2. GENUS: MYCOBACTERIUM Classification – -Family Mycobacteriaceae -1 genus of medical importence = Mycobacteria -All are slow growing -All are acid-fast and contain large amounts of lipids intheir cell walls -Tubercle bacilli = M. tuberculosis, M. africanum, andM. bovis
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4. The Mycobacteria are divided into 4 groups (Runyon groups) based on growth rate and pigmentation:Photochromagens: - are non-pigmented when grown in the dark. - produce photoactivated pigments upon exposure to light e.gM. kansasii, M. marinum, M. asiaticum, M. simiae
5. 2.Scotochromogens: -Produce deep yellow to orange pigments when grown in light or dark, - The color deepens upon two weeks exposure to light e.gM. gordonae, M. scrofulaceum, M. szulgai, M. xenopi. 3. Nonphotochromogens: -May produce pigment ranging from white to yellow, -The pigment does not intensify upon exposure to light.e.g. M. tuberculosis. M. avium, M. intracellulare, M. terrae, M. ulcerans. 4. Rapid growers: - organisms that form colonies within seven days.eg. M.phlei, M. smegamtis, M. fortuitum, M. chelonei.
10. Several acid fast stains that may be used:1. Ziehl-Neelsen: -uses heat to get the primary stain of carbolfuchsin to penetrate the cell wall; - acid alcohol destaining; - methylene blue as the counterstain.
16. For primary isolation complex media should be used – Use of a nonselective, a selective and possibly a liquid media is recommended. Nonselective -May be egg or agar based. - May include malachite green to suppress growth of contaminating bacteria. Lowenstein-Jensen -egg based; -Colonies grow in 18-24 days. b. Middlebrook 7H10 and 7H11 – agar based; - colonies grow in 12-14 days.
17. 2. Selective media: – Consists of one of the nonselective media plus added antimicrobial agents (malachite green, cyclohexamide, and nalidixic acid are often used) -The colonies of M. tuberculosis on the solid media are rough, dry, granular, nonpigmented to buff colored colonies. 3. Liquid media: - Media usually contains tween 80 and albumin and the organisms will grow faster than on solid media NB: Most Mycobacteria grow best in 5-10% CO2 and at 35-370 C.
20. Further biochemical testing includes:Niacin reduction -M. tb. Is nitrate reduction+ and – for catalase at 680 C 2. Tween hydrolysis, 3. Arylsulfatase production, 4. Tellurite reduction, 5. Salt tolerance, and 6. Pyrazinamidase production
53. • TREATMENT – Penicillin, Ciprofloxacin • IMMUNIZATION –Animals > Live spore vaccine (Sterne strain) – Workers at Risk of Exposure > Anthrax Vaccine Absorbed (AVA) >> “Alum precipitated toxoid”
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55. PATHOGENICITY: >> Due to an Enterotoxin. • Also Causes Disease in Patients with Underlying Disease. TREATMENT: >> Tetracycline, Erythromycin. • iii. B. subtilis: • iv. B. stearothermophilus.
67. Clostridium perfrigens Synm: C. welchii. Disease:enterotoxemia Occurrence: C. perfrigenstype A more widespread, present in air, soil, dust, manure, water of lakes, streams, and rivers. Has been isolated from vegetables, milk, cheese, canned food, fresh meat, shellfish and mollusks.
68. FOOD POISONING: • Cl. perfringens Type A >> Enterotoxin. > Acute Abdominal Pain and Diarrhoea.
75. Blood agar plate with Cl. Perfringenscharacteristic double zone of hemolysis
76. Clostridium chauvoeisynonym: C. feseri Disease: blackleg Wide spread, found in intestine and in normal tissues Toxins α toxin: hemolysin, necrotoxin ß toxin: deoxyribonuclease γ toxin: hyaluronidase ∆ toxin: hemolysin
77. Phathogenicity Ruminats: Blackleg (cattle 4 months to 2yr)- ingestion/endogenous, sheep and goats- wounds lession dry, dark, with gas bubles, and a rancid odor, there may be bacteremia. Immunity: Formalized whole-broth cultures- life long Recovery from disease—renders the animal immune for life
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79. LABORATORY DIAGNOSIS: • Important: Diagnosis of Clostridium MyonecrosisShould Be Rapid and Made on Clinical Grounds. Direct Smear and Gram Stain of Material from Deep Within the Wound. ii. Culture: Tissue Aspirates or Deep Swabs Taken from Affected Muscle.
80. TREATMENT: • Clostridium myonecrosis: Surgical removal of all infected and necrotic tissue. ii. Antibiotic and Antitoxin therapy. iii. Adminstration of hyperbaric oxygen.
81. Clostridia that may be associated with gas gangrene: • Cl. perfringens Type A • Cl. Septicum • Cl. novyi Type A • Cl. Histolyticum • Cl. Sordellii
92. VIRULENCE FACTORS • Botulinum Toxin >>> Neurotoxin. – Serologically 8 types of Toxins >>A, B, C1, C2, D, E, F & G. > Affect the Cholinergic System > Blocks the Release of Acetylcholine (at Points in Peripheral Nervous System).
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94. TREATMENT & PREVENTION Important: Specific Treatment should begin as quick as possible. >Polyvalent Antitoxin >>> Immediately. >Physiological support >NEVER Use a swollen or defective can.
