated with referral indicate referral to A&E?
Signs of septicaemia such as grossly elevated temperature (39.5C, lethargy, tachycardia)
Spreading cellulitis
Swelling that may compromise the airway or cause difficulty in swallowing or closure of the eye
Dehydration
Significant trismus associated with a dental infection
Failure to respond to previous treatment
An uncooperative patient
What is the virulence factor of pseudomonas aeruginosa?
Capsule production
What are endogenous sources of pseudomonas aeruginosa?
Oral flora
Hands
What are the exogenous sources of pseudomonas aeruginosa?
Water (Dental unit water lines)
Suction system
Aerosol turbines/ultrasonics
Hands
Inadequate decontamination
What patients are susceptible to pseudomonas aeruginosa?
Cystic fibrosis
Post op eye infections
Septicaemia in neutropenic
Ecthyma gangrenosa
Burn/graft infections
Hospital acquired pneumonia
Catheter assosciated urine infections
How can you break the reservoir chain of infection in regard to pseudomonas aeruginosa?
Avoid damp/wet conditions
Use fresh detergent/disinfectant solutions
Frequently change ultrasonic bath/denture disinfectant
Steriliser reservoir- puridied water and change frequently
How can you break the portal of exit chain of infection in regard to pseudomonas aeruginosa?
Use sterile single use solutions where possible
How can you break the mode of transmission chain of infection in regard to pseudomonas aeruginosa?
Hand hygiene
Use type b steriliser
How can you break the portal of entry chain of infection in regard to pseudomonas aeruginosa?
Aeseptic technique
What cells does HIV attack?
CD4+ T cells- allows virus to enter and infect cells
What is low CD4+ associated with?
AIDs
What does Koch’s postulate signify?
Causal relationship between a microorganism and disease
What are the four factors of Koch’s postulate?
- Micro-organism present in all cases of the disease
- Micro-organism must be cultured from a diseased individual
- Inoculation of a healthy individual with the micro-organism must cause disease
- The same causative agent can be isolated from the diseased inoculated individual
What are the two types of Pattern Recognition Receptors?
Pattern Associated Molecular Patterns (PAMPs)
Damage Associated Molecular Patterns (DAMPs)
What are PAMPs?
Conserved exogenous (non-self) factors expressed by pathogens
What are examples of PAMPs?
Nucleic Acids
Lipopolysaccharides (LPS)
Peptidoglycan
What are DAMPs?
Endogenous (host) factors released following cell damage
What are examples of DAMPs?
Heat shock proteins
Nucleic acids
What is the overall result of PAMPs and DAMPs?
Activation of inflammatory signalling pathways
What is the role of TNF-alpha in sepsis?
TNF-alpha drives sepsis
Why does TNF-alpha drive sepsis?
Causes systemic vasodilation
Increases vascular permeability
Decreases blood pressure
Causes systemic blood clotting of microvasculature
How is the complement system activated?
PRR recognition of PAMPs and DAMPs
C3a and C5a (peptides)
Immunopathogenesis
What are the stages of pathogenicity?
Enter
Attach
Colonise
Evade host immunity
Produce harmful proteins
Disseminate
Release from host
What is the microbiome?
All of the micro-organisms in a particular ecosystem
What is the human microbiome?
All of the micro-organisms living in the body
Where is resident flora from?
Delivery; (vaginal>c section)
Feeding (breast>bottle)
What are the effects of host microbiome symbiosis?
Resistance to pathogen colonisation
Cardiovascular resistance
What are the benefits of a normal flora?
Vitamin synthesis and excretion
Prevention of pathogen colonisation
Anatagonise other bacteria
Stimulate tissue development
Stimulate production of cross-reactive proteins
When does microbial biomass increase?
As alkalinity increases
What are the barriers for microbes in the gastointestinal tract?
Low pH
Saliva and bile
Immune system
What are the effects of antibiotics on the gut microbiome?
Increased infection susceptibility
Compromised immune homeostasis
Dysregulated metabolism
Accumulation of antibiotic resistances
Why do antibiotics cause increased infection susceptibility in the gut microbiome?
Loss of potential competition
Lower antibacterial and IgG exposure
Reduced neutrophil activity
Why do antibiotics cause compromised immune homeostasis in the gut microbiome?
Disruption of Treg/Th balance
Elevated inflammatory tone
Why do antibiotics cause dysregulated metabolism in the gut microbiome?
Elevated inflammatory tone
Altered insulin sensitivity
Altered metabolism of SCFA and bile acids
Why do antibiotics cause accumulation of antibiotic resistances in the gut microbiome?
Establishment of resident bacteria
Transfer of resistant genes to pathogens
What is oral dysbiosis driven by?
Major ecological pressure
Increase in GCF
Increase in inflammation
Increased temp/pH
Diet/decreased pH
What are the 9 factors associated with oral dysbiosis?
Disease
Diet
Smoking
Alcohol
Oral Hygiene
Antibiotics/Antimicrobials
Act of Salivary Proteins
Salivary Flow
Innate/Adaptive Immune Factors
What is 16s RNA?
Biomarker for determining bugs in the mouth