Mycobacterial diseases Tuberculosis Classification according to mode of infection: 1- exogenous inoculation: A- tuberculous chancre B- tuberculosis veruucosa cutis 2- endogenous by autoinoculation & direct spread: A- scrofuloderma B- tubeculosis cutis orificialis

Tuberculosis 3- haematogenous spread : A- Lupus vulagaris B- miliary TB 4- Tuberculides: A- Papulonecrotic tuberculides B- Erythema induratum C- Lichen scrofulosorum 3- haematogenous spread :

Diagnosis Tuberculine testing: detects cell mediated immunity to TB, by Mantoux test; 5 TU of PPD is injected intradermally & results read 48-72 hrs later, any induration of 10 mm or more indicates infection, biopsy with acid fast staining PCR detecting the DNA of the organism Culture is the golden standard determining antibiotic sensitivty & resopnse to treatment

LEPROSY Caused by mycobacterium leprae Weak acid fast, never grown in vitro Target organs are nerves & skin Lives in temp. 30°C which is below core temp lesions are in cooler areas of body sparing central body & scalp male to female is 1.5:1 incubation period 5-20 years, that’s why patients are usually adults

CLINICAL FEATURES Types of leprosy 1- indeterminate leprosy: one or more hypopigmented macules, occur anywhere, nerve function & hair growth unimpaired 2- Tuberculoid leprosy (TT) 3- Lepromatous leprosy(LL) 4- Borderline leprosy: lesions are intermediate in no & asymmetrical with characteristic punched out appearance

BT BL Tuberculoid Borderline Lepromatous leprosy leprosy leprosy (TT) (BB) (BL) decreased immunity & increased organsism no.

Differences between polar types Lepromatous Tuberculoid Clinical feature Few Single or few skin lesion Number Any size Size Wide spread & symmetrical Asymmetrical Distribution Not Well demarcated Margin Elevated Elevation Smooth Dry, scaly, absent hair Surface Late & mild Early & marked Sensory loss Late Early Sweat loss

No of bacilli in skin lesions Lepromin test Histopathology LEPROMATOUS TUBERCULOID CLINICAL FEATURE &Late bilateral symmetrical Early & near the lesion Nerve involvement Many Scanty or absent No of bacilli in skin lesions Negative Positive Lepromin test Foamy histeocytes Epithelial cell granuloma Histopathology Progressive Spontaneous healing Natural course Immune complex Cell mediated Lepra reactions Common Does not occur Systemic involvement