Infection in the immunocompromised host Flashcards
what is the classical infection type that patients with CVID get?
what about any other patients with humoral deficiency?
recurrent resp tract infections, particularly with Strep pneumoniae and H. influenzae
it’s pretty much the same for humoral deficiency - encapsulated organisms are the concern.
what types of organisms are typical of impaired cellular immunity?
in contrast to neutrophil deficiency - where things like candida and E. coli and pseudomonas are problematic - impaired cellular immunity leads to issues with intracellular organisms.
bacteria: listeria, legionella, salmonella, MTB/MAC, nocardia
viruses: pretty much all
fungi: pneumocystis, cryptococcus, aspergillus, histoplasma
parasites: strongyloidiasis
how do you test for complement dysfunction that is leading to immunodeficiency?
the major issue is terminal complement.
biggest concern is Neisseria
C3, C4 will not demonstrate appropriate level
CH100 is the important test
what sorts of infection do people with chronic granulomatous disease get?
it is typically problems with staph aureus and aspergillus
CGD is a condition whereby neutrophils have trouble forming reactive oxygen species
Listeria:
tell me Gram stain
where it’s found
how it infects
how we treat it
Gram pos bacillus
cold tolerant and food borne. So infected food in the fridge will be a great source
it is neurotropic
treated with penicillin. In transplant patients, we also consider co-trimoxazole
Nocardia:
Gram stain
where is it found
how does it get in
how do we detect it (special stain?)
this is a Gram positive branching bacillus - looks filamentous
found in the soil, and is inhaled. threfore 80-90% of patients with it have pulmonary nodules and cavities
Modified ZN stain is positive
usually susceptible to sulphur drugs
causes a ring-enhancing lesion on CT
SIDE NOTE: if HIV with ring enhancing lesion think toxo
If no HIV with ring, think nocardia
how do we diagnose PCP
how do we treat?
what is the second line for treatment?
when do we use for prophylaxis in renal transplant?
induce sputum with PCR is important for diagnosis
treatment is with cotrimoxazole
secondline is pentamidine
the PA now recommends that all patients with renal Tx have lifelong bactrim prophylaxis
what is the drug of choice for prophylaxis of CMV?
valganciclovir is the most important for this virus
how do we treat patients with EBV infection?
which transplants are associated with PTLD?
there isn’t a specific treatment. If someone’s EBV viral load goes up, typically we should decrease their immunosuppression.
all transplants are associated with PTLD.
approx 1% of renal get it
approx 10% of heart Tx get it
what is HHV8 associated with?
this is the Kaposi’s sarcoma virus
Strongyloides can cause a hyperinfection syndrome. What are the circumstances where this is more likely?
there seems to be a particular concern with steroids. Apparently they lead to Th2 apoptosis and reduction of the eosinophil count, inhibiting the mast cell response.
once the worm infects the mucosa, this can lead to bacteria superinfection in the blood stream.
because it hangs out in the GIT, it is most commonly a Gram neg bacteraemia
is the risk of OPSI higher or lower with traumatic splenectomy as opposed to elective?
what is the #1 cause of OPSI? (far and away most common)
the risk os lower with traumatic. This is because usually you get small amount of seeding with the trauma, and little spleens elsewhere in the abdomen
pneumococcus is the most common cause of OPSI. Much much higher
