**5.5 Gruber-Widal reaction**

Gruber Widal reaction is used to reveal infections caused by *Salmonella* group bacteria. *Salmonella* typhi, *Salmonella* paratyphi B bacteria are used in the reaction, because they are most common species in our country. *Salmonella* paratyphi A is added for many times. Bacteria such as *Salmonella* paratyphi C are also important in another countries. Both O and H antigens of bacteria are used separately in the reaction. Because, only O or G agglutinins occur especially in first episode of the disease. O agglutinins appear before H agglutinins generally in typhoid fever. As O antigen fractions of Salmoenalla typhi are present in Salmoenalla paratyphi B, they give common agglutination. H agglutination is more valuable as it is not common.

Gruber Widal reaction is performed quantitatively, because serum titration is important. It is impossible to put definite rules to improve various titrations. Reaction is improved by considering other findings. It should be considered that in which day of the disease serum has been taken, whether an infection appeared previously, whether protective vaccination is performed and normal antibody level in healthy persons in the population.

Agglutinins may exist normally in the serum. H agglutinins of *Salmonella* typhi and *Salmonella* paratyphi B may be 1/40 titration and O agglutinins may be as 1/50 titration. Therefore, reaction is started as final dilution of the serum in the first tube will be as 1/50.

If a non-specific antigen such as fimbria antigen is present in the bacteria suspension, false positive Gruber-Widal reaction occurs with an agglutinin in the human serum.

Specific antibodies occur in serums of those who had typhoid-paratyphoid vaccination and Gruber-Widal reaction is positive in them. If previously vaccinated persons have a pyretic disease, agglutination titration elevates. When vaccinated persons are examined after months, it is seen that they have H agglutinins mainly. Therefore, high H agglutinin titration of those who was vaccinated is meaningless. However, if more than six months has passed from the vaccination date and titration of O agglutination is more than 1/100 and titration elevates in continuous assays, such result is insignificant in the diagnosis.

Presence of both O and H agglutinins in persons who had undergone the infection may last long.

Detection of O antibodies in the serum shows that a new infection was experienced. H agglutinins are 1/400 or higher in those who had new infections and they stay for a long time, sometimes for years. Serum titration elevates during an pyretic disease (anamnestic reaction). O agglutinins decrease rapidly in the blood and it may be shown rarely after one year. High O titration is not seen with anamnestic reaction.

1/100 positive O agglutination and 1/200 positive agglutination are valuable in persons who was not infected and vaccinated. 1/200 O agglutination and 1/400 H agglutination in persons who was infected and vaccinated before is valuable in terms of diagnose of a new infection. Only 1/100-1/200 positive H agglutination shows an undergone infection, new vaccination or anamnestic reaction.

#### **Making the Assay;**

154 Salmonella – A Dangerous Foodborne Pathogen

a 1, 2, 3 b 1, 2, 4 c 1, 2 d 1, 3, 4 eh 1, 3 G complex 1, 4 i 1 k 2, 3, 4 r 2, 4 y 2 z 3, 4

z4 complex 4 z10 4 z9 2, 3 enx, enz15 en complex 1v, 1w, 1z13, 1z28 1 complex 1,2; 1,5; 1,6; 1,7; z6 complex

Gruber Widal reaction is used to reveal infections caused by *Salmonella* group bacteria. *Salmonella* typhi, *Salmonella* paratyphi B bacteria are used in the reaction, because they are most common species in our country. *Salmonella* paratyphi A is added for many times. Bacteria such as *Salmonella* paratyphi C are also important in another countries. Both O and H antigens of bacteria are used separately in the reaction. Because, only O or G agglutinins occur especially in first episode of the disease. O agglutinins appear before H agglutinins generally in typhoid fever. As O antigen fractions of Salmoenalla typhi are present in Salmoenalla paratyphi B, they give common agglutination. H agglutination is more valuable

Gruber Widal reaction is performed quantitatively, because serum titration is important. It is impossible to put definite rules to improve various titrations. Reaction is improved by considering other findings. It should be considered that in which day of the disease serum has been taken, whether an infection appeared previously, whether protective vaccination is

Agglutinins may exist normally in the serum. H agglutinins of *Salmonella* typhi and *Salmonella* paratyphi B may be 1/40 titration and O agglutinins may be as 1/50 titration. Therefore, reaction is started as final dilution of the serum in the first tube will be as 1/50. If a non-specific antigen such as fimbria antigen is present in the bacteria suspension, false

performed and normal antibody level in healthy persons in the population.

positive Gruber-Widal reaction occurs with an agglutinin in the human serum.

Table 3.

**5.5 Gruber-Widal reaction** 

as it is not common.

H antigen Positive reaction with Spiecer

Edward *Salmonella* H antiserum

6 series of tubes are taken, 6 tubes are put in every series as 1/50, 1/100, 1/200, 1/400 serum dilutions, antigen control and serum control. To make serial dilution, 0,5 cm3 salty water except 1st tube and last serum control tube and 0,5 cm3 diluted immunized serum is put into the last tube. Immunized serum which was generally obtained from rabbits as immunized serum is used by diluting 100 or 1000 times and adding 0,5% phenol. First Tube 7.2 cm3 and 0.3 cm3 of saline placed in serum 1 / 25 dilution of each series after the 1st and 2 tube is added 0.5 cm3. Serum was diluted as 1/25 in the 1st tube. Same amount of salty water was diluted as much in the 2nd tube and dilution has become 1/50.
