Online Microbiology and Biology Notes
Biochemical Test of Bacteria Biochemical reactions are very important in the identification of bacterial isolates and in the identification of different bacterial species. These tests depend on the presence of certain enzymes, such as catalase, oxidase, urease, gelatinase, etc., produced by the bacteria. Different bacteria produce varying spectra of enzymes. For example, some enzymes are necessary for the bacterium’s individual …
Laboratory Diagnosis of Clostridium perfringens For Diarrheal Disease Laboratories diagnose C. perfringens food poisoning by detecting a type of bacterial toxin in feces or by tests to determine the number of bacteria in the feces. A count of at least 106 C. perfringens spores per gram of stool within 48 hours of when the illness began is required to diagnose …
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Clostridium perfringens- Pathogenesis, Clinical Features Clostridium perfringens (previously named Clostridium welchii) is a Gram-positive, rod-shaped, anaerobic, spore-forming pathogenic bacterium, which is found commonly in decaying vegetation and soils. Along with many environmental sources, it is also found in the intestines of humans and animals. Clostridium perfringens is the causative agent of a number of human diseases, such as gas gangrene and …
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Some of the characteristics are: Clostridium perfringens is large rectangular gram-positive bacilli with rounded or truncated ends. It is pleomorphic with straight or curved rods. Size is about 3-8 µm X 0.4-1.2 µm. It is capsulated, non-motile and non-flagellated pathogenic bacteria. It contains spores with central or sub-terminal spores but spores are rarely seen. Endospores are able to survive long …
Biochemical Test of Clostridium perfringens Basic Characteristics Properties (Clostridium perfringens) 20% Bile Positive (+ve) Capsule Positive (+ve) Catalase Negative (-ve) Flagella Negative (-ve) Gas Positive (+ve) Gelatin Hydrolysis Positive (+ve) Gram Staining Gram-positive Hemolysis Positive (+ve) Indole Negative (-ve) Motility Negative (-ve) Nitrate Reduction Variable Oxidase Negative (-ve) Shape Rod shaped; straight rods with blunt ends Spore Positive (+ve) 2 …
Objective of Lecithinase Test The objective is to determine the ability of microorganisms to produce the enzyme lecithinase and to identify the bacteria which are capable of producing lecithinase enzyme. Principle of Lecithinase Test Lecithinases or phospholipases are enzymes released by bacteria that have the ability to destroy animal tissues and play a role in pathogenecity. Lecithinase, which is also called phospholipase C, …
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Cultural characteristics of Clostridium perfringens It is an anaerobic bacteria but can grow under micro-aerophilic condition. They form large, translucent, flat and filamentous colonies with irregular edges. PH: 5.5 to 8.0 (Average PH: 7.2) Temperature: 20°C to 50°C (Average: 37°C) At 45°C, generation time is 10 minutes. Clostridium perfringens on Robertson’s Cooked Meat Broth Saccharolytic species turn meat pink. Meat …
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Habitat of Clostridium perfringens Clostridium perfringens are isolated from fecal specimens from human and animals. They are an inhabitant of human normal intestinal flora. They are present in nature and can be found as a normal component of decaying vegetation, marine sediments and soil. Beef, poultry, gravies and dried or pre-cooked foods are common sources of Clostridium perfringens infections. Also …