Training a Drug to Do New Tricks: Insights on Stability of Meropenem Administered as a Continuous Infusion.

BACKGROUND: The antibiotic armamentarium used to combat multi-drug resistant organisms (MDROs) include carbapenems. Continuous infusion (CI) dosing is frequently employed to maximize beta-lactam efficacy; however, use of meropenem CI has been limited due to concerns with product instability. OBJECTIVE: The primary objective of this study was to quantify meropenem serum concentrations to reflect drug stability when administered as CI over 8- or 12-h exchanges. In addition, a stability experiment was performed to further establish meropenem integrity over 12 h. The secondary objectives were to assess the ability of meropenem to achieve target pharmacokinetic/pharmacodynamic (PK/PD) exposures relative to the minimum inhibitory concentration (MIC) of the pathogen, and to determine clinical cure. METHODS: This was a retrospective, observational study on use of CI meropenem (infused either over 8- or 12- h) at a 1% concentration. The stability experiment was conducted on 1% meropenem at room temperature. RESULTS: In 22 patients, a median meropenem daily dose of 6 g/day (range 2-6 g/day) resulted in a median serum concentration of 17.8 mg/L (interquartile range, 9.3-27.8 mg/L). In 95% of cases, meropenem delivered as CI resulted in free drug concentrations at or above the MIC of the pathogen for the entire dosing interval. Clinical cure was achieved in 80% of patients included in this review. The stability experiment revealed negligible drug degradation at the end of the 12-h dosing interval. CONCLUSIONS: The data from this study provides compelling evidence for the use of meropenem as CI utilizing either a 12- or 8-h exchange process.

Impact of the CYP2C19 genotype on voriconazole exposure in adults with invasive fungal infections.

OBJECTIVES: Voriconazole, a first-line agent for the treatment of invasive fungal infections (IFIs), is metabolized by CYP2C19. A significant proportion of patients fail to achieve therapeutic trough concentrations with standard weight-based voriconazole dosing, placing them at increased risk for treatment failure, which can be life threatening. We sought to test the association between the CYP2C19 genotype and subtherapeutic voriconazole concentrations in adults with IFIs. PATIENT AND METHODS: Adults receiving weight-based voriconazole dosing for the treatment of IFIs were genotyped for the CYP2C19*2, *3, and *17 polymorphisms, and CYP2C19 metabolizer phenotypes were inferred. Steady-state voriconazole trough plasma concentrations and the prevalence of subtherapeutic troughs (<2 mg/l) were compared between patients with the CYP2C19*17/*17 (ultrarapid metabolizer, UM) or *1/*17 (rapid metabolizer, RM) genotype versus those with other genotypes. Logistic regression, adjusting for clinical factors, was performed to estimate the odds of subtherapeutic concentrations. RESULTS: Of 70 patients included (mean age 52.5±18 years), 39% were RMs or UMs. Compared with patients with the other phenotypes, RMs/UMs had a lower steady-state trough concentration (4.26±2.2 vs. 2.86±2.3, P=0.0093) and a higher prevalence of subtherapeutic troughs (16 vs. 52%, P=0.0028), with an odds ratio of 5.6 (95% confidence interval: 1.64-19.24, P=0.0044). CONCLUSION: Our findings indicate that adults with the CYP2C19 RM or UM phenotype are more likely to have subtherapeutic concentrations with weight-based voriconazole dosing. These results corroborate previous findings in children and support the potential clinical utility of CYP2C19 genotype-guided voriconazole dosing to avoid underexposure in RMs and UMs.

Clinical and economic impact of antimicrobial stewardship interventions with the FilmArray blood culture identification panel.

The purpose of this study was to evaluate the impact of the FilmArray Blood Culture Identification (BCID) Panel on the management of patients with blood cultures growing gram positive cocci and Candida. We retrospectively compared clinical and economic outcomes between patients during the BCID testing period and a matched historical control group before BCID testing was introduced. A total of 84 BCID patients were matched to 252 historical controls. BCID identification of coagulase negative staphylococci contaminants resulted in shorter post-culture length of stay (P < 0.008) and saved roughly $30,000 per 100 patients tested. The BCID led to shorter duration of empirical vancomycin for patients with contaminated blood cultures (P = 0.005) and methicillin-susceptible Staphylococcus aureus bacteremia (P < 0.001). Patients with vancomycin-resistant enterococcal bacteremia received active therapy earlier than historical controls (P = 0.047). The BCID, coupled with antimicrobial stewardship intervention, was a cost effective tool to improve patient care.

Moving Closer to Zero: Effect of "Just in Time" Dosing of Prophylactic Antibiotics on Surgical Site Infections.

