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View/Open - ARAN - National University of Ireland, Galway

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Chapter 2<br />

2.6.4. Mean log 10 density <strong>of</strong> S. enterica bi<strong>of</strong>ilm<br />

Each surface type was tested using 3 coupons from each <strong>of</strong> 3 CBR runs (9<br />

coupons in total) for all strains. As previously discussed S. Typhimurium LT2<br />

was not completely removed from the surfaces via sonication. Therefore<br />

the mean log 10 density results for this strain are not incorporated into any<br />

comparative work. However the mean log 10 density <strong>of</strong> cells removed from<br />

the surfaces are listed in Table 2.4 to demonstrate dense bi<strong>of</strong>ilm recovered<br />

from the surfaces despite incomplete removal.<br />

The layout <strong>of</strong> the results is based on the aims <strong>of</strong> the project outlined in<br />

chapter one. Firstly to investigate if the S. Agona strains SAGOXB.0066<br />

formed a more dense bi<strong>of</strong>ilm than other variants <strong>of</strong> S. Agona. To achieve<br />

this aim the bi<strong>of</strong>ilm density <strong>of</strong> the S. Agona strains linked to the<br />

SAGOXB.0066 outbreak were compared to investigate if the strains were<br />

similar. Secondly the S. Agona strain S08-0601 linked to the outbreak was<br />

chosen as a representative strain to compare to the non outbreak related S.<br />

Agona strains. The mean log 10 density <strong>of</strong> S. Agona cells recovered from the<br />

surfaces is discussed in section 2.6.5.<br />

In order to investigate if S. Agona formed a more dense bi<strong>of</strong>ilm than other<br />

serovar commonly associated with food-borne outbreaks, the S.<br />

Typhimurium (section 2.6.6) and S. Enteritidis (section 2.6.7) strains were<br />

compared to each other to investigate any intra-serovar differences<br />

between the strains. The mean log 10 density for each serovar was then<br />

examined as described in section 2.6.8.<br />

The density <strong>of</strong> S. enterica bi<strong>of</strong>ilm attached to the surfaces was examined in<br />

order to investigate if particular surface had a higher propensity to support<br />

bi<strong>of</strong>ilm growth (section 2.6.9). The relationship between surface roughness<br />

and bi<strong>of</strong>ilm density was also investigated in section 2.6.10.<br />

Page<br />

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