Infections in immunocompromised patients Flashcards
Other than use of broad spectrum Abx, what 3 factors can alter normal gut flora?
1) Extremes of age
2) Pregnancy
3) Malnutrition
What are the 2 classes of immunodeficiencies?
1) Congenital or primary
2) Aquired or secondary `
What 2 kind of defects can arise in neutrophils, which is more likely to be dealt with in general practise?
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
Qualitive neutrophil defects in chemotaxis can involve problems with what processes? 3
(Rare and congenital)
1) Inadequate signalling
2) Abnormality in receptors
3) Abnormality in movement
What disease is due to a qualitative neutrophil defect in killing power - what substance is absent?
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)
Patients with chronic granulomatous disease are particularly at risk of which infection?
Staph aureus
What is the term for a patient with a quantitative deficiencies in neutrophils?
Neutropenia
What 3 reasons could a patient have acquired neutropenia?
1) Cancer treatment
2) Bone marrow malignancy
3) Aplastic anaemia caused by drugs
If a patient with neutropenia gets an infection what is the prognosis?
Highly lethal if not treated quickly with correct Abx
What is the prognosis for patients with neutropenia is the pseudomonal infections?
Over 50% will die within 24 hours if not treated
What 3 bacterial infections are neutropenic patients particularly at risk of?
1) Gram negative bacilli (eg. e coli)
2) Gram positive cocci (eg. s. aureus)
3) Often normal flora eg. coagulase negative staph
What 2 fungal infections are neutropenic patients particularly at risk of?
1) Candida spp
2) Aspergillus spp
What is GCSF treatment that can be given to neutropenic patients?
Drugs given to try and get immune system working again after having a serious infection
What is the treatment for neutropenic patients? 3
1) Broad spectrum Abx until know the infection
2) An aminoglycoside and an antipseudomonal penicillin
3) 2nd line treatment eg. carbapenem, then antifungals
Do congenital T cell deficiencies occur?
Yes but very rare
What 2 drugs can lead to acquired T cell deficiencies?
1) Ciclosporin after transplantation (decreases graft versus host disease and rejection)
2) Steroids
Other than drugs what other factors can lead to T cell deficiencies?
Viruses eg. HIV
In T cell deficiencies, what 2 opportunistic bacterial infections are common?
1) Listeria monocytogenes (food)
2) Mycobacteria - MTB, MAI
In T cell deficiencies, what 3 opportunistic viral infections are common?
1) Herpes simplex virus
2) Cytamegalovirus
3) Varicella zoster virus
In patients with T cell deficiencies what is the treatment process for viral infections?
1) Serological testing
2) Prophylaxis
3) Treatment with acyclovir and ganciclovir
In T cell deficiencies, what 2 opportunistic fungal infections are common?
1) Candida spp
2) Cryptococcus spp
What 2 protozoan infections are common in patients with T cell deficiencies, how is it spread and what is the treatment/ symptoms?
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
In patients with T cell deficiencies which parasitic infection is common, how is it spread?
Strongyloides stercoralis - nematode
Larvae penetrate skin, migrate
What are the differences in symptoms of Strongyloides stercoralis infection in patients with T cell deficiencies and healthy patients?
Healthy pt - Asymptomatic or rash
T cell deficient patients - Mutliplication, huge invasion of tissues, eosinophilia, may get gram negative septicaemia as larvae move
In which patients should you suspect strongyloides infection?
1) Pnts from tropical countries
2) Old POW pnts
What are hypogammaglobulinaemias?
Abnormal low levels of all classes of immunoglobulins
Give 3 reasons for acquired hypogammaglobulinaemias?
(Can get congenital but rare)
1) Mutliple myeloma
2) Chronic lymphocytic leukaemia
3) Burns
What are the 2 common infections in patients with hypogammaglobulinaemias?
Encapsulated bacteria eg.
1) S. pneumonia in the resp tract
2/3) Gardia lamblia or cryptosporidium in GIT
Can patients have acquired complement deficiency?
No, its hereditary but rare
Why do patients with complement deficiency commonly get infected with encapsulated bacteria?
Need complement to help kill organisms - lysis using the MAC - have an earlier defect in pathway then greater no. of organs may be affected
Patients with a complement deficiency of C5-C8 commonly get infected by what bacteria?
Neisseria meningitides - lysis not achieved via MAC
Why do patients with complement deficiency commonly get infected by s. pneumoniae?
Poor quality opsonisation
What is the role of the spleen in immunology?
Source of complement and Ab producing B cells, removes opsonised bacteria from blood
What are the 3 main causes of splenectomy?
1) Traumatic
2) Surgical
3) functional eg. sickle cell anaemia
What 4 pathogens are patients with a splenectomy at particular risk of?
1) Streptococcus pneumonia
2) Haemophilus influenza type B
3) N meningitides
4) Malaria
What is the procedure for treating splenectomy?
1) Vaccination
2) Prophylactic penicillin
3) Education - seek help if unwell
NB. splenectomy associated with high mortality
Patients being treated with biologics are at risk of what 4 infections particularly?
1) TB
2) Herpes zoster
3) Legionella pneumophilia
4) Listeria moncytogenes
What are biologics?
Ab or other peptides which inhibit inflammatory cytokine signals
What are the 5 steps in a ‘diary of infections in organ transplantation’?
1) Organ receipt (toxoplasmosis, CMV)
2) Opportunistic infections during initial immunosuppression (CMV, aspergillus)
3) Later opportunistic infection (zoster, listeria)
What is the general procedure for managing infection in immunocompromised patients?
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
What are the 4 processes in prevention used to manage infection in immunocompromised patients?
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
Which patients should not be given vaccines?
Patients with T cell deficiencies
Is the spleen a primary or secondary lymphoid organ?
Secondary
