MYCOBACTERIA 2/2
M. leprae & Atypical
Professor Sudheer Kher
KEYWORDS
• Acid Fast
• Ziehl-Neelsen Stain
– 5% H2SO4
•
•
•
•
•
•
Mycolic acids
M. leprae
Non cultivable
Armadillo, Mouse footpad
Lepromin test
Ridely Jopling
classification Tuberculoid /
Lepromatous
• Lab diagnosis –Skin
clippings
• Atypical
• Runyon groups
• Antibiotic
resistance
• Opportunistic
infection
• Skin pathogens
M.marinum & M.
ulcerans
• Buruli ulcer
Mycobacteria
Mycobacterium leprae
Hansen's disease, leprosy
Chronic granulomatous communicable
disease occurring in tropical and
subtropical regions; characterized by
inflamed nodules beneath the skin and
wasting of body parts; caused by the
Mycobacterium leprae.
•Chronic disease, disfigurement, common in third world,
millions of cases
•Infects the skin –neural involvement, low temperature
Ridley Jopling Classification of Leprosy
Basis - Immunological
RR-Reversal reaction; ENL-Erythema nodosum leprosum; PB-Paucibacillary, MBMultibacillary
Ulcers, resorption of bone worsened from careless use of hands (nerve damage)
Leprosy
• tuberculoid
• few organisms
• active cell-mediated immunity
• lepromatous
• many organisms
• immunosuppression
Production of M. leprae antigens and
pathogenesis studies
• in vitro
– uncultivable
• in vivo growth
– low temperature
– armadillo
– mouse footpad
Leprosy
• lepromin
– skin testing
• acid-fast stains
– skin biopsies
• clinical picture
Tuberculoid Leprosy
Lepromatous leprosy
Skin biopsy shows intradermal formation of epithelioid granulomas without
caseous necrosis (HE). The papillary dermis is involved. Acid-fast staining is
negative. Diagnostic hints include clinical information of numbness and
histologic identification of nerve involvement by the granulomatous lesion.
Lepromatous leprosy (35 y-o) Male
Biopsy from erythematous and scaling nodules on the extremities. The
bacilli forming "globi" are stained with PAS method.
Lepromin test
A test utilizing an intradermal injection of a lepromin,
such as the Dharmendra antigen or Mitsuda antigen,
to classify the stage of leprosy based on the lepromin
reaction, such as the Fernandez reaction or Mitsuda
reaction.
It differentiates tuberculoid leprosy, in which there is a
positive delayed reaction at the injection site, from
lepromatous leprosy, in which there is no reaction
(i.e., a negative test result) despite the active
malignant Mycobacterium leprae infection; the test is
not diagnostic, since normal uninfected persons may
react.
Erythema Nodosum Leprosum (ENL)
An inflammatory complication of leprosy that
results in painful skin lesions on the arms and
legs and face
Cause – Type III hypersensitivity Immune
complex Vasculitis.
Lab Diagnosis Leprosy
• Easy in Lepromatous, difficult in Tuberculoid.
• Demonstration of AFB
– Nasal mucosa
– Skin Lesion
– Ear lobule
• Skin clippings from 5-6 areas
–
–
–
–
–
Buttocks
Forehead
Chin
Cheek
Ear
Mycobacteria
Atypical Mycobacteria
Mycobacteria other than human or
bovine tubercle
Synonyms –
• Atypical
• Anonymous
• Unclassified
• Non tuberculous mycobacteria
• Paratubercle
• Tuberculoid
• MOTT Mycobacteria Other Than Tubercle
Runyon Classification (1959)
Basis – Pigment production & Rate of growth
• Group I –
Photochromogens
– Form pigment after
exposure to light
– Example – M. kansasii
– Habitat – Water & animals
– Causes Pulmonary, skin,
systemic, LN infections.
