Non tuberculous mycobacterium Notes
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This Osmosis High-Yield Note provides an overview of Non tuberculous mycobacterium essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Non tuberculous mycobacterium:
NOTES NOTES NON TUBERCULOUS MYCOBACTERIUM MICROBE OVERVIEW ▪ Pleomorphic acid-fast bacillus; usually rodshaped ▪ Thick waxy coating ▪ Obligate intracellular microorganism ▪ Optimal growing conditions: cool temperatures (27–33ºC/80.6–91.4°F), aerobic environment ▪ Proliferates slowly; cannot be cultivated in vitro ▪ Appearance: red; Ziehl–Neelsen stain MYCOBACTERIUM LEPRAE osms.it/mycobacterium-leprae PATHOLOGY & CAUSES ▪ Primarily infects skin, superﬁcial nerves, upper respiratory tract mucosa, eyes ▪ Chronic infection: leprosy; AKA Hansen’s disease ▪ Targets Schwann cells → nerve damage → sensation loss → repeated injuries, infections → gradual destruction of extremities ▪ Inﬁltration of skin, cutaneous nerves → hypopigmented skin lesions Ridley-Jopling classiﬁcation ▪ Tuberculoid ▫ ↑ cell-mediated immunity response ▫ AKA paucibacillary (↓ mycobacteria) ▪ Lepromatous ▫ ↓ cell-mediated immunity response ▫ AKA multibacillary (↑ mycobacteria) ▪ Broad disease spectrum ▫ Borderline tuberculoid, mid-borderline, borderline lepromatous, indeterminate 458 OSMOSIS.ORG RISK FACTORS ▪ Close contact with infected individuals (esp. in areas of poverty), armadillos (enzootic in Dasypus novemcinctus) ▪ Older age, genetic factors, immunosuppression COMPLICATIONS ▪ Lifelong neuropathy → severe disﬁgurement, disability ▪ Severe ophthalmic injury → vision loss ▪ Social stigma (falsely believed contagious) SIGNS & SYMPTOMS ▪ Can be asymptomatic for years ▪ ↓ sensation ▫ Glove, stocking pattern → repeated painless injuries ▪ Hypopigmented/reddish skin lesions, heal spontaneously ▫ Tuberculoid: rare, well-demarcated ▫ Lepromatous: numerous, poorly demarcated
Chapter 83 Non Tuberculous Mycobacterium Nodular swelling (face, earlobes) Body hair loss (esp. eyebrows, eyelashes) Tender, thickened peripheral nerves Ocular involvement ▫ Chronic uveitis (common) ▫ Facial nerve paralysis (lagophthalmos) → corneal exposure, dry eye → corneal ulceration ▪ Late stages ▫ Claw ﬁngers, toes ▫ Foot droop (inability to lift front of foot); peroneal nerve inﬁltration ▫ Nasal septum destruction → nose collapse (saddle nose) ▪ ▪ ▪ ▪ Figure 83.1 A skin lesion on the scalp of an individual with leprosy. DIAGNOSIS LAB RESULTS ▪ Skin biopsy of active lesion ▫ Mycobacteria in cutaneous nerve ▪ Polymerase chain reaction (PCR) ▫ M. leprae DNA in tissues OTHER DIAGNOSTICS ▪ Clinical examination Figure 83.2 The hands of an individual with leprosy. The distal portions of almost all the digits, aside from one, have been lost. TREATMENT MEDICATIONS ▪ Multidrug therapy to prevent resistance ▫ Tuberculoid: dapsone, rifampicin; six months ▫ Lepromatous: dapsone, rifampicin, clofazimine; 12 months OTHER INTERVENTIONS Figure 83.3 Skin changes on the chest of an individual infected with Mycobacterium leprae. ▪ Bacillus Calmette–Guérin (BCG) vaccination ▫ Administered at birth in regions with increased leprosy rates (e.g. Brazil, India, Indonesia) OSMOSIS.ORG 459
Osmosis High-Yield Notes
This Osmosis High-Yield Note provides an overview of Non tuberculous mycobacterium essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Non tuberculous mycobacterium by visiting the associated Learn Page.