According to the World Health Organization (WHO) emergence of antibiotic-resistant 'superbugs' is now a global concern, which can spell the end of modern medicine and a return to the days when routine operations, simple wounds or straightforward infections were potentially life-threatening. On the other hand scientists have come to realize that the vast majority of bacteria is beneficial and should be left intact. Antibiotics do not distinguish between bad and good bacteria and their use can lead to side effects and resistance.