Microbiology and Pathology (before Xmas) Flashcards
How do you identify between gram positive and gram negative bacteria?
Carry out gram staining and:
Gram positive= purple
Gram negative= pink
What is the significance of the catalase test to gram positive bacteria?
positive test = staphylococci
negative test= streptococci
What occurs when a haemolysis test is done to streptococci
Beta or alpha
Beta = Clear
Alpha = green
Beta haemolytic strip becomes
Lancfield Group (A(pyogenes), B, C, D, G)
Alpha Haemolytic Strip (complete optochin test)
How do you distinguish Staphylococci bacteria?
Coagulase Test
positive= staph. aureus (GOLD on blood agar)
negative= staph. epidermidis
What is Lancefield Grouping?
beta haemolytic streptococci differentiation
What organism in lancefield group A is resistant to optochin?
strep. pyogenes
How do we differentiate different gram negative bacterias?
MacConkey
1) They may be lactose fermenters or
2) Non lactose fermenters
carry out oxidase test also on non-lactose fermenters
Name examples of lactose fermenter gram negative bacteria
e. coli
klebsiella
Name some examples of non lactose fermenter gram negative bacteria
shigella
salmonella
pseudomonas
Why do gram positive bacteria stain purple
Due to a thick layer of peptidoglycan in cell wall
Name the two big groups of gram + bacteria
Streptococci
Staphylococci
What is the physical appearance difference between staph and strep
strep= chains
staph= clusters
What is inflammation?
Local physiological response to tissue injury
Why does inflammation occur?
To bring all the cells require for healing to the damaged area
Benefits of inflammation?
destruction of invading microbes
infection and injury
Harmful effects of inflammation?
- digestion of normal tissue
- swelling
- inappropriate response
- autoimmunity and over-reaction
ACUTE vs CHRONIC inflammation?
sudden vs slow onset
short vs long duration
usually resolves vs may never resolves
hypersensitivity vs autoimmunity
tissue necrosis and infections vs transplant rejection and persistant acute
5 cardinal signs of ACUTE inflammation>
1) swelling- oedema
2) redness - dilation of BV’s
3) Heat- hyperaemia (more blood flow)
4) pain- stretch of tissue
5) loss of function
What cells are involved in acute inflammation?
- neutrophils- phagocytosis
- Macrophages- secrete chemical mediators for chemotaxis
What do chemical mediators do?
spread the inflammation response
Where does histamine get released from?
mast cells
What is the function of thrombin?
increase vessel permeability through platelets
What does histamine and thrombin cause?
Neutrophil adhesion to endothelial surface
What are the 3 main stages of Acute Inflammation?
1) changes in vessel calibre- (vasodilation so l=blood to the area)
2) Fluid exudate (vasodilation and chemical mediators means permeability increases, this allows proteins to leave= decreased oncotic pressure)
3) Cellular Exudate (accumulation of neutrophils into Extracellular space)
What is Chemotaxis?
Attraction of cells to a site through release of chemicals. e.g. neutrophils attracted to mediators released
What are the 3 outcomes of acute inflammation?
- resolution (complete restoration)
- suppuration (pus formation, granulation tissue and scarring)
- organisation (tissue replaced with granulation tissue as part of healing process)
What are the 3 primary influences predispose to thrombus formation? (Virchow’s Triad)?
- Stasis of Blood flow (atherosclerosis, aneurysm, AF)
- Endothelial Injury (MI, atherosclerosis, smoking)
- Hypercoagulability (genetic and acquired)
What are neutrophil polymorphs?
- short lived cells first on the scene of inflammation
- cytoplasmic granules with enzymes that kill bacteria
- release chemicals that attract other cells such as macrophages
What are macrophages
- long lived
- present antigens to lymphocytes
- ingest and carry debris
What are lymphocytes?
- long lived
- produce chemicals to attract other cells
- can produce memory cells
wHAT ARE ENDOTHELIAL CELLS?
Cells that line capillary blood vessels in areas of inflammation
- Sticky= inflammation cells adhere
- Porous= allows inflammatory cells to pass into tissues
- Grow into damaged areas to form new capillary vessels
What are fibroblasts?
Long lived cells that form collagen in areas of chronic inflammation
What is the difference between repair and resolution?
repair is when tissue is unable to regenerate and is replaced with fibrous tissue. Initiating factor still present
Which cells in the body cant regenerate?
Myocardial cells
neurones
What is Thrombosis?
Solid mass of blood constituents formed within intact vascular system during life
what is an Embolus?
Mass of material in vascular system able to become lodged within a vessel ands block it
What is Ischaemia?
