Infection and immunity - Clinical medicine Flashcards
When should a urinalysis be done?
- When a UTI is suspected
- Diabates
- Screening of pregnancy
- Suspected renal disease
a) What are the 3 key urinary sympoms of a UTI?
b) What should you do if a patient has 1/3 symptoms?
c) What should you do if a patiet has 2/3 symptoms?
a) Dysuria, Nocturia, Cloudy urine
b) Urinalysis
b) Urine culture and start antibiotic
a) What issue arise when a man has symptoms suspicious of a UTI?
b) How can this issue be solved?
a) Dipstick becomes unreliable when ruling a UTI
b) A urine culture should be taken and antibiotics started
a) What type of people are dipstick uneliable in?
b) Why is this?
a) 65+ and those with catheters
b) Half of adults (more liekly as you ages) and those with catheters will have bacteria sitting around in their bladder or urine without causing an infection. This is known as asymptomatic bacteriuria
What is the cut off age for dipstick urianalysis?
65 years
What may a dark urine suggest?
Dehydration
What may red ringed urine suggest?
- Blood (haematuria)
- Drugs e.g.,fampicin (antibiotic)
- Certain foods (e.g., beetroots)
What may brown urine suggest?
- Bile pigments (e.g., jaundice)
- Myoglobin (protein) (e.g., rhabdomyolysis)
- Some antimalarial medication e.g., chloroquine
What may green/blue urine suggest?
Medications such as amitriptyline
What may cloudy urine suggest?
Pyuria (pus in the urine) – infection, renal stones
What may frothy urine suggest?
Proteinuria (nephrotic syndorme)
What may sweet swelling urine suggest?
- Diabetic ketoacidosis (DKA)
- Glycosuria (diabetes mellitus)
What may unpleasant urine suggest?
UTI
What may the present of glucose in urine suggest?
- Diabetes mellitus
- DKA
- Cushing’s disease
- Some diabetic medications (e.g., SGLT2 inhibitors)
What may the presence of bilirubin in urine suggest?
- Haemolytic disease
- Liver damage (e.g., from hepatitis)
What may blood (haematuria) in urine suggest?
- Infection
- Tauma
- Renal disease
- Enlarged prostate
- Contamination with menstrual blood
- Cancer
What should you investigate for if a patient has asymptomatic haematuria?
Cancer
What may the presence of protein (proteinuria) suggest?
- Infection
- Renal disease
What may the presence of leukocytes in urine suggest?
UTI
What may the presence of ketones in urine suggest?
- DKA (Ketones in combination with glucose – DKA, must be ruled out),
- Starvation
- Pregnancy
What may the presence of nitrates in urine suggest?
- Gram-negative YTI
- Gall bladder disease/obstruction
- Haemolysis
What may a high specifc gravity of urine suggest?
- Dehydration
- Urinating glucose &/or protein
What may a low specific gravity suggest?
- Diuretic use
- Renal disease
- Diabetes insipidus
What may an acidic pH suggest?
- Uric acid
- Kidney stones
What may an alkalike pH suggest?
- UTI
- Vomiting
- Diuretics
What may urobilinogen in urine suggest?
- Haemoytic disease
- Liver damage
Lady in her 30’s who is complaining of thirst and passing urine frequently. These are her urine results. What is the suspected diagnosis and why?
Suspected diabetic ketoacidosis because of raised glucose and ketone levels
40 year old male IV drug user reporting some brownish urine. These are his urine results. What is your suspected diagnosis and why?
- Suspected liver damage
- Bilirubin and urobilinogen can be raised if bile ducts are blocked, or liver is damaged
- Possible liver damage from hepatitis as risk is increased due to use of needles in IVF drug abuse
70 year old man with a long term catheter, feels well and no other complaints. These are his urine results. What is your suspected diagnosis?
- Suspected UTI due to positive erythrocyte and nitrate count and high leukocyte and specific gravity count.
