Evaluation of the VIDAS Listeria (LIS) immunoassay for the detection of Listeria in foods using demi-Fraser and Fraser enrichment broths, as modification of AOAC Official Method 999.06 (AOAC Official Method 2004.06).

A multilaboratory study was conducted to compare the VIDAS LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types--brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef--at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance.

[Etiologic diagnosis of pneumoccocal pneumonia by counterimmunoelectrophoresis (author's transl)]. / Diagnóstico etiológico de la neumonía neumocócica por contrainmunoelectroforesis.

The antigenic composition of the pneumoccocal capsule and its easy detection by counterimmunoelectrophoresis led us to carry out a comparative study of this method and the results obtained from cultures. A series of 159 patientes with suspected bacterial pneumonia were included in the study. Blood cultures were prepared for all of the patients; sputum cultures were practiced on 35 and cultures of pleural fluid on 32. Serum from all of the patients, urine from 104, sputum from 34, and pleural fluid from 16 were analyzed by counterimmunoelectrophoresis for pneumoccocal antigen. This method was particularly useful for detecting the germ in sputum and pleural fluid. Furthermore, a higher number of positive indexes in serum were obtained by counterimmunoelectrophoresis than by blood cultures (p less than 0.01). This was also true for tests with sputum and pleural fluid. Urine tests resulted in an even greater number of detections. Counterimmunoelectrophoresis is thus a simple, quick method for detecting pneumococcus and is especially useful when accompanied by cultures tests, since they are complementary. We were able to discover a positive indication of penumoccocus in bacterial pneumonia in 39.6 percent of cases with this technique, as opposed to 15 percent using cultures alone.