Reduction in blood flow
What is infarction?
Reduced bllod flow with subsequent death of cells
What is in a Plaque?
- fibrous tissue
- lipids (cholesterol)
- lymphocytes
Types of Skin wounds?
- ABRASION
HEALING BY 1ST INTENSION - healing by 2nd intension
What is apoptosis?
programmed cell death
What is necrosis?
TRAUMATIC CELL DEATH
Definition of acquired?
caused by non genetic environmental factors
What is the definition of congenital?
present at birth
What is Metaplasia?
change in differentiation of a cell. 1 fully differentiated cell changes into another
What is Dysplasia?
Morphological changes seen in cells progressing to cancer
Name some evidence of Ageing?
- dermal elastosis
- osteoporosis
- cataracts
- sarcopenia
- dementia
- deafness
If there is basal cell carcinoma of the skin, which cells does it invade?
only invades locally
How do carcinomas spread?
to the lymph nodes that drain the site of carcinoma and can spread from blood to bone
What is Adjuvant Therapy?
extra treatment after surgical excision
Which tumours commonly metastasise to the liver?
Colon
Stomach
Pancreas
Carcinoid tumour of intestine
which tumours commonly metastasise to bone?
Prostate
breast
thyroid
lung
Kidney
What is carcinogenesis?
malignant neoplasms
What is oncogenesis?
both benign and malignant
What is cancer causing?
Carcinogens
What is tumour causing?
Oncogens
What is a tumour?
abnormal swelling
List examples of chemical carcinogens?
- aromatic amines
- nitrosamines
- alkylating agents
- polycyclic aromatic carbons
Name the classes of carcinogens?
- Viral
- Ionising/ non radiation
- hormones
- parasites
What are host factors?
premalignant conditions
What is a neoplasm?
a new growth. A lesion that persists after initiating stimulus is removed
What are benign neoplasms?
- non-invasive
- slow growth
- low mitotic activity
- no necrosis/ ulceration
What are malignant neoplasms?
- invasive and rapid growth
- irregular shape with metastases
- necrosis and ulceration can be found
How are malignant neoplasms caused?
they outgrow their blood supply
Name some types of neoplasm?
- lipoma = adipocytes
- chondroma = cartilage
- osteoma = bone
- angioma = vascular
- Rhabdomyoma = striated muscle
- Leiomyoma= smooth muscle
What is a Carcinoma
Malignant epithelial neoplasm
What is a sarcoma?
Malignant connective tissue neoplasms
What do we call cells of unknown origin?
Anaplastic
What is melanoma
Malignant neoplasm of melanocytes
What is lymphoma
malignant neoplasm off lymphoid cells
Describe the pathology of Metastases?
Invasion –erosion of tissue boundaries by enzymes secreted by
- Intravasion- gain access to metastatic routes e.g. blood/lymph
- Evasion of host defence
- Adherence- to endothelium
- Extravasation- colonisation of new site
- Angiogenesis- develops its own bloody supply
wow.
What is an adenoma?
benign secretory epithelial neoplasm
What is a papilloma?
benign non secretory epithelial neoplasm
What are the 3 types of Complement Activation?
Classical pathway= Antibody-antigen immune complexes
Alternate pathway= foreign surface antigens
Lectin pathway= mannose binding lectin- mannose residues on pathogen surface
What is the mechanism of action of complement factors?
1) Lyse microbes directly (membrane attach complex MAC)
2) Increase chemotaxis (C3a and C5a), and inflammatory response
3) Opsonisation- increase phagocytosis (C3b)
Differences between innate and adaptive immunity.
Present at birth vs develops over time
non specific vs specific
no memory vs memory
barriers (skin) vs lymphoid organs (nodes, thymus)
Phagocytes vs Lymphocytes
Natural Killer cells vs
Basophils and eosinophils vs
complement proteins vs antibodies
PAMPS vs Epitopes
Limited receptors vs receptor diversity requires somatic mutation
What is the function of Pattern recognition receptors?
Distinguishing foreign bodies by pattern recognition, recognising PAMPs and DAMPs, to then trigger innate response and an inflammatory response
What are PAMPs and DAMPs?
- Pattern associated molecular patterns
- Damage associated molecular patterns
Name some types of PRR’s?
- Nod like receptors (NLR’s)
- Toll like receptors (TLR’s- main is TLR4)
- Secreted and circulating mannose binding lectins and collectins
What happens when the innate response is triggered?
- opsonise pathogen
- activate complements (mannose binding lectin)
- activate inflammatory mediators
- secrete interferons and pro- inflammatory cytokines
- induce apoptosis of infected cells
Signs of chronic inflammation?
