How did the dysbiosis index compare between the CIE and control dogs for the overall population, and what about the individual bacterial taxa?

• A. DI significantly higher in CIE; individual taxa not significantly different
• B. DI significantly higher in CIE; individual taxa significantly different
• C. DI lower in CIE; individual taxa not significantly different
• D. DI not different; individual taxa significantly different

Answer: (A)

The main idea here is that the dysbiosis index (DI) is a combined measure of how much the gut microbiome as a whole deviates from a healthy baseline. A higher DI means a greater overall disruption in the microbial community, not just a change driven by one or two taxa.

In this scenario, the DI was significantly higher in dogs with CIE compared with controls when looking at the entire study population. That tells us that CIE dogs, on average, have a more disrupted gut microbiome overall.

However, when each bacterial taxon is examined individually, none showed a significant difference between CIE and control groups. This can happen because the dysbiosis is distributed across many taxa, with small shifts in multiple organisms that, taken together, raise the DI, but individually each taxon doesn’t reach statistical significance after correcting for multiple comparisons. It can also reflect variability between dogs or limited statistical power to detect small effects in single taxa.

So, the overall community is more dysbiotic in the disease group, even though no single bacterial taxon stands out as significantly different.