Comparison of the Microplate-Test and the conventional method.

<p>Part A shows the degree of susceptibility for infection by phage 1 of isolates from the four susceptibility ranks. (a,b,c,d: significance, p<0.005). Part B shows the degree of susceptibility for infection by phage 2 of Isolates from the four susceptibility ranks. (a,b,c,d: significance, p<0.02). Part C shows the degree of susceptibility for infection by phage 5 of Isolates from the four susceptibility ranks. (a,b,c: significance, p<0.003). Part D shows the degree of susceptibility for infection by phage 13 of Isolates from the four susceptibility ranks. (a,b: significance, p<0.02).</p

Emergence of less susceptible/resistant <i>Campylobacter</i> isolates.

<div><p>Part A shows the percentage of isolates from the cocktail treated group of trial I with reduced susceptibility against the individual phages and the cocktail. Data for phage 5 on day 14 after treatment are lacking.</p> <p>Part B shows the percentage of isolates from the cocktail treated group of trial II that are resistant to infection by the individual phages and the cocktail.</p> <p>Part C shows the percentage of isolates from the single phage treated group of trial II that are resistant to infection by phage 1 or the cocktail. Resistance for phages 2, 5 and 13 was not separately tested for this group.</p></div

<i>Campylobacter</i> counts, phage counts and bacterial phage susceptibility of the unintentional phage infected control group of trial I.

<p>The bars show the percentage of <i>Campylobacter</i> isolates that were less susceptible to the represented phages. The lines show the corresponding <i>Campylobacter</i> counts and the unwanted phage infection. The detection of phages coincided with loss of phage susceptibility and a decrease of <i>Campylobacter</i> counts in the control group of trial I.</p

Comparison of Microplate-Test and conventional method.

1<p>EOP = Efficiency of Plating.</p

Examples of the four susceptibility ranks in the Microplate-Test.

<p>The pictures show a close up view of the four susceptibility ranks (from left to right): rank 0 = confluent lysis, high susceptible; rank 1 = semiconfluent lysis, susceptible; rank 2 = single plaques, reduced susceptible; rank 3 = no plaques, low susceptible and resistant.</p

Interpretation key of Microplate-Test.

<p>Interpretation key of Microplate-Test.</p

Influence of phage resistant bacteria on the reduction potential of phages.

<div><p>Comparison of the mean <i>Campylobacter</i> level of i) treated birds harboring a pure susceptible <i>Campylobacter</i> population ii) treated birds harboring resistant isolates and iii) untreated birds.</p> <p>For the birds harbouring resistant isolates (ii) two mean counts were calculated: the mean of the <i>Campylobacter</i> counts, including the resistant isolates and the mean of the <i>Campylobacter</i> counts after deducting the resistant subpopulation.</p></div

Reisolation of phages.

<div><p>Part A shows the percentage of phage positive birds for each treated group.</p> <p>Part B shows the mean phage count (log₁₀) of the positive birds for each treated group.</p> <p>dpa = <u>d</u>ays <u>p</u>ost phage <u>a</u>pplication.</p></div

Phage-susceptibility of <i>C. jejuni</i> strain 1474-06.

<p>Part A and B show the rate (%) of <i>Campylobacter</i> isolates belonging to the respective rank before and after phage treatment. Part A shows the susceptibility pattern of <i>C. jejuni</i> against four different phages without phage treatment. Hundred isolates of the original strain were examined in the Microplate-Test. Part B shows the susceptibility pattern of reisolated <i>C. jejuni</i> against four different phages after phage treatment <i>in vivo</i> in the intestinal tract of broilers. Eight hundred isolates were examined in the Microplate-Test. Part C shows the development of susceptibility of <i>C. jejuni in vivo</i> after phage treatment over the course of time. The graph shows the rate of isolates in rank 3 representing low susceptible and resistant isolates for the phage cocktail on each day of sampling. Part D shows the susceptibility of <i>Campylobacter</i> isolates originating from one chicken. The bars show the percentage of chicken, harbouring isolates with i) only similar susceptibility as the original strain ii) broad scattering susceptibility and iii) only low susceptibility or resistance.</p

<i>Campylobacter</i> counts of birds harboring different amounts of phage resistant bacteria.

<p>All birds from the treated groups were categorized into four groups, depending on the amount of phage resistant <i>Campylobacter</i> isolates in their ceca (measured as SMean).</p