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Enterobacteriaceae

Enterobacteriaceae

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Enterobacteriaceae

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  1. Enterobacteriaceae

  2. Escherichia • E. coli • Theodore Escherich in 1885 • most significant species • common isolate from the colon flora • black/green metallic sheen on EMB • posesses O (Shigella), H and K (Group B N. meningitidis) Ag. • other species: blattae, vulneris, fergusonii, hermanii

  3. Diarrheal Infections* EPEC – enteropathogenicE. coli - infantile diarrhea - watery stool w/ mucus but w/o blood* ETEC – enterotoxigenicE. coli - traveller’s diarrhea - infective dose of 106- produce LT and ST toxin (hypersecretion) - non-bloody, watery diarrhea with abdominal cramps and low grade fever

  4. Diarrheal Infections • EIEC – entero invasive E. coli • cause dysentery ( direct penetration, invasion and destruction of the intestinal mucosa) – similar with dysentery • scanty stool with pus, mucus and blood • Sereny test – determines the invasiveness of EIEC • (+) result – keratoconjunctivitis in guinea pig

  5. Diarrheal Infections EAEC – enteroadherent E. coli cause diarrhea by adhering to the mucosal surface of intestine. watery diarrhea, vomiting and dehydration EHEC – enterohemorrhagic E. coli or VTEC (E. coli 0157:H7) Hemorrhagic diarrhea, colitis and hemolytic uremic syndrome (HUS) Bloody diarrhea and crampy abdominal pain

  6. Microscopic Exam E. coli

  7. Growth on Eosin Methylene Blue (EMB)

  8. Other Infections • Septicemia and Meningitis • accounts for 40% of neonatal meningitis • Urinary Tract Infections • 90% of cases of UTI

  9. Shigella 4 subgroups Fermentation of lactose mannitol ODC ONPG A S. dysenteriaenegnegnegneg B S. flexnerinegposnegneg C S. boydiinegposnegneg D S. sonneinegpospospos

  10. Shigellosis or Bacillary Dysentery watery diarrhea bloody stool with WBC’s & mucus fecal-oral route (human – only known reservoir) self-limiting but highly communicable bec. of low infective dose (200 bacilli) Gay bowel syndrome (S. flexneri) Clinical Infections - Shigella

  11. Shigella on CM

  12. Edwardsiella • Edwardsiella • tarda (human pathogen – bacteremia and wound infection) • hoshinae (snakes, birds and water) • ictaluri (enteric septicemia in fish)

  13. Salmonella • Salmonella • 2200 species • 3 common species (cholerasuis, typhi, enteritidis) • 7 subgroups (with Arizona as groups 3A & 3B) • Virulence factors • O, H and Vi antigens

  14. Salmonella • Gram negative rods • Do not ferment lactose • Produce H2S • Major cause of food poisoning in the U.S. • Cause intestinal infections (enterocolitis); enteric fevers (typhoid fever); and systemic infections (septicemia) • Chickens are a major reservoir for this bacteria • Identification on basis of antigens (O, H, Vi)

  15. Salmonella - pathogenesis Enterocolitis: invasion of epithelial cells of intestines infectious dose (ID50) ~ 100,000 organisms infection of gut - inflammation and diarrhea, self correcting Typhoid: starts in small intestine: enters and multiplies in mononuclear cells; spreads to liver, gallbladder, spleen. Leads to bacteremia with onset of fever. carrier state - organisms excreted in feces Septicemia: minority of infections, usually in patients with underlying disorder

  16. S. enteritidis S. typhimurium S. typhi

  17. Salmonella

  18. Citrobacter • resembles Salmonella but are ONPG (+) & LDC (-) • Citrobacter species • freundii(UTI, pneumonia, intraabdominal abscess) • diversus (neonatal meningitis) • amalonaticus (extraintestinal infections) C. freundii S. diversus H2S + - Indole - + KCN + -

  19. Klebsiella Klebsiella-Enterobacter-Serratia-Hafnia K. pneumoniae >Friedlander’s bacilli (encapsulated and mucoid) > (+) String test K. oxytoca – similar w/ K. pneumoniae except for its indole production K. ozanae– from nasal secretions K. rhinoschleromatis– rhinoscleromatis (infection of nasal cavity with intense swelling and malformation of the entire face and neck)

  20. Klebsiella

  21. Enterobacter • species: habitat: soil, water, dairy products • normal flora of the git of animals & humans • motile, ODC & ONPG (+)

  22. Enterobacter LDC ADH ODC Urease Yellow pigment • E. cloacae - + + V - • E. aerogenes + - + - - • E. gergoviae + - + + - • E. sakazakii - + + - + • E. taylorae - + + - -

  23. Enterobacter

  24. Serratia • opportunistic pathogens • DNAse, lipase, gelatinase • S. marcescens • S. liquefaciens • S. rubidaea • S. oderifera

  25. Serratia

  26. Hafnia • Hafniaalvei • 2 biotypes • H. alvei • H. alvei Biotype 1 – associated in breweries • delayed (+) citrate reaction is its major characteristic

  27. Proteus • rapid urease producers • Swarming, burned chocolate odor P. mirabilis P. vulgaris Indole - + ODC + - Fermentation • Maltose - + • Xylose + + • Salicin - + Chloramphenicol S R

  28. Proteus mirabilis Swarming pehomenon Proteus

  29. Morganella • Formerl known as Proteus • M. morganii – only specie • UTI’s and wound infections

  30. Providencia Providencia ( 4 species – P. alcalifaciens, P. rustigianii) P. rettgeri P. stuartii Urease + - Citrate + +

  31. Yersinia • 11 species • Y. pestis (plague) – bipolar staining (wayson) • Bubonic – bite of infected flea • Pneumonic • Prefered growth at 25 deg C • Y. enterocolitica (acute enteritis – appendictis like) • Pig, cats and dogs • Cold enrichment • Motile at RT • Y. pseudotuberculosis • Pathogen in animals (turkey, geese, doves, farm and domestic animals)

  32. Agent of bubonic plague, pneumonic and septicemic plagues • Bubonic plague contracted via flea bites • Y. pestis sheds capsule while growing in invertebrate host. • In humans most of the microbe is taken up and killed by PMN cells • Some organisms taken up by Macrophages which can’t kill pestis. • Organism multiples in Mac and resynthesizes capsule • Organism kills Mac and is released into extracellular environment. • The encapsulated microbe resists phagocytosis and spreads to lymph nodes which become swollen, and hemorrhagic giving the black buboes characteristic of the disease. • Microbe rapidly spreads through blood, liver, spleen, lung giving rise to highly contagious pneumonia (highly fatal).

  33. Yersinia pestis Yersinia Safety pin appearance

  34. Erwinia • Plant pathogens • Fail to grow in CM used in the isolation of enteric bacilli

  35. End of Presentation