Determinative Bacteriology Flashcards with Answers
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Unlock answersList some characteristics of Mycobacteria |
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Which species of Mycobacterium are slow growers, and what defines a slow grower? |
A slow grower will have visible colonies in 7 or more days |
What species of Mycobacterium has rapid growth and what defines rapid growth? |
Rapid growth will have grossly visible colonies in less than 7 days |
What species of Mycobacterium needed special requirements, and what were these requirements? |
They are grown in vitro, in 9 banded armadillo and mouse foot pads. |
Explain the acid fast stain, and why we use it. What is the importance of heat? What are the two methods |
The acid fast stain is used because the cell wall of mycobacteria are comprised of mycolic acids. These cell walls are very waxy and heat is used to soften the waxy coat. This allows the stain to enter, and then once it cools the stain is locked in, and not decolorized with the acid alcohol.
There are two methods, the Ziehel-Neelson method -boil in acid alcohol, stain with dye, because of lipid rich cell wall it stains.
THE REAL METHOD Carbolfuschin acid alcohol methylene blue-counterstain |
What is the doubling time of M. tuberculosis? |
18hrs |
Characteristics of M. tuberculosis |
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What is the importance of mycolic acids C78-C90?
What is the importance of Wax D?
What is the importance of Phasphatides? |
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How does M. tuberculosis grow, and what factor is correlated to this growth? |
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Identification profile of M. tuberculosis ; pigment niacin nitrate tween 80 68 C catalse Urease Growth in egg based media containing 5% NaCl |
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Explain what a granuloma is ; what are they called in TB? |
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Explain how a mycobacterium infection occurs. ; The first step is Mycobacterium bind to CR4 on macrophages and produce.... |
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What are the two types of tubercles and what are the differences? |
Caseating tubercle
Non caseating tubercle
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Pathogenesis of M. tuberculosis ; How does it escape death? + 5 factors |
****NO EXOTOXINS, ENDOTOXINS OR HISTOLYTIC ENZYMES**** ;
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What group of Mycobacterium does M. kansasii belong to? What is its growth rate? pigment produced in the light? pigment produced in the dark? How do colonies appear? Niacin? Nitrate? Tween? Catalase? Urease? Infections? ; |
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Name a member of Group 2 Mycobacterium What is this group called? Pigment in light? Pigment in dark? Appearance of colonies? Growth rate? Niacin? Nitrate? Tween? Catalase? Urease? Infections? ; |
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M. avium-intracellulare, what group? Growth rate? Pigment in light? Pigment in dark? Colonies? Niacin? Nitrate? Tween? Catalase? Urease? Infection? ; ; |
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Group 4, what organism? Group name? pigment in light? pigment dark? colonies? Niacin? Tween? Nitrate? catalase? urease? infection? |
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TB epidemiology world wide ; TB epidemiology in the US |
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TB trends |
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Risk factors associated with TB |
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TB History |
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What is a Ghon complex? ; |
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How does a host respond to TB? ; There are two types of TB, primary and secondary explain them... |
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Two main types of transmission of TB discuss them.... |
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Lesions that occur in TB ; |
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Symptoms in TB |
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Clinical manifestations of TB |
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Complications of TB ; (3 major complications) |
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Factors that may increase chances for TB |
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Immunity and Hypersensitivity of TB |
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Skin test for TB |
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Drugs used to treat TB |
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Drug resistance of TB mortality rate? what kind of therapy works best? three different drug resistant strains |
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New drugs used to treat TB |
