This confirms what researchers such as Dr. Martin Blaser (in his book Missing Microbes) and others (such as Drs. Sonnenburg and Sonnenburg) have been saying about antibiotic use in infants and children: that there are negative effects to the gut microbiome from antibiotic use in early childhood, and the more frequent the use, the greater the negative effects. It is because the use of antibiotics in early childhood "disrupts the microbiome".
Penicillins appear to be less disruptive, but macrolides (e.g., Clarithromycin, azithromycin) much more disruptive - the researchers found that the gut microbiota recovered within 6–12 months after a penicillin course, but did not fully recover from a macrolide course even after 2 years . Antibiotics can be life-saving, but they absolutely should not be used casually because there are hidden costs (such as microbiome changes). From Medical Xpress:
The use of antibiotics in early childhood interferes with normal development of the intestinal microbiota, shows research conducted at the University of Helsinki. Particularly the broad-spectrum macrolide antibiotics, commonly used to treat respiratory tract infections, have adverse effects. Macrolides appear also to contribute to the development of antibiotic-resistant strains of bacteria. ...continue reading "Childhood Antibiotic Use Disrupts Gut Microbiome"