There was a lack of consistency in the dosing of A+G across participants, which was dosed depending on kidney function, and in monitoring of serum drug levels. Photo Credit: CDC/Pete Wardell

Ampicillin plus ceftriaxone (A+C) was an effective treatment for penicillin-susceptible Enterococcus faecalis infective endocarditis (EFIE) when compared with ampicillin plus gentamicin (A+G), according to a retrospective cohort study published in Journal of Infection.

Data from 85 individuals diagnosed with EFIE, ≥18 years of age and treated with either A+C or A+G at Mayo Clinic campuses in Rochester, Minnesota, and Phoenix, Arizona, were analyzed and 1-year mortality, nephrotoxicity, and EFIE relapse rates were measured.

Most participants (79%) received A+G and the rest received A+C. The 1-year mortality rates were similar in both groups, 17% vs 17% (P =.982), and 1 case of relapsing EFIE occurred in each group. Those who received A+G had greater decreases in kidney function at the end of treatment as shown by greater increases in serum creatinine level compared with participants who received A+C (median interquartile range difference, +0.4 [0.2, 0.8] vs -0.2 [-0.3, 0.1] mg/dL, P ≤.001). Of note, acute kidney infection developed in 11% of participants in the A+C group compared with 25% of the A+G group.

One limitation of this study was the lack of power because of the small sample sizes in the A+C group. This may have prevented obtaining statistically significant differences between groups. In addition, there was a lack of consistency in the dosing of A+G across participants, which was dosed depending on kidney function, and in monitoring of serum drug levels. Finally, the inclusion of median serum creatinine values may comprise the outcomes of kidney function comparisons and using a 1-year cut-off for relapse rate may falsely increase the rate of relapse in the A+G group.

According to investigators, the data still suggest that A+C is a safe alternative to A+G, citing high levels of resistance to aminoglycosides and no difference in mortality. The findings also show that A+G was associated with high rates of nephrotoxicity and investigators suggest that “a clinical trial is needed to compare the 2 treatment regimens for EFIE.”