Enterobacteriaceae

3,632 views

Published on

Published in: Health & Medicine, Technology

Enterobacteriaceae

  1. 1. Enterobacteriaceae Coliforms-proteus Shigella Salmonella
  2. 2. <ul><li>Aerobic </li></ul><ul><li>Non- sporing, </li></ul><ul><li>Non-acid fast, </li></ul><ul><li>G-ve bacilli </li></ul><ul><li>Intestinal flora </li></ul>
  3. 3. Old classification Salmonella, Shigeela Non lactose fermenters Shigella sonnei/Paracolons Late lactose fermenters Escheria,Klebsiella Lactose fermenters
  4. 4. New classification Erwinia Erwinieae Tribe 4 Proteus,Morgenella.Providencia Proteeae Tribe 3 Klebsiella,Enterobacter,Hafnia,Serratia Klebsielleae Tribe 2 Escherichia,Edwardsiella,Citrobacter,Salmonella,Shigella Escherichiae Tribe 1
  5. 5. E.coli <ul><li>Motile-peritrichate flagella,aerobe & facultative anerobe </li></ul><ul><li>Good growth in ordinary media </li></ul><ul><li>Culture-fresh isolation-S/smooth form-easily emulsifiable in saline </li></ul><ul><li>Rough forms-/R forms-irregular,dull surface-autoagglutinable in saline </li></ul><ul><li>S-R variation occurs due to subculture-loss of surface antigens and virulence </li></ul>
  6. 7. <ul><li>MacConkey’s agar- bright pink- </li></ul><ul><li>IMViC ++--(Indole ,Methyl red,Voges-Proskauer and citrate utilisation tests </li></ul>
  7. 9. Antigenic structure
  8. 10. <ul><li>Somatic antigen O, </li></ul><ul><li>capsular antigen K-1 and 2,(1resp for neonatal meningitis..) </li></ul><ul><li>Flagellar antigen H </li></ul><ul><li>Toxins-exo-hemolysisns and enterotoxins </li></ul><ul><li>Enterotoxins-heat labile(LT)—heat stable(ST)—verotoxin (VT)/Shiga like toxin/SLT </li></ul>
  9. 12. <ul><li>ST- two types –A &B- </li></ul><ul><li>A-activate cGMP---fluid accumilation </li></ul><ul><li>B-activate cGMP/cAMP </li></ul><ul><li>VT-similar to Shigella dysenertae Type 1 toxin- </li></ul><ul><li>VT A & B subunits-phge encoded </li></ul><ul><li>Fimbrae-imp in UTI-P fimbriae binds specifically to the P blood group substance on RBC and uroepithelial cells </li></ul>
  10. 13. Clinical infections <ul><li>UTI </li></ul><ul><li>Diarrhea </li></ul><ul><li>Pyogenic infections </li></ul><ul><li>Septicemia </li></ul>
  11. 14. Urinary Tract infection <ul><li>Majority of naturally occuring UTI </li></ul><ul><li>By those found in feces-O grops-1,2,4,6,7. </li></ul><ul><li>Infection may be precipitated by obstruction,prostatic enlargement,calculi,pregnancy </li></ul><ul><li>Asyymptomatic bacteriuria-5-7% of pregnant-UTI without no symptoms----can lead to pyelonephritis,hypertension,premature births,death of fetus </li></ul>
  12. 15. <ul><li>Significant bacteriuria-collect mid tream sample of urine—sterile wide mouthed container---lab without delay </li></ul><ul><li>In presence of Active infection->= 1 lakh bacteria /ml----significant bacteriuria </li></ul><ul><li>Less than 10’000-not sig </li></ul><ul><li>Between equivocal </li></ul><ul><li>Semi quantitative-one loopful of urine in non-inhibitery medium & other in indicator medium </li></ul><ul><li>Former gives quantitative measurement of bacteriuria-later presumptive diagnosis </li></ul>
  13. 16. <ul><li>Antibiotics sensitivity is very imp-done using urine sample as inocula </li></ul><ul><li>Screening tests for presmptive d/g of significant bacteriuria </li></ul><ul><li>Griess Nitrate test-+ve –Nitrate reducing b. </li></ul><ul><li>Catalase test-+-bacteriuria and hematuria </li></ul><ul><li>Triphenyl Tetrazolium chloride test/TTC – </li></ul><ul><li>Microscopic demo </li></ul><ul><li>Glucose test paper </li></ul><ul><li>Dip slide culture methods </li></ul><ul><li>The antibody coated bacteria test-to find site of infection-specific antibodies are present in urine only whn the kidnes are affected,otherwise inf. In bladder </li></ul>
  14. 17. <ul><li>Diarrheagenic E coli </li></ul><ul><li>EP-pathogenic </li></ul><ul><li>ET-toxigenic </li></ul><ul><li>EH-haemorrhagic </li></ul><ul><li>EA-aggregative </li></ul><ul><li>EI-invasive </li></ul>Diarrhea
  15. 18. EPEC <ul><li>Infants </li></ul><ul><li>Do not produce enterotoxin,not invasive </li></ul><ul><li>Ininfantile enteritis-bacilli are seen adherent to the mucosa of SI,to cup like projections of enterocyte membrane---disruption of brush border microvilli </li></ul>
