Infections in the Immunocompromised Host COPY Flashcards
What is the Adaptive Immune Response split up in to?
- Humoral (B cells)
- Cellular (T cells)
What results if there is a compromised immune defence system?
Increased susceptibility to infection
What conventional pathogens may take advantage of a compromised defence system?
- Endogenous flora
- Hospital acquired bacteria
- Environmental organisms
Name some opportunistic pathogens which may take advantage of a compromised immune system?
- CoNS
- Aspergillus
What are the different types of immunodeficiency?
- Primary
- Secondary
Describe primary immunodeficiency?
- Inherited
- Exposure to i**n utero environmental factors
Describe secondary immunodeficiency?
- Underlying disease state
- Treatment for disease
What is the principal cause of morbidity and mortality in the immunocompromised host?
Infection
What is the most important risk factor for infection?
Neutropaenia
How is neutropenia defined?
Less than 0.5 x109/L
OR
Less than 1x109 and still falling
Draw a flowchart to show how neutropaenia can arise?
What happens to the incidence of infection neutropaenia duration?
The higher the duration of neutropaenia, the greater incidence of infection
What else is also important regarding neutrophils?
Neutrophil function
What can occur after a patient has received any of the following: cytotoxic drugs, irradiation and steroids?
- Reduced:
- Chemotaxis
- Phagocytic activity
- Intracellular killing
Describe Chronic Granulomatous Disease
- Inherited
- X-linked inheritance is most common
What is the cause of Chronic Granulomatous Disease?
- Defect in NADPH oxidase gene
- Oxygen radicals deficiency
- Normally give neutrophils their damaging effect
- Defective intracellular killing
How does Chronic Granulomatous Disease manifest?
- Abscesses
- Recurrent infections
- Granuloma formation
What is the pulmonary infection in Chronic Granulomatous Disease often caused by?
- S. aureus
- Aspergillus
What does this child suffer from?
Chronic granulomatous disease
What is cellular immunity suppressed by?
- DiGeorge syndrome
- Malignant lymphoma
- Cytotoxic chemotherapy
- Extensive irradiation
- Immunosuppressive drugs
- Infections
Name some infections which can suppress immunity?
- HIV
- EBV
- CMV
- Mycobacterial
What do radiotherapy and chemotherapy ultimately cause?
Hypogammaglobulinaemia
What role does the spleen play in immunity?
- Splenic macrophages eliminate encapsulated bacteria
- Site of the primary immunoglobulin response
What is the site of the primary immunoglobulin response?
The spleen
What infections are you at risk of if you suffer from any of the following:
- Humoral deficiency
- Splenectomy
- Hyposplenism
- S. Pneumoniae
- H. Influenzae b
- N. Meningitidis
Name some are the principal physical barriers against infection?
- Skin
- Conjunctivae
- Mucous membranes
- GIT
- RT
- GU tract
What does desquamate mean?
The process where the top layer of skin dies and falls off to give place to newer skin
Describe the normal physiological environment of the skin?
What can impair the integrity of the skin?
- Dry
- pH 5-6
- 5o cooler than the rest of the body
- Secretory IgA present in sweat
Chemotherapy
Draw the flow chart for what happens with GI mucosal barrier injury and colonization resistance?
What is important to note about mucosal barriers?
- They have a high mitotic index
- ie mitosis occurs rapidly -> fast healing
How is a severe nutritional deficiency defined?
- Less than 75% ideal body weight
- OR
- Rapid weight loss
- +
- Hypoalbuminaemia
What can a severe nutritional deficiency result in?
Compromised integrity of host defences
What can iron deficiency specifically result in?
Reduces killing capacity of neutrophils and T cells
How can tumours cause local organ dysfunction?
Which organ is particularly susceptible?
- Due to the obstruction of the tumour
- Can lead to infection
Lung
What can a CNS tumour cause?
- Spinal cord compression
- Loss of cough/swallowing reflex
- Incomplete bladder emptying
All increase risk of infection
Describe the effect of stress and diabetes on the immune system?
- Stress
- reduced T cell function
- Diabetes Mellitus
- reduced opsonization
What are the general principles of infection in solid organ transplant?
- Optimal tissue typing
- Donor evaluation
- Organ procurement
- Surgical technique
- Tailored immunosuppressive regimen
- Prevention of infection
What transplants have the highest infection rate and mortality related to infection?
Heart and lung transplants
What should be used for the diagnosis of an infection following an SOT (solid organ transplant)?
- Radiology
- Histology
- Serology
- Molecular medicine
What is an important consideration regarding infection relating to solid organ transplant?
- The inflammatory response is impaired
- Less clinical signs
- Less radiological signs
What ensures good clinical outcomes with infection in SOT?
- Early diagnosis
- Fast, aggressive radiotherapy
What infections can occur following Solid Organ Transplant?
- Donor-derived infections
- latent
- active blood stream infection at procurement
- Reactivation of infections
- Opportunistic pathogens
What are the latent donor-derived infectious agents to worry about?
- TB
- HIV
- Syphilis
What infections can be active bloodstream infection at procurement from a donor following SOT?
- E. Coli
- Salmonella
- Pneumococci
- Staphylococci
What infections can be reactivated following SOT?
- HSV
- CMV
- M. tuberculosis
What opportunistic pathogens can cause infection following SOT?
- Aspergillus
- Pneumocystis
What is pictured here?
What would cause it?
Severe lung infection in a transplant recipient
Pneumocystis jerovecii
What is pictured here?
Herpetic stomatitis caused by HSV
What is pictured here?
Shingles caused by Varicella zoster virus
What would cause the following?
CMV
What is neutropaenic fever until proven otherwise?
Infection
What percentage of haematology malignancies and solid tumour cases does neutropaenic fever develop in?
- Haematological malignancies
- 100%
- Solid tumours
- 50%
What are 2/3 of neutropaenic fever cases due to?
- Infection
- endogenous or exogenous
What are the most common infection sites in febrile neutropaenic patients with a haematological malignancy?
What is the single most common site?
The single most common site is the blood stream
Name some anaerobic bacteria?
- Bacteroides spp.
- Clostridium spp.
What is rigors?
Sudden feeling of cold with shivering accompanied by a rise in temperature
What is Sepsis?
SIRS and evidence of infection
What is septic shock?
Sepsis-induced hypotension requiring inotropic support
What is Neutropenic Sepsis / Febrile Neutropenia?
- Neutrophil count less than 0.5
- +
- Fever/Hypothermia OR SIRS OR Sepsis
What is used to assess the severity of sepsis?
NEWS score
What is the sepsis 6?
- Administer high flow oxygen
- Take blood cultures
- Give IV fluid
- Give broad spectrum antibiotics
- Measure serum lactate and FBC
- Measure hourly urine output
What makes a sepsis patient a standard risk patient?
NEWS <= 5
What is the treatment pathway for a standard risk patient with Neutropaenic Sepsis?
What makes a Neutropenic shock patient high risk?
NEWS >= 5
How do you treat a high-risk patient with Neutropenic sepsis?
What do you add to Neutropaenic Sepsis treatment if a skin or soft tissue infection is suspected?
Vancomycin
What do you add to Neutropaenic Sepsis treatment if there is a suspected atypical pneumonia?
Clarithromycin
What do you add to Neutropaenic Sepsis treatment if there is a previous/known ESBL infection/carrier?
Meropenem
CMV?
- Causes problems in babies
- Once infected, you have it for life
- Cold sores, chicken pox
- Newborn hepatosplenomegaly
Pneumocystis jiroveci?
- Fungus
- Pneumonia in immunocompromised host
- Green
