Chronic exposure to ampicillin alters lung microbial composition in laboratory rat.

Purpose: High-throughput sequencing technologies have revealed that the lungs contain a variety of low biomass microbiota associated with various lung diseases. Rat model is an important tool to understand the possible causal relationship between pulmonary microbiota and diseases. Antibiotic exposure can alter the microbiota, however, a direct influence of long-term ampicillin exposure on commensal bacteria of healthy lungs has not been investigated, which could be useful in the study of the relation between microbiome and long-term lung diseases, especially in animal model-making of lung diseases.

Methods: The rats were aerosolized ampicillin of different concentrations for five months, and then the effect on the lung microbiota was investigated using 16S rRNA gene sequencing.

Results: The ampicillin treatment by a certain concentration (LA5, 0.2 ml of 5 mg/ml ampicillin) administration leads to profound changes in the rat lung microbiota but not in the low critical ampicillin concentration (LA01 and LA1, 0.1 and 1 mg/ml ampicillin), when compared to the untreated group (LC). The genus Acidobacteria_Gp16 dominated the ampicillin treated lung microbiota while the genera Brucella, Acinetobacter, Acidobacteria_Gp14, Sphingomonas, and Tumebacillus dominated the untreated lung microbiota. The predicted KEGG pathway analysis profile revealed some difference in the ampicillin treated group.

Conclusions: The study demonstrated the effects of different concentrations of ampicillin treatment on lung microbiota of rats in a relatively long term. It could serve as a basis for the clinical use of antibiotic and the use of ampicillin to control certain bacteria in the animal model-making of respiratory diseases such as chronic obstructive pulmonary disease.