  16. 19. ETEC <ul><li>Endemic diarrhoea </li></ul><ul><li>Mild watery to fatal d/s </li></ul><ul><li>Traveller’s diarrhoea- </li></ul><ul><li>Entero toxins produced-LT/ST/both </li></ul><ul><li>First adhesion by fimbrial / Colonisation factor antigens(1,2,3,4,) </li></ul><ul><li>D/g- ligated rabbit ilial loop,LT(invitro methods-tissue culture) </li></ul>
  17. 20. EIEC <ul><li>Resembles shigella-nonmotile,O antigen cross reactivity </li></ul><ul><li>Enter invasive-capacity to invade interstitial epithelial cellsinvivo, penetrate HeLa cells </li></ul><ul><li>C/f-mild diarrhoea to frank dysentery(resmble shigellosis) </li></ul><ul><li>Children and adults </li></ul><ul><li>Lab dig- Sereny test-instillation of a suspension of freshly isolated EIEC /shigella—g.pig eyes-mucopurulent conjuntivitis </li></ul><ul><li>Cell penetration of HeLa/HEP2-d/gtic </li></ul><ul><li>Ability to penetrate-plasmid- </li></ul><ul><li>Plasmid codes for OM antigens called VMA(Virulence Marker Antigens) which can be detected by ELISA </li></ul>
  18. 21. EHEC/Shigatoxigenic/Verotoxigenic <ul><li>Producing VT—mild diarrhoea to fatal hemorrhagic colitis and hemorrhagic uraemic syndrome/HUS-young children and yelderly </li></ul><ul><li>Primary target of VT is vascular endothelial cells </li></ul><ul><li>In HUS_ch. Renal lesion-capillary micro angiopathy </li></ul><ul><li>Source –contaminated human/animal feces </li></ul><ul><li>Food poisoning in veg-salad vegetables </li></ul><ul><li>Lab d/g-demo.,VT—DNA probes for VT1 and VT2 genes –more sensitive- </li></ul>
  19. 22. EAEC <ul><li>Appear aggregated in stacked brick formaation on hep 2 cells </li></ul><ul><li>Persisitant diarr. </li></ul>
  20. 23. Septicaemia <ul><li>Blood stream invasion-shock </li></ul><ul><li>Systemic Inflammatory Response Syndrome(SIRS) </li></ul>
  21. 24. Shigella
  22. 25. Imp species <ul><li>Shigella dysenteriae---Mannitol non fermenting </li></ul><ul><li>Shigella sonnei-mannitol fermenting </li></ul><ul><li>Shigella boydii---mannitol fermenting </li></ul><ul><li>Shigella flexneri---mannitol fermenting </li></ul>
  23. 26. <ul><li>Dysentery-frequent passage of blood stained mucopurulent stools </li></ul><ul><li>Bacillary and amoebic </li></ul><ul><li>MacConkey agar colourless-except shigella sonnei-pink </li></ul><ul><li>Deoxycholate citrate agar-selective medium </li></ul><ul><li>Growth is inhibited in Wilson –Blair Bismuth sulphite medium </li></ul><ul><li>Fermentation of mannitol is imp. In classification-by SH.flexneri,boydii,sonnei </li></ul><ul><li>Not by Sh.dysenteriae </li></ul>
  24. 27. <ul><li>Antigens-O,K, </li></ul><ul><li>Classification </li></ul><ul><li>Sh.dysenteriae-mannitol non fermenting-indole –ve,only member that is always catalase +ve </li></ul><ul><li>Toxin –Shiga toxin by Sh.dysenteriae type 1-earliest eg. Of an exotoxin produced by Gram –ve bacillus </li></ul><ul><li>Neuro,entero,cyto toxicity </li></ul><ul><li>Shiga toxin has A and B units </li></ul><ul><li>A-A1 & A2-A1 inactivates host cell 60S ribosomes </li></ul>
  25. 28. <ul><li>Sh.sonnei-catalase –ve,late lactose fermenters </li></ul><ul><li>Mildest of the bacillary dysentery </li></ul><ul><li>MC shigellosis in developed countries </li></ul>
  26. 29. Pathogenicity <ul><li>Shigella causes bacillary dysentery-infestion occurs by ingestion </li></ul><ul><li>Low minimal infective dose-10-100 bacilli only-as they survive gastric acidity than other enterobacteria </li></ul><ul><li>Pathogenic mech. Similar to EIEC </li></ul>
  27. 31. <ul><li>Invasive property of bacillus can be demonstrated by its ability to penetrate cultured HeLa/Hep2 cells </li></ul><ul><li>Invasive property is related to the presence in the bacillus of large plasmids coding OMP responsible for cell penrtration—these proteins are called VMAL(Virulence Marker Antigens) </li></ul><ul><li>Detection of VMA by ELISA serves as a virulence test for Shigella,as for EIEC </li></ul>
  28. 32. Bacillary dysentery <ul><li>Ingestion----IP-1-7days,usually 48hrs </li></ul><ul><li>Frequent passage of loose,scanty feces containing blood and mucus,along with abdominal cramps and tenesmus </li></ul><ul><li>Cx-Sh.dysenteriae-type 1-arthritis,toxic neuritis,conjunctivitis,parotitis,intussusception </li></ul><ul><li>HUS </li></ul><ul><li>T/t- based on sensitivity </li></ul>

×