MYCOBACTERIA Flashcards
What kind of pathogen is Mycobacteria?
Acid fast bacteria (bacilli, rods)
Where is mycobacteria more common?
Developing countries
What are two common strains of mycobacteria?
-Tuberculosis
-M. avium (also considered atypical)
What are Atypical strains of Mycobacteria?
-M. abscessus
-M. fortuitum
-M. marinum
What do the Atypical strains of mycobacteria cause?
Usually wound and skin infections which are nodular, ulcerative, and can last for months
-Related to environmental inoculation/nosocomial (hospital) infection
-Salt/H20 exposure (sea water) related to M. marinum (Think marinum = aquarium)
How can you diagnose an atypical Mycobacteria infection?
Culture or skin biopsy
What does atypical Mycobacteria infection treatment depend on?
Depends on site and organism ID consult recommended
How is M. avium transmitted? What does it cause?
-Waterborne, soil, etc.
May cause lung disease if inhaled
Who is more susceptible to an M. avium infection?
-Advanced age
-Women more commonly than men
-People with lung disease (like CF, COPD)
What kinds of infections does M. avium cause?
-Hypersensitivity disease: hot tub lung (inflammation caused by inhaling water droplets from hot tub)
-Disseminated (spread): in immunocompromised patients can be severe and progress, CD4 immune cells <100
-Pulmonary: Nodular, cavitary (spaces in lungs) lung disease
How can M. Avium be treated?
Pulmonary: Macrolide+Ethambutol+Rifampin
Disseminated/immunocompromised: Macrolide+Ethambutol+Rifampin for at least 12 months, no sign of MAC disease, and immune CD4 cell count >100 for >6 months
How is TB transmitted?
Person to person by inhalation of air droplets
What is the pathogenesis of TB?
When in the lungs, TB is phagocytosed by macrophages but not killed and form granulomas
*Can cause active infection in about 10%, others will remain dormant, increased active disease within 1 year of exposure or if immunocompromised
What are the signs of an active TB infection?
-Chronic cough greater than 3 weeks
-Hemoptysis (coughing up blood)
-Fever/night sweats
-Weight loss
*Contagious
What are the signs of a disseminated TB infection?
Disease in any organ system
-Lymph nodes
-Laryngeal
-GU tract
-Orthopedic
-CNS
-Peritoneum
-Pericardium
*if not in lungs, not usually contagious
What are the signs of a latent TB infection?
Cells are walled off in granulomas, can reactivate later in life if immune system is weakened
*not contagious unless reactivated
Where does TB commonly infect the lungs?
UPPER LOBE, primary TB will look like pneumonia on an X-ray
How can you diagnose a TB infection?
-Sputum collection (3 collections in the morning)
-Chest x-ray or CT scan
-Bronchoscopy
-Gastric Aspirate (collect gastric material)
-Serology (a Quantiferon/T spot test will show presence of mycobacteria)
-TB testing
Why could someone have a positive test for TB even though they are not infected?
If they were vaccinated for TB, will give false positive PPD from antibodies
How is a TB infection treated?
Active TB:
-Airborne isolation, Notify public health
-Combo of 4 meds: Isoniazid, Rifampin, Pyrazinamide, Ethambutol (standard regimen)
-Second line meds can be used in the case of resistance
-NO SINGLE MEDICATION THERAPY: increases risk of resistance
-6 month treatment
Latent TB:
-Isoniazid for 9 months
-Isoniazid + Rifepentine weekly for 12 weeks
**To prevent reactivation
