A comparison of conventional culture and three rapid methods for the detection of Salmonella in poultry feeds and environmental samples

Abstract

Three rapid methods, an impedance method (Malthus 2000 Analyzer), a colorimetric DNA hybridization method (Gene-Trak) and a post-enrichment enzyme-linked immunosorbent assay (Salmonella-Tek) were compared with conventional culture for the detection of Salmonella in poultry feeds, and in fluff and dust samples from poultry housing. The percentage positive samples for Salmonella by each of the methods were 25.5% for conventional culture, 38.4% for the Malthus, 28.9% for the Gene-Trak and 28.5% for the Salmonella-Tek. By any method 60/153 (39.2%) of the samples tested were positive on confirmed culture.

Implications of Electrical Impedance-Based Microbiological Technology in Pork Meat Processing Industry for the Rapid Detection and Quantification of Salmonella Spp.

“…Only differences between results given by plate and impediometry appear for high levels of bacteria since the slope of the regression line becomes higher than 1. This fact may indicate a higher sensitivity of impediometry (112% ± 2%) against standard count plate (100%) which is in agreement with Donaghy and Madden [18], Bolton and Gibson [13], Quinn et al [21], Wawerla et al [22], Hoorfar [8] and Russell [14]. Moreover, higher errors are attained by standard plate count (horizontal error bars) compared to those of impedance-based method (vertical error bars) which reduces the reproducibility of the quantification assay when using classic microbiology [14,28].…”

“…However, the impedance-based method exhibits a higher accuracy (66.7%) compared to the standard method (44.4%) as well as a lower rate of false positive out of 15, corresponding to 13.3% (2/15) in comparison with 33.3% (5/15) obtained for the conventional method. In general, a higher number of false negatives and positives are identified for the conventional method according to Quinn et al [21], and Wawerla et al [22]. It may be due to natural flora [1] present in meat sample which may either hinder the growth of the target microorganism or lead to misleading results as happens for Proteus spp.…”

“…These metabolites are responsible for the decrease in the impedance of the medium [2,[12][13][14]. After the important work of Torry Research Station [15] in 1978 and Eden and Eden [16] in 1984, and Owens et al [17] in 1989 reporting the principle of indirect impedance, several efforts have been made on the detection of Salmonella by impedance-based technology in food samples [9,12,13,[18][19][20][21][22][23].…”

Efficacy of low-pressure foam cleaning compared to conventional cleaning methods in the removal of bacteria from surfaces associated with convenience food

“…All samples were analysed on the same day. A total of 477 microbiological samples (Table 1) were collected according to the SABS swab technique 40 and all analyses were performed at least twice. …”

“…21 Similarly Salmonella species were also isolated by culturing the NSEB culture onto solid media using the Malthus's method. 21,40 All bacteria were characterized using morphological and biochemical characteristics before serological confirmation. Presumptive positive colonies were confirmed using latex agglutination kits as follows: Salmonella latex kit (SWJM 42) (Swift Micro Laboratories) for Salmonella spp., 48 Latext agglutination test kit (Hardy Diagnostics) for E. coli, Staph latex kit (Remel) for S. aureus and DR1126 Listeria test kit (Oxoid) for Listeria spp.…”