1951. Nephrotoxicity Associated With Imipenem/Cilastatin/Relebactam (IMI/REL) vs. Imipenem/Cilastatin Plus Colistin (IMI+CST) in Patients With Imipenem-Nonsusceptible (NS) Bacterial Infections

Background

Methods

Results

Conclusion

Disclosures

Impact of Educational Interventions to Prevent Drug Interactions between Oral Fluoroquinolone or Tetracycline Antibiotics with Polyvalent-Cation Supplements

Purpose

Fluoroquinolone and tetracycline antibiotics are routinely used for the treatment of a variety of bacterial infections. A disadvantage with their oral administration is the potential for a drug interaction leading to decreased absorption when coadministered with oral supplements containing polyvalent cations. The objective of this study was to evaluate the impact of several inservices aimed at educating nursing staff on reducing this drug interaction.

Methods

To assess the impact of the educational interventions, a retrospective chart review was conducted in two phases to determine the incidence of the drug interaction. Phase 1 was conducted before implementation of the educational inservices. Following the educational inservices, phase 2 was conducted to determine their impact on reducing coadministration.

Results

This interaction occurs frequently in hospitals; we found that these antibiotics were given within 2 hours of polyvalent-cation containing supplements in 72.5% of patients before inservices. An inservice involving multiple approaches significantly reduced the frequency of the drug interaction to 10%; P < 0.001.

Conclusion

Educational inservices directed toward nursing staff were successful in significantly reducing the incidence of this drug interaction.

Epidemiology of Clostridium difficile infection

There has been dramatic change in the epidemiology of Clostridium difficile infection (CDI) since the turn of the 21st century noted by a marked increase in incidence and severity, occurring at a disproportionately higher frequency in older patients. Historically considered a nosocomial infection associated with antibiotic exposure, CDI has now also emerged in the community in populations previously considered low risk. Emerging risk factors and disease recurrence represent continued challenges in the management of CDI. The increased incidence and severity associated with CDI has coincided with the emergence and rapid spread of a previously rare strain, ribotype 027. Recent data from the United States and Europe suggest that the incidence of CDI may have reached a crescendo in the recent years and is perhaps beginning to plateau. The acute care direct costs of CDI were estimated to be US$4.8 billion in 2008. However, nearly all the published studies have focused on CDI diagnosed and treated in the acute care hospital setting and fail to measure the burden outside the hospital, including recently discharged patients, outpatients, and those in long-term care facilities. Enhanced surveillance methods are needed to monitor the incidence, to identify populations at risk, and to characterize the molecular epidemiology of strains causing CDI.

Implementation of Weight-Based Antimicrobial Dosing for Surgical Site Infection Prophylaxis

Surgical site infections (SSIs) increase morbidity, mortality, and health care costs. Morbid obesity has been identified as an independent risk factor; it has been demonstrated that higher doses of antimicrobials are warranted to achieve adequate tissue concentrations. In 2008, the University of Michigan Health System (UMHS) implemented weight-based dosing such that patients with a documented weight of ≥80 kg would receive a larger initial dose of antibiotic for surgical prophylaxis. This process included a pharmacy dose optimization program provided by an operating room pharmacy where pharmacists could automatically increase the dose based on weight if the initial order was noncompliant with institutional guidelines. The objectives of the study were to assess rates of compliance with the guidelines prior to and after implementation. This study was a retrospective evaluation of SSI prophylaxis dosing in obese patients prior to (April through June 2008) and after (September through November 2008) implementation of a dose optimization program. After implementation, there was a 29.7% increase in weight-based antibiotic surgical prophylaxis; pharmacy intervention accounted for 15% of the change. The implementation of a dose optimization program could prove to be cost-effective by ensuring patients receive the correct weight-based antibiotic and by perhaps reducing the incidence of SSIs.

