SUMMARY The indirect immunofluoresceuce (FA) technique was used. Absolute correlation between culture and FA results was observed in the aualysis of dried foods. The FA procedure was significantly more sensitive than cultural methods for quantitative and qualitative analysis of Salmonella in liquid eggs.

Approximately 800 fresh and frozen meat and poultry samples collected at the point of slaughter were analyzed for Campylobacter jejuni. C. jejuni and C. coli isolates were never discriminated. Isolation levels of C. jejuni from fresh tissues were 5-fold higher (12.1%) than those from frozen tissues (2.3%). The prevalence of C. jejuni in fresh tissues was also higher when results were compared by animal species rather than by individual tissues.

A collaborative study was conducted in 15 laboratories to evaluate 2 different techniques for enumerating Bacillus cereus in foods. A direct plating technique using mannitol-egg yolk-polymyxin agar and a most probable number (MPN) technique using trypticase-soy-polymyxin broth were compared for the enumeration of high and low populations of B. cereus in mashed potatoes. The collaborative results showed that the overall mean recovery obtained with the low population level was essentially the same by both techniques. However, the overall mean recovery was significantly higher by the direct plating technique at the high population level. A statistical evaluation of the data also showed that the direct plating technique had better repeatability and reproducibility than did the MFN technique at both the high and low population levels. These results suggest that the MPN technique is suitable for examining foods containing low populations of B. cereus, but that the direct plating technique is preferable for foods that contain a high population of this organism. The confirmatory technique used in the proposed method is reliable for presumptive identification of isolates as B. cereus. The method has been adopted as official first action.

A survey was conducted to determine the incidence of salmonellae in processed, ready-to-market, whole young chickens. Carcasses from 15 federally inspected chickens eviscerating plants were analyzed using a carcass washing technique for determining the presence of salmonellae. The results obtained during the 1979 incidence survey were compared to results obtained in an identical 1967 Salmonella survey. In the 1967 study, salmonellae were isolated from 171 ot the 597 (28.6%) whole chickens tetrathionate broth rinsings analysed. In the 1979 study, 222 of 601 (36.9%) of similarly analysed chicken samples were positive. Percentile positive findings from individual plants range from 7.5 to 73.7% in 1967 and from 2.5 to 87.5% in 1979.