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Salmonella

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Salmonella

  1. 1. Salmonella Enterobacteriaceae 3
  2. 3. <ul><li>Salmonella can cause </li></ul><ul><li>Enteric fever </li></ul><ul><li>Gastroenteritis </li></ul><ul><li>Septicemia with or without focal suppuration </li></ul><ul><li>Carrier state </li></ul>
  3. 4. <ul><li>Salmonella typhi—typhoid fever </li></ul><ul><li>Eberth-Gaffky bacillus/Eberthella typhi </li></ul><ul><li>Practically salmonella has been divided into </li></ul><ul><li>The enteric fever group-typhoid,paratyphoid bacilli </li></ul><ul><li>The food poisoning group </li></ul>
  4. 5. <ul><li>Gram –ve,rods,motile except S gallinarum-pullorum which is always nonmotile </li></ul><ul><li>Aerobic and facultative anerobic </li></ul><ul><li>Grows readily on simple media </li></ul><ul><li>MacConkey and DCC media- colourless </li></ul><ul><li>Wilson and Blair bismuth sulphite medium-jet black colonies </li></ul><ul><li>Selenite F &tetrathionate broth are commnly employed as enrichment media </li></ul>
  5. 6. <ul><li>S typhi- anerogenic </li></ul><ul><li>MR+,VP-ve,C+ </li></ul><ul><li>Typhi- donot grow in Simmon’s citrate medium as they need tryptophan as the gowth factor </li></ul><ul><li>Antigenic structure- </li></ul><ul><li>Flagellar antigen-H </li></ul><ul><li>Somatic antigen O </li></ul><ul><li>Surface antigen-Vi </li></ul>
  6. 8. <ul><li>H antigen- heat labile-strongly immunogenic,induces antibody formation in high titres </li></ul><ul><li>O antigen-phospholipid-Protein-Polysacharide complx—also called Boivin antigen---heat stable </li></ul><ul><li>Vi antigen- analogue to K antigen in the coliforms-surface Polysacharide antigen enveloping the o antigen—heat labile—tend to loss in serial subculture </li></ul><ul><li>Vi polysacharide acts as a virulence factor by inhibiting phogocytosis-resisting complement activation and bacterial lysis </li></ul><ul><li>Poorly immunogenic </li></ul>
  7. 9. <ul><li>Purified Vi vaccine </li></ul><ul><li>Total absence of vi antibody in a proven case of typhoid fever indicates poor Prgns </li></ul><ul><li>Antibody disappears early in convalescence </li></ul><ul><li>Its persistance indicates dvlpmnt of carrier state. </li></ul>
  8. 10. Antigenic variation <ul><li>H-O </li></ul><ul><li>V-W-loss of Vi by sub culture-now agglutinable with O antiserum (W form) </li></ul><ul><li>S-R-by loss of O antigen & virulence </li></ul><ul><li>O antigen </li></ul>
  9. 11. H-O variation <ul><li>Associated with loss of flagella </li></ul><ul><li>Phase Variation-flagellar antigens two types </li></ul><ul><li>Phase 1 –specific for species </li></ul><ul><li>Phase 2 –group specific </li></ul><ul><li>Diphasic-both- </li></ul><ul><li>S.typhi –monophasic </li></ul><ul><li>Phase 1 can b converted to 2 by Craigie’s method </li></ul>
  10. 13. Pathogenicity <ul><li>Enteric Fever- </li></ul><ul><li>Typhoid fever- S. typhi </li></ul><ul><li>Paratyphoid fever – S.paratyphi A,B,C </li></ul>
  11. 15. D/s course <ul><li>IP-7-14 days </li></ul><ul><li>Gradual onset-headache,malaise,anorexia-caoted tongue-abdominal discomfort-constipation/diarrhoea </li></ul><ul><li>Step ladder pyrexia-typical- </li></ul><ul><li>Hepato splenomegaly </li></ul><ul><li>Rose spots-in skin which blanch on pressure </li></ul><ul><li>Complications-perforation,he,circulatory collpase </li></ul><ul><li>Relapse may occur in convalescence-higher if treated early with chloramphenicol </li></ul>
