Evaluation of pre-PCR processing approaches for enumeration ofSalmonella entericain naturally contaminated animal feed

Abstract

Aims: Three pre-PCR processing strategies for the detection and/or quantification of Salmonella in naturally contaminated soya bean meal were evaluated. Methods and Results: Methods included: (i) flotation-qPCR [enumeration of intact Salmonella cells prior to quantitative PCR (qPCR)], (ii) MPN-PCR(modified most probable number method combined with qPCR) and (iii) qualitative culture enrichment PCR. The limit of quantification was 1Á8 9 10 2 CFU g À1 (flotation-qPCR) and 0Á02 MPN g À1

Molecular‐based identification and detection ofSalmonellain food production systems: current perspectives

“…; Schelin et al . ). This can be particularly problematic when samples are being retrieved from batches such as animal feeds that are typically prepared in large bulk quantities (Schelin et al .…”

“…This can be particularly problematic when samples are being retrieved from batches such as animal feeds that are typically prepared in large bulk quantities (Schelin et al . ). In addition, sampling and recovery can be problematic if Salmonella is physically attached in some fashion to the food or feed particles.…”

“…Schelin et al . () compared a flotation‐qPCR, a most probable number (MPN)‐qPCR approach, and a qualitative cultural enrichment as pre‐PCR processing methods for detecting S. enterica in naturally contaminated feeds. The flotation approach used centrifugation with discontinuous gradients to dislodge attached Salmonella cells, which were subsequently accumulated in the upper layers and subjected to qPCR and selective plating.…”

Enumeration of Salmonellae in Table Eggs, Pasteurized Egg Products, and Egg-Containing Dishes by Using Quantitative Real-Time PCR

“…We tried to establish such an average relation based on bacteria cultured in laboratory media; however, the curve was found not to represent the relation between CFU and C q for all the different egg products. Therefore, a specific standard curve should be constructed for each matrix, as previously emphasized by others (36,37). We also conclude that individual standard curves should be constructed for different thermocyclers.…”

A Descriptive Tool for Tracing Microbiological Contaminations

“…Infectious cycles start to build up (Berends et al, 1998;Davies et al, 2004) and cross-contamination scenarios can mask the identification of the ultimate source. This fact may be related to the presence of a large proportion of nonculturable cells (Schelin et al, 2014). Difficulties with respect to source tracing at the farm level are mainly related to sampling questions and the comparison of isolates by type matching.…”