- less swelling and exudate
- inflammation and repair occurring at same time
- fibrosis (scar formation)
Causes of chronic inflammation?
- agent resistant to phagocytes
- agent indigestible
- autoimmune disease
- Crohns/ UC
- Transplant rejection
Cells involved in chronic inflammation?
- B-lymph (differentiate into plasma cells)
- T-lymph (cell- mediated immunity)
- Plasma (antibody production)
- M1 Macrophages (encourage inflammation)
- M2 Macrophages (decrease inflammation and encourage repair)
Fucntion of Macrophages?
To eat up debris and display antigen on surface
What is a granuloma?
Aggregate of Epitheloid Histocytes
What do epithelioid Histocytes secrete?
- ACE (which is a blood marker if someone has systematic granulomatosis disease)
Function of Lymph Nodes?
- house T cells, B (plasma) and phagocytes
What are the two parts of the spleen
- red pulp (old blood cells are destroyed)
- white pulp= filters blood, antibodies made by B cells, antibody coated bacteria are filtered out
function of the thymus
involved in the development of T cells and destroys t cells that react to self-antigens
What does aspirin do?
irreversible COX 1>2 inhibition
What does an NSAID do
non-selective competitive reversible COX inhibition
Overdose management of opiate/ opioid
Naloxone
overdose management of aspirin
Haemodialysis
Process of Phagocytosis
1) Chemotaxis and adherence of microbe to phagocyte
2) Ingestion of microbe by phagocyte
3) formation of phagosome
4) Fusion of phagosome and lysosome= phagolysosome
5) Digestion of ingested microbe by enzymes
6) Formation of residual body containing indigestible material
7) Discharge of waste material
Function of Natural Killer T cells
Kill own cells by apoptosis if infected with virus/ become cancerous
function of mast cells
release: histamine, heparin, chemokines and cytokines
function of basophils
hypersensitivity reactions and parasitic infections/ release histamine
function of eosinophils
Raised in allergy and parasitic infections
Humoral Adaptive Immunity response control freely circulating pathogens, describe the process
1) A B cell binds to its specific antigen
2) B cell differentiates into plasma cell
3) plasma cell proliferates and produce antibodies against the pathogens
Cell- mediated Adaptive Immunity controls intracellular pathogens, describe the process
1) T cell binds to antigen and this activates its cytokine receptors
2) Helper T cell produces cytokines that cause differentiation into a cytotoxic T cell. These cytokines also influence formation of B cells, macrophages and plasma cells
3) Infected cell is lysed by cytotoxic T cell
definition of an antigen
a toxin or other foreign substance which induces an immune response in the body
Name 3 antigen- presenting cells
macrophages, dendritic cells, B cells
What are major histocompatibility complexes
Proteins that mark a cell as SELF (show antigen)
class 1= all cells
class 2= antigen- presenting cells
What do B cells do?
proliferate into plasma cells/ memory B cells and recognise soluble antigens in the blood
What is a FAB
region on antibody that recognises antigen
Function of Helper T cells
- stimulate proliferation of other T cells
- stimulate B cells to produce antibodies
WHat is an Epitope?
Part of the antigen that binds to an antibodies FAB region
How do antibodies protect against infection?
- Neutralisation (specific binding neutralise toxins and form complexes)
- Opsonisation ( Enhance innate mechanisms; activate classical complement pathway, release of inflammatory mediators by mast cells, enhancing phagocytosis)
Immunoglobulin classes and function?
IgM- 1st response to antigen, cant cross placenta
IgG- most common, crosses placenta (passive immunity)
IgA- Secreted from mucous membranes
IgD- B cell activation; cant cross placenta
IgE- histamine reactions and allergies
What is Pharmacodynamics?
How the drug affects the body
What is Pharmacokinetics?
How the body affects the drug
- absorption
- distribution
- metabolism
- excretion
What is Absorption
process of transfer from where the drug was administered to the circulation
What is Distribution
Drug reversibly leaves blood stream and enters extracellular fluid and tissues
What is Metabolism?
Transformation of drug molecule into different molecule
What is Ecretion?
Molecule expelled in liquid, solid or gaseous waste
Whats Bioavailability?
Fraction of administered drug that reaches the systematic circulation unaltered
What is Efficacy?
How well a ligand activates a receptor
WHat is Potency?
The binding affinity
What is the difference between parasympathetic receptors and sympathetic receptors on a target organ
?
Para= muscarinic
Symp= NAd receptor (alpha or beta)
What is a Thrombus?
