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Chapter 5 studies such as the microtitre plate based system [82, 86, 96, 159]. As previously discussed Solomon et al. [96] and Castelijn et al. both [159] used the microtitre plate method to correlate rdar morphology and biofilm density. Castelijn and colleagues also found there was no significant difference between the density of biofilm formed on stainless steel coupons or plastic surfaces (using the microtitre plate method) [159]. However, the author found there were intra- and inter-serovar differences in the density of biofilm formed on the surface particularly for S. Typhimurium and S. Infantis [159]. In addition, Castlelijn et al. also found that when biofilm was assessed using a Live/Dead® fluorescent stain that biofilm density peaked after 24 hours incubation and declined in viable cells over the remaining 14 days. However, measurement of bacterial attachment to the surface after 24 hours may only reflect planktonic cell attachment as opposed to formed biofilm. Previously published research in this area used incubation times of ≥48 hours [56, 96, 111, 227]. Similar to Castelijn et al. [159], Díez-García et al. used a short incubation time of 24 hours to investigate biofilm density of 69 S. enterica strains using a microtitre plate based system and confocal microscopy [165]. Díez- García et al. reported that biofilm formation was influenced by the Salmonella serotypes, with the strains of S. Agona (n=3) and S. Typhi (n=1) forming a more dense biofilm than most other serovar groups including S. Enteritidis (n=36) and S. Typhimurium (n=3). Bridier et al. also used a microtitre plate method to quantify biofilm formation for ten strains of S. enterica and 5 other bacterial species [178]. The strains of S. enterica included S. Agona (n=1), S. Enteritidis (n=1), and S. Typhimurium (n=2). Bridier and colleagues combined the used of the microtitre plate method with the use of confocal microscopy to measure biofilm density and assess the biofilm structure for the sixty bacterial Page 159
Chapter 5 strains. However the method used by Bridier et al. differs substantially from other methods described in this chapter. In order, to attach a dye (Syto9 – green fluorescent nucleic acid marker), the bacterial attachment was interrupted after 1 hour when the wells were rinsed with 150mM of sodium chloride to eliminate any non-adherent cells. This was followed by adding sterile TSB and 5µl Syto9 to wells of the microtitre plate after which the plates were incubated for 24 hours at 30°C to allow biofilm development. This method is similar to that described by Peeters et al. who used a 4 hour initial incubation period before rinsing the wells of a microtitre plate when using a crystal violet and Syto 9 to quantify biofilm formation of clinically associated organisms [229]. As previously described in chapter 3, Vestby et al. used the microtitre plate method and a pellicle formation assay to investigate the biofilm forming capability of 21 S. enterica strains including S. Agona, S. Montevideo, S. Senftenberg and S. Typhimurium [56]. They concluded that particular strains which persisted in the environment were able to form a more dense biofilm than the other strains examined. Moreover, the results indicated that using this method, S. Agona and S. Montevideo strains formed a more dense biofilm than S. Typhimurium and S. Senftenberg [56]. 5.1.4. Assessing the efficacy of disinfectants using the microtitre plate method Although there is a substantial body of literature investigating Salmonella biofilm formation using the microtitre plate method in most instances the research is switched to detachable surfaces once large scale screening is complete and the research moves into disinfectant assays [56, 113, 134, 159, 227, 230]. Disinfectant assays are frequently performed on detachable surfaces suitable for traditional methods of plate count enumeration as Page 160
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Salmonella enterica - biofilm forma
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Table of Contents Page Number 1.16.
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Table of Contents Page Number 4.1.2
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Table of Contents Page Number 6.8.4
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List of Abbreviations Table Page Nu
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List of Abbreviations List of Abbre
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Summary of Content Summary of Conte
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“To show your true ability is alw
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Acknowledgements ever met, Fiona th
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Acknowledgements This Ph.D. thesis
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Chapter 1 1.1. Salmonella Salmonell
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Chapter 1 may impose enormous costs
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Chapter 1 cracks or penetration of
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Chapter 1 detected by agglutination
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Chapter 1 become colonized with >10
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Chapter 1 antigens [z27],[z45] [1].
