Infections in immunocompromised patients

Question 1

Other than use of broad spectrum Abx, what 3 factors can alter normal gut flora?

Answer 1

1) Extremes of age
2) Pregnancy
3) Malnutrition

Question 2

What are the 2 classes of immunodeficiencies?

Answer 2

1) Congenital or primary

2) Aquired or secondary `

Question 3

What 2 kind of defects can arise in neutrophils, which is more likely to be dealt with in general practise?

Answer 3

1) Qualitative defects - eg. lose ability to kill or chemotaxis
2) Quantitative defects - less present
Quantitative is more likely to be dealth with in GP

Question 4

Qualitive neutrophil defects in chemotaxis can involve problems with what processes? 3

Answer 4

(Rare and congenital)

1) Inadequate signalling
2) Abnormality in receptors
3) Abnormality in movement

Question 5

What disease is due to a qualitative neutrophil defect in killing power - what substance is absent?

Answer 5

Chronic granulomatous disease
Neutrophils fail to carry out phagocytosis due to deficiency in NADPH oxidase so hydrogen peroxide not formed (needed to destroy engulphed pathogen)

Question 6

Patients with chronic granulomatous disease are particularly at risk of which infection?

Answer 6

Staph aureus

Question 7

What is the term for a patient with a quantitative deficiencies in neutrophils?

Answer 7

Neutropenia

Question 8

What 3 reasons could a patient have acquired neutropenia?

Answer 8

1) Cancer treatment
2) Bone marrow malignancy
3) Aplastic anaemia caused by drugs

Question 9

If a patient with neutropenia gets an infection what is the prognosis?

Answer 9

Highly lethal if not treated quickly with correct Abx

Question 10

What is the prognosis for patients with neutropenia is the pseudomonal infections?

Answer 10

Over 50% will die within 24 hours if not treated

Question 11

What 3 bacterial infections are neutropenic patients particularly at risk of?

Answer 11

1) Gram negative bacilli (eg. e coli)
2) Gram positive cocci (eg. s. aureus)
3) Often normal flora eg. coagulase negative staph

Question 12

What 2 fungal infections are neutropenic patients particularly at risk of?

Answer 12

1) Candida spp

2) Aspergillus spp

Question 13

What is GCSF treatment that can be given to neutropenic patients?

Answer 13

Drugs given to try and get immune system working again after having a serious infection

Question 14

What is the treatment for neutropenic patients? 3

Answer 14

1) Broad spectrum Abx until know the infection
2) An aminoglycoside and an antipseudomonal penicillin
3) 2nd line treatment eg. carbapenem, then antifungals

Question 15

Do congenital T cell deficiencies occur?

Answer 15

Yes but very rare

Question 16

What 2 drugs can lead to acquired T cell deficiencies?

Answer 16

1) Ciclosporin after transplantation (decreases graft versus host disease and rejection)
2) Steroids

Question 17

Other than drugs what other factors can lead to T cell deficiencies?

Answer 17

Viruses eg. HIV

Question 18

In T cell deficiencies, what 2 opportunistic bacterial infections are common?

Answer 18

1) Listeria monocytogenes (food)

2) Mycobacteria - MTB, MAI

Question 19

In T cell deficiencies, what 3 opportunistic viral infections are common?

Answer 19

1) Herpes simplex virus
2) Cytamegalovirus
3) Varicella zoster virus

Question 20

In patients with T cell deficiencies what is the treatment process for viral infections?

Answer 20

1) Serological testing
2) Prophylaxis
3) Treatment with acyclovir and ganciclovir

Question 21

In T cell deficiencies, what 2 opportunistic fungal infections are common?

Answer 21

1) Candida spp

2) Cryptococcus spp

Question 22

What 2 protozoan infections are common in patients with T cell deficiencies, how is it spread and what is the treatment/ symptoms?

