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استفسار عن طريقة اجراء مزارع للبراز لتحري السالمونيلا و الشيغلا

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  • استفسار عن طريقة اجراء مزارع للبراز لتحري السالمونيلا و الشيغلا

    السلام عليكم و كل عام و أنتم بخير
    يا اخوان أرجو منكم شرح طريقة زرع البراز للكشف عن السالمونيلا و الشيغلا و بالتفصيل الممل و مع الصور ان أمكن فقد بحثت في كثير من المنتديات المختصة سواء العربية أو لأجنبية و لم أوفق.
    و شكرا مقدما و دمتم بخير

  • #2
    Stool Culture
    Routine, Salmonella & Shigella
    Aim of the test
    Detect bacterial pathogenic organisms in the stool; diagnose typhoid fever,
    enteric fever, bacillary dysentery, Salmonella infection
    Types of specimen
    Stool or rectal swab or stool (fresh random) in fecal transport system
    Criteria of specimen rejection
    Formed stool, specimen contaminated with urine, residual soap, or
    disinfectants. Specimens received in grossly leaking transport containers;
    diapers; dry specimens; specimens submitted in fixative or additives;
    Pathogen and commensals
    Gastrointestinal tract
    Common pathogens Commensal flora
    Helicobacter pylori Enterobacteriaceae other than the common pathogens
    Salmonella spp. Bacteroides spp
    E. coli O157:H7 Streptococcus spp
    Staphylococcus aureus Lactobacilli
    Campylobacter spp. Pseudomonas spp.
    Vibrio cholerae Coagulase negative staphylococci
    Yersinia enterocolitica Bacteroides
    Clostridium difficile Clostridium
    Shigella spp. Peptostreptococcus
    Pre specimen processing
    Patient preparing
    Instruct the patient on how the specimen should be collected and
    transferred to the container; provide him/her with sticks and containers.
    Specimen collection
    A single stool specimen cannot be used to rule out bacteria as a cause of
    diarrhea. More than two specimens should only be submitted from patients
    for whom there is a high degree of suspicion.
    The stool should be collected on collected in sterile bedpan. A sample is
    transferred with the sticks to the container. The specimen should contain
    at least 5 g of faeces and, if present, those parts that contain blood and/or
    mucus should be selected. The specimen should not be contaminated with
    urine. Close the lid.
    Rectal swab: Pass swab beyond anal sphincter, carefully rotate, and
    withdraw. Swabbing of lesions of rectal wall or sigmoid colon during
    proctoscopy or sigmoidoscopy is preferred
    Duodenal or sigmoid aspirate: Specimen should be collected by a
    physician trained in this procedure
    Who will collect the specimen
    The patient. If stool is unobtainable, nursing staff or physician will collect
    fecal swab.
    Quantity of specimen
    The specimen should contain at least 5 g of faeces
    Time relapse before processing the sample
    Stool samples should be examined and cultured as soon as possible after
    collection. As the stool specimen cools, the drop in pH will inhibit the
    growth of most Shigella spp. and some Salmonella spp.
    Storage
    Refrigerated (2-8 °C)
    Specimen processing
    Media
    􀂉 SSA or XLD
    􀂉 Selenite-F broth or tetrathionate
    Reagents
    􀂉 API 20 E Kit
    􀂉 Salmonella and Shigella antiserum (polyvalent and
    monovalent)
    Culturing procedure
    1 gram of stool is transferred to a tube of Selenite-F broth and a loop is
    streaked on XLD or SSA. Incubate at 37 oC. After an overnight incubation
    do subculture from Selenite-F broth onto a fresh plate of XLD or SSA.
    Post specimen processing
    Interfering factors
    Patient on antibiotic therapy.
    Improper sample collection.
    Result reporting
    A positive report will be issued only in case salmonella or shigella were
    isolated, otherwise, a negative report will be issued.
    Turn around time
    Negative results are sent out 48 hours after receipt of the specimen.
    Results of positive cultures can be expected in 3-4days.
    Additional Information
    Indications for stool culture include:
    􀂉 Bloody diarrhea
    􀂉 Fever
    􀂉 Tenesmus (is the constant feeling of the need to empty the bowel, accompanied
    by pain, and cramping)
    􀂉 Severe or persistent symptoms
    􀂉 Recent travel to a third world country
    􀂉 Known exposure to a bacterial agent
    􀂉 Presence of fecal leukocytes
    Notes
    In enteric fever caused by Salmonella typhi, S. choleraesuis, or S.
    enteritidis, blood culture may be positive before stool cultures, and blood
    cultures are indicated early; urine cultures may also be helpful.
    Stool samples should be examined and cultured as soon as possible after
    collection. As the stool specimen cools, the drop in pH will inhibit the
    growth of most Shigella spp. and some Salmonella spp.
    Diarrhea is common in patients with the acquired immunodeficiency
    syndrome (AIDS). It is frequently caused by the classic bacterial
    pathogens as well as unusual opportunistic bacterial pathogens and
    parasitic infestation. (Giardia, Cryptosporidium, and Entamoeba histolytica
    frequently reported.) Cryptosporidium and Pneumocystis can occur with
    AIDS. Rectal swabs are useful for the diagnosis of Neisseria gonorrhoeae
    and Chlamydia infections. AIDS patients are also subject to
    cytomegalovirus, Salmonella, Campylobacter, Shigella, C. difficile, herpes,
    and Treponema pallidum gastrointestinal tract involvement
    حاول ان تكون