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Chapter 1 S. Agona has also been im
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Chapter 1 isolated from undercooked
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Chapter 1 The S. Typhimurium strain
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Chapter 1 ecosystem with the use of
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Chapter 1 [82]. Previous research h
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Chapter 1 to genes involved in flag
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Chapter 1 observation has also been
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Chapter 1 [119] and flow cell react
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Chapter 1 based disinfectant) the s
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Chapter 1 formation of two strains
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Chapter 1 shield the S. Agona cells
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Chapter 1 Key Objectives of this st
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Chapter 2 2. Abstract Food-borne pa
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Chapter 2 indicated that there may
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Chapter 2 taken from industrial set
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Chapter 2 2.1.4. CDC Biofilm Reacto
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Chapter 2 can be performed without
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Chapter 2 To summarise, previous au
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Chapter 2 2.3. Methods for examinin
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Chapter 2 and the biofilm formed th
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Chapter 2 2.4. Statistical Analysis
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Chapter 2 Table 2.1: Strain charact
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Chapter 2 XII. The gas port and med
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Chapter 2 II. Primary fixative cons
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Chapter 2 IX. Once the conditions w
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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
Page 130 and 131: Chapter 3 As discussed in section 3
Page 132 and 133: Chapter 3 increased biofilm appeare
Page 134 and 135: Chapter 4 Examining the efficacy of
Page 136 and 137: Chapter 4 through laboratory based
Page 138 and 139: Chapter 4 acid and quaternary ammon
Page 140 and 141: Chapter 4 the surface the temperatu
Page 142 and 143: Chapter 4 availability of multiple
Page 144 and 145: Chapter 4 peracetic acid (100, 200,
Page 146 and 147: Chapter 4 As discussed previously,
Page 148 and 149: Chapter 4 Dey/Engley (Difco) neutra
Page 150 and 151: Chapter 4 sterilisation was achieve
Page 152 and 153: Chapter 4 IX. Aliquots of 100µl of
Page 154 and 155: Chapter 4 XV. XVI. XVII. XVIII. XIX
Page 156 and 157: Chapter 4 4.3. Results 4.3.1. Suspe
Page 158 and 159: Chapter 4 Table 4.3: Mean log 10 de
Page 160 and 161: Chapter 4 Benzalkonium chloride was
Page 162 and 163: Chapter 4 4.4. Discussion Suspensio
Page 164 and 165: Chapter 4 effective at eliminating
Page 166 and 167: Chapter 4 Surprisingly, Nguyen et a
Page 168 and 169: Chapter 4 though a contact time of
Page 170 and 171: Chapter 4 provide a more standardis
Page 172 and 173: Chapter 4 hours instead of the stan
Page 174 and 175: Chapter 5 5. Abstract Examining bio
Page 176 and 177: Chapter 5 dry and rough (bdar) morp
Page 178 and 179: Chapter 5 absence of curli and cell
Page 182 and 183: Chapter 5 discussed in chapter 4. T
Page 184 and 185: Chapter 5 5.2. Methods 5.2.1. Colon
Page 186 and 187: Chapter 5 XIII. XIV. XV. XVI. XVII.
Page 188 and 189: Chapter 5 XVI. XVII. XVIII. XIX. XX
Page 190 and 191: Chapter 5 5.3.2. Repeatability of m
Page 192 and 193: Chapter 5 Figure 5.2: Stained biofi
Page 194 and 195: Chapter 5 was formed at room temper
Page 196 and 197: Chapter 5 Table 5.3: The density of
Page 198 and 199: Chapter 5 5.3.4. The density of bio
Page 200 and 201: Chapter 5 Table 5.6: The difference
Page 202 and 203: Chapter 5 Table 5.7: The difference
Page 204 and 205: Chapter 5 Table 5.8: Summary of ass
Page 206 and 207: Chapter 5 interpretation therefore
Page 208 and 209: Chapter 5 measures of S. enterica b
Page 210 and 211: Chapter 5 cells peaks [165, 191]. D
Page 212 and 213: Chapter 5 5.5. Limitations of the s
Page 214 and 215: Chapter 6 Discussion of S. enterica
Page 216 and 217: Chapter 6 However, a number of auth
Page 218 and 219: Chapter 6 It is of interest to exam
Page 220 and 221: Chapter 6 were similar at 48 hours.
Page 222 and 223: Chapter 6 attributable to a small n
Page 224 and 225: Chapter 6 chosen as an appropriate
Page 226 and 227: Chapter 6 undetermined. However, th
Page 228 and 229: 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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Appendix 3 Appendix 3-Figure 2: PFG
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Appendix 4 Poster Presentation Envi
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