Of what consequences is the antibiotic therapy for gut microbiota composition? Established dogma that extensive is only partially correct. We have shown in chickens that two days after the administration of antibiotics, the differences in gut microbiota are indeed extensive. However, the differences started to disappear in the following days and original microbiota composition began to restore when the chickens were still under the therapy (for additional information click here). Antibiotic therapy therefore led to a selection of resistant clones in each of original microbiota member. One week after withdrawal of the therapy we were unable to differentiate treater and not treated chicken according to their gut microbiota composition. Such findings are consistent with general well-known facts. First, antibiotic therapy helps in curing of bacterial infections. If antibiotics were of seriously negative impact, this would have been already discussed. Secondly, antibiotic therapy will never eradicate all bacteria from the intestinal tract and when the therapy is over, decreased numbers of each of the original microbiota members will quickly allow for the recovery and restoration of the original population.
However, above mentioned facts are valid for a single antibiotic therapy in otherwise healthy individual. Antibiotic therapy repeated in short intervals, repeated with different types of antibiotics, is of much extensive consequence on gut microbiota composition as well as overall health status of treated individuals and has to be seriously considered.