Microbiological Diagnosis of Tuberculosis.
MSc. Sarah Ahmed
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Importance of Optimal Specimens
Pulmonary Tuberculosis is the commonest presentation of Tuberculosis
Sputum is the Most important specimen for identification and isolation of Acid fast bacilli.
The developing countries suffers the most important step in getting an ideal sample.
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Sputum Specimens*
*Train the staff to obtain the appropriate specimen
A few minutes of education to patients on importance of ideal sample make a great difference and improves the Diagnosis.
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Mucoid Sample
Purulent Sample
Bloody Sample
Salivary Sample
Microscopy and Tuberculosis
Microscopy with Ziehl – Neelsen’s staining A century old procedure *
Smear showing Acid Fast Bacilli.
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Processing Direct smear Negative specimens
Sputum Microscopy can be improved with Sputum liquefaction, concentration and gravity sedimentation.Popular solvents Sodium hypochlorite. Sodium hydroxide. Ammonium Sulphate N-acetyl-L-cysteine –sodium hydroxide.Treating specimens with Sodium hypochlorite is Mycobactericidal and also kills HIV and improves the safety and acceptability by technical staff. *
Culturing Mycobacterium
Culturing for isolation of Mycobacterium spp continues to be a Gold standard, particularly in Developing countries.Need only 10 – 100 bacilli / 1 ml of sputum. *
Methods of Culturing.
Culturing on Lowenstein Jenson’s culture medium remain the affordable ,economical method in developing world.Mycobacterium spp are slow growing.Need 6 – 8 weeks for growing. *
raised, dry, cream (buff) colored colonies
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