- However, because he is 65 and has a catheter the urinalysis is not useful due to the fact, he would have some bacteria sitting around. This bacterium is not causing an issue.
- Therefore, he has asymptomatic bacteriuria and does not need to be treated.
List the acute phase proteins
- C-reactive protein (CRP)
- Complement system
- Serum amyloid A
- Haptoglobin
- Fibrinogen
Describe the function of C-reactive protein
- Binds to the receptors of monocytes and neutrophils to stimulate production of cytokines
- Works as an opsonin
- Activates complement
What is the complement system?
A system of pro-inflammatory serum proteins produced by the liver and circulate blood as inactive precursors until they are activated by 1 of 3 pathways
List the 3 pathways of the complement system
- Classical pathway
- Alternative pathway
- Mannose-binding lectin pathway
Name the 3 complement system activation pathways and explain how they are activated
- Classicle pathway - antigen binds IgG or IgM which activates C1 (complement protein)
- Alternative pathways - activated by microbial components directly (does not need antigen-antibody components for activation)
- Mannose- binding lectin pathway - where mannose-binding lectin (MBL) binds to mannose in bacterial surface
Why is C3 important in the complement cascade?
- It is activated by the classic and alternative pathway
- Activates the membrane attack compleck: C5b, C6, C7, C8, C9
C3 can directly act in the process of inflammatin. Describe how.
- Dilating arterioles
- Stimulating mast cells to release histamine
- Causing chemotaxis of phaygocytes
- Opsonisation of microbes
Describe the role of serum amyloid A
- Appears to have some direct and indirect actions on cells of the innate system including macrophages, monocytes, and neutrophils
- Appears to have chemotactic effects
- Involved in the resolution of the inflammatory response
Describe the role of haptoglobin
Binds free haem that has come about due to intra-vascular haemolysis
Describe the role of fibrinogen
Changed by the enzymatic activity of thrombin to produce fibrin clots and can activate bridges between platelets
What stimulates the the production of acute phase proteins
Cytokines - IL1, IL6 and TNF-alpha stimulate haptocytes (liver cells) to produce acute phase reactants
Describe the relationship between the production of acute phase proteins and albuin levels
As the production of acute phase proteins increases albumin levels reduce
What are the two main inflammatory markers?
CRP and ESR
a) Is ethrocyte sedimentation rate (ESR) an acute phase reactant?
b) What principle is it based on?
c) Why does ESR increase with age?
a) No
b) Based on how fast the ethrocytes clump together
c) Increases with age due toincrease in serum amyloid A and anaemia
List how GPs tell the differnence between bacterial and viral throat infections
- Guesswork
- Clinical scoring systems e.g., feverPAIN criteria, centor criteria
- Modern near-patient testing using immunology e.g., throat swabs
Why would it be helpful to GPs to be able to tell whether streptococcus pyogenes is causing a sore throat?
- Antibiotic stewardship
- This is a coordinated program that promotes the appropriate use of antimicrobials.
- This aims to improve patient outcomes, reduce microbial resistance and decrease the spread of infections caused by multi-drug resistant organisms.
Give three reasons for doctors to engage in antibiotic stewardship
- To improve patient outcomes by giving the most appropriate antibiotics for the correct length of time
- To reduce microbial resistance
- To decrease the spread of infections caused by multi-drug resistant organisms. Both in the community and hospital settings
List the high risk groups eligibe for flu vaccinations
- Respiratory disease e.g., COPD, asthma requiring regular inhaled steroids
- Cardiac disease e.g., IHD
- Renal disease
- Immunosuppression
- Liver disease
- Stroke or a transient ischaemic attack (TIA)
- Diabetes
- Neurological condition, such as multiple sclerosis (MS) or cerebral palsy
- A learning disability
- Splenic disease, e.g., sickle cell disease, or splenectomy
- Morbid obesity (BMI of 40 and above)
How can STI’s be prevented?
- Condoms
- Monogomy if both take part
What other contraceptions apart from condoms can prevent STI’s?
None
