Comparison of Automated BAX PCR and Standard Culture Methods for Detection of Listeria monocytogenes in Blue Crabmeat (Callinectus sapidus) and Blue Crab Processing Plants

Abstract

This study compared the automated BAX PCR with the standard culture method (SCM) to detect Listeria monocytogenes in blue crab processing plants. Raw crabs, crabmeat, and environmental sponge samples were collected monthly from seven processing plants during the plant operating season, May through November 2006. For detection of L. monocytogenes in raw crabs and crabmeat, enrichment was performed in Listeria enrichment broth, whereas for environmental samples, demi-Fraser broth was used, and then plating on both Oxford agar and L. monocytogenes plating medium was done. Enriched samples were also analyzed by BAX PCR. A total of 960 samples were examined; 59 were positive by BAX PCR and 43 by SCM. Overall, there was no significant difference (P ≤0.05) between the methods for detecting the presence of L. monocytogenes in samples collected from crab processing plants. Twenty-two and 18 raw crab samples were positive for L. monocytogenes by SCM and BAX PCR, respectively. Twenty and 32 environmental samples were positive for L. monocytogenes by SCM and BAX PCR, respectively, whereas only one and nine finished products were positive. The sensitivities of BAX PCR for detecting L. monocytogenes in raw crabs, crabmeat, and environmental samples were 59.1, 100, and 60%, respectively. The results of this study indicate that BAX PCR is as sensitive as SCM for detecting L. monocytogenes in crabmeat, but more sensitive than SCM for detecting this bacterium in raw crabs and environmental samples.

Listeria monocytogenes in Aquatic Food Products—A Review

“…In 2000, imitation crabmeat was identified as a source of a small listeriosis outbreak in which L. monocytogenes serotype 1/2b strains were isolated from healthy individuals; these cases were traced to consumption of imitation crabmeat, which contained 2.1 × 10 9 CFU/g in a household refrigerator (Farber and others ). Pagadala and others () observed L. monocytogenes in 6.1% of RTE crabmeat samples collected monthly from 7 processing plants during the plant operating season in the U.S.A. The same group performed a more comprehensive study using 1248 samples (environmental and product) and observed L. monocytogenes in 0.2% of cooked crabmeat samples and 2.1% of processing environment samples.…”

Design Elements of Listeria Environmental Monitoring Programs in Food Processing Facilities: A Scoping Review of Research and Guidance Materials

“…The overarching goal of these studies was to develop and test detection methods that were more sensitive, more rapid and/or more cost effective, focusing on optimizing the enrichment steps and differential culture media or developing automated molecular methods. Eight studies validated detection techniques involving PCR (both commercial and lab‐scale) compared to traditional culturing methods (either ISO or FDA approved methods) (Bolocan et al., ; D'Amico & Donnelly, ; Dalmasso et al., ; Hoffman & Wiedmann, ; Kovacevic et al., ; Medrala, Dabrowski, & Szymanska, ; Norton, Wiedmann, Boor, & McCamey, ; Pagadala, Parveen, Schwarz, Rippen, & Luchansky, ). Three studies compared commercial detection techniques (Kabuki, Boor, Wiedmann, & Kuaye, ; Schirmer, Langsrud, Moretro, Hagtvedt, & Heir, ; Vongkamjan, Fuangpaiboon, Jirachotrapee, & Turner, ).…”