Infection and immunity Flashcards
What is a fever?
Body temperature over 38 degree Celsius
What does a fever indicate?
It indicates an elevated core body temperature in response to cytokines and acute phase proteins
Name some accompanying symptoms of fever
- shivering
- night sweats
- severe headaches
- delirium
- muscle pain: common in viral infections
- shock: in severe infections and sepsis
Fever is an indicator of underlying disease. TRUE OR FALSE
TRUE
Name some investigations that should be carried out in patients with a fever
- FBC and eosinophil count
- urea and electrolytes
- liver function test
- inflammatory markers (esr and crp)
- ECG
- Throat swab
- Stool culture
- Urinalysis and urine culture
Name 3 infections that present with a fever (differential diagnosis)
- Hepatitis
- Meningitis
- Pneumonia
How do you manage a fever?
- simple analgesia e.g ibuprofen or paracetamol
- tepid sponging to cool the skin
- further management should be based on the underlying cause
What is sepsis?
- extreme medical condition that arises as a result of body’s inflammatory response to infection
Sepsis is one of the most common causes of multi-organ failure. TRUE OR FALSE
TRUE - sepsis causes severe inflammatory response in the entire body and immune system goes into overdrive
What population is generally more likely to develop sepsis?
Elderly
What are the kind of symptoms present in sepsis?
- Hypotension
- Altered mental status (Delusion etc.)
- Tachypnoea ( respiratory rate more than 22 b/m)
- suspected infection
- fever
- dizziness
- warm skin
How do you investigate sepsis?
- Deliver high - flow oxygen
- Take blood cultures
- Administer IV antibiotics
- Measure serum lactate (corresponds to the level of oxygen starvation)
- Start IV fluids (increases blood pressure)
- Measure urine output
- Check vitals e.g bp, tpr etc.
What is the prognosis of sepsis?
high mortality rate
- hospitalisation with sepsis can cause muscle wasting and damage inflicted organs
What is the pathophysiology of sepsis
- Infection
- WBC release inflammatory cytokines
- Blood vessels permeability increases so that wbc can infiltrate
- Vasodilation throughout the body occurs
- Blood pressure drops
- Blood pressure also means less oxygen is supplied to cells and tissue
- Immune response causes fluid build up that makes oxygen diffusion to cells and tissues more difficult
- Leads to cell oxygen starvation
List 3 microorganism which cause infections which commonly present to primary care
- C. diff
- E.coli
- Staphylococcus aureus
Name some of the innate systems barriers against infection
- Physical
- Stomach acid
- Ciliated epithelial cells
- Mucus lining trachea
- Skin surface (flora)
- Co enzymes in tears - Internal defences
- Inflammatory response
- Complement system
- Phagocytosis
- Natural killer cells
Common defects in innate immunity resulting in disease
- Toll - like receptors deficiency: found on the surface of many wbc and react with proteins present on many microbes - activate secretion of cytokines for adaptive immunity
- Natural Killer Cell deficiency: important in the killing of viral- infected of malignant cells (called NK cells because they do not need T- cells)
- Defects in interferon - y and interleukin- 12 signalling: causes susceptibility to mycobacteria and salmonella infections
How do NK cells kill viruses
They insert toxic proteins into their membranes and are particularly important in the defence against herpes virus
How do PAMPS recognize MAMPS
They recognise that its not one of the self antigens so they bind to it
ANTIBODIES MODE OF ACTION:
- Prevents antigen from …..(2)…. to its target
- Tagging a pathogen for destruction by ….(2) ……or neutrophils
- Activating the ……(3)…… cascade
- Opsonization
- A…..(4)…….
- binding
- macrophages
- complement
- agglutination
Describe the positive and negative selection of T and B cells
Positive selection requires signaling through the antigen receptor for the cell to survive. Developing B cells are positively selected when the pre-B receptor binds its ligand. (Developing T cells are positively selected for their ability to bind MHC as well as peptide.) Negative selection means that binding to the receptor results in cell death. Both immature B and T cells are negatively selected if they bind self antigen.
What are effector cells?
Short lived cells that are activated and defend the immune system
What is the role of effector cells in the cell mediated and humoral response?
Effector B cells are called plasma cells and secrete antibodies (humoral), and activated T cells include cytotoxic T cells and helper T cells, which carry out cell-mediated responses.
What is sequestrum?
segment of necrotic bone that becomes separated or “sequestered” from the healthy intact bone.
