Infection in the Immunocompromised Flashcards
What are the important immune cells and what infections do they fight?
Neutrophils - bacterial and fungal Monocytes - fungal Eosinophils - parasitic T lymphocytes - fungal and viral B lymphocytes - bacterial
What are the supportive measures aimed at reducing the risk of sepsis in haematological malignancy?
Prophylaxis
- antibiotics (ciprofloxacin)
- anti-fungal (fluclonazole or itraconazole)
- anti-viral (acyclovir, prophylaxis for VZV and HSV)
- PJP (co-trimoxazole)
Growth factors e.g. G-CSF, shortens duration of neutropenia
Stem cell rescue/transplant - replaces immune system more quickly
Protective environment e.g. laminar flow room
IV immunoglobulin replacement
Vaccination - annual flu vaccine, should not receive live vaccines
How long does neutropenia occur for after chemotherapy?
7-10 days
Onset depends on patient’s bone marrow reserve and type of chemotherapy
What are the risks of neutropenia?
Cause - marrow failure higher risk than immune destruction
Degree
< 0.5 x 10^9/L is significant risk i.e. this level needs to be reached before there is any significant risk of neutropenia
< 0.2 x 10^9/L high risk
Duration
> 7 days = high risk
AML therapy and stem cell transplantation produce profound neutropenia for 14-21 days
What are the additional risk factors for infection in the immunocompromised?
Disrupted skin/mucosal surfaces
- Hickman line, venflons
- Mucositis affecting GI tract
- GVHD
Altered flora/antibiotic resistance
- prophylactic antibx
Lymphopenia
- disease process e.g. lymphoma
- treatment e.g. fludarabine, ATG
- stem cell transplantation, GVHD
Monocytopenia
- hairy cell leukaemia
- chemotherapy
Bacterial causes of febrile neutropenia
Gram positive bacteria 60-70%, associated with lines
Gram negative bacilli 30-40%
Gram positive bacteria that commonly cause infection in immunocompromised patients
Staphylococci - MSSA, MRSA, coagulase negative
Streptococci - viridans
Enterococcus - faecalis/faecium
Corynebacterium species
Bacillus species
Enterococcus, corynebacterium and bacillus less common
Gram negative bacteria that commonly cause infection in immunocompromised patients
Escherichia coli - commonest
Klebsiella species - ESBL
Pseudomonas aeruginosa
Enterobacter species
Acinetobacter species
Citrobacter species
Stenotrophomonas maltophilia
Common sites of infection in immunocompromised patients
Respiratory tract GI Dental sepsis Mouth ulcers Skin sores Exit site of central venous catheters Perianal
Features of fungal infection in immunocompromised patients
Candida species
Aspergillus (commonly pulmonary)
Life-threatening deep-seated infection
Lung, liver, sinuses and brain commonly affected
What are the main risk factors for fungal infection in the immunocompromised?
Monocytopenia and monocyte dysfunction contributes to risk of fungal infection but main risk factors are chronic neutropenia and T cell dysfunction
Presentation of neutropenic sepsis
Fever with no localising signs - single reading of > 38.5 or 38 on two readings one hour apart, have high suspicion and treat as neutropenic sepsis Rigor Chest infection/pneumonia Skin sepsis - cellulitis UTI Septic shock
What will severe sepsis/septic shock cause?
Signs of systemic inflammation (SIRS) and presumed infection and organ dysfunction
What is the sepsis 6?
Administer high flow oxygen
Take blood cultures, other cultures, consider source control
Give appropriate IV antibiotics within one hour
Measure serum lactate concentration
Start IV fluid resuscitation
Assess/measure urine output
In sepsis, every hour’s delay in administering antibiotics increases chance of mortality by
8%