• Group II –
Scotochromogens
–
–
–
–
Pigment produced in dark
Example – M. scrofulaceum
Habitat – Water, soil, fomites
Causes cervical
lymphadenitis in children
• Group IIINonphotochromogens
– No pigment production
– Examples – M. intracellulare,
M. avium & M. xenopi
– Habitat – Soil, Seawater,
animals
– Causes Pulmonary,
gastrointestinal, renal,
systemic, LN infections
Pulmonary, epididymis
• Group IV –Rapid growers
– Colonies appear within seven
days
– Example –M. fortuitum,
– Habitat- Water, soil & animals
– Causes Pulmonary,
gastrointestinal, renal, systemic,
LN infections
Atypical mycobacteria
• infect immunocompromised host
• not transmitted man -man
– healthy people
Atypical mycobacterial diseases
• tuberculosis-like
• leprosy-like
Mycobacteria and AIDS
• M. avium is much less virulent than M. tuberculosis
– does not infect healthy people
– infects AIDS patients
• M. avium infects
– when CD4 (helper T cell) count greatly decreased
• M. tuberculosis infection
– infects healthy people
– infects AIDS patients
* earlier stage of disease
* more systemic
Other atypicals
• pigmented or not
• pigmentation
– in the light
– in the dark
• growth
– fast
– slow
Mycolic acids
• mycobacteria
– longest chain length
– strongly acid fast
• nocardia
– intermediate chain length
– weakly acid fast
• corynebacteria
• shortest chain length
– not acid fast
Mycobacterium avium complex (MAC)
1) Most common bacterial opportunistic
infection (OI) in adults infected with HIV
in the developed world.
2) Most found in US – Rare in Africa.
3) Annual frequency in AIDS – 10-20%.
4) Occurs late in HIV infection. Mean CD4+
Count ~ 10-30/μL. (TB occurs early.)
5) Inhaled or ingested from environment.
6) Spreads via lymphatics then
hematogenously.
7) Taken up in reticuloendothelial organs.
Mycobacterium avium complex (MAC)
Symptoms in the AIDS Patient:
Disseminated
Gastrointestinal
Fever
Chronic Diarrhea &
Night Sweats
Abdominal Pain
Weight Loss
Malabsorption
Malaise
Cholestatic Jaundice
Anemia
Elevated LFTs
(Alkaline Phosphatase)
MAC in the Non-HIV/AIDS Patient:
1) More common as a cause of pulmonary
disease in persons born in United States
than TB.
2) Increasing in incidence over the last 20-30
years.
3) Progressive pulmonary disease on x-ray
and clinically.
4) Sputum culture positive.
5) Dissemination rare to non-existent.
Diagnosis of MAC in AIDS
Biopsy of the involved reticuloendothelial
organs with acid fast stain and/or culture.
Blood culture. (85% of
patients with disseminated
MAC are mycobacteremic.)
EID CDC
CDC/Dr. Edwin P. Ewing, Jr.
Colon Biopsy
Mycobacterium
avium –
Acid Fast Stain →
← MAC
infection of
lymph node.
Acid-fast bacilli
within plump
histiocytes.
© Dr. Peter Anderson, University of Alabama at
Birmingham, Dept of Path.
Mycobacteria
SKIN PATHOGENS
NAME OF DISEASE:
Buruli ulcers, Mycoburuli ulcers
ETIOLOGICAL AGENT:
Mycobacterium ulcerans. It grows only at temperatures below 37° C, is
non-chromogenic and niacin-negative and extracellular
OVERVIEW:
An ulcer of the skin and underlying tissue is the sole symptom due to
the unique temperature requirements of the organism. The disease is
most common along the Nile River but is also found in Southeast
Asia, Australia and Mexico.
PATHOGENESIS:
The organism can apparently penetrate the unbroken skin where it
produces an ulcer. Despite extensive necrosis, lesions are painless,
symptoms of systemic disease are absent and there is little
histological evidence of an initial acute inflammatory response. Focal
necrosis extends through the dermis and adipose tissue and into
muscle. The cause of this necrosis is mycolactone.
Mycobacterium marinum
Swimming pool granuloma: Localized nodular skin
inflammation (small reddish raised areas of skin) caused by a
bacterium called Mycobacterium marinum
Atypical Mycobacterium found in salt and fresh water. M
marinum is the most common atypical Mycobacterium to
cause infection in humans. Infection occurs following primary
inoculation of a skin abrasion or puncture and manifests as a
localized granuloma
Contact with an aquarium, salt water, or marine animals such
as fish or turtles. Exposure to M marinum via swimming
pools is rare these days because most pools are chlorinated.
Cultures at 25-32°C may grow acid-fast bacilli in 7-21 days.
The organisms are photochromogens
KEYWORDS
• Acid Fast
• Ziehl-Neelsen Stain
– 5% H2SO4
•
•
•
•
•
•
Mycolic acids
M. leprae
Non cultivable
Armadillo, Mouse footpad
Lepromin test
Ridely Jopling
classification Tuberculoid /
Lepromatous
• Lab diagnosis –Skin
clippings
• Atypical
• Runyon groups
• Antibiotic
resistance
• Opportunistic
infection
• Skin pathogens
M.marinum & M.
ulcerans
• Buruli ulcer