Lectures 15-17-Escherichia coli, Shigella, Salmonella

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Lectures 15-17-Escherichia coli, Shigella, Salmonella

  1. 1. ENTEROBACTERIACEAE Prof. Khalifa Sifaw Ghenghesh
  2. 2. • • • • Gram-negative rods Facultative anaerobes Oxidase-negative Most members are motile
  3. 3. • Gastrointestinal diseases (Diarrhoea and Dysentery) – – – – Escherichia coli (Lac+) Salmonella (Lac-) Shigella (Lac-) Yersinia entercolitica (Lac-)
  4. 4. Salmonella E. coli
  5. 5. • Opportunistic diseases – – – – • • • • • • • • • septicemia, pneumonia, meningitis urinary tract infections Citrobacter Enterobacter Escherichia Hafnia Klebsiella Morganella Proteus Providencia Serratia
  6. 6. IDENTIFICATION • In Stool: – E. coli • lactose positive • not usually identified • Common in healthy intestine – Shigella, Salmonella,Yersinia • lactose negative • identified • Other sites: – identified biochemically
  7. 7. SEROTYPING • Reference laboratory: – antigens • O (lipopolysaccharide) • H (flagellar) • K (capsular)
  8. 8. Escherichia coli
  9. 9. • Enteropathogenic E. coli (EPEC): – Adhere to surface of mucosal cells inducing dramatic alteration on microvilli and the rearrangement of the host cell actin cytoskeleton. – Adhesion is medicated by two genes: • A Plasmid-encoded gene (bfpA), responsible for the formation of the bundle forming pilus. • A chromosomal-mediated gene (eae) coding for the adhesion intimin. • • • • • fever diarrhea vomiting nausea non-bloody stools
  10. 10. • Enterotoxigenic E. coli (ETEC): – Cholera-like diarrhoea – milder – Travellers diarrhoea • Heat labile toxin (LT) – – – – like choleragen (Cholera toxin) activate enterocyte adenyl cyclase cyclic AMP chloride and water secretion >>Diarrhea • Heat stable toxin (ST) – activate enterocyte guanylate cyclase – cyclic GMP – Chloride and water secretion >> Diarrhea
  11. 11. • Enteroinvasive E. coli (EIEC): – Dysentery – resembles shigellosis
  12. 12. • Enterohemorrhagic E. coli (EHEC): – Usually O157:H7 – Meat • Hemorrhagic – bloody, copious diarrhea – few leukocytes – afebrile • Hemolytic-uremic syndrome – hemolytic anemia – thrombocytopenia (low platelets) – kidney failure • Vero toxin (Shiga-like): – 2 toxins: SLTI and SLTII (coded by sxt1 and sxt2)
  13. 13. TREATMENT • Gastrointestinal disease: – Fluid replacement – Antibiotics • not used usually unless systemic –e.g. hemolytic-uremia syndrome • UTIs: – Antibiotic Sensitivity Is Necessary.
  14. 14. Resistance of Escherichia coli isolated from urinary tract infections in Benghazi to antibiotics. ------------------------------------------------------------------------------------Hospital Community Antibiotic acquired acquired (n=62) (n=148) ------------------------------------------------------------------------------------Ampicillin 52(84)* 111(75) Carbenicillin 53(85) 117(79) Cephaloridine 22(35) 53(36) Chloramphenicol 37(60) 67(45) Gentamicin 19(31) 27(18) Nalidixic acid 3(5) 15(10) Nitrofurantoin 4(6) 10(7) Tetracycline 45(73) 121(82) Trimethoprim 52(84) 120(81) sulphamethoxazole *(%) -------------------------------------------------------------------------------------
  15. 15. Shigella
  16. 16. • Bacillary Dysentery • Shigellosis – bloody faeces – intestinal pain – pus • • • • • 4 Major O Antigenic Groups: Serogroup A = Sh. dysenteriae Serogroup B = Sh. flexneri Serogroup C = Sh. boydii Serogroup D = Sh. sonnei • No H-Antigens.
  17. 17. Shiga Toxin • enterotoxic • cytotoxic • inhibits protein synthesis – lysing 28S rRNA
  18. 18. • The Organism Survive the Passage Through the GIT. >> Due to O Antigen • Attach to Colonic Cells. • Penetrate the Epithelial Cells. • Multiply Inside • Pass to Another Cell. >> >> "Invasiveness" "Inflamation, Cell Death, Ulceration, Impaired Colonic Fluid Absorbtion and a Discharge of Blood, Mucus and Pus"
