Pretend a human had their body "reflected": heart on the wrong side, etc.; but also at the biochemical level: proteins, sugars, cells, DNA, everything.
What would the effects be of that human's exposure to other Earth life?
I assume that quick death from malnutrition would be inevitable, but would there be more immediate life-threatening consequences?
Would anyone who comes into contact with the mirrored person be at risk?
Would reflected bacteria pose an immediate threat to the ecosystem?