Prolonged use of broad-spectrum
tetracycline antibiotics such as
minocycline and
doxycycline may significantly alter the gut and skin microbiome leading to
dysbiosis.
Sarecycline, a narrow-spectrum
tetracycline-class
antibiotic used for
acne treatment, is hypothesized to have minimal impact on the gastrointestinal tract microbiota. We evaluated the effect of
sarecycline compared to
minocycline against a panel of microorganisms that reflect the diversity of the gut microbiome using in vitro minimum inhibitory concentration (MIC) and time-kill kinetic assays. Compared to
minocycline,
sarecycline showed less antimicrobial activity indicated by higher MIC against 10 of 12 isolates from the Bacteroidetes phylum, three out of four isolates from Actinobacteria phylum, and five of seven isolates from the Firmicutes phylum, with significantly higher MIC values against Propionibacterium freudenreichii (≥3 dilutions). In time-kill assays,
sarecycline demonstrated significantly less activity against Escherichia coli compared to
minocycline at all time-points (p < 0.05). Moreover,
sarecycline was significantly less effective in inhibiting Candida tropicalis compared to
minocycline following 20- and 22-h exposure. Furthermore,
sarecycline showed significantly less activity against Lactobacillus paracasei (recently renamed as Lacticaseibacillus paracasei subsp. paracasei) (p = 0.002) and Bifidobacterium adolescentis at 48 h (p = 0.042), when compared to
minocycline. Overall,
sarecycline demonstrated reduced antimicrobial activity against 79% of the tested gut microorganisms, suggesting that it is less disruptive to gut microbiota compared with
minocycline. Further in vivo testing is warranted.