In those with infection dominated by organisms other than P. aeruginosa , erythromycin caused a significant change in microbiota composition ( p = @ -LSB- by analysis of similarity -RSB- ) , representing a reduced relative abundance of Haemophilus influenzae ( @ % -LSB- @-@ -RSB- vs @ % -LSB- @-@ -RSB- ; median difference @ % , @ % CI @-@ ; p = @ ; interaction p = @ ) and an increased relative abundance of P aeruginosa ( @ % -LSB- @-@ -RSB- vs @ % -LSB- @-@ -RSB- ; median difference @ % , @ % CI @-@ ; p = @ ; interaction p = @ ) .