3- non-tuberculosis mycobacteria + fungal infections Flashcards
what is NTM?
non-tuberculosis mycobacterial = mycobacterial species other than those belonging to mycobacterium tuberculosis complex or mycobacterium leprae (causing leprosy)
where is NTM found?
in infected soil + water, contracted through environment to susceptible host (usually not transferred person to person, only in CF)
what is the most common NTM organism?
there are more than 120 but most common is the mycobacterium avium complex (MAC) that has m.avium, m.intracellulare + m.chimaera
who gets infected by NTM?
- not common in healthy idnividuals = in rare circumstances when exposed to enough of it, you can get infected
- immunosuppressed people
what is a typical susceptible host for NTM?
immunocompromised, other pre-existing lung condition (COPD, CF)
where does NTM affect?
lots of different parts of the body, skin & soft tissue, bone & joints, cervical lymph nodes, pulmonary
what are the 3 pillars for NTM pulmonary disease diagnosis?
- symptoms (breathlessness, cough, weight loss, night sweats)
- bug has to be grown, positive sputum culture x2 or one deep sample on bronchoscopy (PCR or BAL)
- distinctive radiology = findings consistent with NTM disease
what are the signs on CT scan for NTM infections?
- Fibro-cavitary→ when fibrosis makes cavity (gap with pus, fluid, dead tissue or air)
- Nodular bronchiectatic →when get nodules (circle areas of inflammation/infection) along with bronchiectasis (narrowing of airways)
what is process of acid fast bacilli (ZN= ziehl neilson) staining? why do you do it?
ZN stain = to test if any mycobacterium present (won’t be able to tell if NTM or TB so will need to do PCR & if PCR negative more likely to be NTM as PCR was looking for sequence in MTB)
- all cells stained pink with carbon fushsin
- acid washed . mycobacetrium cell wall is acid fast remains pink ,other cells de-stained
- slide washed by green/blue dye
- other cells take up green/blue dye
what is the treatment for NTM?
18 months antibiotics →3 or 4 at same time
cavitary (presence of cavities) means treated more aggressively
if resistant to macrolides then poorer outcome
- non-severe = rifampicin, ethambutol, azithromycin
- if severe disease = up to daily treatments and consider adding to amikacin
where does aspergillus grow?
in warm, wet environment - good in tayside - often in poorly built housing that is poorly insulated etc. not all black mould aspergillus and not all aspergillus black mould
= spreads quickly
who gets infections from fungals like aspergillus?
normal people shouldn’t, if exposed to aspergillus should have appropriate host response which means get’s rid of but if immunocompromised, weak host response and get ill
what are diagnostic tests for aspergillus?
- PCR detects aspergillus DNA well
- try culture it →actually difficult to grow in lab
- Galactomannan (microbiology + fungal marker): detects hyphal growth of Aspergillus
- Aspergillus IgG: detects memory antibodies to Aspergillus
- Aspergillus IgE: detects ‘allergic’ antibodies to Aspergillus
what is ABPA?
allergic bronchopulmonary aspergillosis (not aspergillus itself but host response to it)
what is treatment of ABPA?
steroids e.g. prednisolone? (pic on slide is prednisolone)
danger = suppress immune system too far
