This article helps to demonstrate that it doesn't take the elimination of major species in the gut to cause major imbalances, as minor species can act as a keystone keeping everything functioning normally. Destroy one of these vital species via antibiotic use and the whole body will suffer.
Importance of rare microbial species is much greater than you thinkhttps://www.sciencedaily.com/releases/2017/03/170303131023.htm