Answer 22

1) Cryptosporidium parvum 
Faecal oral route
Symptomatic treatment only 
2) Toxoplasma gondii
Humans infected with cat faeces
May present with lesion in brain and neurological signs

Question 23

In patients with T cell deficiencies which parasitic infection is common, how is it spread?

Answer 23

Strongyloides stercoralis - nematode

Larvae penetrate skin, migrate

Question 24

What are the differences in symptoms of Strongyloides stercoralis infection in patients with T cell deficiencies and healthy patients?

Answer 24

Healthy pt - Asymptomatic or rash
T cell deficient patients - Mutliplication, huge invasion of tissues, eosinophilia, may get gram negative septicaemia as larvae move

Question 25

In which patients should you suspect strongyloides infection?

Answer 25

1) Pnts from tropical countries

2) Old POW pnts

Question 26

What are hypogammaglobulinaemias?

Answer 26

Abnormal low levels of all classes of immunoglobulins

Question 27

Give 3 reasons for acquired hypogammaglobulinaemias?

Answer 27

(Can get congenital but rare)

1) Mutliple myeloma
2) Chronic lymphocytic leukaemia
3) Burns

Question 28

What are the 2 common infections in patients with hypogammaglobulinaemias?

Answer 28

Encapsulated bacteria eg.
1) S. pneumonia in the resp tract
2/3) Gardia lamblia or cryptosporidium in GIT

Question 29

Can patients have acquired complement deficiency?

Answer 29

No, its hereditary but rare

Question 30

Why do patients with complement deficiency commonly get infected with encapsulated bacteria?

Answer 30

Need complement to help kill organisms - lysis using the MAC - have an earlier defect in pathway then greater no. of organs may be affected

Question 31

Patients with a complement deficiency of C5-C8 commonly get infected by what bacteria?

Answer 31

Neisseria meningitides - lysis not achieved via MAC

Question 32

Why do patients with complement deficiency commonly get infected by s. pneumoniae?

Answer 32

Poor quality opsonisation

Question 33

What is the role of the spleen in immunology?

Answer 33

Source of complement and Ab producing B cells, removes opsonised bacteria from blood

Question 34

What are the 3 main causes of splenectomy?

Answer 34

1) Traumatic
2) Surgical
3) functional eg. sickle cell anaemia

Question 35

What 4 pathogens are patients with a splenectomy at particular risk of?

Answer 35

1) Streptococcus pneumonia
2) Haemophilus influenza type B
3) N meningitides
4) Malaria

Question 36

What is the procedure for treating splenectomy?

Answer 36

1) Vaccination
2) Prophylactic penicillin
3) Education - seek help if unwell
NB. splenectomy associated with high mortality

Question 37

Patients being treated with biologics are at risk of what 4 infections particularly?

Answer 37

1) TB
2) Herpes zoster
3) Legionella pneumophilia
4) Listeria moncytogenes

Question 38

What are biologics?

Answer 38

Ab or other peptides which inhibit inflammatory cytokine signals

Question 39

What are the 5 steps in a ‘diary of infections in organ transplantation’?

Answer 39

1) Organ receipt (toxoplasmosis, CMV)
2) Opportunistic infections during initial immunosuppression (CMV, aspergillus)
3) Later opportunistic infection (zoster, listeria)

Question 40

What is the general procedure for managing infection in immunocompromised patients?

Answer 40

1) Treat the unknown infection - empirical, need specimens from likely site of infection to guide therapy
2) Remove catheters (or other possible infection risks)
3) Reverse defect if possible/ stop immunosuppression

Question 41

What are the 4 processes in prevention used to manage infection in immunocompromised patients?

Answer 41

1) Handwashing/aseptic technique/protective isolation/ HEPA air filtration
2) Vaccines (avoid vaccines in T cell deficient patients)
3) Prophylactic antimicrobials and passive immunoglobulin
4) Special diet

Question 42

Which patients should not be given vaccines?

Answer 42

Patients with T cell deficiencies

Question 43

Is the spleen a primary or secondary lymphoid organ?

Answer 43

Secondary