    لطيف القلوب مثل الحديقة
    عميق الأفكار مثل الجذور
    رقيق الكلمات مثل الأزهار

    تعليق


    • #3
      جزاك الله كل خير و أسعدك الله

      تعليق


      • #4
        السلام عليكم
        ارجو ان يفدك هذا:
        Stool culture :
        In stool culture main bacterial pathogens are Shigella and Salmonella in adults , and E.coli in infants less than 2 years of age. Other bacteria like Campylobacter and V.cholera might also be found.
        1st Day:
        Media used :
        a) These media are used routinely for culturing fecal specimens in the first day:
        1. MacConkey agar
        2. Selenite F broth
        3. Hektoen Enteric agar
        b) In case of infants ( <2 yrs ): blood agar is added.
        c) In case of watery stool: Alkaline Peptone Water (APW ), Butzler and Skirrow's media are added.
        • MacConkey agar :
        - Contain crystal violet and bile salt that inhibit growth of Gram +ve organisms.
        - pH indicator : neutral red
        - When bacteria ferments lactose, acid is produced increasing pH of the media and causing neutral red to give pink colonies.
        - Salmonella and Shigella form colorless (pale yellow) colonies like other non-lactose fermenter organisms e.g. Proteus and Pseudomonas.
        - E.coli give pink colonies.


        • Selenite F broth :
        - The most commonly used enrichment medium for specimens that may contain either Salmonella or Shigella.
        - Providing the pH of the media is near neutral , it inhibits the growth of coliforms.
        • Butzler and Skirrow's media :
        - Used as selective media for isolation of Campylobacter.
        - Incubate at 42 °C for 48 hrs. with gas-generating pack (campy pack).
        • Alkaline Peptone Water (APW) :
        - Used as enrichment media for V.cholera and other vibrios.
        - pH = 8.6 – 9
        - Favors the growth of V.cholera and inhibits the growth of fecal commensals.
        2nd Day :
        Examine and report the cultures :
        1. Organisms are identified as non-lactose fermenter (colorless colonies) or lactose fermenter (pink colonies).
        2. Look for Salmonella and Shigella, which are both non-lactose fermenting, and for E.coli, which is lactose fermenting, in infant (2 yrs and less).
        3. Subculture from Selenite F broth on the following media :
        a) SS ( Shigella Salmonella )
        b) MacConkey
        c) XLD (Xylose Lysine Deoxycholate) agar
        4. If APW was performed , we do subculture on Thiosulphate Citrate Bile salt Sucrose (TCBS) agar for the identification of Vibrio cholera.
        • Xylose Lysine Deoxycholate :
        - Contain 3 sugars: xylose, lactose, and sucrose.
        - pH indicator: phenol red, giving yellow in acid ( LF), and pink in alkaline (NLF).
        - Has H2S indicator system.
        - Shigella form pink-red colonies because they do not ferment xylose, lactose, or sucrose.
        - Salmonella also form pink-red colonies even through they ferment xylose with acid production. This is because they break down the amino acid lysine which gives an alkaline reaction. H2S producing Salmonella form red colonies with black centers.


        • Thiosulphate Citrate Bile salt Sucrose (TCBS) agar :
        - Excellent selective media for primary isolation of V.cholera.
        - pH indicator: Bromothymol blue.
        - V.cholera grow as yellow, sucrose fermenting colonies.
        - Incubate aerobically at 37 °C for 24 hrs.(over night).



        3rd Day :
        1. Examining and reporting cultures : growth could be :
        - Non lactose fermenting colonies: yellow on MacConkey and pink on XLD, which is considered significant and further testing to identify the organism is performed.
        - Lactose fermenting colonies: pink on MacConkey and yellow on XLD, which is considered insignificant. It is reported as non enteric pathogen isolation.
        • Oxidase test : to exclude Pseudomonas if the growth is non lactose fermenter. If oxidase is positive the organism is Pseudomonas, which is non pathogenic in stool. If oxidase is negative ,it could be Salmonella or Shigella, so we identify them by API system.
        2. Sensitivity testing : same as mentioned earlier in urine culture.
        3. API-20E system : test is mentioned earlier for detection of Gram negative bacilli (Enterobacteriaceae ).
        4. Serological testing :
        - Procedure :
        1. Prepare heavy bacterial suspension.
        2. First use poly OA1+VI and VI antiserum. If poly OA1+VI and VI are positive, the organism is Salmonella typhi.( a positive test will show strong clear agglutination within 1 min.).
        3. If poly OA1+VI is positive and VI is negative, the organism is Salmonella enteritidis, which is non pathogenic.
        4. If both poly OA1+VI and VI are negative, confirm biochemically. If confirme, report Salmonella species.
        Note : the type of Salmonella enteritidis should be identified serogically also Salmonella typhi. Shigella is identified by 5 type of antigens A, B, C, D, and E.
        :sm199:

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        • #5
          شكرا لكم

          للتحري المباشر نزرع العينة على s.s agar

          و هي بيئة اختيارية لتنمية السالمونيلا و الشقيلا
          http://up5.m5zn.com/photos/00300/6yovc5ylol7s.jpg

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          • #6
            شكرا جزيلا لكل من تطوع بالرد و جزاكم الله خيرا

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            • #7
              شكرااااااا

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