The use of a marked strain of Pseudomonas fluorescens to model the spread of brain tissue to the musculature of cattle after shooting with a captive bolt gun

Abstract

Aims: The aim of this study was to use a marked strain of Pseudomonas fluorescens to model the spread of central nervous system (CNS) tissue in cattle following captive bolt stunning. Methods and Results: The marked organism was introduced by injection through the captive bolt aperture immediately after stunning and was subsequently detected in a wide range of derived tissues, including blood, organs, and the musculature of the entire forequarters of test animals. This was dependent on the use of high concentrations of the organism that were recovered sufficiently and rapidly to minimize the bactericidal properties of the circulatory system. These results suggest that a marked organism could potentially be used to model the effects of captive bolt stunning on the dissemination of CNS tissue from the brain. Conclusions:These results indicate that current commercial methods of captive bolt stunning may induce widespread and significant mobilization of CNS tissue within beef carcasses. This may lead to the widespread dissemination of such materials within meat destined for human consumption. Significance and Impact of the Study: In the absence of rapid, simple and sufficiently sensitive methods for the direct detection of prion in commercially slaughtered animals, marked organisms can provide useful models in studies of the dissemination kinetics of prion disease in captive bolt stunned animals.

Survival of antibiotic resistant and antibiotic sensitive strains of E. coli O157 and E. coli O26 in food matrices

“…Laboratory-developed antibiotic resistance (AR) strains created by the method of Blackburn and Davies (1994), are commonly used in microbiology as "marked" strains, to facilitate ready detection of such pathogens from other phenotypically similar strains or species in experimental protocols (Dombroski et al, 1999;Daly et al, 2002;Prendergast et al, 2004). In this study, the impact of laboratory acquired antibiotic resistance to nalidixic acid and streptomycin on the growth and survival of E. coli O157:H7 (AR) and E. coli O26 (AR) was examined.…”

Detection of Bovine Central Nervous System Tissues in Rendered Animal By-Products by One-Step Real-Time Reverse Transcription PCR Assay

“…Contamination of animal organs and bloodstream with small CNS tissue fragments during a stun gun slaughtering process was reported previously (9,23). In our study, organs and tissues were harvested from animals euthanized by a barbiturate intravenous injection which excluded dissemination of CNS tissues.…”

The influence of storing beef aerobically or in vacuum packs on the shelf life of mince

“…Bacterial counts were transformed to log 10 CFU cm )2 ml )1 . To all data, 0AE001 was added to the original values prior to log transformations (Prendergast et al 2004). This manipulation gave zero counts a value of )3AE0 on the log scale, while making no appreciable difference to the log values of all other (nonzero) counts and allowed mathematical treatment of all the data obtained (including zero counts), with minimal significant effect on the overall results obtained.…”

“…Bacterial counts were transformed to log 10 CFU cm −2 ml −1 . To all data, 0·001 was added to the original values prior to log transformations (Prendergast et al. 2004).…”