THE USE OF BACTERIAL-MEMBRANE FRACTIONS FOR THE DETECTION OF CAMPYLOBACTER SPECIES IN SHELLFISH

Selected enrichment broths supplemented with the enzyme Oxyrase(R) a m embrane-bound enzyme derived from E. coli were evaluated for recoverie s of Campylobacter under normal atmospheric conditions from shellfish. Results indicate that Oxyrase is useful for the recovery of Campyloba cter from shellfish. Effect of Oxyrase on growth of Campylobacter were dependent upon physical parameters such as media volume and surface v olume area. For example, in the comparision of growth of Campylobacter sp (low to high Levels, 1 x 10(1 to 6)/mL) in various media volumes i n Stomacher(R)400 closure bags and 250 mL and 500 mL screw-capped Erle nmeyer flasks, no campylobacters were recovered using the closure bags . However, all levels of Campylobacter were recovered in the Erlenmeye r flasks. Oxyrase was useful for the recovery of C. jejuni from Pacifi c oysters (Crossostrea gigas). In one study, Pacific shellstock oyster s were allowed to take up 1 x 10(6) cells of C. jejuni per ml for a pe riod of 5 to 7 h in an artificial seawater aquarium system. Oysters we re removed and stored at 4C for 24 days. Uptake in oysters ranged from 0.4 to 114 cells/g. At intervals, oysters were removed and analyzed f or C. jejuni by using the Oxyrase method and the FDA/Bacteriological A nalytical Manual standard method. Comparison of these methods showed t hat the Oxyrase method was as reliable as the official FDA method. Oxy rase was also useful for recovering naturally occurring Campylobacter in market oyster shellstock. To measure reproducibility of the method, an in-house preliminary collaborative study was conducted in the Univ ersity of Central Venezuela (Caracas). Participants consisted of 6 gro ups of three microbiologist each from various countries in Central and South America. All groups were successful in recovering Campylobacter jejuni and Campylobacter coli using Oxyrase. Our results indicate tha t Oxyrase provides microaerobic conditions for growth of Campylobacter from shellfish.