ICS Flashcards
what is the most common cause of bacterial pneumonia?
strep pneumoniae
which antibiotics inhibit cell wall synthesis?
Benzylpenicillin, Cefotaxime, Teicoplanin, Vancomycin
which heart valve is most commonly affected in infective endocarditis?
tricuspid
state 4 symptoms of severe infective gastroenteritis
bloody diarrhoea, fever, headache, reduced skin turgor
state some complications of C. difficile infection
ascending cholangitis, diverticulitis, ischaemic colitis, peptic ulcer
list the gram positive cocci
- staphylococci
- streptococci (including enterococci)
list the gram negative diplococci
- Neisseria meningitidis
- Neisseria gonorrhoeae
- also Moraxella catarrhalis
list the gram positive bacilli
mneumonic: ABCD L
- Actinomyces
- Bacillus anthracis (anthrax)
- Clostridium
- Diphtheria: Corynebacterium diphtheriae
- Listeria monocytogenes
list some common gram negative bacilli
- Escherichia coli
- Haemophilus influenzae
- Pseudomonas aeruginosa
- Salmonella sp.
- Shigella sp.
- Campylobacter jejuni
why is phenoxybenzamine prescribed to prepare for phaeochromocytoma surgery?
- during removal of the tumour it is possible for a large amount of catecholamine release to occur - causing refractory hypertension.
- therefore, pre-blocking the a-receptors with phenoxybenzamine you prevent this
what medication is used to treat heroin addiction?
methadone
what is co-amoxiclav a mix of?
amoxicillin and clavulanic acid
what food decreases warfarin’s effect and how?
spinach
- warfarin is a vit K antagonist
- vit K is required for the synthesis of clotting factors 2,7,9,10 - antagonism decreases production of these
- blood becomes thinner and increases INR
- spinach is high in vit K so may decrease effect of warfarin
what is the mechanism of action for penicillin antibiotics?
inhibits bacterial wall synthesis
define pharmacodynamics
action of drug on body
define pharmacokinetics
action of body on drug
what makes mycoplasma resistant to β-lactam antibiotics?
they lack a cell wall
What is the mechanism of dobutamine?
B1-agonist
what is the basic mechanism of furosemide?
Na+/K+/2Cl- inhibitor
which leukocyte in peripheral blood can become pulmonary macrophages in chronic irritation?
monocytes
Which investigations is used to confirm a nickel allergy?
patch test
which antibody is the initial response to a hep B infection?
IgM
Antibody transfer from a mother to infant during breastfeeding is most likely an example of which type of immunity?
naturally acquired; passive
What is secreted by virally infected cells as part of a signalling mechanism, and what is its action?
interferon-a - they bind target innate cells such as macrophages and NK cells and induce an antiviral state
Which cell in the normal lymph node is a specialised, highly efficient antigen-presenting cell (APC) found mostly in areas of T-cell concentration?
dendritic cell
What investigations will be most useful in estimating risk of developing an opportunistic infection in HIV?
CD4 count
What is the most common causative organism of traveller’s diarrhoea?
E.Coli
Which pathogen is most commonly isolated in cases of chronic diarrhoea associated with HIV?
campylobacter
what are toll-like receptors?
a type of intracellular pattern recognition receptor that proteins recognise and then bind to PAMPs
what are pathogen associated molecular patterns (PAMPs)?
an immune cell that recognises some general molecular features common to many types of pathogen
what is TLR1 associated in detecting?
malaria
what is TLR2 associated with detecting?
lipoteichoic acid on gram positive bacteria
what is TLR4 associated with detecting?
Lipopolysaccharide on the surface of gram negative bacteria
what is TLR5 associated with detecting?
flagellin
Which diuretic increases sodium and water excretion by competitively binding to aldosterone receptors in the distal tubules of the kidney?
spironolactone
What is the mechanism of action of alendronic acid (bisphosphonate)?
Inhibits osteoclastic activity to decrease bone resorption, which reduces bone turnover and improves bone mass
What is the mechanism of action of rivaroxaban (anticoag. medication used in patients with a.fib to reduce risk of stroke)?
