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Chapter 1 isolated from undercooked bacon produced by the Company (Company A). The undercooked meat had come as a result of a cooker failure on one of their production lines, the bacon was subsequently quarantined, however at this point, the contaminated undercooked products had already entered the food chilling area, where it may have come into contact with surfaces or other meats [58]. The food processing plant (Company A), supplied two chain stores (Chain A and Chain B) implicated through patient interviews. Therefore the hypothesis was that the breakdown of a cooker in the food processing plant may have allowed the pathogen to remain viable in the cooked meat food supplied by the company. After inspecting the food processing plant and the outlets of the two chain stores, multiple samples of beef strips from Company A supplied to Chain A were found positive for the outbreak strain in Northern Ireland, Wales and Ireland. Bacon pieces from chain B which were sourced back to company A were also found to be positive for the outbreak strain. In addition to the microbiological testing of the food, extensive environmental testing was performed within the food plant. The outbreak strain was isolated in the low risk area in the environment (raw food area) during the outbreak which may have allowed its travel into the high risk area (cooked, ready to eat area). All contaminated products (beef and bacon) were withdrawn from the market, in addition nine other products that may have come in contact with the contaminated batches were also recalled. Production and circulation of food products ceased until all health authorities were assured it was safe to restart. A pharmaceutical grade clean (using vaporised hydrogen peroxide) was applied throughout the plant and bio-markers were used to detect any post cleaning contamination. All personnel were also tested for carriage of Salmonella but none was detected [58]. Company A was a major exporter of processed foods throughout the EU, which may provide an explanation as to how the outbreak disseminated so Page 15
Chapter 1 rapidly throughout Europe. In total 163 cases of the outbreak strain of S. Agona SAGOXB.0066 were reported involving 10 countries over a 10 month period including eleven cases in Ireland, 143 cases in the UK [England (n=96), Wales (n=11), Northern Ireland (n=2), Scotland (n=34)] and nine cases in mainland Europe [France (n=3), Luxembourg (n=2), Sweden (n=2), Finland (n=1) and Austria (n=1)] . The infection was quite severe as 25 patients were hospitalized and 2 elderly patients died [57-58]. Through an investigation of previous S. Agona isolates, it was noted that the outbreak strain SAGOXB.0066 had been circulating in Ireland for the previous 3 years and was associated with one sporadic human salmonellosis case reported in 2005. In 2005, the outbreak strain had previously been found in a poultry processing plant with additional strains found in broiler carcasses and the poultry farm that supplied the poultry processing plant. The outbreak strain was also identified in milk filter residues in cork in 2003 and in goat’s milk filters in Monaghan in 2005 [58]. Even though the outbreak strain has been detected in the food chain for 3 years, there were no outbreaks prior to 2008. The outbreak strain was also detected in river water samples during the outbreak [57-58]. 1.12.2.2. The variant strain – remnants of SAGOXB.0066 Continuous environmental swabbing performed both inside and outside the plant revealed a variant of the strain was persisting in drains of the plant for an extended period of time despite intensive cleaning and disinfection (personal communication with members of the investigation team [58]). The persistence of Salmonella (including S. Agona), despite intensive cleaning may be indicative of biofilm formation [56]. The differences in strains between the outbreak strain and the variant are visible through PFGE, see image provided by the NSSLRL (see appendix 3). 1.13. S. Typhimurium and “S. Typhimurium-like” strains Page 16
Page 1: Salmonella enterica - biofilm forma
Page 4 and 5: Table of Contents Page Number 1.16.
Page 6 and 7: Table of Contents Page Number 4.1.2
Page 8 and 9: Table of Contents Page Number 6.8.4
Page 10 and 11: List of Abbreviations Table Page Nu
Page 12 and 13: List of Abbreviations List of Abbre
Page 14 and 15: Summary of Content Summary of Conte
Page 16 and 17: “To show your true ability is alw
Page 18 and 19: Acknowledgements ever met, Fiona th
Page 20 and 21: Acknowledgements This Ph.D. thesis
Page 22 and 23: Chapter 1 1.1. Salmonella Salmonell
Page 24 and 25: Chapter 1 may impose enormous costs
Page 26 and 27: Chapter 1 cracks or penetration of
Page 28 and 29: Chapter 1 detected by agglutination
Page 30 and 31: Chapter 1 become colonized with >10
Page 32 and 33: Chapter 1 antigens [z27],[z45] [1].
