Exploring the Factors Affecting the Transferability of Vancomycin to Cerebrospinal Fluid in Postoperative Neurosurgical Patients with Bacterial Meningitis.

Vancomycin (VCM) is a standard treatment for bacterial meningitis. However, little is known about the transferability of VCM to cerebrospinal fluid (CSF), thus evidence of the transferability of VCM to CSF during bacterial meningitis is needed. In this study, we evaluated the concentration of VCM in the plasma and CSF of postoperative neurosurgical patients with bacterial meningitis and evaluated the factors that affect the transferability of VCM to CSF. The concentrations of VCM in plasma (trough) and CSF were determined in eight patients (four males and four females) with bacterial meningitis who were treated with VCM using HPLC. The ratio of the VCM concentrations in CSF/plasma was also calculated by estimating the blood VCM concentration at the same time as the VCM concentration in CSF was measured. The results showed that the VCM concentration in CSF was 0.9-12.7 µg/mL and the CSF/plasma VCM concentration ratio was 0.02-0.62. We examined the effect of drainage on the transferability of VCM to CSF, which showed that the VCM concentration in CSF and the CSF/plasma VCM concentration ratio were significantly higher in patients not undergoing drainage than in patients who were undergoing drainage. The CSF protein and glucose concentrations, which are diagnostic indicators of meningitis, were positively correlated with the VCM concentration in CSF and the CSF/plasma VCM concentration ratio. Thus, VCM transferability to CSF may be affected by changes in the status of the blood-brain barrier and blood-cerebrospinal fluid barrier due to drainage or meningitis.

Stability of antimicrobial agents in an elastomeric infusion pump used for outpatient parenteral antimicrobial therapy.

OBJECTIVES: The long-term stability of antimicrobials dissolved in infusion solution is necessary to establish and spread the outpatient parenteral antimicrobial therapy (OPAT). In this study, we evaluated the stability of antimicrobial agents dissolved in infusion solutions. METHODS: The antimicrobial agents were dissolved in infusion solutions and kept at 25 °C and 31.1 °C for 24 h or 4 °C for 10 days in a polypropylene tube or an elastomeric infusion pump. The stability was measured by high-performance liquid chromatography. RESULTS AND CONCLUSION: The residual ratio of cefazolin (CEZ), cefmetazole (CMZ), piperacillin (PIPC), and tazobactam (TAZ) at 31.1 °C for 24 h was as follows: 95.7 ± 3.0%, 94.8 ± 0.9%, 102.6 ± 1.8%, and 103.9 ± 3.6% in saline, respectively; 94.7 ± 3.0%, 94.3 ± 1.5%, 106.1 ± 3.0%, and 107.3 ± 2.4% in 5% dextrose solution, respectively. The residual ratio of these antimicrobials at 4 °C for 10 days was maintained above 90% in both saline and 5% dextrose solution. The residual ratio of all the above antimicrobials in an elastomeric infusion pump at 31.1 °C for 24 h was equivalent to that in the polypropylene tube. On the other hand, doripenem and meropenem were not stable in any infusion solution at 31.1 °C. CEZ, CMZ, and PIPC/TAZ dissolved in saline or 5% dextrose solution can be used in OPAT with continuous infusion pumps.