No significant difference between Ceftriaxone and Cefotaxime on the emergence of antibiotic resistance in the gut microbiota of hospitalized patients: a pilot study

Abstract Background Ceftriaxone and cefotaxime share a similar antibacterial spectrum and similar indications but have different pharmacokinetic characteristics. Ceftriaxone is administered once daily and 40% of its clearance is by biliary elimination, whereas cefotaxime requires three administrations per day and shows less than 10% biliary elimination. The high biliary elimination of ceftriaxone suggests a greater impact of this antibiotic on the gut microbiota than cefotaxime. Objectives The objective of our study was to compare the impact of ceftriaxone and cefotaxime on the gut microbiota Patients and methods We performed a prospective clinical trial that included 55 patients treated with intravenous ceftriaxone (1 g/24 h) or cefotaxime (1 g/8 h) for at least three days. We collected three fresh stool samples from each patient (days 0, 3, and 7 or at the end of intravenous treatment) to assess the emergence of third-generation cephalosporine (3GC)-resistant Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, Pseudomonas aeruginosa, toxigenic Clostridioides difficile, and vancomyci-resistant Enterococci. Results The emergence of 3GC-resistant Gram-negative enteric bacilli (Enterobacteriaceae) (5.9% vs. 4.7%, p > 0.99), Enterococcus spp., or non-commensal microorganisms was not significantly different between the groups. Both antibiotics reduced the counts of total Gram-negative enteric bacilli and decreased the cultivable diversity of the microbiota but the differences between the groups were not significant. Conclusion No significant difference was observed between ceftriaxone and cefotaxime in terms of emergence of resistance