Correlation between Antimicrobial Resistance and the Hospital-Wide Diverse Use of Broad-Spectrum Antibiotics by the Antimicrobial Stewardship Program in Japan.

Increased antibiotic use and antibiotic homogeneity cause selective pressure. This study investigated the correlation between antibiotic diversity and antimicrobial resistance (AMR) in Gram-negative organisms. The days of therapy/100 patient-days (DOT) for four broad-spectrum antibiotic classes were evaluated for 2015-2022. The antibiotic heterogeneity index (AHI) for the equal use of four classes (25%) and the modified AHI for the equal use of three classes (30%), excluding fluoroquinolones (10%), were measured (target: 1.0). Quarterly antibiotic use markers and the resistance rates against ≥2 anti-Pseudomonas antibiotics were compared. The DOT value was 9.94, and the relative DOT were 34.8% for carbapenems, 32.1% for piperacillin/tazobactam, 24.3% for fourth generation cephalosporins/ceftazidime/aztreonam, and 8.9% for fluoroquinolones. Although no correlation was found between the total DOT and the resistance rate for any bacterium, a significant negative correlation was found between the heterogeneity indices and resistance rates for Pseudomonas aeruginosa and Klebsiella pneumoniae. The significant cutoffs that discriminate the risk of resistance were 0.756 for the AHI and 0.889 for the modified AHI for K. pneumoniae. Antibiotic diversity is more important in preventing AMR than overall antibiotic use. The ideal ratio of broad-spectrum antibiotics should be studied for diversified use to prevent AMR.

Correction of thrombocytopenia caused by linezolid with scheduled sequential tedizolid use in patients with vertebral osteomyelitis by antibiotic resistant Gram-positive organisms.

INTRODUCTION: Because of thrombocytopenia, linezolid treatment tends to be stopped before the completion of therapy for complicated infections that require prolonged antimicrobial administration. In contrast, tedizolid shows a favorable hematologic profile. The primary end-point of this study was to evaluate the efficacy of switching treatment to tedizolid in patients who developed thrombocytopenia during linezolid therapy. METHODS: This retrospective study was conducted in patients with vertebral osteomyelitis (VO) caused by antibiotic-resistant Gram-positive bacteria. Treatment failure was defined as the reappearance of infection signs within 2 weeks after stopping tedizolid and discontinuation of tedizolid because of continued thrombocytopenia or other adverse effects. RESULTS: Eight patients with native VO (n = 3) and postoperative VO (n = 5) were included in the study. The causative organisms were MRSA in all patients except one. Platelet counts decreased from 35.2 ± 11.5 × 104/mm3 to 17.8 ± 6.2 × 104/mm3 during linezolid therapy and improved without washout period in all patients after switching to tedizolid on days 5-7 (28.6 ± 4.9 × 104/mm3, p = 0.002). Tedizolid therapy was completed and treatment failure was not observed in any patient. The duration of treatment was 20.0 ± 11.2 days for linezolid and 30.3 ± 9.5 days for tedizolid (total, 50.3 ± 10.7 days). One patient died because of underlying disease, and there was no recurrence in the remaining 7 patients (median follow-up 501 days). CONCLUSIONS: Switching therapy to tedizolid improved thrombocytopenia that occurred during linezolid therapy, and it enabled the completion of therapy for VO patients.

Validation of Vancomycin Area under the Concentration-Time Curve Estimation by the Bayesian Approach Using One-Point Samples for Predicting Clinical Outcomes in Patients with Methicillin-Resistant Staphylococcus aureus Infections.

Area under the concentration-time curve (AUC)-guided vancomycin treatment is associated with decreased nephrotoxicity. It is preferable to obtain two samples to estimate the AUC. This study examined the usefulness of AUC estimation via trough concentration (Cmin)-only sampling of 260 adults infected with methicillin-resistant Staphylococcus aureus (MRSA) who received vancomycin. The exact Cmin sampling time was used for Bayesian estimation. A significantly higher early treatment response was observed in patients with a day 2 AUC ≥ 400 µg·h/mL than those with <400 µg·h/mL, and a significantly higher early nephrotoxicity rate was observed in patients with a day 2 AUC ≥ 600 µg·h/mL than those with <600 µg·h/mL. These AUC cutoff values constituted independent factors for each outcome. In sub-analysis, the discrimination ability for early clinical outcomes using these AUC cutoffs was confirmed only in patients with q12 vancomycin administration. A significant difference in early treatment response using the 400 µg·h/mL cutoff was obtained only in patients with low-risk infections. The usefulness of the vancomycin AUC target to decrease nephrotoxicity while assuring clinical efficacy was even confirmed with a single Cmin measurement. However, assessment with two samples might be required in patients with q24 administration or high/moderate-risk MRSA infections.

