Week 2-3 Flashcards
Give an example of a microorganism and how it inhibits chemotaxis to survive the phagocyte and complement attack
Strep pyogenes - C5a peptidase
Give an example of a microorganism and how it kills the phagocyte before ingestion to survive the phagocyte and complement attack
Staph aureus
- alpha toxin
- Panton-Valentin leukocidin
Give an example of a microorganism and how it avoids ingestion
Strep pneumo
- bacterial capsule
Gram negatives
- K capsule and O antigen
Give an example of a microorganism and how it avoids complement lysis
N. meningitidis
- coats with IgA antibodies
N. gonorrhoea
- porin binding factor H
- C4 binding protein
Strep pyogenes
- M protein
Give an example of a microorganism and how it survives within phagocytes
C. trachomatis
- inhibits phagolysosome fusion
L. monocytogenes
- escapes from phagolysosome
Salmonella typhi
- inhibits NADPH oxidase fusion with phagosome
M. tuberculosis
- inhibits acidification of phagosome due to exclusion of vacuolar H+-ATPase
Give an example of a microorganism and how it exhibits antigenic variations
Influenza A
- shift and drift
N. gonorrhoea
- pilin variation
Give an example of a microorganism and how it causes immunosuppresion
HIV
- CD4 cell depletion
H. influenza
- IgA protease
Give an example of a microorganism and how it is present in inaccessible sites
Herpes simplex
- latent infection in dorsal root ganglia
Name invasive microorganisms
Shigella
Listeria
N. meningitides
Entamoeba histolytica
Name non-invasive microorganisms
Diphtheria
Mycoplasma pneumonia
Trichomonas vaginalis
What is the tropism of M cells in shigella?
Colonic mucosa
What is the tropism of M cells in salmonella?
Terminal ileum
Give examples of bacteria that produce toxins
Gram negatives (LPS)
Diphtheria
Tetanus
Give examples of bacteria that produce enzymes
Staph aureus
- protease
- coagulase
- DNAse
Give examples of microorganisms that induce apoptosis
HIV (CD4 cells)
Shigella (macrophages)
Give examples of virus-induced cytopathic effects
CMV
- cell enlargement and lysis
RSV
- format of syncytium eg multinucleate giant cells
Give examples of viruses with inclusion bodies
Rabies
- intracytoplasmic
Herpes
- nuclear
Give an example of a virus that causes neoplastic transformation
HPV16
Give examples of microorganisms involved with a cytotoxic T cell and NK lymphocyte reaction
Measles
Hepatitis A
Give examples of microorganisms involved with autoimmunity
Strep pyogenes
- acute rheumatic fever
Give examples of microorganisms involved with immediate hypersensitivity
Helminthic infections
- rashes
Give examples of microorganisms involved with cytotoxic hypersensitivity
Hepatitis B
- cell necrosis
Give examples of microorganisms involved with immune complexes
Subacute endocarditis
Glomerulonephritis
Give examples of microorganisms involved with delayed type hypersensitivity
M. tuberculosis
- granulomas
- caseous necrosis
Which virus causes intranuclear and cytoplasmic inclusion bodies?
Measles
What is the difference between sensitivity, specificity, positive predictive value and negative predictive value
Sensitivity - chance test is positive in patient who has the condition
Specificity - chance test is negative in patient who does not have condition
PPV - chance patient has condition if test is positive
NPV - chance patient does not have condition if test is negative
As prevalence increases, what happens to PPV and NPV?
PPV increases and NPV decreases
True or false: diagnostic tests are less helpful at extremes of pre test probability
True
Name the principles of outbreak investigation
Verify diagnosis
Establish existence of outbreak
Identify and count cases
Describe epidemiology
Formulate and test hypothesis
Assess local response
Address resource gaps
Set up control measures
Communicate findings
Intensify surveillance
What were the 6 disease covered by the IRS?
Cholera
Typhoid
Plague
Smallpox
Yellow fever
Relapsing fever
What WHO grade is a public health emergency of international concern (PHEIC)?
WHO grade 3
Which microorganisms causes a neutrophilic/suppurative response?
Bacterial
Fungi
TB
Which microorganisms causes a granulomatous response?
TB
Fungi
Which microorganisms causes a granulomatous with eosinophilic response?
Parasites
What are the 2 types of epidemiology categories?
Observational
Experimental
What are the 2 types of observational studies?
Descriptive
Analytical
Name examples of descriptive studies
Case report
Cross-sectional
Surveillance
Ecological
Name examples of analytical studies
Cross-sectional
Case control
Cohort
Name experimental studies
RCTs
Quasi-experimental
What is a necessary versus sufficient causes according to the Bothman sufficient-component cause model
Necessary - NEED the factor to develop the disease
Sufficient - disease always develops in the present of the factor
What is the issue with the Bothman model?
Association does not mean cause
How do you calculate incidence risk?
No of new cases during specific time period over total population at risk at start
How do you calculate incidence rate?
No of new cases during specific time period over total person-time of risk
How do you calculate attack rate (incidence proportion)?
No of people who are and become ill over number of people who ate
How do you calculate secondary attack rate?
No. of case among contacts of primary case over total number of contacts
What is the serial interval?
The time between onset of clinical disease from primary to secondary case
What is the basic reproductive number (R0)?
Average number of secondary infections in susceptible hosts
What is the net reproductive number (R)?
Average number of secondary cases in a population of susceptible and non-susceptible hosts
Name ratio measures
Relative risk
Risk ratio
Odds ratio
Name difference measures
Attributable risk
How do you calculate vaccine effectiveness?
1 - odds ratio x 100
What is the resistance mechanism of tetracyclines?
Efflux pump
What is the resistance mechanism of fluconazole in candida spp?
Efflux pump
What is the resistance mechanism of carbapenems in pseudomonas?
Reduced permeability
What is the resistance mechanism of aminoglycosides in anaerobes?
Reduced permeability
What is the resistance mechanism of beta lactams in MRSA?
Target modification
What is the resistance mechanism of glycopeptides in enterococci?
Target modification
What is the resistance mechanism of rifampicin in TB?
Target modification
What is the resistance mechanism of ciprofloxacin in enterobacteriaceae?
Target modification
What is the resistance mechanism of linezolid in staph and enterococci?
Target modification
What is the resistance mechanism of NDM-1 in enterobacteriaceae?
Enzymatic degradation
What is the resistance mechanism of chloramphenicol in staphylococci?
Enzyme degradation
What is the key aspect of an ecological study?
Document co-occurence of disease and other factors in a population
What is the key aspect of a cross sectional study?
Establish magnitude of disease and factors in population at a single point in time
What is the key aspect of a case-control study?
Compare prevalence of a suspected risk factor in cases and controls and identify associations
What is the key aspect of a cohort study?
Measure risk of disease association with exposure to a factor in a prospective design
What is the key aspect of a experimental study?
Provide strong evidence of a causal relationship between exposure and disease
Which study design is cheap and relatively easy?
Ecological
Which study design is useful for chronic diseases with high prevalence but low incidence?
Cross sectional
What is the model of choice for studying rare diseases?
Case-control
Which study design can determine spectrum of disease resulting from exposure?
Cohort
