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Chapter 2 can be performed without the labour intensive process within a closed sterile environment. The handling of the surfaces for enumeration of viable cells also allows an opportunity for contamination if aseptic techniques are not maintained. 2.1.6. Reproducibility of biofilm studies using the CBR In addition to examining biofilm density on multiple surfaces and using multiple strains it is also important to investigate the limits of intralaboratory reproducibility derived from repeated experiments. Reproducibility is frequently represented through the use of the standard deviation (SD). In similar research using the CBR and polycarbonate as a biofilm substrata Goeres et al. found the SD of the mean log 10 density to be 0·30 for Klebsiella pneumoniae, 0·22 for Streptococcus pneumoniae and 0·17 for Pseudomonas aeruginosa [72]. Goeres and colleagues investigated intra-laboratory reproducibility (also referred to as repeatability) and the impact of altering the conditions such as flow rate, media concentration and stir rate. In total 21 experiments were performed and the results were assessed on triplicate coupons taken at random from each run. Replicate experiments were undertaken to investigate the reproducibility under each alternative set of conditions. Goeres found that overall that altering the conditions slightly such as 2°C temperature change or 10% reduction in concentration of media did not significantly reduce the density of biofilm formed on the surface [72]. Buckingham-Meyer et al. also compared the SD of measures of S. pneumoniae and P. aeruginosa biofilm density attached to glass coupons using the CBR model and four other biofilm models [117]. All experiments repeated in duplicate with two glass coupons used in each experiment for all models (n=4). The other models included a drip-flow reactor model (inoculum flowed over the coupons using syringe device), a static biofilm model (inoculum infused in solid media in contact with the surface over Page 45
Chapter 2 time) and a dried biofilm (cell suspension and organic substances were dried onto the surface to simulate organic soil). The comparative work also incorporated a dehydrated biofilm model where the coupons were released from the CBR and dried in a petri-dish over a 2 hour period. The SD for the mean log 10 density of cells on the two glass coupons was 0.211 and 0.224 for P. aeruginosa and S. pneumoniae biofilm respectively [117]. When examining P. aeruginosa biofilm density, the CBR model had a lower SD than the drip-flow (SD of 0.788), the dehydrated biofilm (0.548) and dried surface biofilm (0.435), but a slightly higher SD than the static biofilm (0.208). The S. pneumoniae biofilm density assessed in the CBR had a lower SD than the drip flow (SD of 0.586), the static biofilm (0.330) and the dehydrated biofilm (0.322). The dried surface biofilm had a lower SD (0.157) [117]. Donlan et al. described the assessment of S. pneumoniae biofilm density in situ and in real time using the CBR model [124]. The biofilm was developed on germanium coupons and biofilm cell density was measured using the plate count technique after 21, 45, 69, 141 and 189 hours development. The mean log 10 density and SD was calculated from 3 replicate coupons, with 2 coupons used to calculate the SD of the 141 hours incubation time. There was no indication if the replicate coupons were taken from the single or multiple runs using the CBR. The SD for biofilm density was between 0.06-0.34 for the five time points [124]. Hadi et al. used X-ray diffraction, spectroscopy and SEM to examine the density of P. aeruginosa biofilm formed on plastic (polytetrafluoroethylene) coupons using the CBR [123]. Hadi et al. reported an SD of 0.655 through crystal violet staining and measurement of the biofilm through a commercial assay used to quantify the volume of proteins remaining on the surface. The SD was calculated on 9 coupons from each run, performed in triplicate (n=27) [123]. Page 46
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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
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 36 and 37: Chapter 1 isolated from undercooked
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 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
Page 86 and 87: Chapter 2 2.6. Results 2.6.1. Asses
Page 88 and 89: Chapter 2 2.6.3. SEM Analysis of su
Page 90 and 91: Chapter 2 Figure 2.6: Complete remo
Page 92 and 93: Chapter 2 2.6.5. Mean log 10 densit
Page 94 and 95: Chapter 2 2.6.6. Mean log 10 densit
Page 96 and 97: Chapter 2 Table 2.5: Mean log 10 de
Page 98 and 99: Chapter 2 The results displayed in
Page 100 and 101: Chapter 2 Table 2.7: Difference bet
Page 102 and 103: Chapter 2 Table 2.8: The mean log 1
Page 104 and 105: Chapter 2 Figure 2.7: Graph of the
Page 106 and 107: Chapter 2 also used “high” soni
Page 108 and 109: Chapter 2 2.8. Summary All 13 strai
Page 110 and 111: Chapter 3 3. Abstract It has been e
Page 112 and 113: Chapter 3 classified as persistent
Page 114 and 115: 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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Appendix 3 Appendix 3-Figure 2: PFG
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Appendix 4 Poster Presentation Envi
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