Tuberculosis

Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis 

-M.tuberculosis is an obligate intracellular bacteria that is aerobic, acid fast, and nonencapsulated

-One-third of the world’s population is infected with TB

-TB usually affects the lung, but virtually all other organ systems may be involved

-Infection is transmitted by aerosolized respiratory droplet nuclei

Symptoms & Signs

Pulmonary tuberculosis: Fatigue, weight loss, fever, cough and night sweats; Primary tuberculosis may coalesce into a small granuloma in the upper lobe (Ghon complex) 

Spinal tuberculosis ( Pott disease):  Pain, deformity, the most common sites involved are the thoracic and lumbar vertebrae 

Lymph nodes(Scrofula): painless swelling of cervical and supraclavicular nodes

TB of the skin (Scrofuloderma): Skin ulcerations in the inguinal or cervical region with lymphadenopathy 

Urinary tract: urethral stricture, nephritis, hematuria, “sterile” pyuria 

Diagnosis 

Tuberculin skin test (TST)

Interferon gamma release assays (IGRAs): QuantiFERON, T-SPOT test

Culture of the sputum, urine, tissue, bone 

Biopsy: Granulomas with caseating necrosis 

Chest X-ray: Diagnostic test of choice; shows upper lobe infiltrates with cavitation and/or lymphadenopathy 

Treatment 

-Treatment is with standard multidrug regimens

-Antimicrobial therapy should be administered for 6–9 months

-Isoniazid, rifampin,Rifapentine, pyrazinamide,streptomycin and ethambutol 

-Pyridoxine should be given to patients taking isoniazid to reduce nervous system side effects 

-Test Visual acuity and red-green color vision before initiating ethambutol

-Perform audiometry before initiating streptomycin 

Prevention: BCG vaccine can prevent up to 50% of TB cases