Infectious disease Flashcards
Which stain is used to differentiate between gram positive and gram negative bacteria? What is the result?
Crystal violet stain. Gram positive bacteria are stained but gram negative don’t
What is the name for rod shaped bacteria?
Bacilli
What is the name for circular shaped bacteria?
Cocci
What is the counterstain called which identifies gram negative bacteria? What colour does it turn?
safarin. Red/ pink
What is the difference in cell structure between gram positive and a negative bacteria?
Gram positive have a thick peptidoglycan cell wall
Name 3 gram-positive cocci?
Staphylococcus
Streptococcus
Enterococcus
What does MRSA stand for?
Methicillin- resistant staphylococcus aureus
Name 3 antibiotic treatment options for MRSA
Doxycyline
Clindamycin
Vancomycin
What are the 2 broad mechanisms of actions of antibiotics?
Bactericidal
Bacteriostatic
Which bacteria does amoxicillin cover?
Streptococcus, listeria and enterococcus (all gram +ve)
Which bacteria does co-amoxiclav cover?
Staphylococcus, haemophilus and e.coli
Which bacteria does tazocin cover?
Pseudomonas
Which bacteria does meropenem cover?
ESBLs (extended spectrum beta lactamases) These are bacteria which produce an enzyme which makes them resistant to beta lactamases
Which bacteria do teicoplanin and vancomycin cover?
MRSA
Which bacteria do clarithromycin and doxycyline cover?
Atypical bacteria
Why is oedema a feature of sepsis?
Massive cytokine release occurs in response to pathogen. This causes the endothelial lining of cells to be more permeable leading to fluid leakage.
What can oedema cause in sepsis and why?
tissue hypoxia because fluid leakage creates a space between vessels and tissue
Why does DIC occur in sepsis?
Coagulation system is activated leading to deposition of fibrin throughout the circulation system. This causes platelets to be used up
Why is blood lactate high in sepsis?
Hypo-perfusion of tissues causes tissues to switch to anaerobic respiration. A by-product of anaerobic respiration is lactate
What are the two main symptoms which measure if a patient is in septic shock?
Systolic blood pressure less than 90
Hyperlactaemia (>4mmol/L)
How is septic shock managed?
IV fluid boluses to improve BP and perfusion. If this doesn’t wrk then use inotropes (such as noradrenalin) to stimulate the CV system, increase BP and perfusion
How is severe sepsis defined?
When sepsis is present and results in organ dysfunction
What is the screening tool for sepsis used in hospitals?
NEWS (national early warning score)
What is often the first sign if sepsis?
Tachypnoea
Investigations for sepsis?
FBC (asses neutrophils) U&Es for kidney function LFTs CRP Clotting (DIC) Blood cultures ABG (lactate, pH and glucose)
What is the sepsis 6?
Three tests:
- Blood lactate
- Blood cultures
- Urine output
Three treatments:
- O2 (94-98% target)
- Empirical broad spectrum antibiotics
- IV fluids
What is neutropenic sepsis?
Sepsis in a patient with a low neutrophil count of less than 1x10^9/L
Which 2 bacteria most commonly cause chest infections?
- Streptococcus pneumonaie (50%)
2. Haemophilus influenzae (20%)
What is the most appropriate initial antibiotic in the community for a chest infection?
Amoxicillin
Which bacteria most commonly cause UTIs?
E.coli
What are the 4 main symptoms of pyelonephritis?
Fever
Loin pain
Haematuria
Renal angle tenderness
What would show on a urine dipstick if someone has a UTI?
Nitrites
Leukocytes
What length of antibiotic treatment should women be put on for UTI?
3 days
What length of antibiotic treatment should women who are immunosupressed or have abnormal kidney function be put on for UTI?
5-10 days
What length of antibiotic treatment should men, pregnant women or people with catheter related UTIs be put on for UTI?
7 days
Which antibiotics are the initial choices for UTI?
Trimethoprim
Nitrafurantoin
Which antibiotic for UTI is avoided in the third trimester?
Nitrofurantoin, causes haemolytic anaemia in newborns
Which antibiotic for UTI is avoided in the first trimester?
Trimethoprim due to anti-folate effects
What does a gold-yellow crust indicate?
Staphylococcus aureus infection
What is the name of the classification used for cellulitis?
Eron classification
Which antibiotic is most commonly used for cellulitis?
Flucloxacillin. Very effective against staph
Which bacteria most commonly causes bacterial tonsillitis?
Group A strep (mainly streptococcus pyogenes)