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Myobacteria
SCC microbiology
Question | Answer |
---|---|
The genus Mycobacterium includes what types of organisms? | Pathogenic, opportunists, and even normal flora |
What areas of the body are the mycobacteria species able to infect in humans? | These organisms are capable of infecting a wide variety of body tissues and systems. |
List some of the clinical manifestations caused by the mycobacteria. | Diarrhea, lung complications, or skin lesions |
What types of specimens can be collected to isolate/identify Mycobacteria spp.? | A wide variety of specimens can be collected because these organisms can invade a wide variety of body tissues/systems. Examples include: sputums, lung, eye, skin, etc. |
What are the names of the staining procedures used to identify Mycobacteria spp.? | Acid-fast staining procedures: Kinyoun and Ziehl-Neelsen methods |
Why do the Mycobacteria spp. stain the way they do with the acid-fast staining procedures? | The cell walls of these organisms contain a high amount of lipids (fats). Within this fat content is a waxy substance known as mycolic acid that allows these organisms to retain the primary stain and stain “acid-fast positive”. |
What is the acid-fast staining reaction and morphology of the Mycobacteria spp.? | acid-fast positive bacilli (AFB),stain red (the color of the primary stain) |
Do mycobacteria stain with the gram stain procedure? Explain. | Mycobacteria spp. do not stain well with the gram stain procedure,these organisms, they would stain “gram variable”, showing both positive and negative gram staining reactions. |
What are the natural habitats for the mycobacteria? | Soil, warm and cold blooded animals |
What are the three classifications for growth rates of Mycobacteria? | 1. slow growers 2. rapid growers 3. special growers |
Explain slow growers... | colonies seen on artificial media after 7+ days of incubation |
Explain rapid growers... | colonies seen on artificial media in less than 7 days, growth at 25C-37C |
Explain special growers... | need special nutritional requirements to grow or have not been cultured in vitro |
What is the Runyon classification for the mycobacteria? | Another classification system for the Mycobacteria spp, based on the pigment production of these organisms. |
What is the name of the organism that causes tuberculosis? | Mycobacterium tuberculosis |
Who discovered the tuberculosis organism? | Robert Koch (a German physician) |
What is the acid-fast staining reaction/morphology of Mycobacterium tuberculosis? | Acid-fast bacilli (AFB) positive, meaning it takes up and retains the primary acid-fast stain (red) |
Describe the signs/symptoms of tuberculosis. | Tuberculosis (TB) is usually asymptomatic. Left untreated patients can experience fatigue, weight loss, chronic cough, low grade fevers, anorexia |
What is the mode of transmission of pulmonary tuberculosis? | Infected respiratory droplets known as droplet nuclei, person-to-person through the air |
How is tuberculosis spread throughout the body? | TB spreads through the lymphatic and circulatory systems to the entire body |
What are exudative lesions? | fluid filled lesions that are associated with acute, active TB—active infectious TB |
What are productive lesions? | nonfluid filled lesions that are associated with chronic TB—dormant, noninfectious TB |
Define tubercle | a small round nodule produced from infection with TB |
Define granuloma | a collection of cells and organisms produced from a productive TB lesion |
Define Ghon complex | a “dormant” tubercle, this complex can harbor the TB organism for years, and then some “incident” can reactive the TB organism, and infection can reoccur. |
What are the two recognized forms of tuberculosis? Explain the disease pattern of each. | Primary and reinfection are the two patterns Primary is the acute exudative lesions type Reinfection is the chronic productive lesion type |
Can Mycobacterium tuberculosis cause infections outside the lungs? Explain. | Yes, this is known as extramedullary TB. Why this can happen is because the organism spreads throughout the entire body by the lymphatic and circulatory systems, and can then invade all parts of the body. |
How are specimens processed for isolation of the mycobacteria? | two-step process,digestion and decontamination.Decontamination rids the specimen of other organisms that might not allow the Mycobacterium organisms to grow. Digestion allows the specimen to “liquefy” in order to get it to culture more easily. |
What types of screening methods are presently available to check for exposure to tuberculosis? | Tine test, mantoux test (chest x-ray) |
If an individual's initial screening test for tuberculosis gives a positive result, what is the usual follow-up protocol? | Chest x-ray |
What is treatment for tuberculosis? | 1st time infections usually heal without treatment. If treatment is indicated, there are a number of anti-TB drugs available. Examples: Isoniazid, ethambutol, rifampin. Usually a combination of drugs is required for treatment. |
What is the name of the disease caused by Mycobacterium leprae? | Leprosy |
What is another name for leprosy? | Hansen’s disease |
What type of staining procedure is required to identify leprosy? | Acid-fast staining procedures |
Can leprosy be grown on artificial media? | No, it has never been grown on artificial media. It is an obligate intracellular bacilli |
What is leprosy? | It is a chronic skin condition that if left untreated causes gross disfigurement |
What is treatment for leprosy? | Diapsone along with rifampin, treatment can last for years |
What does MOTT stand for? What are these organisms? | Mycobacteria Other Than Tuberculosis, these organisms are other than tuberculosis and leprae, that can cause infections in man and other animals |
What kinds of media do the mycobacteria need to grow? Name a couple. | Middlebrook 7H10 Lowenstein-Jensen |