A SURVEY FOR SALMONELLA BY DRAG SWABBING MANURE RILES IN CALIFORNIA EGG RANCHES

A cross-sectional study was conducted between August 1995 and November 1996. Sixty California egg-producing ranches were chosen at random; 3 3 ranches agreed to participate in the study. The surface of the manur e pile in one house on each ranch was sampled by drag swabbing. The dr ag swabs were tested for Salmonella using a most probable number proce dure that had a detection level of one to five Salmonella per drag swa b. In 12 ranches (32.4%), the drag swabs were negative for Scrlmonella ; the remaining had Salmonella counts in the range of 1 to over 1700 p er swab. Twenty-two different serotypes were found. Salmonell heidelbe rg and SalmoMella cerro represented the majority of the typed isolates . Salmonella enteritidis (SE) was found on only one ranch. This study found SE to be rare in California egg ranches, which implies that thes e ranches are not a major source of S. enteritidis.