Mycobacteria

Mycobacteria
It is curved rods, non-motile acid fast staining bacteria (e.g. Ziehl-Neelsen). Most mycobacteria are found in habitats such as water or soil. The cell wall contains complex waxes and glycolipids account for 60% of cell wall weight and its responsible for many characteristics: acid Fastness, antibiotic resistance, resistance to detergents, drying and acids. It is can be cultured, but require complex medium, M. leprae fails to grow in vitro. It is intracellular parasite and its basis for survival in macrophages. It is produces no exotoxins or enzymes that contribute to infectiousness and diseases from immune response
Classification of mycobacterium
Mycobacteria are classified into members of the Mycobacterium tuberculosis complex (M tuberculosis, M bovis, M africanum, M microtii) cause the disease known as tuberculosis (TB) and nontuberculous species
Mycobacterium tuberculosis
Pathogenesis and Immunity
Primary TB
Secondary reactivation TB
Extrapulmonary TB: Systemic TB
Clinical Manifestations

Treatment
Mycobacterium leprae
General characteristics
- M. leprae is similar to other mycobacteria; the cell wall contains unique phenolic glycolipids. - Humans natural host and it?s endemic in many regions throughout the world - It cannot be cultivated in vitro and it multiplies very slowly in vivo (12-day generation time). - Optimum growth temperature 30C, therefore it?s grow in toes, fingers and nose. - Affects and multiples in skin and peripheral nerve and abundance of bacteria in two types of cell.
- Dermal macrophages
- Schwann cells
- Causes Leprosy (Hansen’s Disease)
Transmitted by prolonged exposure with nasal secretions and skin lesion - - Different immune responses cause different form of leprosy



Diagnosis
Diagnosis is based on acid-fast stain and cytologic examination of affected skin and response to the lepromin skin test; M leprae cannot be cultured.
Treatment

Atypical Mycobacteria

Atypical mycobacteria can be divided into two groups, those that cause TB-like disease and those that cause soft-tissue infections.
- Causing TB-like infections:
- M. kansasii
- M. avium-intracellulare (MAC) complex
- M. scrofulaceum