Page 34 and 35: Chapter 1 S. Agona has also been im
Page 38 and 39: Chapter 1 The S. Typhimurium strain
Page 40 and 41: Chapter 1 ecosystem with the use of
Page 42 and 43: Chapter 1 [82]. Previous research h
Page 44 and 45: Chapter 1 to genes involved in flag
Page 46 and 47: Chapter 1 observation has also been
Page 48 and 49: Chapter 1 [119] and flow cell react
Page 50 and 51: Chapter 1 based disinfectant) the s
Page 52 and 53: Chapter 1 formation of two strains
Page 54 and 55: Chapter 1 shield the S. Agona cells
Page 56 and 57: Chapter 1 Key Objectives of this st
Page 58 and 59: Chapter 2 2. Abstract Food-borne pa
Page 60 and 61: Chapter 2 indicated that there may
Page 62 and 63: Chapter 2 taken from industrial set
Page 64 and 65: Chapter 2 2.1.4. CDC Biofilm Reacto
Page 66 and 67: Chapter 2 can be performed without
Page 68 and 69: Chapter 2 To summarise, previous au
Page 70 and 71: Chapter 2 2.3. Methods for examinin
Page 72 and 73: Chapter 2 and the biofilm formed th
Page 74 and 75: Chapter 2 2.4. Statistical Analysis
Page 76 and 77: Chapter 2 Table 2.1: Strain charact
Page 78 and 79: Chapter 2 XII. The gas port and med
Page 80 and 81: Chapter 2 II. Primary fixative cons
Page 82 and 83: Chapter 2 IX. Once the conditions w
Page 84 and 85: Chapter 2 Figure 2.1: Image of CBR
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Chapter 2 2.6. Results 2.6.1. Asses
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Chapter 2 2.6.3. SEM Analysis of su
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Chapter 2 Figure 2.6: Complete remo
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Chapter 2 2.6.5. Mean log 10 densit
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Chapter 2 2.6.6. Mean log 10 densit
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Chapter 2 Table 2.5: Mean log 10 de
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Chapter 2 The results displayed in
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Chapter 2 Table 2.7: Difference bet
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Chapter 2 Table 2.8: The mean log 1
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Chapter 2 Figure 2.7: Graph of the
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Chapter 2 also used “high” soni
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Chapter 2 2.8. Summary All 13 strai
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Chapter 3 3. Abstract It has been e
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Chapter 3 classified as persistent
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Chapter 3 was plated onto TSA for e
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Chapter 3 Figure 3.1: The mean log
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Chapter 3 Figure 3.3: SEM image of
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Chapter 3 Table 3.2: Difference bet
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Chapter 3 3.4.3. Intra-serovar vari
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Chapter 3 3.4.4. Strain variation i
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Chapter 3 3.4.5. The density of bio
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Chapter 3 3.5. Discussion As illust
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Chapter 3 As discussed in section 3
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Chapter 3 increased biofilm appeare
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Chapter 4 Examining the efficacy of
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Chapter 4 through laboratory based
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Chapter 4 acid and quaternary ammon
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Chapter 4 the surface the temperatu
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Chapter 4 availability of multiple
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Chapter 4 peracetic acid (100, 200,
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Chapter 4 As discussed previously,
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Chapter 4 Dey/Engley (Difco) neutra
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Chapter 4 sterilisation was achieve
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Chapter 4 IX. Aliquots of 100µl of
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Chapter 4 XV. XVI. XVII. XVIII. XIX
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Chapter 4 4.3. Results 4.3.1. Suspe
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Chapter 4 Table 4.3: Mean log 10 de
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Chapter 4 Benzalkonium chloride was
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Chapter 4 4.4. Discussion Suspensio
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Chapter 4 effective at eliminating
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Chapter 4 Surprisingly, Nguyen et a
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Chapter 4 though a contact time of
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Chapter 4 provide a more standardis
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Chapter 4 hours instead of the stan
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Chapter 5 5. Abstract Examining bio
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Chapter 5 dry and rough (bdar) morp
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Chapter 5 absence of curli and cell
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Chapter 5 studies such as the micro
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Chapter 5 discussed in chapter 4. T
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Chapter 5 5.2. Methods 5.2.1. Colon
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Chapter 5 XIII. XIV. XV. XVI. XVII.
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Chapter 5 XVI. XVII. XVIII. XIX. XX
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Chapter 5 5.3.2. Repeatability of m
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Chapter 5 Figure 5.2: Stained biofi
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Chapter 5 was formed at room temper
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Chapter 5 Table 5.3: The density of
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Chapter 5 5.3.4. The density of bio
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Chapter 5 Table 5.6: The difference
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Chapter 5 Table 5.7: The difference
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Chapter 5 Table 5.8: Summary of ass
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Chapter 5 interpretation therefore
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Chapter 5 measures of S. enterica b
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Chapter 5 cells peaks [165, 191]. D
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Chapter 5 5.5. Limitations of the s
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Chapter 6 Discussion of S. enterica
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Chapter 6 However, a number of auth
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Chapter 6 It is of interest to exam
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Chapter 6 were similar at 48 hours.
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Chapter 6 attributable to a small n
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Chapter 6 chosen as an appropriate
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Chapter 6 undetermined. However, th
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Chapter 6 reason for this may be du
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Chapter 6 Moreover, based on the re
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Chapter 6 responsible for increased
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Chapter 6 not fully capture the ran
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Chapter 6 However, the extent of bi
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Chapter 6 6.10. Conclusions and rec
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Chapter 6 studies may solve some of
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Bibliography Bibliography Page 221
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Bibliography 12. T. Takata, J.L., H
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Bibliography 29. Barker, J., M. Nae
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Bibliography 47. Threlfall, E.J., H
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Bibliography 65. CDC. Investigation
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Bibliography 83. Ledeboer, N., Frye
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Bibliography 100. Chia, T., Goulter
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Bibliography 117. Buckingham-Meyer,
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Bibliography 133. European Committe
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Bibliography Supernatant of a Hafni
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Bibliography 165. Díez-García, M.
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Bibliography cultivation of Staphyl
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Bibliography Compounds. 2012. Appli
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Bibliography 215. Buck, et al., A q
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Bibliography Canadian Journal of Ps
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Appendix 1 Appendix 1— List of Re
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Appendix 1 Appendix 1 - List of Equ
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Appendix 2 Colour index High outlie
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Page 280 and 281:
Page 282 and 283:
Page 284 and 285:
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Appendix 3 Appendix 3-Figure 2: PFG
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Appendix 4 Poster Presentation Envi
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