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Nothing that I am aware of, and really, for good reason. Swarms are very powerful in the hands of the players since it is not common for the enemies to have area attacks and so are usually relegated to doing half or no damage at all with their weapons. A swarm with scaling HD is particularly terrifying because now that distraction ability has a very high DC. Players don't need swarm animal companions.
The first thing I think of is the vomit swarm and summon swarm spells, and it doesn't allow the all the time functionality that an animal companion provides. It becomes an option at third level.
You could animate a dead swarm. That would allow you to keep it around all the time. I probably go with a swarm of skeleton rats or a swarm of zombie bats. Healing it would be difficult. You could manage an all the time undead swarm yourself as a fifth level cleric/oracle, and earlier if you grab a scroll.
It doesn't level, though, and you'd likely have to replace it with better swarms like undead swarms of wasp/centipede/ant as you go.
Note that even with the summon swarm spell, the caster has no control over the warm once it has appeared.
An animal companion needs to have intelligence, something which swarms lack. IIRC even in the specific examples where vermin can become animal companions, they are imbued with intelligence in the process.