Mycobacterium Flashcards
1
Q
Mycobacteria General Characteristics
A
- Acid fast
- Aerobic
- Non spore forming
- Non motile
- Have a high lipid cell wall content
- Temperature Requirements
- Most mycobacteria can be isolated at 36 o C with 7 10% CO 2
- There are several species which require a significantly lower primary recovery temperature
- 30 to 32 o C.
- There are also some which require a higher temperature for recovery as well.
2
Q
Group I Photochromogens
A
- They are defined as colonies which develop a yellow orange pigment on exposure to the light of a 60 watt bulb placed 6 inches above the tube for 60 minutes. They take longer than 7 days to appear on solid media.
- Members include:
- M. kansasii , M. simiae , M. marinum , M. asiaticum
3
Q
Group II Scotochromogens
A
- They are defined as colonies that develop a yellow-orange pigment in the dark or light and take longer than 7 days to appear on solid media.
- Members of this group include
- M. gordonae
- M. scrofulaceum
- M. szulgai (at 37 o C)
4
Q
Group III Nonphotochromogens
A
- They are defined as colonies that are non-pigmented regardless of whether they are grown in the dark or light and take longer than 7 days to appear on solid media.
- Members include:
- M. avium complex
- M. intracellulare
- M. xenopi
- M. ulcerans
- M. malmoense
5
Q
Group IV Rapid Growers
A
- They are defined as colonies that grow on solid media in less than 7 days.
- Mycobacteria forming colonies within 7 days are termed rapid growers, those requiring longer periods are termed, slow growers
- Inoculate well isolated colony of organism to 7H9 broth containing Tween 80
- Incubate broth for several days until medium faintly turbid
- Dilute broth 1:100, streak inoculate to Middlebrook 7H10 agar plate. Observe cultures at 5 to 7 days and (if no growth) weekly thereafter for visible colonies
- Members of this group include:
- M. fortuitum
- M. chelonae
- M. peregrinum
- M. abscessus
- M. thermoresistibile
6
Q
M. leprae General
A
- Cause of Hansen’s Disease or Leprosy
- Discovered by the Norwegian G. H. Armauer Hansen in 1873
- 2 3 million cases worldwide
- WHO listed 91 countries where it is endemic
- In 2004 there were 407,791 new cases world wide
- In 2015 the CDC reported 178 cases in the United States
- There are 4 strains of M. leprae
7
Q
M. leprae Clinical Picture
A
- Causes severe, disfiguring skin sores and nerve damage in the arms, legs and skin areas around the body.
- It can also attack the eyes and the thin mucus lining of the nose.
- The main symptom is disfiguring skin sores, lumps or bumps that do not go away after several weeks or months.
- Skin sores are pale colored.
- Nerve damage is also common.
8
Q
M. leprae Laboratory Testing
A
- There are no serological or skin tests available.
- Skin biopsy needed for the definitive diagnosis.
- PCR for M. leprae DNA may be needed in special circumstances.
- Cardinal signs along with skin biopsy is the most common way to diagnosis leprosy.
9
Q
Leprosy Treatment
A
- Treatment is done as a multi drug regimen.
- Treatment for paucibacillary leprosy:
- 6 month regimen
- Adult: 100 mg Dapsone/daily & 600 mg
- Rifampicin/monthly
- Treatment for multibacillary leprosy:
- 12 month regimen
- Adult: Dapsone 100 mg/daily & Clofazimine 300 mg/monthly & Rifampicin 600 mg/monthly or 50 mg/daily
10
Q
M. Tuberculosis Complex
A
- M. tuberculosis
- M. africanum
- M. bovis & the Bacillus Calmette Guerin strain (humans +)
- M. microti
- M. canetti
- M. caprae
- M. pinnipedii
- M. suricattae
- M. mungi
11
Q
M. Tuberculosis Complex Symptoms & Transmission
A
- Symptoms:
- Early symptoms include
- Weight loss
- Fever
- Night sweats
- Loss of appetite
- Early symptoms include
- Transmission:
- Aerosol from one person to another usually thru coughing or sneezing even singing!
- Extrapulmonary TB
- M. tuberculosis can infect any organ of the body
- Symptoms vary by site of disease
- Pulmonary TB
- Cough >2 weeks
- often productive (sputum), can be bloody
- Fever
- Night sweats
- Weight loss
- Chest pain
12
Q
Diagnosis of TB Disease
A
- Signs and Symptoms consistent with TB
- Chest X ray
- Clinical Judgment
- Bacteriology
- AFB smear microscopy
- Nucleic Acid Amplification Testing
- Culture and Identification
- Drug susceptibility testing
13
Q
TB Specimens for Testing
A
- Sputum 3 first morning collections
- Bronchial washes
- Stool
- Biopsies
- CSF
- Gastric washings
- Urine
14
Q
TB Primary Isolation Medias
A
- Lowenstein Jensen (LJ’s) slants
- Lowenstein Jensen Gruft’s
- Middlebrook 7H9 broth
- Middlebrook 7H10 plates
- Middlebrook 7H11 plates
15
Q
Digestion Methods
A
- 3 most common methods for sputum are;
- NAOH method (sodium hydroxide)
- Zephiran trisodium phosphate method
- NALC NaOH method (N-Acetyl L-cysteine)
