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Enteric Bacteria

Enterobacteriaceae Gram negative bacilli ferment glucose oxidase (-). Enteric Bacteria. Escherichia Enterobacter Klebsiella Serratia Citrobacter. Proteus (usually nonpathogenic) Shigella Salmonella. Normal Flora vs. Pathogens. COLIFORMS. NON-COLIFORMS. Lactose Fermentation?. yes.

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Enteric Bacteria

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  1. EnterobacteriaceaeGram negative bacilli ferment glucose oxidase (-) Enteric Bacteria

  2. Escherichia Enterobacter Klebsiella Serratia Citrobacter Proteus (usually nonpathogenic) Shigella Salmonella Normal Flora vs. Pathogens COLIFORMS NON-COLIFORMS

  3. Lactose Fermentation? yes no normal flora pathogen Enterobacteriaceae: Coliform or non-coliform?

  4. Shigella dysenteriae Salmonella typhimurium http://www.mpg.de/news02/news0209.htm http://www.co.boulder.co.us/health/hpe/FactSheets/salmonella.htm Obligate Enteric Pathogens

  5. http://www.quarks.de/milch/06.htm Escherichia coli O157:H7 http://www.jfha.or.jp/saikin/shashin/o157.html

  6. Eosin Methylene Blue (EMB) Agar E. coli http://www.cat.cc.md.us/courses/bio141/labmanua/lab3/embeacolony.html E. aerogenes S. Typhimurium P. aeruginosa

  7. Electrons from carbos(or other food source) Electron carriers NO3-, SO42-,CO2 O2(Aerobic respiration) Pyruvic acid (Anaerobic respiration) (Fermentation) Black, J.G (2002) Microbiology: Principles and Explorations 5th Ed. Fig. 5.21

  8. Fermentation Pathways Glucose(or other sugar) Butyric acid, butanol,isopropyl alcohol,acetone & CO2 Propionic acid,acetic acid,& CO2 Pyruvic acid Butyric-butylicfermentation Propionic fermentation Black, J.G (2002) Microbiology: Principles and Explorations 5th Ed. Fig. 5.11 Butanediol& CO2 Ethyl alcohol& CO2 Acetic aid,succinic acid,ethyl alcohol, CO2 & H2 Butanediolfermentation Lactic acid Alcoholic fermentation Mixed-acidfermentation Homolactic acidfermentation

  9. API 20 E Test Strips

  10. Sugar Fermentation • Melibiose • Amygdalin • Arabinose • Sorbitol • Rhamnose • Sucrose • Glucose • Mannitol • Inositol Must use additional reagents to GLU to see result

  11. Catabolic Enzymes • Beta galactosidase • Arginine dehydrogenase • Lysine decarboxylase • Ornithine decarboxylase

  12. Citrate Utilization blue indicates citrate utilization and alkaline by-products

  13. Sulfur Reduction CH2 SH CH3 cysteine desulfurase H2S COOH + CH H2N CH COOH H2N (hydrogen sulfide) (alanine) (cysteine + sodium thiosulfate) Fe++ (in medium) FeS (iron sulfide) (black ppt)

  14. H2N NH2 urease 2 NH3 + CO2 C (ammonia) O (urea) Nitrogen Fixing

  15. H2O + H2N Tryptophan deaminase (indole) COOH CH2 CH N (tryptophan) N + NH3 (ammonia) + CH3 C = O (pyruvic acid) COOH Tryptophan - Indole Reaction Must add Kovac’s reagent to see result

  16. Acetoin Reaction Must add KOH and α-naphthol to see result

  17. Gelatinase(s) • Large group of proteolytic enzymes • Degrade collagen • Metalloproteases • Virulence factors

  18. API Test : Sample Prep • Pick ONE SINGLE colony (no agar) • Emulsify colony by pipetting up and down in small amount of liquid

  19. Inoculating API Test Strips Overlay with mineral oil: • ADH, LDC, ODC, H2S, & URE • Fill tubules & cupules: • CIT, VP & GEL • (see pg. 223 in lab manual)

  20. Reading API Test Strips • Use chart on pp. 225-8 in manual to determine results • Record + or – results for each test • Add + results in oval below tests • Record 7-digit code and look up ID

  21. Why did we inoculate withPseudomonas aeruginosa?

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