Complex sentence: If antibiotics are administered too late, even if the antibiotics eradicate the bacteria, some hosts will still die of toxemia because the toxins produced by the bacilli remain in their system at lethal dose levels.
Split into simpler sentences: If antibiotics are administered too late, even if the antibiotics eradicate the bacteria, some hosts will still die of toxemia. This is because the toxins produced by the bacilli remain in their system at lethal dose levels.