Tuberculosis Flashcards
Worldwide TB incidence rate trend
Falling at 2% each year
Number 1 killer of communicable diseases
Tuberculosis
Vulnerable groups in the UK
From high prevalence countries (70% are non UK born), aged 15-44, HIV positive, immunosuppressed, elderly, neonates, diabetics, homeless, alcoholics, injection drug user, prison inmates
Species responsible for TB
Mycobacteria Tuberculosis, M.africanum, M.bovus
Mycobacteria
Non motile bacillus which are very slow growing, aerobic so like apices of lungs, have a very thick fatty cell wall so resistant to MQ, neutrophils. Are acid and alcohol fast bacilli (ziehl neilson stain)
Transmission
Airborne mostly (prolonged close contact but not outside cause of UV and dilution)
Immunopathology
MQ are activated, cause Langhans giant cells then granulomas and central caseating necrosis. Tissue destruction is a consequence of MQ
Primary TB infection
No preceding exposure, mycobacteria spread via lymphatics to hilar lymph nodes, usually no symptoms but can have fever, malaise, erythema nodosum. On cxr pleural effusion, mediastinal lymphadenopathy (mainly bilateral)
Tuberculous bronchopneumonia
1% of primary infections. Primary focus enlarges, lots of lymph node enlargement which can cause local collapse if they compress the bronchi
Miliary TB
Fine mottling on xray, hematogenous spread to multiple organs
Post primary disease
Not in animals, either dormant stage or balance of replication and destruction. Can flare up typically 1-5 years later. Fluffy apices and cavitation on CXR, lymphadenopathy rare
Clinical presentation
Cough, (fever, sweats, weight loss). Fluffy apices on xray
How to get a sample
Sputum (3 tries) Bronchoscopy, lumbar puncture for CNS, urine in urogenital
TB drugs
Isoniazid (H), pyrazinamide (Z), rifampicin (R), streptomycin, ethambutol (E)
Standard TB treatment
2 R/H/Z/E + 4 R/H
