Bacteria are present in most of the Earth's habitats, frequently living in a symbiotic relationship with other organisms, benefiting humans, plants and animals. But not all bacteria are so helpful. Some can cause infectious diseases, thus changing the relationship into pathogenic and parasitic. The most common solution has been antibiotic. But they come with their own set of problems and side effects - most importantly they also kill the 'good' bacteria, thus destabilising organisms' natural microbiota.