No changes in levels of bone formation and resorption markers following a broad-spectrum antibiotic course

Intestinal bacteria influence bone remodeling in rodents, and antibiotic manipulation of the rodent gut microbiota increases bone formation and prevents ovariectomy-induced bone loss. In theory, these effects may be mediated by changes in sex hormone biotransformation in the gut, gut serotonin secretion or nutrition-induced secretion of glucagon-like peptide 2 (GLP-2) and glucose-dependent insulinotropic hormone (GIP). Antibiotics change the human gut microbiota, but the effect of antibiotic treatment on human bone turnover is unknown.

We analyzed serum levels of bone turnover markers, serotonin, GLP-2 and sex hormones before, immediately after, and eight, 42 and 180 days after a 4-day per oral antibiotic cocktail (vancomycin 500 mg, gentamycin 40 mg and meropenem 500 mg once-daily) in twelve healthy adult males. Fasting and meal-stimulated procollagen type I amino-terminal propeptide (P1NP), C-telopeptide of type I collagen (CTX) and osteocalcin levels were measured.

While the antibiotic course reduced the stool abundance and composition of anaerobic bacteria as confirmed by cultivation studies, neither short nor long-term alterations in serum P1NP, CTX and osteocalcin were observed. Furthermore, we did not observe any changes in levels of serum GLP-2, serotonin or sex hormones.

Eradication of anaerobic bacteria from healthy adult males had no effect on serum bone turnover markers.