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 micrograms per mL of novobiocin (XLDN); 3) brilliant green sulfapyridine agar (BGSP); and 4) brillant green agar containing 20 micrograms 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.

Development of an Improved Selective and Differential Medium for Isolation of Salmonella spp

“…However, colonies of C. freundii and Proteus spp., such as P. mirabilis, may resemble these of Salmonella due to hydrogen sulfide production on HE agar (2). Although XLD has a high sensitivity and specificity, Proteus and Citrobacter produce colonies indistinguishable from those of Salmonella on this medium (6,28,32).…”

“…XLD and HE agar are the most popular media for isolating Salmonella spp., and their differentiation abilities rely on characteristics of Salmonella, such as hydrogen sulfide production and the nonfermentation of lactose (28). However, these characteristics are shared with other microorganisms, such as Proteus and Citrobacter (11,32). Thus, numerous false-positive results are observed on these media which require further confirmation testing, a time-consuming and labor-intensive activity (13).…”

Evaluation of sampling methods for the detection of Salmonella in broiler flocks

“…Although the sampling site is of great significance, the methods and media used for bacteriological examination are also of importance, especially in cases where Salmonella forms only a minority of the competing flora. Great efforts have been made in recent years to improve and evaluate media for the enrichment and plating of Salmonella (Tate et al 1990;Waltman et al 1993;Read et al 1994). Evaluation of the media used in the different laboratories in relation to relevant sampling material, Salmonella concentrations and the competitive flora present is necessary for the determination of the limit of detection.…”

Alternative antigens reduce cross‐reactions in an ELISA for the detection of Salmonella enteritidis in poultry

“…The classical salmonella monitoring system, i.e. bacteriological sampling of the faeces, is known to be fallible as none of the methods of enrichment and selection can detect all salmonellas of public health significance (Tate et al 1990;Cherrington and Huis in 't Veld 1993). Furthermore, excretion of the organism in the faeces is intermittent (Williams 1972).…”