The Isolation of Salmonellae from Poultry Environmental Samples by Several Enrichment Procedures Using Plating Media with and Without Novobiocin

Abstract

A two-part study was conducted to examine the efficacy of several enrichment-broth techniques and of plating media for detecting salmonellae from poultry environmental samples. The data are reported on pooled samples collected from five poultry houses. The samples were cultured for salmonellae, using up to four different enrichment procedures and employing plating media with and without novobiocin. The primary enrichment-broth procedures were: 1) buffered peptone water preenrichment to Hajna's tetrathionate (TT) broth; and 2) direct inoculation in TT broth. The delayed secondary-enrichment procedure involved prolonged incubation at room temperature and transfer of the primary broths. The plating media consisted of: 1) xylose lysine desoxycholate agar (XLD); 2) xylose lysine desoxycholate agar containing 15 or 20 μg per mL of novobiocin (XLDN); 3) brilliant green sulfapyridine agar (BGSP); and 4) brilliant green agar containing 20 μg per mL of novobiocin (BGN).Of the 94 Salmonella-positive recoveries from the enrichment broths in which complete comparisons could be made, an average of 75% were recovered from the primary enrichment broths and an average of 86% were recovered from the delayed secondary-enrichment broths. Of the 254 Salmonella- positive isolations in which complete comparisons could be made, an average of 65% were isolated on the plating media without novobiocin and an average of 97% were isolated on the plating media containing novobiocin. Overall, the delayed secondary enrichment and enteric plates supplemented with novobiocin significantly improved Salmonella detection from the farm environmental samples.