Session 5 - Hospital Acquired Infections and Adaptive Immunity Flashcards
(29 cards)
What are hospital acquired infections?
An infection that has taken place and/or originated in a hospital setting.
What are the most prevalent types of hospital acquired infections?
- Urinary Tract Infections
- Pneumonia
- Surgical wound infections
- Skin and soft tissue infections
- Primary bloodstream infections
- Gastro-intestinal infections
Give examples of viruses that can cause a hospital acquired infection
- Blood borne viruses (Hep B, C, HIV)
- Norovirus
- Influenza
- Chickenpox
Give examples of bacteria that can cause a hospital acquired infection
- Staph. aureus
- inclusive of the MRSA strain
- Clostridium difficile
- E. coli
- Klebsiella pneumoniae
- Pseudomonas aeruginosa
- Mycobacterium tuberculosis
Give examples of fungi that can cause a hospital acquired infection
- Candida albicans
- Aspergillus species
Give examples of parasites that can cause a hospital acquired infection
- Malaria
What general patient measures can we take to prevent hospital acquired infections?
- Optimise the patient’s conditions
- Antimicrobial prophylaxis
- Skin preparation
- Hand hygiene
What specific patient measures can we take to prevent hospital acquired infections?
- Conduct MRSA screens
- Mupirocin nasal ointment
- Disinfectant body wash
- Halting patient to patient transmission by isolation of infected patients and protection of susceptible patients
What measures can be taken to prevent healthcare worker to patient spread of infection?
Healthcare workers:
- Should be healthy
- disease free
- vaccinated
- Should use good practice methods
- good clinical techniques (sterile non-touch)
- hand hygiene
- PPE
- anti-microbial perscribing
What environmental interventions can be taken in order to prevent hospital acquired infections?
- Cleaning
- disinfectants
- steam cleaning
- hydrogen peroxide vapour
- Medical devices
- single use equipment
- sterilisation
- decontamination
- Good food hygiene practice
What is the adaptive immune response?
The second part of the immune response that follows the innate immune response.
When does adaptive immunity come into action?
Adaptive immunity begins if the innate immune and inflammatory response are unable to clear the infection. It is a more specific form of immunity.
How is the adaptive immune response activated?
Antigens are presented to the adaptive immune system by APC (antigen presenting cells) with digested antigens travel to the lymph nodes.
What are the different antigen presenting cells (APCs)?
- Dendritic cells
- Langerhans’ cells
- Macrophages
- B cells
What do APC cells do when they reach the lymph nodes?
They present the antigen to the naive T helper cells by the MHC molecules present on the T cell’s surface.
This activates the naive T helper cells and allows them to mature into active T helper cells.
What are the different MHC molecules and in which types of cells are they found?
MHC molecules come in two different classes:
- MHC I
- found on all nucleated cells
- MHC II
- found on dendritic cells, macrophages, and B cells
What are the key features of MHC I and MHC II?
- They have co-dominant expression
- They are polymorphic genes (different alleles for everyone)
- They have different main functions:
- MHC I: present peptides from intracellular microbes
- MHC II: present peptides from extracellular microbes
Which T cells recognise MHC I molecules?
CD8+ T cells
Which T cells recognise MHC II molecules?
CD4+ T cells
What are some clincal problems with MHC molecules?
Is a major cause for organ transplant rejection due to conflicting MHC molecules from the donor and the patient.
What do CD4 T cells do in the adaptive immune response?
Activate humoral immunity to act on extracellular microbes:
- B cells
- Complement system
What do CD8 T cells do in the adaptive immune response?
Activate cell-dependent immunity for intracellular microbes:
- B cell activation
- Completment system
- Macrophages
- Cytotoxic T cells
CD4 T cells are needed to activate CD8 T cells, therefore MHC II is needed for activation.
How are B cells activated?
B cells are activated by T cells, which encourage them to start producing antibodies.
What do B cells produce to help fight infections?
B cells produce various different kinds of immunoglobulin antibodies that have different functions.
