Infection

Question 1

Which immune cells are involved in infection and what do they do?

Answer 1

• Neutrophils: bacterial and fungal infections
• Monocytes: fungal infections
• Eosinophils: parasitic infections
• T lymphocytes: fungal and viral infection, PJP
• B lymphocytes: bacterial infection

Question 2

Which supportive measures aim to reduce the risk of sepsis in haematological malignancy?

Answer 2

• Prophylaxis: antibiotics (ciprofloxacin), anti-fungal (fluconazole or itraconazole), anti-viral (aciclovir) and PJP (co-trimoxazole)
• Growth factors e.g. G-CSF
• Stem cell rescue/transplant
• Protective environment e.g. laminar flow rooms
• IV immunoglobulin replacement
• Vaccination

Question 3

What are the factors that determine the neutropenic risk?

Answer 3

• Cause of the neutropenia (marrow failure > immune destruction)
• Degree of neutropenia (<0.5 significant risk and <0.2 high risk)
• Duration: >7 days is high risk

Question 4

What are the additional risk factors for infection?

Answer 4

• Disrupted skin/mucosal surfaces: hickman line, venflons GVHD etc.
• Altered flora/antibiotic resistance
• Lymphopenia: disease process, treatment, stem cell transplantation and GVHD
• Monocytopenia: hairy cell leukaemia and chemotherapy

Question 5

What are the most common bacterial causes of febrile neutropenia?

Answer 5

• Gram positive: MSSA, MRS, coagulase negative staph, strep viridans, enterococci, corynebacterium and bacillus (60-70%)
• Gram negative: E coli, klebsiella, pseudomonas, enterobacter, acinectobacter, citrobacter and stenotrophomonas maltophilia (30-40%)

Question 6

Where are the possible sites of infection?

Answer 6

• Resp tract
• GI
• Dental sepsis
• Mouth ulcers
• Skin sores
• Exit site of central venous catheters
• Perianal

Question 7

What fungi can cause infection in immunocompromised paients and where does it infect?

Answer 7

• Candida species
• Life threatening deep seated infection
• Lung, liver, sinuses and brain

Question 8

How does neutropenic sepsis present?

Answer 8

• Fever with no localising signs
• Rigors
• Chest infection/pneumonia
• Skin sepsis - cellulitis
• UTI
• Septic shock

Question 9

How should you manage suspected sepsis?

Answer 9

Sepsis six

Question 10

How should neutropenic fever be investigated?

Answer 10

• History and exam
• Blood cultures
• CXR
• Throat swab and other sites of infection
• Sputum if productive
• FBC, renal, LFTs and coagulation screen

Question 11

How should neutropenic sepsis be managed?

Answer 11

• Resus
• Broad spectrum IV antibiotics (Tazocin and gentamicin)
• If gram positive then add vancomycin or teicoplanin
• If no response at 72hrs add IV antifungal treatment e.g. caspofungin
• CT chest/abdo/pelvis
• Modify treatment based on culture results

Question 12

Which patients are severely lymphopenic and as such at risk of infection?

Answer 12

• Stem cell transplant recipients esp. allogeneic
• Recipients of total body irradiation
• GVHD
• Nucleoside analogues (fludarabine) or ATG
• Lymphoid malignancy

Question 13

Which infections do patients who are severely lymphopenic get?

Answer 13

• Atypical pneumonia: PJP, CMV and RSV
• Viral: shingles, mouth ulcers, adenovirus and EBV
• Fungal: candida, aspergillus and mucormycosis
• Atypical mycobacteria: skin lesions, pulmonary and hepatic involvement