Background: A local quality initiative to improve compliance with surgical antibiotic prophylaxis measures resulted in a high percentage of patients receiving antibiotics within minutes of surgical incision. Studies examining the association between timing of prophylaxis and the risk for surgical site infection (SSI) have produced heterogeneous results. Objective: To examine risk factors for SSI, including "just in time" dosing of antibiotic prophylaxis (dose administered within 5 minutes of incision). Methods: This was a retrospective matched case-control study. Case patients developed SSI in the 30 days following a clean or clean-contaminated surgical procedure. Control patients did not develop SSI following similar procedures and were matched to ensure comparable baseline risk. We assessed the rate of guideline-compliant antibiotic prophylaxis and calculated odds ratios (ORs) to determine the association of patient covariates with the risk for SSI. Results: Forty case patients and 104 controls were included in the study. The rate of appropriate prophylaxis was high in both groups (98% and 94% for case and control groups, respectively). Approximately 15% of case and control patients received antibiotic prophylaxis within 5 minutes of incision, thus, "just in time" dosing did not appear to increase the risk for SSI (OR, 0.814; 95% CI, 0.274-2.415). There was a nonsignificant association between receipt of vancomycin and SSI (OR, 2.844; 95% CI, 0.926-8.737). Conclusion: "Just in time" dosing of prophylactic antibiotics was not associated with increased risk for SSI. Further study is needed to clarify the impact of antibiotic choice on the risk for subsequent SSI.

Beyond Vancomycin: The Tail of the Lipoglycopeptides.

PURPOSE: The purpose of this comparative review is to provide clinical information on the semisynthetic lipoglycopeptides (telavancin, oritavancin, and dalbavancin) for the management of gram-positive infections. METHODS: A PubMed search was conducted using the following terms: telavancin, dalbavancin, and oritavancin. Clinical trials evaluating pharmacokinetic properties, pharmacodynamic properties, clinical efficacy, and safety profiles were included in the review. FINDINGS: The lipoglycopeptides are approximately 4- to 8-fold more potent than vancomycin against gram-positive organisms, including activity against vancomycin-intermediate or vancomycin-resistant strains of Staphylococcus and Enterococcus species. In addition, oritavancin maintains activity against Enterococcus species harboring vanA operon. Clinical trial data revealed equal efficacy to vancomycin in the management of acute bacterial skin and skin structure infections and, in the case of telavancin, hospital-acquired pneumonia. A benefit of oritavancin and dalbavancin is that a full course of therapy consists of a single- or 2-dose regimen, respectively. These agents are well tolerated with similar adverse event rates to vancomycin. Telavancin requires a thorough assessment before initiation of therapy to minimize the risk of acute kidney injury and teratogenicity. IMPLICATIONS: The lipoglycopeptides enhance the antibiotic gram-positive armamentarium at a time when methicillin-resistant Staphylococcus aureus prevalence and overall resistance is at an all-time high. These agents serve to fill different clinical roles in the management of gram-positive infections. On the basis of the available data, telavancin should be considered a plausible agent for the management of gram-positive organisms when patients do not respond or develop adverse effects to vancomycin. Dalbavancin and oritavancin are new therapeutic options, and their potency and pharmacokinetic properties may provide benefit over existing therapies. Clinical trial data indicate that patients with signs or symptoms of skin and skin structure infections may be successfully treated using 1 or 2 doses of these agents. Eliminating the need for inpatient admission, central catheter placement, and/or daily outpatient parenteral antibiotic therapy is a major advance in treatment of skin and skin structure infections. This strategy may reduce costs associated with resource utilization and iatrogenic morbidity, resulting in overall improvements in care.

Detection of Neisseria meningitidis from negative blood cultures and cerebrospinal fluid with the FilmArray blood culture identification panel.

The FilmArray blood culture identification (BCID) panel is a rapid molecular diagnostic test approved for use with positive blood culture material. We describe a fatal case of meningococcemia with central nervous system (CNS) involvement detected using the BCID test with culture-negative blood and cerebrospinal fluid.

Time to positivity of blood cultures supports antibiotic de-escalation at 48 hours.

BACKGROUND: Appropriate de-escalation of empirical antimicrobial therapy is a fundamental component of antimicrobial stewardship. Concern for the late detection of bloodstream pathogens may undermine early streamlining efforts and subject patients to protracted courses of nonessential therapy. OBJECTIVE: To quantify the prevalence of bacterial bloodstream infection (BSI) detection after more than 48 hours of culture incubation. We also assessed the impact of antimicrobial therapy delivered prior to blood sample collection. METHODS: We retrospectively evaluated time to blood culture positivity (TTP) in adult patients at an academic tertiary care hospital. Microbiology reports were reviewed to identify the TTP for the first positive blood culture bottle for each episode of BSI occurring from February 1, 2011, to July 31, 2011. Isolates were classified as true pathogens or contaminants. Blood culture results after 48 hours of incubation were compared with results after 120 hours of incubation. RESULTS: The median TTP of 416 monomicrobial BSIs and 210 contamination episodes was 13.7 and 24.4 hours, respectively (P < .001). The median TTPs in those who received and did not receive prior antibiotics were 17.0 and 12.8 hours, respectively (P < .001). By 48 hours, 98% of aerobic Gram-positive and Gram-negative BSIs were detected. Culture results at 48 hours were 97% sensitive and had a negative predictive value of 99.8%. CONCLUSION: Few true BSIs are detected after more than 48 hours of culture incubation. Clinicians may adjust empirical antibiotic coverage at this time with little risk for subsequent bacterial pathogen detection.