Directly inhibits activated clotting factor X to prevent conversion of prothrombin to thrombin
name 4 drugs that inhibit the action of COX enzymes and therefore inhibit formation of prostanoids and prostaglandins?
aspirin, celecoxib (NSAID), paracetamol, ibuprofen
name 2 side effects of diclofenac (NSAID)?
heartburn, abdo pain
name 1 side effect of codeine
constipation
how does bendroflumethiazide work?
inhibits sodium reabsorption at the DCT by blocking the Na+/Cl- symporter
name one medication contraindicated in parkinson’s disease and explain why
metoclopramide - D2 receptor antagonist that crosses the BBB and can cause extra-pyramidal side effects and parkinsonism
The culture showed gram positive cocci, found in clusters. A coagulase test was positive. Name the organism
staphylococcus aureus
what does staphylococcus look like on blood cultures / microscopy?
gram positive cocci found in clusters. coagulase positive
what substance gives green / yellow colonies in beta haemolysis?
biliverdin
What causes a positive coagulase test?
Organisms that produce an enzyme that converts soluble fibrinogen to insoluble fibrin
What colour do gram positive organisms stain and why?
- Purple
- they have a thick layer of peptidoglycan in their cell walls which retains the crystal violet
What organism does the optochin test identify?
streptococcus pneumoniae
What is the antibiotic used for treatment of streptococcal pneumonia?
flucloxacillin
gram positive, catalase negative microorganism family?
streptococcus
what does beta haemolysis look like?
clear/colourless zone around colonies
What is the recommended treatment for a confirmed group A streptococci infection?
- IV benzylpenicillin
- IV clindamycin
- Urgent surgical exploration with extensive debridement
- amputation
What do gram-positive bacteria secrete which causes pathogenicity?
exotoxin
Give 3 differences between the structure of the cell envelope of gram- positive and gram-negative bacteria.
- Gram positive have single cytoplasmic membrane
- Gram positive have large layer of peptidoglycan
- Gram positive do not have endotoxin/LPS
What is the name for a malignant tumour of smooth muscle?
leiomyosarcoma
what is the name for a malignant striated muscle neoplasm
rhabdomyosarcoma
what is the definition of a granuloma?
an aggregate of epithelioid histiocytes
name 4 constituents of an atherosclerotic plaque
connective tissue, foam cells, lymphocytes, smooth muscle cells
typical history of legionella pneumophila?
productive cough, rusty coloured sputum, achy joints, headaches, recent travel (spain!!), crackles in right lung base
immediate treatment for suspected septic meningitis?
IM benzylpenicillin
describe strep pyogenes
beta-haemolytic gram-positive streptococcus with Lancefield grouping A
first line treatment for UTI?
- usually nitrofurantoin
- if non-pregnant or male, trimethoprim pay be used if low risk of resistance
classical triad of encephalitis?
- fever, altered mental state, headache
- can present with flu like symptoms and be a DD for meningitis
what nutrient agar is used to grow mycobacterium tuberculosis?
Lowenstein-Jensen
describe pseudomonas
non-lactose fermenting aerobic bacilli with positive oxidase test
what is the most common cause of infective endocarditis in adults with poor dental hygeine? describe it
strep. viridans - optochin resistant alpha-haemolytic strep
Which test is used to distinguish between staphylococcus and streptococcus?
catalase
which organisms does the 1,3 beta D-glucan assay detect?
- aspergillus fumigatus
- candida albicans
- pneumocystis jirovecii
which cell wall feature enables a causative pathogen to resist phagocytic killing?
mycolic acid
what is the mechanism of action for flucloxacillin?
disrupts peptidoglycan
what is a papilloma?
benign tumour of non-glandular, non-secretory epithelium
what is the ligand for TLR-4?
lipopolysaccharide, part of the bacterial cell wall
what is an adenoma
benign tumour of glandular or secretory epithelium
what is a carcinoma?
malignant tumour of non-glandular, non-secretory epithelium
what is a sarcoma?
malignant tumour of connective tissue
which structure in the bacterial cell do macrolide antibiotics (e.g rifampicin) interfere with to exert their bactericidal effect?
ribosome (50s subunit)
what is margination?
slowing of blood velocity to allow neutrophils to line up along endothelium
what is adhesion?
