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Bacteriological diagnosis of enteric fever consists of: Isolation of bacilli Demonstration of antibodies Demonstration o

LAB DIAGNOSIS. Bacteriological diagnosis of enteric fever consists of: Isolation of bacilli Demonstration of antibodies Demonstration of circulating antigen Other laboratory test. ISOLATION OF BACILLI. Specimens:Blood Urine Faeces

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Bacteriological diagnosis of enteric fever consists of: Isolation of bacilli Demonstration of antibodies Demonstration o

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  1. LAB DIAGNOSIS Bacteriological diagnosis of enteric fever consists of: • Isolation of bacilli • Demonstration of antibodies • Demonstration of circulating antigen • Other laboratory test

  2. ISOLATION OF BACILLI Specimens:Blood Urine Faeces Aspirated duodenal fluid,etc..

  3. BLOOD CULTURE Positive in, 90%-1st week 75%-2nd week 60% -3rd week 25%-till the subsidence of pyrexia

  4. contd… • Blood collected is cultured on glucose &taurocholate broth.. • We must take care of contamination with external environment • Dilute or add sodium polyanethol sulphonate • Incubated at 37degrees • Castaneda’s method is also practiced

  5. CLOT CULTURE • Aseptically collected blood is allowed to clot • Serum-used in widal test • Blood clot-added to bile broth containing streptokinase(causes lysis of blood clot)

  6. FAECES CULTURE • Salmonella are shed in the faeces through out the disease even in convalescence • Antibiotic does not eliminate the bacilli from the GUT as it does 4m BLOOD

  7. CULTURE • On McConkey agar & DCA media-Paleyellowcolonies • On wilson blair media • S.typhi-black colinies(with metallic sheen) • S.paratyphi-green colonies(due to absense of hydrogen sulphide • Enrichment media are incubated and then subcultured on selective media

  8. On mac conkey agar

  9. S.typhi S.paratyhi WILSON BLAIR MEDIA

  10. URINE CULTURE • Not much more imp as blood & faeces culture • Positive only in 2nd& 3 rd weekes • Urine sample is centrifuged &inoculated into enrichment &selective media

  11. Other specimens • Bone marrow • Bile • Rose spots discharge • Pus • Suppurative lesions • Csf&sputum At autopsy-gallbladder,liver,spleen & mesenteric lymphnodes

  12. SLIDE AGGLUTINATION TEST • A loopful ofgrowth from a nutrientagarisemulsified in two drops ofsaline on amicroscopic slide

  13. 1st emulsion-control To show the strain not agglutable 2nd emulsion-test Polyvalent “o”&polyvalent “H”are added Positive-presence of salmonella sps Then monovalent anti sera belongs to S.typhi are added If the isolate is fresh agglutination is done with “vi”antisera,alternatively the bacterial suspension is boiled for 20 mins which removes the vi antigens CONTD..

  14. Non typhoid Salmonella sproducing acid and gas 4m carboydrates is tested for “O” &”H”antisera for groups A,B,C….. • NATIONAL SALMONELLAREFERENCE CENTRE at the CRI • INDIAN VETERINARY RESEARCH INSTITUTE,Izatnagar

  15. SLIDE AGGLUTINATION

  16. DEMONSTRATION OF ANTIBODIES WIDALTEST PROCEDURE: DREYER”S TUBE - H agglitination FELIXTUBE - O agglutination 28 test tubes are arranged in 4 rows each row containing 7 tubes and named as 1st row-To 2nd row-Th 3rd row-Ah 4th row-Ao

  17. Contd…. • To &Th for the detection of S.typhi • Ao &Ah for the detection of S.paratyphi • Of the 7 tubes one acts as control &remaining tubes as test

  18. Contd…. • A low dilution of patient serum is 1:20 to 1:640 • All tubes in rack are incubated at 37 degrees for 24hrs&results are read after over night refrigeration at 4 degrees

  19. Contd…. • Positive H agglutination-formation of loose,cotton wooly clumps • Positive O agglutination-disc like pattern at the bottom of tube • In both supernatent fluid is clear • Paratyphoid O antigens are not employed because theycross react with typhoid O antigen due to their haring of factor 12…

  20. RESULT

  21. INTERPRETATION • Titre depends on stage of disease • On immunistion with TAB vaccine individuals may show high titres of antibody • In non immunised individuals high titre of H agglutinin indicates entericfever or latent infection • ANAMNESTIC REATION: • In carriers

  22. DEMONSTRATION OF ANTIGENS • Ag present in blood and urine • PREPARATION OF ANTIGENS: S.aureus is stabilised with fprmaldehyde &then coated with S.typhi antibody • PROCEDURE: Patients serum is mixed with staphylococcal cells Positive-1st week.. • CIEP,ELISA

  23. OTHER…. • TLC • DIAZO TEST IN URINE • TLC-leucopenia with a relative lymphocytosis is found • DIAZO TEST: • Positive -in b/w 5th &14th weeks

  24. DIAGNOSIS….. • SPECIMENS: stool,urine,bile,duodenaldrainage Antibody ti vi antigen in serum is clamied indicate thecarrier state Convalescent &healthy carriers shed bacilli in faeces from 2 months to 1 yr… Where as chronic carriers shed bacilli in faeces from 1yr to several years

  25. BACTERIOPHAGE TYPING: • BIO TYPING • PLASMID TYPING

  26. TREATMENT • ANTOIBIOTICS: • chloramphenicol • ampicillin • furazolidone • cotrimoxazole • For multiresistent cases: • flouroquinolones • 3rd generation cephalosporins • Resistence has been devoloped to antibiotics • In salmonella gastro enterits antibiotics should not be used

  27. Maintaining highgenic conditions Carriers should not be engaged in food preparation Vaccination PROPHYLAXIS

  28. TAB vaccine • Heat killed,whole celled, • S.typhi-1,000 millions/ml • S.paratyphi A-750 millions/ml • S.paratyphi B-750 millions/ml • Dose schedule: • Protection: • Side effects:

  29. TYPHOID VACCINE • Live oral, • Avirulent mutent strain • S.typhi lacking UDP-galactose-4-epimerase has been used`as live oral vaccine • Dose schedule: • Protection:

  30. TYPHIM-Vi • Purified Vi antigen • Dose schedule :im • singledose • 25 micro grams

  31. THANK YOU

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