  19. 19. • Man only "reservoir" • Mostly young children – fecal to oral contact – children to adults • Transmitted by adult food handlers – unwashed hands
  20. 20. Treating Shigellosis • Manage dehydration • Patients respond to antibiotics – disease duration diminished
  21. 21. CONTROL – Adequate Sanitization. – Detection and Treatment of Carriers. – Carriers Should Not Be Allowed to Handle Food. – Proper Sewage Disposal and Chlorination of Water. – FLIES >>>>>>>>>>>>>>>>
  22. 22. Information about Libyan children with diarrhea and their Shigella isolates Patient Sex Age (Mo) Month of Length of Episode Species and occurrence diarrhea per day serotype of (days) Shigella -------------------------------------------------------------------------------------------------------1. F 11 Sep 1 5 S. sonnei 2. F 30 Sep 2 3 S. flexneri type2 3. M 27 Oct 1 6 S. sonnei 4. F 18 Oct 1 8 S. flexneri type2 5. F 36 Oct 2 5-7 S. flexneri type2 6. M 7 Dec 7 7-8 S. flexneri type1 7. M 7 Apr 1 10 S. flexneri type2 8. M 13 Jun 10 6-7 S. flexneri type3 9. M 32 Jul 1 4 S. sonnei
  23. 23. Information about Libyan children with diarrhea and their Shigella isolates Patient Faeces with Mucus Blood Presence of Fever Vomiting Species and serotype of Shigella --------------------------------------------------------------------------------------------------------------------1. + + --S. sonnei 2. ----S. flexneri type2 3. --+ -S. sonnei 4. ----S. flexneri type2 5. + + + -S. flexneri type2 6. --+ -S. flexneri type1 7. + + + + S. flexneri type2 8. + + + + S. flexneri type3 9. + + + + S. sonnei
  24. 24. Salmonella
  25. 25. • More than 2000 antigenic types (Serotypes). – Salmonella Typhi – Salm. Enteritidis – Salm. Cholera-suis – Salm. Typhimurium • Genetically single species – Salmonella enterica • Salm. enterica serotype Typhi ANTIGENIC STRUCTURE: – O & H Antigens >>> Serotyping. – Vi-Antigen (protective) >>> Salm. Typhi.
  26. 26. CLINICAL INFECTION AND PATHOGENSIS 1. S. Typhi, S. Paratyphi A and B: – Gastroenteritis, bacteremia and typhoid fever. – Typhoid Fever (Enteric fever): • Fever, headache, diarrhoea, and abdominal pain. – Human Carriers Are the Only Source of Infection. – Transmission: • contaminated food • water supply • poor sanitary conditions – Mortality Rate: – Relapse:
  27. 27. 2. S. Enteritidis, S. Typhimurium, etc.. – Salmonellosis: • Self-limiting gastroenteritis with fever for <2 days and diarrhoea < 7 days. – Source: • poultry, eggs • no human reservoir – Transmission: – Pets:
  28. 28. • TREARMENT: – Supportive Therapy and Maintaining Fluid and Electrolyte Balance. – Enteric Fever or Septicaemia: • Antibiotics – essential – Carriers of Salm. typhi: • CONTROL: – Carriers: – Food Cooked Properly – Water Standards Be Observed.
  29. 29. Salmonella Serotypes Isolated from Diarrhoeic Faeces in Tripoli (1975-1980) – S. Wien – S. Muenchen – S. Typhimurium Salmonella Serotypes Isolated from Children with Diarrhoea in Tripoli (1992-1993) – S. Saintpaul – S. Muenchen Salmonella Serotypes Isolated from Children with Diarrhoea in Zliten (2000-2001) – S. Heidelberg – S. Enteritidis
  30. 30. Reistance of Salmonella species isolated from children with diarrhoea in Zliten (2000-2001) to antibiotics ________________________________________________ Antibiotic No. (%) resistant: (n=23) --------------------------------------------------------------------------------Ampicillin 23 (100) Amoxicillin+calvulanic acid 22 (95.7) Cefoxitin 20 (87) Gentamicin 18 (78.3) Doxycycline 21 (91.3) Chloramphenicol 22 (95.7) Nalidixic acid 1 (4.3) Norfloxacin 0 (0.0) Trimethoprim-sulphamehtoxazole 1 (4.3) ________________________________________________
  31. 31. • Department e-mail = dmi.ly • Khalifa Sifaw Ghenghesh e-mail = ghenghesh_micro@yahoo.com

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