Infections In Immunocompromised Patients Flashcards
Which organisms are commonly associated with complement deficiency?
Neisseria, streptococcus pneumoniae.
What are the major clinical settings in which deficiencies in the immune system increase the risk of infection?
HIV patients
Neutropenic patients
Organ transplant recipients
Splenectomy and sepsis
Which cells does HIV infect primarily?
CD4+ lymphocytes
How is HIV diagnosed?
Detection of HIV antibodies via ELISA, confirmed by western blot for viral proteins and glycoproteins.
At what stage in AIDS is the patient more likely to contract an AIDS defining infection?
When the T helper cell count falls below 200*10^6 cells/litre.
Which antiviral agents are used against HIV?
A mixture of agents to prevent resistance:
Eg
Ritonavir + squinavir + zidovudine + lamivudine
What infections can occur in AIDS patients?
Pneumocystis jirovecci pneumonia Cytomegalovirus Atypical bacteria causing lung infection eg mycobacterium avium TB Infective diarrhoea Candidiasis Skin infectoins toxoplasmosis Cryptococcosis HIV encephalopathy
What conditions can cause neutropenia?
Acute leukemia
Cytotoxic therapy
What can cause fever in a neutropenic patient?
Pneumonia UTI Skin sepsis Oral and perianal infection Septicaemia
Splenectomy patients are more at risk of infectoin from which organisms?
At risk of infection with encapsulated bacteria. Eg strep pneumoniae, HIb, and Neisseria meningitidis.
What is an immunocompromised host?
State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms
What is primary immunodeficiency?
Congenital, due to intrinsic gene defect eg missing protein, missing cell, non functional components
What is secondary immunodeficiency?
Acquired- due to an underlying disease/treatment
Either decreased production of immune components or increased loss of immune components
What kind of infections might make you suspect an immunodeficiency?
SPUR
Severe
Persistent
Unusual
Recurrent
What are the primary immunodeficiency disease of clinical importance?
Common variable immunodeficiency Selective IgA deficiency SCID Chronic granulomatous disease Severe congenital neutropenia Di george syndrome
When would a T cell or phagocyte defect commonly present?
<6 months old
When would a B cell/antibody or phagocyte defect present?
Between 6 months and 5 years old
When would a B cell/antibody/complement or secondary immunodeficiency present?
> 5 years old
What kinds of microbes infect complement deficient patients?
Neisseria, streptococci, Hib, (encapsulated bacteria)
What are the symptoms of complement deficiency?
Pyogenic infections (C3 defect)
Meningitis/sepsis/arthritis (C5-C9)
Angioedema (c1 inhibitor)
Which organisms are commonly found in phagocytic defects?
Staph aureus, pseudomonas aeruginosa, non tuberculous mycobacteria
What are the symptoms of phagocyte defects?
Skin/ mucous infections
Deep seated infections
Invasive fungal infection (aspergillosis)
What organisms are found in antibody deficiency?
Streptococci, staphylococci, Hib, moraxella catarrhalis, pseudomonas aeruginosa, mycoplasma pneumoniae
What are the symptoms of antibody deficiency?
Sinorespiratory infections
Arthropathies
Gi infections
Malignancies
Autoimmunity
What bacteria commonly cause infections in those patients with T cell defects?
strep, staph, hib, moraxella catarrhalis, pseudomonas aeruginosa, mycoplasma pneuoniae, salmonella typhi, listeria monocytogenes
What are the symptoms of T cell defects?
Death if not treated
Failure to thrive
Deep skin and tissue abcesses
Opportunistic infections
At what stage do maternal antibodies dissappear from the infants blood?
Around 1 year.
What is britons disease?
An antibody immunodeficiency. Presents at 1 year generally. Is x linked inheritance
What is chronic granulomatous disease?
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
What sign will be picked up on CT with pulmonary aspergillosis?
Halo signs
What is common variable immunodeficiency?
A very common immunodeficiency. Is a problem with immunoglobulins.
Often presents with recurrent bacterial respiratory and GI infections
How is primary immunodeficiency managed?
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
What is the goal for IgG in immunoglobulin replacement therapy?
IgG > 8g/l
What can cause decreased production of immune components as a cause of immunodeficiency?
Malnutrition Infection eg HIV Liver disease Lymphoproliferative disease Splenectomy (infarction, trauma, autoimmune haemolytic disease, tumour, coeliac disease)
What is the immune function of the spleen?
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
How are splenectomy patients managed?
Life long penicillin prophylaxis
Immunisation against encapsulated bacteria
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