Effect of the Minimum Inhibitory Concentration of Vancomycin on the Clinical Outcome of Enterococcus faecium Bacteremia.

BACKGROUND/AIM: Vancomycin (VCM) is an antibiotic widely used in the treatment of resistant bacteria. In patients with methicillin-resistant Staphylococcus aureus (MRSA) infection, the clinical outcome differs according to the VCM minimum inhibitory concentration (MIC) of isolates. However, the effect of VCM MIC on the clinical outcome is unclear for bacterial species other than MRSA. This study evaluated the relationship between the VCM MIC and clinical outcomes in patients with Enterococcus faecium bacteremia. PATIENTS AND METHODS: This study included patients who had E. faecium detected in at least one set of blood cultures between April 2011 and March 2022. The study assessed the outcome according to the VCM MIC. The primary outcome was the 30-day mortality rate. Measures of interest included the initial serum concentration of VCM, MIC, the area under the curve (AUC), and the AUC over 24-48 hours (AUC24-48 h). RESULTS: A total of 26 patients were included in the study, of whom 5 died and 21 survived. The 30-day mortality was higher in patients with higher MICs and lower serum albumin levels. Patients with a serum albumin level <2.0 mg/dl and a MIC ≥1 µg/ml had significantly shorter survival than those who did not (p=0.013, log-rank test). CONCLUSION: The 30-day mortality rate of patients with E. faecium bacteremia is associated with the VCM MIC of E. faecium isolates and the patient's nutritional status. Patients with albumin <2 mg/dl and MIC ≥1 µg/ml may have a poor outcome and require careful clinical monitoring.

Effect of Different Approaches to Antimicrobial Therapy with Cefmetazole and Meropenem on the Time to Defervescence in Non-Severe Extended-Spectrum ß-Lactamase-Producing Escherichia coli Bacteremia.

Carbapenems are antimicrobial agents commonly used to treat extended-spectrum ß-lactamase (ESBL)-producing bacteria. Although cefmetazole (CMZ) is considered effective for ESBL-producing Escherichia coli (ESBL-EC) bacteremia, previous studies showed its limitations, including the influence of the initial antimicrobial agent. Here, we examined the effects of different approaches to antimicrobial therapy with CMZ and meropenem (MEPM) on the time to defervescence in ESBL-EC bacteremia. Notably, the influence of previous antimicrobial agents was excluded. Inpatients with ESBL-EC detected in blood cultures between April 2018 and March 2023 were included and assigned to CMZ (n = 14), MEPM (n = 8), de-escalation to CMZ (dCMZ; n = 9), or escalation to MEPM (eMEPM; n = 11) groups. The median time to defervescence was 3.5, 1.0, 2.0, and 4.0 days in the CMZ, MEPM, dCMZ, and eMEPM groups, respectively, with no significant differences. Cox proportional hazards analysis showed a significant difference in the hazard ratio (95% confidence interval) of 0.378 (0.145-0.984) for the time to defervescence with CMZ versus MEPM (p = 0.046). The extent of a delayed time to defervescence is greater with early CMZ administration than with MEPM administration in patients with non-severe ESBL-EC bacteremia.