Microbiology: Mycobacteria Flashcards
Tuberculosis and other Mycobacteria
Outline the microbiology Mycobacteria
Microbiology of Mycobacteria:
- Gram positive
- Aerobic
- Acid alcohol fast
- Cell wall with long chain (mycolic) acids, as well as glycolipids which is Thick, waxy and with complex immunogenics
- Nonmotile rod shaped bacteria
- Relatively slow growing for bacteria
Tuberculosis and other Mycobacteria
Exaplain how the host’s immune response shapes the clinical outcome
- (Different types of disease with worse immune response going down)
- Healthy contact (LTBI)
- Lymph node
- Localised Extraplumonary
- Pulmonary (localised)
- Pulmonary (widespread)
- Meningeal
- Miliary
Tuberculosis and other Mycobacteria
Outline the presentation of TB
Presentation:
- Cough in 80%
- Haemoptysis in 6 to 40%
- Fever
- Weight loss
- Malaise
Tuberculosis and other Mycobacteria
Outline the classification of Mycobacteria
Tuberculosis and other Mycobacteria
Outline the first line treatment of TB
- 6 month treatemnt, RIPE for 2 months then just Rifampicin and Isonazid for 4 months
Tuberculosis and other Mycobacteria
What are the main types of investigation for TB?
Types of TB Investigations
- Imaging CXR/CT
- Sputum microscopy
- Cultures
- Histology
- Mantoux test:
- Interferon gamma release assay (IGRA)
- Nuclear Acid Amplification test (NAAT)
Tuberculosis and other Mycobacteria
Outline the features of Extrapulmonary TB
Extrapulmonary TB:
-
Lymphadenitis:
- Known as scrofula or King’s disease
- Cervical Lymph nodes are most common
- Abscesses and sinuses
-
GI:
- Swallowing of tubercules
- Dominant form in children
-
Peritoneal:
- Ascitis or adhesive
-
Genitourinary:
- Can present with just epydidimytis
-
Bone:
- Spinal TB most common
-
MIliary:
- Millet seeds on CXR
- Progressive disseminated haemtogenous TB
- Increasing due to HIV
-
Caridac:
- Pericarditis
Tuberculosis and other Mycobacteria
Outline the pathopysiology, investigations and treamtent of Spinal TB
Pathophysiology:
- Haematogenous spread
- Initial discitis
- Vertebral destruction and collapse
- Anterior extension
Investigations:
- MRI/CT
- Biopsy/Aspirate
Treatment:
- 12 months of anti-TB
Tuberculosis and other Mycobacteria
Outline the main types of Non Tuberculous TB
Two types of NTMs:
-
Slow growing
- M.Amvium
- M.Marinum
- M.Ulcerans
-
Rapidly growing
- M.Abscessus, M.Chelonae. M.Foruitum
- Skin and soft tissue infections
- In hospital settings, isolated from blood cultures
Tuberculosis and other Mycobacteria
Outline the features of TB Vaccination
- BCG= Bacille Calmette-Guerin
- Live attenuated vaccine
- Only given to babies in areas of >10/100,000, since 2005
- Efficacy is 70 to 80%
- Doesn’t work well in adults
- Treatment with biologics, Infliximab: Anti TNF, screens for latent TB before giving the vaccine.
Tuberculosis and other Mycobacteria
Outline the 3 types of Leprosy
3 Types:
-
Paucibacilliary: Tuberculoid leprosy
- Few bacilli
- Large and vigorous cell mediated immune response
- Develop peripheral neuropathy > lose limbs
-
Multibacilliary: Lepromatous leprosy
- Heavy bacterial loads
- Smaller cell response
- Develop lumps and bumps
-
Boarderline (BB)
- Multiple plaques
EMQ Buzzwords: Thickened sural nerve, Shaved outer eyebrows
Tuberculosis and other Mycobacteria
Outline the features of Primary TB
- Multiplies at the pleual surface (Ghon focus)
- Rarely can get allergic reactions such as erythema nodosum
- Taken to a lymph node (primary complex)
- Granulomata is the characteristic lesion with Langhan’s giant cells
- Can be asymptomatic, especially in children
Tuberculosis and other Mycobacteria
Outline the presentation of TB in HIV
Tuberculosis and other Mycobacteria
Outline the features of Post Primary TB
Post Primary:
- Reactivation is over 5 years since last infection
- 5 to 10% lifetime risk
- Upper lobes affected
- Classic lesion = caseating granuloma
- healing = fibrosis and calcification
- Risk factors:
- immunosupression,
- alcoholism,
- malnutrition,
- aging
Tuberculosis and other Mycobacteria
Outline the resistance of TB
Resistance:
- Mono= 1 drug only
- MDRTB= Rifampicin and Isonazid
- XDRTB= Rifampicin and Isonazid + Injecatables and Quinolones
Tuberculosis and other Mycobacteria
What are the side effects of Rifampicin?
