Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Gastroenteritis wikipedia , lookup
Microorganism wikipedia , lookup
Phospholipid-derived fatty acids wikipedia , lookup
Quorum sensing wikipedia , lookup
Anaerobic infection wikipedia , lookup
Carbapenem-resistant enterobacteriaceae wikipedia , lookup
Bacterial cell structure wikipedia , lookup
Marine microorganism wikipedia , lookup
Human microbiota wikipedia , lookup
Triclocarban wikipedia , lookup
Practical Microbiology/ Enterobacteriaceae family The Enterobacteriaceae are a large family of Gram - negative bacteria that includes, along with many harmless symbionts , many of the more familiar pathogens, such as Salmonella , Escherichia coli , Klebsiella , Shigella and Yersinia pestis. Other disease-causing bacteria in this family include Proteus , Enterobacter, Serratia, and Citrobacter. Characteristics Members of the Enterobacteriaceae are rod-shaped , and are typically 1-5 μm in length. They appear as small grey colonies on blood agar. Like other proteobacteria, enterobacteria have Gram-negative stains , and they are facultative anaerobes , fermenting sugars to produce lactic acid and various other end products. Most also reduce nitrate to nitrite, Most have many flagella used to move about, but a few genera are nonmotile. They are not spore-forming. Catalase reactions ( + ) Many members of this family are a normal part of the gut flora found in the intestines of humans and other animals, while others are found in water or soil , or are parasites on a variety of different animals and plants. Escherichia coli is one of the most important model organisms , and its genetics and biochemistry have been closely studied. This family is divided into two groups depending on the fermentation of lactose 1- Lactose Fermentation (the colony appear rose or pink on MacConkey agar) such as Esherichia coli , Klebsiella , Citrobacter. 2- Non Lactose Fermentation ( the colony appear pile or colorless on MacConkey agar ) such as proteus , Shigella , salmonella 1 CHARACTERISTICS OF ESCHERICHIA COLI 1-Grows with and without air .2-Grows between 45ºF and 114ºF .3-Survives freezing temperatures • 4-Many strains are harmless ,Source of pathogenic strains is infected animals and people.. 5-Found in raw milk, raw meat, nonchlorinated water ,contaminated fruits and vegetables 6-Vegetative cells multiply and produce toxins in intestinal tract to cause illness . 7-Vegetative cells killed by cooking / pasteurization • Bacterial Characteristics may or Escherichia coli is a gram negative, non-spore forming rod. It may not be mobile. (Some rods are flagellated and some are not.) The organism is a facultative anaerobe and ferments simple sugars such as glucose to form lactic, acetic, and formic acid . 2 Table 1 Differentiating characters of main genera of Enterobacteriaceae Acid Genus from Lactose Gas from glucose Motility Urease Citrate Voges – Utlized Proskauer Escherchia + + + - - - Shigella - - - - - - Citrobacter + + + d + - Salmonella - + + - + - Enterobacter + + + d + + Klebsiella + + - + + + Serratia d d + - + + Proteus - + + + d - + = positive reaction Escherichia coli : - = negative reaction is d= variable reactions a Gram-negative, facultatively anaerobic, rod-shaped bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms (endotherms ) 3 Characterization of Escherichia coli It is gram negative facultative bacteria non-spore forming bacilli and most strains (about 80%) are motile and few strains are capsulated , fermentive lactose with production gas within 48 hours at 37 C º on MacConkey medium , E.coli colonies are smooth , glassy and translucent , rose –pink in color . On blood agar the colonies of some strains are surrounded by zone of hemolysis , that it is motile , forms gas from glucose , ferments lactose produce indol (+) , gives a positive methyl-red reaction and VP(-) and dose not utilize citrate(-) , grow in KCN , liquefy gelatin. GENERAL CHARACTERISTICS OF PROTEUS Gram-negative rods that are distinguished from other members of the Enterobacteriaceae by their ability to produce the enzyme phenylalanine deaminase Produce the enzyme urease(+), which cleave urea(+) to form NH3 and CO2 Certain species are very motile and produce striking a swarming effect on blood agar, characterized by expanding rings (waves) of organisms over the surface of the agar.(Swarming Phenomenon) 4 LABORATORY DIAGNOSIS 1-Culture . A . On MacConkey agar produce non-lactose fermenter (colorless) colony b . On blood agar produce characteristic Swarming phenomena which considered as diagnostic feature for Proteus however, can cause misdiagnosis for other bacteria as it can cover other colonies and cannot obtain pure culture 2-Staining by Gram stain : Gram –ve rods . 3-P. vulagaris and p. mirabilis produce H2S which blacken the butt of TSI agar 4- P. mirabilis is indole negative, while others are indole positive . 5-Ferment glucose producing acid and gas . 6-Urea agar (urease test) = Pink (+) 7-Citerate (-) 8-MR(+) , VP(-) 5 GENERAL CHARACTERISTICS OF Klebsiella pneumoniae 1- Normal inhabitant in digestive & respiratory system of animal &humane. 2- Lactose Fermenters 3-thick-short rod rounded end. 4-Its dimension (1-2 ×0.5-0.8) 5- arrangement single or diplobacilli 6-Non motile 7-have fimbriae 8-produce capsule (thick from lipopolysaccharide) 9- Easily grow on normal culture media 10- Mucous textures 11- Citrate Utilization (+) ,VP(+),urease (+) / indol(-), MR(-) , Gelatin Utilization(-) 12-sensitive to heat, you die during 30 minute on 55Cº GENERAL CHARACTERISTICS OF Salmonella 1- its dimensions (2-4 ×0.4-0.6 µ) , long or short (coccobacilli ) 2-Non spore-forming 3-Aerobic or facultative anaerobic 4-Selective media 1-selenite broth 2-tetrathionate broth 3-salmonella-shigella agar 4-brilliant green agar 5-Xylose lysine deoxycholate agar (XLD agar) 5-indole(-) ,VP(-) , Urase (-) / H2S(+) ,Citrate (+) decarboxylase (+) 6-sensitive to heat, you die during 20 minute on 60Cº 6 Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised (usually hospitalized) hosts and in those who are on mechanical ventilation. The urinary and respiratory tracts are the most common sites of infection. The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms (or thermotolerant coliforms) group of bacteria, unlike Escherichia coli, because it is incapable of growth at 44.5 °C in the presence of bile salts. Some of them showed quorum sensing properties as reported before Two clinically important species from this genus are E. aerogenes and E. cloacae. The genus Enterobacter ferments lactose with gas production during a 48hour incubation at 35-37 C° in the presence of bile salts and detergents. It is oxidase (-) , indole (-) , urease (V) , Citrate Utlized(+), VP(+) Citrobacter genus of Gram negative coliform bacteria in the Enterobacteriaceae family. The species C. amalonaticus, C. koseri, and C. freundii can use citrate as a sole carbon source. Citrobacter species are differentiated by their ability to convert tryptophan to indole (+), ferment lactose, and Urease (-) 7