Primary antifungal prophylaxis in adult hematopoietic stem cell transplant recipients: current therapeutic concepts

In recipients of hematopoietic stem cell transplants (HSCTs), the mortality associated with invasive fungal infections (IFIs) remains high, despite the introduction of broad-spectrum antifungal agents over the past 2 decades. Preventing exposure to fungal pathogens in this population is impossible; therefore, clinicians have focused on prophylactic use of antifungal agents to prevent IFIs in high-risk HSCT recipients. It is important to target antifungal prophylaxis by type of HSCT (autologous or allogeneic), local epidemiology, and risk factors for IFIs so that patients can receive the most appropriate agent while balancing costs and the risks of toxicity, and minimizing the development of resistance. To assist clinicians in weighing the pros and cons of currently available antifungal agents when choosing a suitable prophylactic regimen, we provide a review of several key prospective randomized trials that evaluated various antifungal agents for primary prophylaxis in adult HSCT recipients. In addition, we describe the epidemiology of and risk factors for IFIs in HSCT recipients, the difficulties in diagnosing IFIs, antifungal agents used for prophylaxis, and the goals of primary prophylaxis. Fluconazole remains the gold standard for primary prophylaxis in autologous HSCT recipients. For allogeneic HSCT recipients, the agent chosen for prophylaxis must be based on the patient's risk factors for IFIs. In low-risk patients, fluconazole is an appropriate agent to use for primary prophylaxis immediately after transplantation. However, in allogeneic HSCT recipients who develop complications, such as graft failure, graft-versus-host disease, or cytomegalovirus infection, prophylaxis with a mould-active agent should be used.

Institutional Experience with Daptomycin Treatment in Patients with Gram-Positive Infections

Purpose

Daptomycin was originally approved for the treatment of complicated skin and skin-structure infections caused by gram-positive bacteria, and recently, its indications were expanded to include bacteremia and right-sided infective endocarditis caused by Staphylococcus aureus. This retrospective chart review examines outcomes and costs for individuals treated with daptomycin at a tertiary care medical center.

Methods

During an 11-month period, records of patients treated with daptomycin at the institution were reviewed. Cases for which complete cost data were available were included in the analysis. Outcomes were assigned to 4 categories: cured, improved, failed, or unevaluable. Hospital stay details were recorded, and antibiotic and total hospital treatment costs were calculated.

Results

Thirty-five patients representing 37 cases were included in the review. Of those cases, 89% (33 of 37) involved documented infections with gram-positive bacteria, 22% involved confirmed methicillin-resistant S. aureus infections, and 32% involved confirmed vancomycin-resistant enterococcus infections. Most cases (27 of 37; 73%) involved infections with multiple bacterial isolates for which previous therapy had failed. Of all clinically evaluable cases, 54% were classified as cured and 42% as improved after daptomycin therapy. Median and mean ± standard deviation (SD) total cost of hospitalization were $46,730 and $111,604 ± $137,138, respectively. Overall median duration of therapy for all 37 cases was 14 days (range, 1 to 143; mean ± SD duration, 25.5 ± 32 days).

Conclusion

Daptomycin cured or improved most evaluable gram-positive infections. The results of this study suggest that daptomycin may be considered a therapeutic option for treatment of drug-resistant gram-positive infections.

Doripenem

Carbapenems play a significant role in the current antibiotic armamentarium. Doripenem is the newest carbapenem to be commercially released. Its antimicrobial spectrum more closely resembles those of meropenem and imipenem than that of ertapenem. Thus, it has significant in vitro activity against streptococci, methicillin-susceptible staphylococci, Enterobacteriaceae (including extended-spectrum beta-lactamase-producing strains), Pseudomonas aeruginosa, Acinetobacter species, and Bacteroides fragilis. Doripenem does not have clinically useful activity against methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and the majority of gram-negative bacilli that are resistant to meropenem or imipenem. In vitro, resistant P. aeruginosa mutants appear to be harder to select with doripenem than with other carbapenems. Doripenem has been approved for use in treatment of complicated intra-abdominal infection and complicated urinary tract infection. Studies of hospital-acquired pneumonia have also been completed, including one that used a 4-h infusion to enhance the pharmacodynamic profile. In vitro, doripenem lacks the propensity to cause seizures, and a low risk of seizures has been demonstrated in clinical studies. Currently unanswered questions regarding doripenem include the utility and dosing in neonatal, pediatric, and cystic fibrosis populations and specific dosage recommendations for patients receiving hemodialysis, peritoneal dialysis, or continuous renal replacement therapies. The longevity of doripenem will depend on our ability to curtail the spread of carbapenem-resistant organisms, which are already a significant problem at some institutions.

