Figure 4.

Antibiotic treatment and L. reuteri abundance in faeces of the L. reuteri-supplemented group. L. reuteri abundance in faeces of L. reuteri-supplemented extremely preterm ELBW infants at one (a), two (b), three (c), and four (d) weeks of age, who were not (grey dots) or were (red dots) treated with antibiotics for at least one day during the week preceding faecal sampling. Abundance is expressed as L. reuteri bacteria per 1 g wet faeces. Boxplots show median with 25% and 75% percentiles and 1.5× the interquartile range. For graphical display, the number of L. reuteri bacteria per 1 g wet faeces was set to 10⁰ for infants with L. reuteri-negative faeces. Numbers below the panels indicate the number of infants in the respective group. This figure only shows antibiotics, for which the sample size at any week was at least 10, while data on less common antibiotics are presented in Table S5. Statistics: Mann–Whitney U test with Benjamini–Hochberg correction. * adjusted p < 0.05, ** adjusted p < 0.01. ELBW = extremely low birth weight.