“sticking” of neutrophils to endothelium via adhesion molecules
what is emigration?
Neutrophils move through the walls of small blood vessels
what is diapedesis?
Where red cells passively escape the circulation due to hydrostatic pressure
what is chemotaxis?
Where neutrophils follow a concentration gradient of certain compounds
what is MHC-1?
- an antigen found on all nucleated cells in the body
- function: display peptide fragments of proteins from within the cell to cytotoxic T cells to allow response to be triggered
describe mycobacteria
slow growing, predominantly immobile, rod shaped, intracellular, gram positive
what is the most common organism to cause menigitis?
strep pneumoniae - gram neg
when is a LP contraindicated in meningitis?
if septicaemia is suspected e.g. rash
what is a dormant malaria spore called?
hypnozoites
Describe the lifecycle of a malarial plasmodium within the human body, naming each stage of plasmodium development
- sporozoites in mosquito saliva enters blood
- matures into a hypnozoite in liver and released into blood as schizont
- then explodes releasing merezoites which enter RBCs and become trophozoites
- eventually they become gametocyes which are taken up by mosquito
what is the gold standard test for malaria?
microscopy of thick and thin blood smears stained with Giemsa stain
what is the treatment for a non-falciparum malaria infection?
chloroquine
what is the treatment for a falciparum malaria infection?
oral quinine sulfate
complications of untreated malaria?
seizures, impaired consiousness, renal impairment, anaemia, hypoglycaemia
name 2 genes of the HIV genome and their function
- Nef - increases infectivity
- Eny - encodes the envelope proteins
give 2 example of an opportunistic infection that can result from HIV infection
- cytomegalovirus
- pneumocystis jiroveci
What cells do HIV antigens bind to and enter?
CD4+ T-lymphocyte
Part of the HIV replication process involves the reverse transcriptase enzyme. Give an example of a drug that can inhibit the reverse transcriptase enzyme
zidovudine - nucleoside reverse transcriptase inhibitor
what is the treatment for syphilis?
first line: benzathine penicillin, second line/contraindicated: azithromycin
what is the mechanism of action of adrenaline?
agonist of beta adrenergic receptors
what is the general antibiotics for UTIs?
trimethoprim or nitrofurantoin
what are DMARDs and give an example
- methotrexate
- Disease Modifying Anti-Rheumatic Drugs
- inhibition of pyramidine synthesis
what hypersensitivity is Coeliac disease?
type 4
first line treatment for tonsilitis?
Phenoxymethylpenicillin QDS 10 days - only given if severe or persistent
Which bacterial structure do glycopeptide antibiotics target?
cell wall
what does rifampicin target?
RNA polymerase
what does ethambutol cause?
optic neuritis
which diuretic can cause hyperkalaemia
spironolactone
mechanism of action of b-lactam antibiotics?
inhibit transpeptidation reactions needed to cross-link peptidoglycans in the cell wall
what is the difference between active and latent TB?
- active -> containment of the disease by the immune system is inadequate so the disease shows symptoms and can be spread
- latent -> infection without disease due to persistence immune system containment
define systemic sclerosis
A multi-system autoimmune disease in which fibrous tissue accumulates in multiple organs
give 4 signs/symptoms of scleroderma
- Calcium deposits,
- Raynaud’s phenomenon,
- oesophageal dysfunction,
- pulmonary hypertension, severe hypertension,
- renal crisis (due to hypertension),
- pulmonary fibrosis,
- skin ulcers
describe the pathophysiology of scleroderma
- an abnormal response to an unidentified trigger.
- This results in the production of cytokines
- These cytokines stimulation of collagen deposition by fibroblasts.
