Immunocompromised Infections Flashcards
Give some examples of non-specific immunity
- Skin/ mucosal integrity
- Mucosal clearly mechanisms (Bronchial)
- Gut defence
- Complement system
- Phagocytosis
What is specific immunity
-Cell mediated response and humeral (antibody) response
What is the difference between primary and secondary immunodeficiency disorders
- Primary immunodeficiency disorders= main feature is immunodeficiency eg. Chronic granulomatous disease (Neutrophil defect), B cell defects (humoral), T cell defects (cell mediated), SCID (severe combined immunodeficiecny)
- Secondary immunodeficiency disorders= disease impacts immune function but it is not it’s main feature eg. AIDS, Hyposplenism, Cancer, Diabetes
What are some iatrogenic/ physiological causes of immunodeficiency
Iatrogenic
-Drugs -Steroids -Anti-cancer chemo -Post transplant immunosuppression -Irritation -Invasive devices- IV lines, catheters etc -Surgeries- splenectomy
Physiological states
-Pregnancy -Neonates -Elderly -Nutritional deficiency
How do you prevent infection in immunocompromised patients
- Avoid increased risk locations eg hosp
- Protective isolation in hosp- side room, ventilation act
- Vaccination- flu in elderly, chronic lung and HD
- Antimicrobial propylaxis- HIV patients
- Restore underlying defect- if neutropenic give granulocyte macrophage stimulating factor
Describe the spectrum of infectious agents and CD4 count in AIDS/HIV
0.5x10 9 /L CD4 t cells= mycobacterium TB - can infect at higher levels of CD4
Less than 0.2 CD4 t cells = pneumocystis, toxoplasmosis
Less than 0.1 CD4 t cells = CMV
What are the various fungi, parasites, bacteria and viral pathogens that are common in HIV
- Fungi= pneumocystis, candida spp, cryptococcus neoformans
- Parasites= Cerebral toxoplasmosis, cryptosporidiosis
- Bacteria- Mycobacterium TB, salmonella
- Viruses- CMV, HSV, Human herpes virus 8
What is pneumocystis carinii/ jiroveci
- Causes lung infection
- Fungi
- Diagnosis: Silver stain/ monoclonal antibody detection in BAL or biopsy of lung specimen
- PCR on bronchial lavage if staining isn’t available
What is pneumocystis Pneumonia (PCP)
- Non-productive cough, dyspnoea, fever
- Perihilar infiltrates
- Severe respiratory distress
- Extra pulmonary infection (rare)
- Treatment= high dose cotrimoxazole and ICU admission
Discuss the features of Cerebral toxicoplasmosis
- Caused by protozoal infection with T gondii
- In healthy hosts- asymptomatic or glandular fever like illness
- HIV- cause of focal CNS lesion that is RING ENHANCING
- Pneumonitis and chorioretinitis can also occur but rare
- Neuro symptoms- seizures and loss of consciousness
- NEED A CONTRAST ENHANCED CT
How do we prevent infections in HIV patients?
- CD4 count is boosted by HAART to stop opportunist infections
- As CD4 count drops start to give infection prophylaxis
- Pneumocystis- cotrimoxazole
- Mycobacterium avium intracellular- rifambutin
- CMV- Gangciclovir
What are the causes and features of acquired immunodeficiency neutropenia
Causes
-Iatrogenic - post chemo -Post bone marrow transplant -Aplastic anaemia -Other drugs
Hard to diagnose due to absence of pus and localisation
FEVER IS THE CARDINAL SIGN
NEUTROPENIC FEVER = SEPSIS
What are the two general rules for infection in an immunocompromised patient
- Infection with typical bacteria and fungi is caused by neutropenia
- Mycobacteria, legionella, listeria and viral infection all caused by cellular immune dysfunction - mainly T cells
What are the two main fungal infections associated with immunocompromised patients
- Aspergillus fumigateurs- mould - rapidly disseminated infection (lung and brain) - lung more common, hard to culture and diagnose, high mortality
- Candidia Albicans- yeast- increased risk with central lines, parenteral nutrition and broad spectrum abx
How do you manage neutropenic sepsis
- Empirical therapy DO NOT WAIT ON CULTURE RESULTS
- Urgent bactericidal broad spectrum antibiotics
- Anti-pseudomonal penicillin + an amino glycoside
Piperacillin + Gentamycin - Add vancomycin/ teicoplnanin if no improvement (resistant gram positive bacteria covered -MRSA)
- Add anti fungal if no better after 48 hrs
- Supportive measures- Oxygen, circulatory support