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BCG vaccine |
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Lab diagnosis of TB What slant? |
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Explain Pigmentation test... |
Photoreactivity Differential test depends on whether color develops upon incubation in dark or stimulated only after exposure to light
14-21 day of exposure to light 48 hours in the dark |
Niacin test... |
Accumulation involves the conversion of free niacin to niacin ribonucleotide reagent impregnated filter paper strips yellow color = + test |
Nitrate Reduction test... |
NO3--->NO2 Red color develops upon adding reagents + test |
Tween 80 Hydrolysis test... |
Test detects the presence of a lipase that splits Tween 80 into oleic acid and polyoxyethylated sorbitol Yellow to pink color change = + test |
Catalase at 68 degrees C pH 7 test |
The culture is exposed to 68 degrees C for 20 minutes and then H2O2 is added Test before and after heat exposure bubbling = + for catalase |
Urease test... |
Color change in urea based broth or disk Yellow to pink = + test |
What is another name for M Leprae? |
Hansen's Bacillus
Organism was described by Hansen in 1879 |
When was Leprosy first discovered, and when in Florida? |
600BC it was discovered, 1758 in Florida |
Who are the natural host of Leprosy and where is the bacterium harbored? |
Humans are the natural host, it affects the skin, superficial nerves, nose and ears It is an obligate parasite of humans and armadillos it is harbored in nasal secretions, ulcerative lesions, and sputum of patients |
Where does M. leprae replicate? |
Replicates intracellularly in skin histocytes and nerve cells |
How many, and what kind of characteristics are associated with intemediate stages of M. leprae? |
There are at least 3 intermediate stages They have characteristics of both tuberculoid and lepromatous |
Leprosy epidemiology... |
Cases in Africa, India, Japan, Asia, FL, TX, and LA 140 cases reported to CDC each year 80,000 new cases a year
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Tuberculoid (M. leprae) |
Cell mediated response is strong, limits growth, very few acid fast bacteria present Lepromin skin test positive exhibit large flattened patch with raised or elevated red edges dry, pale, hairless centers on any body surface loss of sensation on the skin due to invasion of peripheral nerves M. leprae multiplies at the site of entry, usually the skin invade and colonizes Schwann cells Microbe induces T giat cell infiltration of the skin Reactivity to lepromin CMI develops and remains vigorous No M. leprae recovered within lesions Macule at the cutaneous entry and loss of pain sensation |
Lepromatous (M. leprae) |
Cell mediated response is poor, skin and mucous membranes contain large numbers of bacteria Lepromin skin test negative Exhibit skin involvement with thickening of looser skin parts of the lips, forehead, and ears Classic lion face is typical Extensive penetration of the microbe in the body may cause severe body damage resulting in the loss of bones More severe Microbe proliferates within the macrophages at the entry site suppressor T cells are numerous but epitheloid and giant cells are rare or absent CMI is impaired, large numbers of the organisms appear in the macrophages and the patients becomes insensitive to lepromin Papules appear at the entry site with marked skin folding of the skin Gradual destruction of cutaneous nerves leads to failure of the patient to recognize trauma |
Immunity to M. leprae |
Impaired CMI status with lepromatous leprosy accounts for the severity and progressive nature of the lesions Vigorous CMI is demonstrated in tuberculoid leprosy where lesions are localized and the microbes are rare or absent |
What is the treatment for leprosy and how long is it given? |
Treatment is Dapssone and it is usually given for 2-3 years, but may be given for the lifetime Prevent and control early detection and treatment of the patient |
Lab diagnosis of M. leprae |
Specimens and direct examination Skin lesion biopsies and nasal secretions Demonstration of acid fast bacilli within phagocytic foam cells observed in lepromatous leprosy but difficult to detect in tuberculoid type Can survive for years in nasal secretions, dried sputum and relatively resistant to disinfecting agents Microscopic morphology Acid fast, non motile, nonencapsulated rods, straight or curved, obligate intracellular parasite Not culturable in artificial media or in tissue culture **only mouse pads and armadillos Antigenic structure: components not defined Extracellular product: no virulence factor identified |
M. avium subsp. paratuberculosis |
MAP causes a Crohn's like gastrointestinal disease in cattle "Johne's disease" considered a prime suspect for the disease in humans test whether the bacterium is transmitted to humans in the food chain symptoms include diarrhea, weight loss, remission drugs that target mycobacterium help these patients isolate is being recovered from Crohn's patients |