Solid mass of blood constituents
What is a Physiological reason for a thrombus?
haemostasis/ prevent bleeding
imbalance in blood coagulation system
What is a Pathological reason for a Thrombus?
imbalance in blood coagulation system
Features of Arterial Thrombosis?
- superimposed on atheroma
- high pressure
- mainly platelets (white)
- cause MI/Stroke
Features of Venous Thrombosis?
- due to stasis
- low pressure- mainly coagulation factors&RBC (red)
- cause DVT/PE
Tretament of Thrombosis?
Antiplatelet= clopidogrel/ aspirin
Anticoagulants= warfarin, heparin, NOACs
Name the process of Atherosclerosis
1) Endothelial cells damaged by cholesterol
2) High levels of LDL accumulate on arterial wall
3) Macrophages attract to site- take up lipid to form foam cells
4) formation of fatty streak
5) Cytokines and growth factors released from macrophage
6) Smooth muscle proliferation around lipid core and formation of a fibrous cap
What is an EMbolism?
Mass of material in vascular system able to get stuck
What is Infarction?
issue death due to lack of blood supply
Name a few inducers and inhibitors of Cytochrome P450
inducers: Antiepileptics, smokers, chronic alcohol intake
inhibitors- erythromycin, allopurinol, anti-fungal, SSRI, acute alcohol
Name some Enteral routes of Administration
- enteric coated (oral)- intestinal absorption
- extended release
- sublingual/ buccal
Name some Parenteral routes of administration
- intravenous
- intramuscular
- subcutaneous
Name mechanisms of Absorption
- diffusion
- active transport
- endocytosis
Name some variables of Absorption
- pH
- vascularity
- surface area
- contact time
how do you work out bioavailability of a drug?
AUC oral/ AUC injected x 100 (e.g IV is 100%)
NAme some factors of bioavailability
first pass hepatic metabolism (liver transforming drug)
solubility
chemical instability (GI breakdown by enzymes)
Factors of Distribution
- blood flow
- capillary permeability
- plasma binding protein
Difference between phase 1 and phase 2 metabolism
1= catalysed by cytochrome P450, polarise lipophilic drug (functionalisation by adding chemically reactive group permitting conjugation) (oxidation, reduction, hydrolysis)
2= conjugation by glucuronic acid e.g
to then be excreted by renal/biliary system (add exogenous compound increasing polarity)
What is a first order and zero order rate?
1st= catalysed by enzymes, rate of metabolism directly proportional to drug conc
zero= enzyme saturated by high drug dose, rate of metabolism is constant
How does elimination occur
- excretion by urine, must be sufficiently polar (role of phase 2 and conjugation)
What is drug signal transduction?
- binding of drug to EC/IC receptor e.g ligang gated ion channels/ G- protein coupled receptor
- leads to amplification or down- regulation of signals
What does allosteric mean?
binds to other site of the cell irreversibly
How do opioids work?
Inhibitng descending pain signals, all durgs are μ receptor agonists
What is naloxone?
opioids antagonist used in overdose or respiratory depression
side effects of opioids?
- respiratory depression
- sedation
- nausea/ vomit
- constipation
effect of Muscarinic receptor M1?
mainly brain
effect of Muscarinic receptor M2?
mainly slowing of the heart
effect of Muscarinic receptor M3
glandular and smooth muscle
bronchoconstriction
sweating
salivary gland secretion
effect of Muscarinic receptor M4 and M5?
CNS
What is Salbutamol
beta 2 adrenoreceptor agonist (SABA)
what is the effect when NAd binds to an alpha 1 receptor?
- vasoconstriction
- mydriasis (pupil dilate)
- contraction of bladder neck (urinary retention)
- increased peripheral resistance
what is the effect when NAd binds to an alpha 2 receptor?
- inhibits release of NAd and ACh
- reduces insulin produced from the pancreas
what is the effect when NAd binds to a beta 1 receptor?
- positive chronotropic effect on the heart
- increased renin from the kidney (increased BP)
- increased lipolysis
what is the effect when NAd binds to a beta 2 receptor?
- bronchodilation
- vasodilation
- decreased GI motility
- decreased peripheral resistance
what is the effect when NAd binds to a beta 3 receptor?
- increased lipolysis
- relaxation of the bladder
beta blocker side effects?
- wheeze
-tired - bradycardia
- hypoglycaemia
what is a COX enzyme?
an enzyme that allows production of thromboxane and prostaglandins
how does aspirin work?
aspirin inhibits COX1 and COX2 enzymes which stops the production of thromboxane’s and prostaglandins
What do thromboxane’s do?
cause vasoconstriction and platelet aggregation therefore aspirin stops this occurring
what can prostaglandins do?
cause inflammation/ anaphylactic reaction and pain! therefore aspirin stops this occurring?
which enzyme catalyses thromboxane production?
