Infections In Immunocompromised Patients Flashcards

1
Q

Which organisms are commonly associated with complement deficiency?

A

Neisseria, streptococcus pneumoniae.

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2
Q

What are the major clinical settings in which deficiencies in the immune system increase the risk of infection?

A

HIV patients
Neutropenic patients
Organ transplant recipients
Splenectomy and sepsis

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3
Q

Which cells does HIV infect primarily?

A

CD4+ lymphocytes

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4
Q

How is HIV diagnosed?

A

Detection of HIV antibodies via ELISA, confirmed by western blot for viral proteins and glycoproteins.

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5
Q

At what stage in AIDS is the patient more likely to contract an AIDS defining infection?

A

When the T helper cell count falls below 200*10^6 cells/litre.

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6
Q

Which antiviral agents are used against HIV?

A

A mixture of agents to prevent resistance:
Eg
Ritonavir + squinavir + zidovudine + lamivudine

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7
Q

What infections can occur in AIDS patients?

A
Pneumocystis jirovecci pneumonia
Cytomegalovirus
Atypical bacteria causing lung infection eg mycobacterium avium
TB
Infective diarrhoea
Candidiasis
Skin infectoins
toxoplasmosis
Cryptococcosis
HIV encephalopathy
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8
Q

What conditions can cause neutropenia?

A

Acute leukemia

Cytotoxic therapy

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9
Q

What can cause fever in a neutropenic patient?

A
Pneumonia
UTI
Skin sepsis
Oral and perianal infection
Septicaemia
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10
Q

Splenectomy patients are more at risk of infectoin from which organisms?

A

At risk of infection with encapsulated bacteria. Eg strep pneumoniae, HIb, and Neisseria meningitidis.

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11
Q

What is an immunocompromised host?

A

State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms

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12
Q

What is primary immunodeficiency?

A

Congenital, due to intrinsic gene defect eg missing protein, missing cell, non functional components

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13
Q

What is secondary immunodeficiency?

A

Acquired- due to an underlying disease/treatment

Either decreased production of immune components or increased loss of immune components

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14
Q

What kind of infections might make you suspect an immunodeficiency?

A

SPUR

Severe
Persistent
Unusual
Recurrent

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15
Q

What are the primary immunodeficiency disease of clinical importance?

A
Common variable immunodeficiency
Selective IgA deficiency
SCID
Chronic granulomatous disease
Severe congenital neutropenia
Di george syndrome
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16
Q

When would a T cell or phagocyte defect commonly present?

A

<6 months old

17
Q

When would a B cell/antibody or phagocyte defect present?

A

Between 6 months and 5 years old

18
Q

When would a B cell/antibody/complement or secondary immunodeficiency present?

A

> 5 years old

19
Q

What kinds of microbes infect complement deficient patients?

A

Neisseria, streptococci, Hib, (encapsulated bacteria)

20
Q

What are the symptoms of complement deficiency?

A

Pyogenic infections (C3 defect)
Meningitis/sepsis/arthritis (C5-C9)
Angioedema (c1 inhibitor)

21
Q

Which organisms are commonly found in phagocytic defects?

A

Staph aureus, pseudomonas aeruginosa, non tuberculous mycobacteria

22
Q

What are the symptoms of phagocyte defects?

A

Skin/ mucous infections
Deep seated infections
Invasive fungal infection (aspergillosis)

23
Q

What organisms are found in antibody deficiency?

A

Streptococci, staphylococci, Hib, moraxella catarrhalis, pseudomonas aeruginosa, mycoplasma pneumoniae

24
Q

What are the symptoms of antibody deficiency?

A

Sinorespiratory infections

Arthropathies

Gi infections

Malignancies

Autoimmunity

25
Q

What bacteria commonly cause infections in those patients with T cell defects?

A

strep, staph, hib, moraxella catarrhalis, pseudomonas aeruginosa, mycoplasma pneuoniae, salmonella typhi, listeria monocytogenes

26
Q

What are the symptoms of T cell defects?

A

Death if not treated
Failure to thrive
Deep skin and tissue abcesses
Opportunistic infections

27
Q

At what stage do maternal antibodies dissappear from the infants blood?

A

Around 1 year.

28
Q

What is britons disease?

A

An antibody immunodeficiency. Presents at 1 year generally. Is x linked inheritance

29
Q

What is chronic granulomatous disease?

A

A defect in phagocytes meaning that they cannot properly kill pathogens via respiratory burst, so have to form granulomas.

Presents early, patients get recurrent infections such as staphylococcal infections and pulmonary aspergillosis

30
Q

What sign will be picked up on CT with pulmonary aspergillosis?

A

Halo signs

31
Q

What is common variable immunodeficiency?

A

A very common immunodeficiency. Is a problem with immunoglobulins.

Often presents with recurrent bacterial respiratory and GI infections

32
Q

How is primary immunodeficiency managed?

A

Supportive treatment-
Infection prevention, treat infections promptly and aggressively, nutritional support, UV irradiated CMV negative blood products only. Avoid live attenuated vaccines

Specific treatment- immunoglobulin therapy, haematopoietic stem cell therapy available in SCID

33
Q

What is the goal for IgG in immunoglobulin replacement therapy?

A

IgG > 8g/l

34
Q

What can cause decreased production of immune components as a cause of immunodeficiency?

A
Malnutrition
Infection eg HIV
Liver disease
Lymphoproliferative disease
Splenectomy (infarction, trauma, autoimmune haemolytic disease, tumour, coeliac disease)
35
Q

What is the immune function of the spleen?

A

Deals with blood borne pathogens—> encapsulated bacteria

Antibody production—> acute response- IgM production, long term protection- IgG production

Splenic macrophages remove opsonized microbes and remove immune complexes

36
Q

How are splenectomy patients managed?

A

Life long penicillin prophylaxis
Immunisation against encapsulated bacteria
Medic alert bracelet