Infection in Immunocompromised Host

Question 1

Two categories of immunosuppressed infections?

Answer 1

More readily getting infections with common primary pathogens

Getting infections with opprotunistic pathogens

Question 2

Spectrum of immune competence?

Answer 2

Healthy>Diabetes>cancer>HIV/transplant

Question 3

Causes of immunosuppression (4)

Answer 3

Primary immunodeficiencies (eg SCID, B or T cell defects, chronic granulomatous disease)

Secondary immunodeficiencies (eg AIDS, cancer, diabetes, any severe systemic illness)

Stressed physiological states (eg pregnancy, elderly, neonates, nutritional deficiency)

Iatrogenic cause (steroids, chemo, immunosuppressant drugs, radiation, IV lines, surgery)

Question 4

Example of opportunistic pathogen?

Answer 4

Asperilligus

Question 5

5 ways to prevent infections in the immunocompromised

Answer 5

Avoid risky activities/places (hospital!!!)

Isolation

Vaccination

Abx prophylaxis

Correct underlying defect

Question 6

AIDS spectrum of opportunistic pathogens

Answer 6

Question 7

Specific infection in HIV: Pneumocystis jiroveci (presentation, diagnosis)

Answer 7

Causes lung infection

Non productive cough, SOB, fever
May progress to severe respiratory distress

Diagnosed using silver staining or immunofluorescence or PCR

Question 8

Tx of pneumocystic pneumonia

Answer 8

High does cotrimoxazole

ICU input

Question 9

Specific infection in HIV: Cerebral toxplasmosis (presentation, diagnosis)

Answer 9

T. gondii

In healthy hosts is asymptomatic or causes glandular fever like illness

In AIDS, main cause of focal CNS lesions, with ring enhancement on CT

Question 10

What is HAART?

Answer 10

Highly active antiretroviral therapy, for prophylaxis of opportunistic infections

Boosts CD4 count

Question 11

What is co-trimoxazole prophylaxis for?

Answer 11

Pneumocystis

Question 12

What is rifabutin prophylaxis for?

Answer 12

Mycobacterium

Question 13

What is ganciclovir prophylaxis for?

Answer 13

CMV

Question 14

What is neutropenia? How is it diagnosed?

Answer 14

Low neutrophils

Lots of causes: chemo, aplastic anaemia, post mone marrow transplant

Difficult to diagnose infection: Absence of pus/localisation, rely on FEVER AS CARDINAL LSIGN

Question 15

What is the cardinal sign of infection in neutropenic patients?

Answer 15

Fever

Question 16

Difference in infection susceptability: neutropaenia and AIDS

Answer 16

So in general terms, those who are neutropenic tend to be susceptible to most typical bacteria such
as Pseudomonas and Staphylococcus aureus. Neutropenic patients are also susceptible to most
fungal infections. This contrasts with individuals with cellular immune dysfunction that affects
principally T-cells, who are more susceptible to organisms such as Mycobacteria, Legionella, Listeria
and viruses.

Question 17

Aspergillus infection in neutropenia

Answer 17

Lung infection which can spread to brain

Difficult to diagnosis due to poor culture

HIGH MORTALITY

Question 18

Candida albicans in neutropenia

Answer 18

Greater risk due to central lines, parenteral nutrition, broad spectrum abx, perforations

Easier to diagnose, high mortality

Question 19

Sepsis management in neutropenia

Answer 19

EMPIRICAL THERAPY:

• don’t wait for cultures
• URGENT BROADSPECTRUM ABX (piperacillin and gentamicin)
• Add vancomycin if no improvement
• Add antifungal if no improvement
• Supportive management eg O2 and fluids

Question 20

What are the two most common organisms to infect burns patietns?

Answer 20

Pseudomonas aeruginosa
Staph aureus

Can spread to bloodstream

Question 21

Prophylaxis of infection in burns patients

Answer 21

Topical silver suphadiazine

Excision of necrotic areas of burn

Question 22

Tx of infection in burn patient

Answer 22

Topical and systemic abx

Question 23

Which bacteria are splenectomy patients susceptible to?

Answer 23

Capsulate bacteria (pneumococcus and also Haemophilus)

Question 24

Prevention of infection in splenectomy patients

Answer 24

Pneumococcal infection before procedure

Prophylactic abx (penicillin V)

Question 25

Infection risks in pregnant women? (2)

Answer 25

Ascending UTI

Listeria infection (+ve bacillus)

Question 26

Tx for severe listeria infections in pregnancy

Answer 26

Ampicillin and gentamicin

Question 27

Causes of Listeria infection in pregnancy

Answer 27

Miscarriage
Stillbirth
Sepsis in mother
Meningitis in mother

Question 28

Prevention of listeria in pregnancy

Answer 28

Avoid raw chilled ready meals, pate, soft cheeses