Ertapenem clearance during modeled continuous renal replacement therapy

PURPOSE

To determine ertapenem transmembrane clearance (CLtm) during continuous renal replacement therapy (CRRT) using a validated in vitro model.

METHODS

Ertapenem clearance during continuous hemofiltration and hemodialysis was assessed with AN69 and polysulfone hemodiafilters at 4 dialysate (Qd) and ultrafiltration rates (Quf): 1, 2, 3, and 6 l/hour. Blood and dialysate samples were collected at each flow rate and assayed for urea (control solute) and ertapenem concentrations. The experiment was repeated 5 times for each hemodiafilter type. Ertapenem and urea sieving coefficient (SC) and saturation coefficient (SA) were assessed, and CLtm calculated.

RESULTS

In continuous hemofiltration mode, urea and ertapenem SC ranged from 1.00 to 1.19 at all Quf and did not differ between hemodiafilter types. Consequently, convective CLtm also did not differ between hemodiafilters. In continuous dialysis mode, urea Cltm did not differ between hemodiafilter types at any Qd. However, ertapenem SA and CLtm were significantly different between hemodiafilter types at Qd 6l/hour (p<0.001). As Qd increased, mean +/- SD AN69 SA declined significantly from 0.87 +/- 0.12 at Qd 1 l/hour to 0.45 +/- 0.02 at Qd 6 l/hour (p<0.001). Ertapenem SA did not differ at any Qd with the polysulfone hemodiafilter (range 0.71-0.80).

CONCLUSION

Ertapenem was cleared substantially in these in vitro CRRT models. However, our findings illustrate discordance between our observed SC and SA and the published unbound fraction of ertapenem. This finding has been reported with many other drugs, including carbapenem antibiotics. If in vivo studies corroborate our SA and SC findings, dosage adjustment for patients receiving CRRT will be required.

Experience with Community-Based Amphotericin B Infusion Therapy

STUDY OBJECTIVES

To identify the types and frequencies of adverse events associated with community-based amphotericin B infusion therapy. A second objective was to validate the effectiveness of a monitoring system, based on guidelines from the Infectious Diseases Society of America (IDSA).

DESIGN

Retrospective medical record review.

SETTING

Outpatient clinic at a tertiary care center.

PATIENTS

One hundred five patients who received amphotericin B therapy from a home care provider between January 1997 and July 2002.

MEASUREMENTS AND MAIN RESULTS

A total of 113 courses of amphotericin B formulations were administered: liposomal amphotericin B, 41 courses (36%), amphotericin B deoxycholate, 31 courses (27%), amphotericin B lipid complex, 31 courses (27%), and amphotericin B colloidal dispersion, 3 courses (3%); an additional 7 courses consisted of sequential therapy with two different formulations. Nephrotoxicity was associated with 46 (41%) courses, electrolyte abnormalities with 40 (35%) courses, venous access device complications with 12 (11%) courses, and infusion reactions with 13 (12%) courses. Nephrotoxicity occurred most frequently in adults aged 60 years or older, solid organ transplant recipients, and those receiving concomitant cyclosporine. Only two (12%) of 17 courses in children younger than 13 years were associated with nephrotoxicity. Thirteen of all 113 courses resulted in patients requiring hospital admission due to their adverse events. Monitoring of electrolyte, serum creatinine, and blood urea nitrogen levels 2 or 3 times/week was adequate for identifying these events.

CONCLUSION

Significant rates of adverse events occurred in patients who received community-based amphotericin B infusion therapy. A monitoring system based on IDSA guidelines was effective in facilitating the detection and management of these adverse events.