Parenteral long-acting amoxicillin reduces intestinal bacterial community diversity in piglets even 5 weeks after the administration

Abstract

We investigated the long-term effects of a single intramuscular administration of amoxicillin (15 mg kg1) 1 day after birth, on piglet intestinal microbiota. Animals received no creep feed before weaning on day 28 of age. For the next 11 days, the piglets received a wheat-barley-based diet. Colon digesta samples were collected on day 39 and subjected to denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments. DGGE fingerprint diversity indices differed between the group treated with amoxicillin and the untreated group (0.80.19 and 1.030.17, respectively, P0.012). Reamplification and sequencing of two bands present in all samples revealed that a Roseburia faecalis-related population was strongly reduced in relative abundance (98% identity) in the treated group, while an enterobacterial population with 100% identity to Shigella spp., Escherichia coli and Salmonella enterica serovar Typhi was enriched. A band corresponding to Lactobacillus sobrius was present only in the control group. The protective effect of prophylactic antibiotic administration may be outweighed by the long-lasting disturbance of the gut ecosystem. © 2007 International Society for Microbial Ecology All rights reserved.