CP14 - Infection in the Immunocompromised Host

Question 1

examples of innate defences in the body

Answer 1

1. skin
2. interferons, lysozymes, complement, acute phase proteins
3. mucous membranes
4. commensal flora in the gut

Question 2

how does the skin protect the body?

Answer 2

forms a physical barrier
has normal flora
secretes sebum

Question 3

how do mucous membranes protect the body?

Answer 3

tears
bring flow
phagocytes
cilia

Question 4

what physiological states make you more susceptible to poor immunity?

Answer 4

extremes of age
pregnancy
(malnutrition)

Question 5

how is immunodeficiency classified?

Answer 5

congenital - primary

acquired - secondary

Question 6

what forms the second line of defence in the body?

Answer 6

neutrophils. fewer neutrophils indicates increasing infection

Question 7

what kind of defects can be observed in neutrophils?

Answer 7

qualitative - lose the ability to kill and chemotaxis

quantitive - either less in numbers or deficient in NADPH oxidase

Question 8

what are the causes of qualitative defects in neutrophils?

Answer 8

(rare)
congenital
inadequate signalling
abnormalities in receptors 
abnormalities in neutrophil movement

Question 9

what is the cause of fewer neutrophils?

Answer 9

CGD

Question 10

what causes neutrophils to have a deficiency in NADPH oxidase?

Answer 10

cancer treatment
bonne marrow malignancy
aplastic anaemia caused by drugs

Question 11

what are patients with NADPH oxidase deficiency at risk of developing?

Answer 11

staph aureus infections

Question 12

what is the medical term for low neutrophils?

Answer 12

neutropenia

Question 13

when is neutropenia significant?

Answer 13

1. less than 0.5 x 10^9 cells/L
   OR
2. prolonged periods of neutropenia

Question 14

what are the possible infections neutropenic patients could develop?

Answer 14

bacteria, fungal, maybe viral

Question 15

which bacterial species can especially cause infections in neutropenic patients?

Answer 15

E coli

staph aureus

Question 16

how can bacterial infections in neutropenic patients be treated?

Answer 16

amino glycoside and antipsuedomonal penicillin

2nd line antibiotics if needed
always give best guess ones before lab results come through

Question 17

which fungi commonly cause infections in neutropenic patients?

Answer 17

candida, aspergillus

Question 18

how can these fungal infections be treated?

Answer 18

antifungals

Question 19

which pathogen is important to keep in mind in neutropenic patients?

Answer 19

pseudomonas. ensure antibiotics cover this species

Question 20

which other form of medication is important to give neutropenic patients?

Answer 20

granulocyte stimulating factors - GCSF

drugs which stimulate the immune system

Question 21

what are the 2 classes of t cells deficiency?

Answer 21

congenital

acquired - either via drugs or viruses

Question 22

what is the consequence of t cell deficiencies?

Answer 22

opportunistic infections

Question 23

how are viral infections in t cell deficient patients managed?

Answer 23

provide pre-emptive treatment for CMV

serology, prophylaxis and treatment with aciclovir and ganciclovir

Question 24

how is cryptosporidiosis treated in a t cell deficient patient?

Answer 24

symptomatic treatment only

Question 25

how can toxoplasma gondii present?

Answer 25

brain lesions/neurological signs

Question 26

what symptoms does strongyloides sercoralis cause in immunodeficient patients?

Answer 26

multiplication of the parasite and tissue invasion. suspect in patients from tropical countries

Question 27

what is a hypogammaglobinaemia?

Answer 27

problem with the antibodies

Question 28

what are the classes of hypogammaglobulinaemias?

Answer 28

I1. congenital

2. acquired - multiple myeloma, burns, chronic lymphocytic leukaemia

Question 29

what bacterial infections can be observed in patients with hypogammaglobulinaemia?

Answer 29

s. pneumoniae in respiratory tract

G. lambia or cryptosporidium in GI

Question 30

how are infected patients with hypogammaglobulinaemias treated?

Answer 30

immunoglobulins, give them a blood product

Question 31

what is the cause of complement deficiency?

Answer 31

genetic

rare

Question 32

what kind of bacteria infect patients with complement deficiency?

Answer 32

encapsulated bacteria, neisseria meningitidis,

frequent but serious S. pneumoniae infections

Question 33

what are the functions of the spleen?

Answer 33

produces substances involved in the complement
B cells
removal of opsonised bacteria from the blood
controls amount of rbcs in blood

Question 34

what are the causes of splenectomy?

Answer 34

traumatic
surgical
functional - eg. sickle cell anaemia

Question 35

which microbes need to be looked out for in splenectomies?

Answer 35

S. pneumoniae
H influenzae type B
N. meningitides
Malaria
consequences - high mortality

Question 36

how can opportunistic infections in patients without spleens be prevented?

Answer 36

vaccination
prophylactic penicillin
education - seek help if unwell

Question 37

what are biologics?

Answer 37

antibodies or other peptides that inhibit inflammatory cytokine signals

Question 38

when are biologics used?

Answer 38

treatment of diseases - 
RA
TB
herpes zoster
L. pneumophila
Listeria monocytogenes

Question 39

what is one dangerous side effect of organ transplantation?

Answer 39

immunosuppression due to anti-rejection treatment

degree of immunosuppression depends on how closely the donor and recipient are matched

Question 40

how can infections after organ transplantation be managed?

Answer 40

treat the known infection
remove catheters/cannula if they are the site of infection
reverse defect if possible or stop immunosuppression

Question 41

how can infections in the immunocompromised be prevented?

Answer 41

hand washing/aseptic/protective isolation
vaccines - avoid live vaccines in t ell deficient patients
prophylactic antimicrobials
passive immunoglobulin
special diet