ENTEROBACTERIACEAE

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)

13. klebsiella Dr. Emad AbdElhameed Morad

14. 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

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

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

17. 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

18. (Klebsiella)

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

20. SHIGELLA Dr. Emad AbdElhameed Morad

21. 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

22. 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

23. (Shigella dysenteriae) Dr. Emad AbdElhameed Morad

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

25. Proteus Dr. Emad AbdElhameed Morad

26. 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

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

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

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

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

31. Thank you Dr. Emad AbdElhameed Morad