Atypical Mycobacteria & M. leprae (4) Flashcards
How are atypical mycobacteria aquired?
through the environment
Are atypical mycobacteria PPD + or -?
PPD -
Are atypical mucobacteria lethal in guinea pigs?
No, they are not
What are the Group 1 Atypicals?
Photochromogens
M. kansasii and M. marinum
What are the characteristics of group 1 atypicals?
Produces pigment in light and does not kill guinea pigs
Where is M. kansasii found?
midwest, texas, england
What disease does M. kansasii produce?
Some lung disease
Where is M. marinum found?
Fresh and salt water
Symptoms of M. marinum?
Forms “fish tank” granulomatous ulcerating lesions on abrasions exposed to swimming water or aquarium water
How is M. marinum treated?
Tetracycline
What are the group 2 atypicals?
Scotochromogens
M. scrofulaceum
What are the characteristics of the group 2 atypicals?
Produces pigment in the dark and does not kill guinea pigs
What illness does M. scrofulaceum produce?
Produces scrofula and is the most common PEDIATRIC cause of scrofula
What is the reservoir for M. scrofulaceum?
water
How is M. scrofulaceum treated?
Surgically removing the affected nodes
What are the group 3 atypicals?
Nonchromogens
M. avium and M. intracellulare
What are the characteristics of group 3 atypicals?
Do not produce pigment and does not kill guinea pigs
What disease do M. avium and M. intraceullare produce?
Pulmonary disease indistinguishable from TB in severely immunocompromised patients
What is the reservoir for M. avium and M. intracellulare?
Environmentally wide spread (soil and water)
Treatment for M. avium and M. intracellulare?
Highly drug resistant!
Treat with a combo of clarithromycin and ethambutol, rifampin or cipro
What are the group 4 atypicals?
Rapidly growing mycobacteria
M. fortuitum / M. chelonei
M. abscessus
M. smegmatis
What are the characteristics of group 4 atypicals?
No pigment, does not kill guinea pigs
Culterable <1 week
Who is generally susceptible to M. fortuitum / M. chelonei infections?
Immunosuppressed, people with prosthetic joints, indwelling catheters, puncture wounds
How are M. fortuitum / M. chelonei infections treated?
Surgical excision, doxycycline, amikacin
Illnesses caused by M. abscessus?
Chronic lung infection, skin and bone infections as well
Where are M. fortuitum / M. chelonei, M. abscessus, M. smegmatis normally found?
M. fortuitum / M. chelonei- environment (soil and water)
M. abscessus- environment (soil and water)
M. smegmatis- normal flora under foreskin
Which group 4 atypical is highly Ab resistant?
M. abscessus
What disease does M. leprae cause?
Leprosy or Hansen’s Disease
Reservoir for M. leprae?
Humans and armadillos
What is the growth rate for M. leprae?
14 day doubling time–> increadibly slow growing
What temperature does M. leprae prefer to grow at?
30C…so it sticks to the periphery of humans
The symptoms of M. leprae are caused by both the ________ and the __________.
the infection and the immune response
Mechanism of transmission for M. leprae?
Exact mechanism is unclear
Requires prolonged contact with infectious case and contact with nasal secretions and skin lesion contact
Rare zoonosis from animals is possible
Where does M. leprae replicate?
Skin histiocytes, endothelial cells, and Schwann nerve cells
Describe the tuberculoid form of Leprosy?
Big CMI response
Few bacilli
Asymmetric immunogenic peripheral nerve damage
Lepromatin PPDGranulomas containing giant cels form +
Describe the Lepromatous form of leprosy?
Poort CMI response
Large numbers of bacilli
Symmetrical peripheral nerve damage from bacterial growth in schwann cells
PPD -
Foamy macrophages from
What are some sensory and motor function loss systems seen in leprosy?
Claw hand, foot drop, plantar insensitivity and clawed toes
Physical exam findings seen tubercloid leprosy?
Few sharply demarcated macules on butt, face or limbs
Superficial nerves lesions can enlarge
Asymmetric peripheral nerve damage–> neuropathic pain and muscle atrophy
Symptoms seen in lepromatous leprosy?
Extensive bilateral symmetric cutaneous macules
Lesios have poorly defined borders and raised centers
Eye infection is possible
T/F: Lepromin skin test is diagnostic of exposure to Leprosy
False…its used to determine patients ability to raise immune response
What will appear in a skin smear of both forms of leprosy?
Lepromatous: “foam cells”
Tuberculoid: granulomatous cahnge with epithelial cells and lymphocytes
What is the treatment for leprosy?
Tuberculoid: Dapsone and rifampin for 2 years
Lepromatous: Dapsone, rifampin and clofazimine for 2+ years
Peds: prophylaxis w/ dapsone after exposure
