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ENTEROBACTERIACEAE

ENTEROBACTERIACEAE. By. Dr. Emad AbdElhameed Morad. Lecturer of Medical Microbiology and Immunology. Enterobacteriaceae are Gram negative bacilli found as flora in the colon of man and animals. They have certain features: Facultative anaerobes. All of them ferment glucose.

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ENTEROBACTERIACEAE

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  1. ENTEROBACTERIACEAE By Dr. Emad AbdElhameed Morad Lecturer of Medical Microbiology and Immunology

  2. Enterobacteriaceae are Gram negative bacilli found as flora in the colon of man and animals. • They have certain features: • Facultative anaerobes. • All of them ferment glucose. • Oxidase negative. • Reduce nitrate to nitrite. • According to the effect on lactose, they are classified into: • Lactose fermenters: E. coli, klebsiella, citrobacter, enterobacter, serratia. They are called coliforms. • Lactose non-fermenters: salmonella, shigella, proteus, yersinia. Dr. Emad AbdElhameed Morad

  3. Escherichia coli Dr. Emad AbdElhameed Morad

  4. Morphology: • Gram negative bacilli, motile, some strains are capsulated • Cultural characters: • Facultative anaerobe • On MacConkey’s medium: rose pink colonies • Strains causing urinary tract infection produce hemolysis on blood agar. Dr. Emad AbdElhameed Morad

  5. (Gram stained film of E. coli) Dr. Emad AbdElhameed Morad

  6. (E. coli on MacConkey’s agar) Dr. Emad AbdElhameed Morad

  7. (Lactose fermenters and non lactose fermenters on MacConkey’s agar) Dr. Emad AbdElhameed Morad

  8. Biochemical reactions: • Ferment glucose, lactose, maltose, mannite, sucrose, salicin with acid and gas production. • Indole +Ve, methyl red +Ve • Voges proskauer’s reaction –Ve, citrate –Ve • H2S –Ve, urease -Ve Dr. Emad AbdElhameed Morad

  9. (E. coli)

  10. klebsiella Dr. Emad AbdElhameed Morad

  11. Klebsiella exists as normal flora in the intestinal and respiratory tracts. • It exists also as saprophytic bacteria in soil and water. • Morphology: • Gram negative bacilli, capsulated, non motile, • Cultural characters: • Facultative anaerobe. • On MacConkey’s medium:it produces rose pink colonies which are mucoid due to production of extracellular slime. Dr. Emad AbdElhameed Morad

  12. (Mucoid colonies of Klebsiella) Dr. Emad AbdElhameed Morad

  13. (Mucoid colonies of Klebsiella) Dr. Emad AbdElhameed Morad

  14. Biochemical reactions: • Ferment glucose, lactose, maltose, mannite, sucrose, salicin with acid and gas production. • Indole -Ve, methyl red -Ve • Voges proskauer’s reaction +Ve, citrate +Ve • H2S –Ve, urease -Ve • Species of klebsiella: • Klebsiella pneumoniae • Klebsiella rhinoscleromatis • Klebsiella ozaenae • Klebsiella oxytoca Dr. Emad AbdElhameed Morad

  15. (Klebsiella)

  16. (Klebsiella pneumoniae in tissue smears from mice) Dr. Emad AbdElhameed Morad

  17. SHIGELLA Dr. Emad AbdElhameed Morad

  18. Morphology: • Gram negative bacilli, non motile, non capsulated. • Cultural characters: • On MacConkey’s medium: pale non lactose fermenting colonies. • On desoxycholate citrate agar medium (DCA): similar to MacConkey’s medium. The stool sample has first to be inoculated in selenite broth for 24 hours followed by subculture on MacConkey’s medium or DCA. Dr. Emad AbdElhameed Morad

  19. Biochemical reactions: • Sh. dysenteriae ferments glucose only with production of acid only. • Other shigella species ferment glucose and mannite with acid production only. • Shigella sonnei is a late lactose fermenter. • All shigella are H2S negative and urease negative. Dr. Emad AbdElhameed Morad

  20. (Shigella dysenteriae) Dr. Emad AbdElhameed Morad

  21. (Shigella flexneri & shigella bodyii) Dr. Emad AbdElhameed Morad

  22. Proteus Dr. Emad AbdElhameed Morad

  23. Morphology: • Gram negative bacilli, highly motile, very pleomorphic. • Cultural characters: • On nutrient agar:colonies with swarming growth in successive waves + Fishyodor. • On MacConkey’s agar:Pale non lactose fermenting colonies. The swarming is inhibited on this medium. Dr. Emad AbdElhameed Morad

  24. (Proteus on nutrient agar) Dr. Emad AbdElhameed Morad

  25. (Proteus on nutrient agar) Dr. Emad AbdElhameed Morad

  26. Biochemical reactions: • Urease +Ve. • H2S +Ve. • Indole +Ve except Pr. mirabilis. (Triple sugar iron (TSI) agar showing H2S production) Dr. Emad AbdElhameed Morad

  27. (Urease test) +Ve -Ve Dr. Emad AbdElhameed Morad

  28. Thank you Dr. Emad AbdElhameed Morad

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