Bacterial Contamination is very well known for its creepy PV, but many people have known its deeper meaning.

As many people have suggested, its about bullying, hence the words at the start where they say that they will harrass her and everyone who has anything to do with her (Correct me if I'm wrong XD). This shows a case of verbal bullying.

Bacterial Contamination is used by Miku (Or Calne Ca) to describe how she feels about the bullying.

So, running through the song, people bully her verbally for whatever reason and she feels like a bacterial contamination: unwanted, but there is another reason for this, which will be explained soon. As she gets bullied, there is that one person who steps up and helps her. They become friends, but she still feels upset about the bullying and decides to bully someone else to make her feel better. This is another meaning to the term "Bacterial contamination" as she is "spreading the bacteria", meaning that she is making people feel the way she had felt. She continues on like this, felling better temporarily. After a while, every one is afraid of her or something like that, and she realises that she is alone once more. She cant handle this, maybe because she doesnt want to be alone anymore, so she decides to kill herself to end her lonliness.

You may already know this and thats great, but i also want to explain the PV.

Yes, everyone who knows Vocaloid knows that this PV is creepy shit, but there is actually some symbolism in the PV.

For starters, Calne Ca.

She is really creepy, but, as you all know, she is the representation of what the girl (In this case Miku) feels about herself. A self image like that could've lowered her self essteem so much, that she felt the need to bully others.

Another one of these 'characters' that i would like to explain is the girls with the top parts of their faces removed. The symbolism in that is the fact that people are verbally bully her. They also appear to be laughing at her, pointing fingers. That shows the teasing and demeaning that they are doing to her.

Another thing, the background. It looks very dark, the forest with sharp trees looks pretty scary. It probably represents her pain, as in the end, it turns to normal as she comitted suicide.

So, now, go... watch the PV with this new found information.

 A/N: So, there's the explanation for the song Bacterial Contamination ^.^ Feel free to request any song you want to see my veiw on. Oh, and if you are the ones who posted those YouTube comments on any version of the song, thnx for giving me ideas :D