Infection And Immunity Flashcards
Why do individuals get particular infections?
Weakened immune system Genetic predisposition Poor living conditions Poor nutrition No access to healthcare - vaccinations Lifestyle
Gram staining process
- positively charged crystal violet binds to negatively charged cell components
- iodine forms a complex with the crystal violet
- methanol/acetone extract complexes through Gram negative cell walls only
- red dye stains the unstinted Gram negative cells
What influences the outcome of an infection?
Immune system
Drugs used
Body systems affected
What is an infection?
Multiplication/colonisation of pathogens in a susceptible host causing damage/dysfunction
Which bacteria do acid fast stains detect?
Mycobacterium - cause TB and leprosy
What is a non-pathogen?
A bacterium that doesn’t cause disease
Lists some DNA enveloped viruses
Hep B
Smallpox
Herpes
Non- enveloped DNA viruses
HPV
RNA enveloped viruses
HIV
Rubella
Rotavirus
Coronavirus
RNA non-enveloped viruses
Picomaviruses - hep A, polio, colds
Give some Gram negative bacteria
Neisseria Escherichia Salmonella Helicobacteria Pseudomonas Legionella Bacteroides
Gram positive bacteria
Staphylococcus
Streptococcus
Clostridium
What size are the ribosomes of prokaryotes?
30 + 50S
Which group does vancomycin belong to and what does this target?
Glycopeptide - cell wall
Which three antibiotic groups target protein synthesis in bacteria?
Aminoglycoside
Macrolide
Polyketide
Which antibiotic belongs to the chemotherapeutic group and what does it target?
Ciprofloxacin
DNA
What does reservoir mean?
Any person, animal, plant, soil or substance in which an infectious agent multiplies
What is a source
A readily available form of an infectious agent
What does carriage mean?
The route taken by a pathogen eg nasal
What does commensal mean?
The symbiotic relationship where one species benefits and the other is unaffected. Time when the microbe is replicating or waiting for the immune system to be compromised.
How does rifampicin work?
Binds to bacterial RNA polymerase preventing transcription.
How does tetracycline work?
Targets bacterial protein synthesis by competing with tRNA at A site of bacterial ribosome.
What is methotrexate and how does it work?
An anti-folate in cancer therapy.
Impairs the synthesis of tetrahydrofolate which is essential for DNA synthesis from folic acid.
Competitively inhibits dihydrofolate reductase (DHFR)
List 5 ways that cells can become resistant to antibiotics
High rate of division Decreased influx Increased efflux Increased transcription of target Altered target
Give features of the innate immune system
The inbuilt immunity to resist infection
Present from birth
Not specific for any particular microbial substance
Not enhanced by second exposure
Has no memory
Uses cellular and humoral components
Poorly effective without adaptive immunity
Give features of adaptive immunity
Immunity established to adapt to infection Learnt by experience Pathogen-specific immunity Enhanced by second exposure Has memory Uses cellular and humoral components Poorly effective without innate immunity
List the cells involved in innate immunity
Macrophages and monocytes Neutrophils Eosinophils Basophils Mast cells Natural killer cells
What are phagocytes?
Cells able to engulf and destroy bacteria, extracellular fibres and immune complexes
What is opsonisation?
The covering of a microorganism by antibodies or complement to render it recognisable as foreign by phagocytes, thus enhancing phagocytosis
What does the complement system do?
Marks pathogens for their destruction by covalently binding to their surface
What are the cells of the adaptive immune response?
T and B cells
What do macrophages do?
Phagocytosis
Present antigens to lymphocytes (adaptive immunity)
What do transferrin and lactoferrin do? In at or adaptive?
Deprive pathogens of iron
Innate
What do interferons do? Innate or adaptive?
Inhibit viral replication
Innate
What does lysozyme do? I or A?
Breaks down peptidoglycan in bacterial cell walls
Innate
What does fibronectin do? I or A?
Opsonises bacteria and promotes their phagocytosis
What does TNF-alpha do?
Suppresses viral replication and activates phagocytes
What role do neutrophils play? I or A?
Phagocytic and antibacterial
Innate
What do eosinophils do? I or A?
Anti-parasite and allergic response
Innate
What do basophils and mast cells do? I or A?
Allergic response
Innate
What do natural killer cells do? I or A?
Recognise and kill abnormal cells eg tumours
Innate
What do cytokines do? I or A
Promote the differentiation and proliferation of lymphocytes
Adaptive
What does penforin do? I or A?
Released by T killer cells and destroys cell walls
Adaptive
What do antibodies do? I or A?
Protects the host by
- neutralisation (prevents binding to epithelia)
- opsonisation
- complement activation (enhances opsonisation and lysis)
Adaptive
T helper cells? I or A?
Become activated when CD4 binds to a specific antigen on the MHC/antigen complex of an antigen presenting cell (APC).
Once activated, it clones itself to form T helper an T memory cells
Adaptive
B cells?
Divide to form plasma cells and memory cells when activated by T helper cells and release cytokines
Plasma cells produce specific immunoglobulin for non-self antigen