  12. 16. <ul><li>Paratyphoid is milder form </li></ul><ul><li>Leads to frank septicemia with suppurative complications </li></ul><ul><li>Infection with Alkaligens faecalis- similar c/f </li></ul><ul><li>Epidemiology- </li></ul><ul><li>Carriers-3w-3m-Convalescent </li></ul><ul><li>3m-1yr-temporary </li></ul><ul><li>More than 1yr-c/c </li></ul>
  13. 17. Lab d/g <ul><li>Isolation and demonstration of antibodies </li></ul><ul><li>,bacilli demonstration </li></ul><ul><li>Blood culture-diagnostic maximum at first week,rapidly –ve on treating with antibiotics </li></ul>
  14. 19. <ul><li>Cultures should be declared –ve only after incubation period of 10 days </li></ul><ul><li>May use Casteneda’s method- </li></ul>
  15. 20. <ul><li>Feces culture-salmonella are shed in the feces thruout the course of disease,even in carriers </li></ul><ul><li>Imp, if antibiotics hav started-as they r slowly eliminated from gut than from blood </li></ul><ul><li>Feces—MacConkey-/DCA/WB </li></ul><ul><li>Clot culture-blood- allowed to clot—serum is used for widal—clot to bile broth—high rate of isolation as bactericidal action of serum is less </li></ul><ul><li>Urine culture-,Bile culture,rose spots,csf,sputum –less imp </li></ul>
  16. 21. Widal reaction
  17. 22. <ul><li>In H- +ve –loose,cotton woolly clumps </li></ul><ul><li>O +ve –disc like pattern at the bottom of the tube </li></ul><ul><li>Result- </li></ul><ul><li>Ab appear by end of first week- ifearly –ve—titre inc steadly till 3/4 th week and it decline after </li></ul><ul><li>Test more samples </li></ul><ul><li>1/100 or more for O & 1/200 or more for H is sigfig </li></ul><ul><li>Ab-may be due to proir d/s,immunisation,carriers </li></ul>
  18. 23. <ul><li>H agglutinins persist longer than O </li></ul><ul><li>If immunised with TAB, Ab against both ,in natural infection only causative org. </li></ul><ul><li>t/ted case –poor Ab titre </li></ul><ul><li>Other serological methods-ELISA,CIE </li></ul><ul><li>Staphylococcal co-agglutination test-in early phase of d/s-S.aureus-/Cowan 1 strain-which contains Protein A is stabilised by formaldehyde and coated with S typhi antibody---1%---with serum –visible agglutination in 2 min </li></ul><ul><li>Not paositive after first week </li></ul>
  19. 24. D/g of carriers <ul><li>Islation from faeces,bile,urine cultures </li></ul><ul><li>Widal is no value in endemic states </li></ul><ul><li>Demo of Vi agglutinins is imp </li></ul><ul><li>Sewer-swab technique-Gauze pads in sewers and drains -cultured </li></ul>
  20. 25. Px <ul><li>TAB vaccine-with S,typhi,S.paratyphi A & B </li></ul><ul><li>Typhi-1000 million </li></ul><ul><li>A & B- 750 million each/ml---killed by heating at 50-60C—preserved in phenol </li></ul><ul><li>In india- divalant Typhoid-paratyphoid A is given </li></ul><ul><li>Two doses—0.5ml s/c at an intervel of 4-6 weeks </li></ul><ul><li>0.1ml I/D </li></ul><ul><li>Newer vaccines </li></ul><ul><li>Typhoral-live oral vaccine </li></ul><ul><li>Typhin-Vi---injectable </li></ul>
  21. 26. T/t <ul><li>Chloramphenicol,tetracycline, streptomycin </li></ul><ul><li>Ampicilline, Aox,cotrimoxazole </li></ul>
  22. 27. Salmonella Gastroenteritis <ul><li>Enterocolitis/food poisoning </li></ul><ul><li>-zoonotic-source of infection –animal products </li></ul><ul><li>Caused by any salmonella except typhi </li></ul><ul><li>Short IP-24 hrs-diarrhoea, vomiting, abdominal pain,fever---loose stools </li></ul><ul><li>Subsides in 2-4 days </li></ul><ul><li>T/t –if uncomplicated-symptomatic- antibiotics not neede </li></ul>

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