COX1
which enzyme catalyses prostaglandin production?
COX2
Describe the breakdown of paracetamol in the body
Paracetamol is converted into a reactive intermediate by CYP450
it then becomes a cellular macromolecule or stable metabolite
It then undergoes cellular necrosis if it become a cellular macromolecule
What is bradykinin?
a potent vasodilator
Alpha 1 agonists?
decongestants (phenylephrine)
alpha 1 antagonists?
Tamsulosin
beta 1 agonists?
Inotropes (epinephrine and dopamine)
BETA 1 ANTAGONISTS?
selective/ non selective beta blockers
beta 2 agonists?
SABA/LABA
beta 2 antagonists?
non selective beta blockers
histamine antagonist?
cetirizine
loratidine
What are the factors of dose- response relationship?
- drug conc (dose of drug + pharmacokinetic profile)
- receptor availability (maximal effect once receptors and saturated irrelevant of increased dose)
parasympathetic pathway?
acetylcholine – nicotinic receptor – acetylcholine – muscarinic receptor
sympathetic pathway?
acetylcholine – nicotinic receptor – norepinephrine – adrenergic receptor
What are type 1 hypersensitivity reactions related to
Allergies (anaphylaxis and asthma)
(IgE, mast cells, histamine)
What are type 2 hypersensitivity reactions related to
Cytotoxic cells, antibody dependant
Ab binds to Ag on target cell and kills it via complement
What are type 3 hypersensitivity reactions related to
Immune complex disease
Circulating Ab binds to Ag to form a complex. Circulating complex deposited in tissue = inflammation e.g reactive arthritis
What are type 4 hypersensitivity reactions related to
Delayed type hypersensitivity
Ag presenting cell presents Ag to T cell, T cell activated to Th1, forms memory Th1 cell. When Ag presented again, memory Th1 cell activates macrophages- inflammation
Definition of Allergy?
Abnormal response to harmless foreign material
Definition of Atopy?
tendency to develop allergies
What is Anaphylaxis?
Acute allergic reaction to an antigen to which the body has become hypersensitive.
Pathogenesis of Allergies?
IgE binds to FceRI on mast cell and basophil
(IgE has high affinity for FceRI 1:1),
this causes degranulation of the cells which releases histamine= bronchoconstriction and arteriolar dilation
What is FceRI found on?
- mast cells (tissues)
- Eosinophils and Basophils (circulating)
Involved in host defence against parasites
What are mast cells derived from and where are they found
myeloid stem cells and found in tissues
Effects of Histamine
bronchoconstriction and arteriolar dilation
Effects of LT
capillary contraction- increasing vascular permeability
Effects of PGD2
Smooth muscle contraction
Effects of Platelet Aggregation Factor (PAF)
Increasing vascular permeability and platelet aggregation
Describe what happens in anaphylaxis in terms of the CVS, Resp, Skin and GI systems
Mast cell/ Basophil activation - IgE activation- histamine elevation
CVS= vasodilation, increased vascular permeability and increased BP
Resp= Bronchial smooth muscle contraction, mucous
Skin= Rash/swelling
GI= pain/ vomiting
Treatment of Allergies?
1) Avoid allergens
2) Desensitisation to allergens- increase dose of Ag
3) Prevent IgE production- block Th2 cytokines (Lumiluximab)
4) Bind to and inactivate receptor of IgE (omalizumab)
5) Prevent mast cell activation- mast cell membrane stabiliser (prednisolone)
6) Inhibit mast cell products- PT/LT antagonist
Describe the Optochin test
Differentiate between Alpha haemolytic streps
resistant= s.viridans (positive) sensitive= s.pneumoniae
What bacteria is it if there is a positive oxidase test (gram negative non lactose fermenter)
Positive oxidase test= pseudomonas oxidase
What antibiotic is given to treat MRSA
vancomycin
Causes of Chronic Inflammation?
Persistent acute
develops from acute
Primary Chronic Inflammation
Sarcoidosis blood marker?
ACE
Final differentiation between bacteria?
Serotyping (API strip)
Name the leukocytes?
Neutrophils, basophils, eosinophils
Efficacy and Affinity are receptor related, what do agonists and antagonists show?
Agonists = both
Antagonists = just affinity
What is Tolerance and Desensitisation?
Tolerance - reduction in drug effect over time (continuously repeated high conc)
Desensitisation - receptors become degraded / uncoupled