Enhanced loading dose of teicoplanin for three days is required to achieve a target trough concentration of 20 µg/mL in patients receiving continuous venovenous haemodiafiltration with a low flow rate.

INTRODUCTION: Because of its lower risk of renal toxicity than vancomycin, teicoplanin is the preferred treatment for methicillin-resistant Staphylococcus aureus infection in patients undergoing continuous venovenous haemodiafiltration (CVVHDF) in whom renal function is expected to recover. The dosing regimen for achieving a trough concentration (Cmin) of ≥20 µg/mL remains unclear in patients on CVVHDF using the low flow rate adopted in Japan. METHODS: The study was conducted in patients undergoing CVVHDF with a flow rate of <20 mg/kg/h who were treated with teicoplanin. We adopted three loading dose regimens for the initial 3 days: the conventional regimen, a high-dose regimen (four doses of 10 mg/kg), and an enhanced regimen (four doses of 12 mg/kg). The initial Cmin was obtained at 72 h after the first dose. RESULTS: Overall, 60 patients were eligible for study inclusion. The proportion of patients achieving the Cmin target was significantly higher for the enhanced regimen than for the high-dose regimen (52.9% versus 8.3%, p = 0.003). In multivariate analysis, the enhanced regimen (odds ratio [OR] = 39.93, 95% confidence interval [CI] = 5.03-317.17) and hypoalbuminaemia (OR = 0.04, 95% CI = 0.01-0.44) were independent predictors of the achievement of Cmin ≥ 20 µg/mL. CONCLUSIONS: An enhanced teicoplanin regimen was proposed to treat complicated or invasive infections by methicillin-resistant Staphylococcus aureus in patients receiving CVVHDF even with a low flow rate.

Clinical efficacy and safety in patients treated with teicoplanin with a target trough concentration of 20 µg/mL using a regimen of 12 mg/kg for five doses within the initial 3 days.

BACKGROUND: A trough concentration (Cmin) ≥20 µg/mL of teicoplanin is recommended for the treatment of serious methicillin-resistant Staphylococcus aureus (MRSA) infections. However, sufficient clinical evidence to support the efficacy of this target Cmin has not been obtained. Even though the recommended high Cmin of teicoplanin was associated with better clinical outcome, reaching the target concentration is challenging. METHODS: Pharmacokinetics and adverse events were evaluated in all eligible patients. For clinical efficacy, patients who had bacteremia/complicated MRSA infections were analyzed. The primary endpoint for clinical efficacy was an early clinical response at 72-96 h after the start of therapy. Five dosed of 12 mg/kg or 10 mg/kg was administered as an enhanced or conventional high loading dose regimen, respectively. The Cmin was obtained at 72 h after the first dose. RESULTS: Overall, 512 patients were eligible, and 76 patients were analyzed for treatment efficacy. The proportion of patients achieving the target Cmin range (20-40 µg/mL) by the enhanced regimen was significantly higher than for the conventional regimen (75.2% versus 41.0%, p < 0.001). In multivariate analysis, Cmin ≥ 20 µg/mL was an independent factor for an early clinical response (odds ratio 3.95, 95% confidence interval 1.25-12.53). There was no significant difference in the occurrence of adverse events between patients who did or did not achieve a Cmin ≥ 20 µg/mL. CONCLUSION: A target Cmin ≥ 20 µg/mL might improve early clinical responses during the treatment of difficult MRSA infections using 12 mg/kg teicoplanin for five doses within the initial 3 days.

Preferable timing of therapeutic drug monitoring in patients with impaired renal function treated with once-daily administration of vancomycin.

The aim of this study was to investigate the timing of therapeutic drug monitoring (TDM) in patients with impaired renal function treated with once-daily administration of vancomycin (VCM). Once-daily administration was selected for patients whose creatinine clearance (Ccr) was <80 ml/min. TDM was conducted on day 3 or on day 4. Adult patients whose VCM dosage was not altered according to initial C min and for whom subsequent follow-up TDM was performed within 1 week were entered into the study. Patients whose renal function deteriorated at follow-up TDM were excluded. One hundred sixty-five patients were eligible for analysis. Among patients with once-daily dosing, relative increases of C min at follow-up TDM compared with initial TDM were 34.5 ± 39.2 % in TDM on day 3 and 16.6 ± 20.6 % in TDM on day 4 (P = 0.016). In contrast, there was no significant difference in the relative increase of C min between TDM on days 3 and 4 (26.1 ± 39.6 vs. 18.4 ± 25.6 %, P = 0.551) in the twice-daily regimen. On multivariate analysis, TDM on day 3 alone (odds ratio, 4.93; 95 % confidence interval, 1.71-14.2) was selected as an independent risk factor associated with a relative increase of C min by >30 % in the once-daily regimen. Steady-state VCM serum concentration was not achieved on day 3 in the once-daily regimen in patients with impaired renal function, and TDM on day 3 caused underestimation of C min.