Side effects:
- Organge sectrations
- Induce cP450
- Hepatoxtoicity
- Increased transmaminases
Tuberculosis and other Mycobacteria
What are the side effects of Isoniazid?
Side effects:
- Peripheral neuropathy (give B6/pyridoxine)
- Hepatotoxicity
Tuberculosis and other Mycobacteria
What are the side effects of Ethambutol?
Side effects
- Optic Neuritis
- Visual disturbances
Tuberculosis and other Mycobacteria
What is the treatment for TB Meningitis?
TB Meningitis Treatment:
- RIPE for 4 months
- R and I for 8-10 months
Tuberculosis and other Mycobacteria
What is is 2nd line treatment for TB?
2nd Line treament for TB:
-
Injectables
- Capreomycin
- Kanamycin
- Amikacin
-
Quinolones
- Moxifloxacin
- Cycloserine
- Ethionamide/Protionamide
- PAS
- Linelozid
- Clofazamine
Tuberculosis and other Mycobacteria
What is the treatment for latent TB?
Latent TB treatment:
- 6-9 months of Isoniazid
Tuberculosis and other Mycobacteria
What is used for T Prophylaxis?
Just Isoniazid
Tuberculosis and other Mycobacteria
What are the features of Sputum Microscopy and Cultures for TB?
-
Sputum Microscopy
- Zeihl Neelson/Auramine staining
- Gram +ve rods, acid fast
-
Cultures:
- Sputum:
- on 3 different occasions
- Bronchoalveolar lavage
- Urine
- Gold standard = Pus in lowenstein jensen medium
- Can take 6 weeks (more like 1 to 3 though)
- Sputum:
Tuberculosis and other Mycobacteria
What are the features of the Mantoux for TB?
-
Mantoux test:
- Inject 2 units of tuberculin to check previous exposure
- Looking for induration not erythema!
- Poor sensitivity
-
Positive result if:
- >5mm in immunocompromised pateint
- >10mm if recent immigrant
Tuberculosis and other Mycobacteria
What are the features of the IGRA and NAAT?
Interferon Gamma Release Assay:
- Episilot quantification
NAAT:
- PCR-line probe analysis. tests for sensitivities
Tuberculosis and Other Mycobacteria
What are the symptoms of TB Meningitis?
- Subacute presentation
- (Classic TB) weight loss, fever, night sweats
-
Signs of meningism:
- Headache
- Neck stiffness
- Personality changes
- Reduced GCS
- Focal Neurological deficit
Tuberculosis and Other Mycobacteria
What are the investigations for TB Meningitis?
- CT: Tuberculomata
- LP: Lymphocytic
Tuberculosis and Other Mycobacteria
What are the treatment for TB Meningitis?
- 12 months of Anti-TB treatment
- Steroids
Tuberculosis and other Mycobacteria
What are the featutres of M.Avium?
-
Children:
- Pharyngitis/cervical adenitis
-
Pulmonary
- Underlying lung disease
-
Disseminated
- Cytotoxics, lymphoma
-
AIDS:
- Disseminated infection.
- Mycobacteraemia
- consider in HIV pateints with longstanding diarrhoea
Tuberculosis and other Mycobacteria
What are the featutres of M.marinum?
- Also called Fish tank granuloma
- Single or in clusters papules/plaques
- Swimming pool/aquarium owners
Tuberculosis and other Mycobacteria
What are the featutres of M.Ulcerance?
- Insect transmission (tropics/Australia)
- Early: painless nodules
- Usually slowly progressive leading to ulceration
- Seldom fatal, hideous deformity
Tuberculosis and other Mycobacteria
How is the TB vaccine contraindicated in HIV pateints?
- BCG is contraindicated in HIV pateints
-
HIV -ve
- latent TB > active
- risk is 5 - 10% lifetime risk
-
HIV +ve
- latent TB > active
- risk is 5 - 10% YEARLY RISK
Tuberculosis and other Mycobacteria
What is the incubation period, transmission route and main damage site in Leprosy?
- Incubation 2-10 years
- Poor transmission via nasal secretion
- Most damage is secondary effects to nerves
Tuberculosis and other Mycobacteria
What is the treatment of Leprosy?
- Rifampicin
- Dapsone
- Clofazimine (if multibacliliary)
Tuberculosis and other Mycobacteria
What are the key manifestations of Leprosy?
-
Skin
- Depigmentation, macules, plaques, nodules, trophic ulcers
-
Nerves
- Thickened nerves, sensory neuropathy
-
Eyes
- Keratinitis, Irdocyclitis
-
Bones
- Periositis nasecptic necrosis
Tuberculosis and other Mycobacteria
Outline the features of “Progressive” Primary TB
- Progressive primary
- Rarely, focus or node ulcerates into bronchus
- causing
- pneumonia
- cavity formation
- bronchiectasis
- consolidation
- collapse
Tuberculosis and other Mycobacteria
Outline the features of Miliary TB
-
Miliary TB:
- progressive, disseminated haematogenous spread with rich foci
