Effects of enrofloxacin administered subcutaneously or orally on the fecal microbiota of chinchillas (chinchilla lanigera)

Background

The gastrointestinal microbiota plays a vital role in the digestion of chinchillas. Antibiotics may exert negative effects on the gut microbiota, with relatively limited research conducted on chinchillas in this regard. This pilot study aimed to assess the effects of enrofloxacin via subcutaneous injection or oral administration on the fecal microbiota of chinchillas.

Methods

In a prospective, randomized, blinded, before and after experiment, nine healthy adult chinchillas were randomly assigned to one of three groups receiving no treatment (n = 3), enrofloxacin injection administered subcutaneously (SC) at 10 mg/kg (q12h, for 5 days, n = 3) and enrofloxacin tablet administered orally (PO) at 10 mg/kg (q12h, for 5 days, n = 3). Fecal samples collected from each group on Day 0, Day 6 and Day 14 underwent 16S rRNA sequencing and the results were statistically analyzed.

Results

The richness of the fecal microbiota was significantly decreased by Day 14 after administration of enrofloxacin in both SC and PO groups, but there was no significant difference between these two groups. Complete separations of bacterial composition were also observed in the PCoA and NMDS plots in PO group between Day 6 and Day 0, in SC group between Day 14 and Day 0. Significant changes in the relative abundance of dominant microbiota at both phylum and genus levels were noted on Day 14 in PO group. Specifically, there were significantly increased in the abundance of genus Bacteroides and norank_f_Oscillospiraceae. No significant changes in the dominant taxa were seen in SC group.

Conclusions

Enrofloxacin at 10 mg/kg SC or PO q12h for 5 days led to a significant decrease in the fecal microbiota diversity and alternations in its composition. Oral administration of enrofloxacin had a more significant effect on specific dominant taxa than subcutaneous injection, although the result needs to be interpreted cautiously as it is possible that the observed changes in microbiome could be due to the stress related to the administration process. Obvious clinical impact was not observed in any of the groups during the study. Therefore, administration of enrofloxacin at 10mg/kg SC and PO q12h for 5 days were both considered clinically safe.