Tehran University Medical Journal

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In our investigation, rabbit hyper-immune serum to V.cholerae ogawa was absorbed with V.cholerae inaba whole-cells and vice versa. Applying ammonium sulphate precipitation method, mono-specific g globulins were purified and concentrated from the absorbed whole serum. These antibodies were fixed on staphylococcus cowan 1 NCTC-8325 whole-cells, using different chemical fixatives. It was observed that maximum fixation of g globulin to protein-A was achieved by 1-propanol 50% at 3 hours, which revealed through single radial immuno-diffusion techniqe. The rectal swab samples were cultured in an enrichment bile-peptons broth. After 5 hours 37°C while agitations, one drop of each sample was mixed with one drop of vibrio-cholerae bivalent mono-specific coagglutination reagent (VBCR). The results were read after 2 to 3 minutes. Finally though statistical analysis sensitivity and specificity of coagglutination test were calculated to be 95.1% and 99.2% respectively, when compared to positive & negative controls and conventional culture methods. Using VBCR, coagglutination test can be therefore considered as a simple, reliable and rapid method to detect V.cholerae O1 in the stool of patients in endemic area and less equipped laboratories

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Background: Bacillus cereus spores distribute widely in nature and can be isolated from different kinds of foods. This bacterium can produce diarrhea and emetic enterotoxins and syndromes. As infants are known to be more susceptible to B. cereus infection due to their incomplete intestinal flora and fast growth of this bacterium during consumption, it is very important to investigate the presence of B. cereus in infant formula and possible pathogenicity of this microorganism in infants. 

Methods: In this study, 60 samples of infant formula were examined for the presence of B. cereus. From a 1/10 dilution of each sample, a total amount of 1 ml was inoculated onto four phenol red agar plates containing mannitol, egg yolk emulsion and polymyxin B sulfate. The plates were incubated at 30°C for 24 hours. Confirmation tests were then performed on suspected colonies.

Results: Among the 60 samples, 11 samples had more than 10 cfu/g, four of which contained more than 102 cfu/g. The other 49 samples showed less than 10 cfu/g of B. cereus. 

Conclusions: We suggest that for infant formula the maximum microbial limit be reduced to less than 10 cfu/g to control B. cereus contamination and to prevent infection in infants. For this purpose, infant formula should be tested by the method and confirmation tests used in this study. In addition, susceptibility to penicillin, ß-hemolysis and growth rate at 45ºC could also be performed.