Mycobacteria Flashcards
how many people have latent TB
1/3 of world population
how is TB transmitted
aerosol
Potts disease
TB in vertebrate
what is resistnace to Isoniazid
katG mutation confers resistance to INH
is BCG vaccine effective?
no
what is #1 killer of Aids patients
TB
M. ulcerans:
optimal growth at 32oC. 3rd most common mycobacterial disease Source – contaminated water. Produces mycolactone toxin: induces necrotic cell death – painless. Surgery often required. picture of bare achilles tendon
Mycobacterium leprae
oldest recorded disease.
Very slow growing (20 day doubling time).
Affects peripheral nerves, skin and mucosa.
Prefers low temperatures.
Infects monocytes.
Humans and armadillos only known natural hosts, can’t be cultured in vitro.
¼ the genes of M. tuberculosis,
common ancestor.
TB vs laprae
Lepromatous - malignant form
- bacteria are present in high numbers
- strong antibody response,defect in the cell-mediated immune response and low or no delayed hypersensitivity to lepromin.
loss of eyebrows, thickened and enlarged nares, ears and cheeks. Damage may be severe with loss of nasal bone and septa, and sometimes of digits. Both the skin and nerves are affected, with loss of local sensation. This in turn often leads to accidental injuries and secondary infections.
Tuberculoid leprosy- in some cases is self-limiting.
- active cell-mediated immune response to lepromin
- very few bacteria in the tuberculoid lesion.
blotchy red lesions on the face, trunk and extremities with loss of local sensation. Bacteria can be observed growing in the nerve sheaths, resulting in comparatively more sensory nerve damage than lepromatous leprosy.
risk factors for TB
HIV infection Transplant or other immunosuppression Medical conditions Injection drug users Recent arrivals from endemic countries
Contacts to infectious cases
Health care workers
Other workers exposed to TB cases
symptoms of TB
cough, hemoptysis, chest pain (pleuritic)
B symptoms
what TB drug is always in the mix
Pyrazinamide
Tuberculin skin test
≥5 mm ≥10 mm ≥15 mm
HIV infection Recent immigrants No risk
Contact to active TB case Injection drug users
Abnormal CXR Children
Immunosuppression High-risk medical conditions
Jail, hospital
what is best test
Interferon gamma relaease assay
what is the side effect of Isoniazid
hepatotoxicity and peripheral neuropathy
give b6
are non tb Mycobacteria transmissible person to person
no
whay are NTM incraeasing?
Great exposure to aerosols
Change in plumbing (copper to PVC, lower water temperatures)
Diagnostics
More sensitive culture methods
More CT scans
Host factors Aging population, more lung disease More immunosuppressed patients Decreasing cross-immunity to M. tuberculosis Organism Increased virulence?
what female is susceptible to NTM
skinny female
NTM presentation
Cough, fatigue, weight loss
CXR- Nodular or cavitary opacities on chest radiograph or
CT- multifocal bronchiectasis with multiple small nodules
leprosy Tx
Multibacillary leprosy -Rifampin once a month -Dapsone daily -Clofazimine one a month + daily Duration -12 month
Paucibacillary leprosy
-Rifampin once a month
-Dapsone daily
Duration - 6 months
buruli ulcer tx
rifampin + streptomycin/amikacin for 8 weeks
Surgery to remove necrotic tissue, cover skin defects and correct deformities
Interventions to minimize or prevent disabilities
Describe disease caused by MAC
Several different syndromes are caused by MAC, comprising M. avium, M. intracellulare, and M. chimaera.
Disseminated infections are usually associated with HIV infection or other forms of immunosuppression.
Pulmonary disease can occur in nonimmunocompromised persons.
In children, the most common syndrome is cervical lymphadenitis.
Although the exact mode of transmission is unclear, MAC is most likely environmentally acquired.
Cure rates for pulmonary disease range from 50 to 80%. Treatment is with a macrolide, ethambutol, rifamycin, and sometimes an aminoglycoside.
leprosy transmission
● Transmission: Leprosy is spread from person to person, but the rate of transmission is very low, 1%-2% exposed population develop clinical disease. In lepromatous leprosy, organisms are shed from the nasal septa resulting in transmission. 240 million leprosy germs can be shed in 24 hours through the nose if untreated. Incubation period: 3-5 years.
