TB Flashcards
Why do mycobacteria not show up on a gram stain?
Because they have a high lipid content in their cell wall (mycolic acid)
What is the drug treatment for TB? How does it change if CNS/meningitis or osteomyelitis TB?
Rifampicin + isoniazid (6/12 > 12/12 if CNS or osteomyelitis TB) and ethambutol + pyrazinamide (2/12)
What else must you give and why?
Vitamin B6 + folate (as isoniazid depletes B6 stores causing peripheral neuropathy)
What are the side effects of Rifampicin?
Hepatitis, renal failure, fever, rash, orange urine
What are the side effects of Isoniazid? What must be given?
Peripheral neuropathy (give vit B6), hepatitis,
What are the side effects of ethambutol?
Red green colour blindness (optic neuritis)
What are the side effects of pyrazinamide?
Hepatitis (hepatotoxic), rash, arthralgia, hyperuricaemia
What are two tests you can do to diagnose TB? Which is more sensitive?
Tuberculin/Mantoux skin test and IGRA test (IFN gamma release assay) = more sensitive
What microbiological test would you do to diagnose an acid fast bacilli infection?
Ziel Neelson stain (stains pink w/ blue background)
What does CXR show in TB?
Latent TB (gohn’s focus) and pulmonary TB (consolidation, cavitation, pleural effusion…etc)
What does a pleural biopsy demonstrate in TB?
Caseating granuloma
What is caseation?
Necrosis
What type of cells are found in a TB granuloma?
Epithelioid histiocytes + Langhan’s giant cells (NOT langerhan’s)
How are Langhan’s giant cells formed?
Fusion of epithelioid histiocytes/macrophages
What test can you do to confirm the diagnosis of TB?
PCR (Xpert) –> identifies the specific organism but also identifies rifampicin resistant genes
