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    Salmonella Salmonella Presentation Transcript

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