|Lay, Jr, Donald - Don|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 1/31/2003
Publication Date: 1/31/2003
Citation: WILLARD, S.T., BAILEY, R.H., RYBOLT, M.L., GANDY, B.S., RYAN, P.L., LAY JR, D.C. REAL-TIME MONITORING OF SALMONELLA IN SWINE: SPECIFICITY AND SENSITIVITY OF BACTERIAL DETECTION THROUGH THE GASTROINFESTINAL TRACTS OF JUVENILE AND MARKET WEIGHT PIGS. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT. V. 81(SUPPL.1): ABSTRACT P. 15.
Technical Abstract: We have demonstrated that Salmonella can be monitored non-invasively using biophotonic paradigms (Salmonella expressing light-emitting proteins) in living neonatal pigs. Nevertheless, questions remain concerning system sensitivity and adaptations of these methodologies for investigations of pre-harvest food safety issues in market weight (MW) pigs. The aim of this study was to quantify the relationship between the amount of bacteria present (colony forming units; CFU), photonic emissions, and the influence of tissue depth on photon detection in juvenile (3 kg) and MW (100 kg) pigs. Gastrointestinal tracts (GI) were collected post-mortem from pigs at 14 (juvenile; n = 6) and 170 (MW; n = 6) days of age, and sectioned into 4 cm segments for the small intestine (SI), large intestine (cecum: CE; colon: CO) and stomach (ST). Skin from the ventral surface of juvenile pigs was also analyzed. GI and skin sections were placed separately on 96-well plates containing varying concentrations of Salmonella-lux (Salmonella anatum engineered to express luciferase). Data were analyzed to ascertain changes in Salmonella-lux-induced specific photonic emissions (SPE) as detected through the GI and skin, and are reported as SPE or as a % of SPE captured. Two levels of photonic emissions were tested (High: 1.8 ± 0.07 x 106 SPE; Low 0.84 ± 0.05 x 106 SPE), which represented a two-fold difference in concentrations of Salmonella-lux. Similar recovery percentages for High and Low SPE were observed (P > 0.10), therefore data were pooled for each GI segment within juvenile and MW pigs. For juvenile pigs, 9.9 ± 1.1, 8.8 ± 1.2, 6.4 ± 0.8 and 1.5 ± 0.5 % of SPE were detectable through the SI, CO, CE and ST, respectively, and 0.98 ± 0.1 % through the skin. For MW pigs, 1.6 ± 0.13, 1.7 ± 0.17, 0.79 ± 0.17 and 0.08 ± 0.05 % of SPE were detectable through the SI, CO, CE and ST, respectively. The respective juvenile GI segments permitted more SPE to pass through (P < 0.05) than MW GI segments. System performance data indicated that quantifiable SPE specific to bacterial presence equated to 0.2 to 2 x 106 CFU depending on the GI section imaged. In summary, real-time imaging of Salmonella is feasible through juvenile and MW pig GI tracts. Through improved imaging technologies, this technology will enable the identification of sites within swine (in vivo or post-mortem) where Salmonella may congregate and establish pathogenicity.