Clinical Studies
Impact of rapid identification of Acinetobacter Baumannii via matrix-assisted laser desorption ionization time-of-flight mass spectrometry combined with antimicrobial stewardship in patients with pneumonia and/or bacteremia,☆☆

https://doi.org/10.1016/j.diagmicrobio.2015.09.018Get rights and content

Highlights

  • We evaluated the impact of MALDI-TOF and antimicrobial stewardship intervention

  • Patients with pneumonia and/or bacteremia due to A. baumannii were included

  • This combination significantly reduced the time to effective therapy by 41 hours

  • Improved time to effective therapy was associated with an increase in clinical cure

Abstract

We evaluated the clinical and economic outcomes of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) with stewardship intervention in patients with Acinetobacter baumannii (AB) pneumonia and/or bacteremia. 66 patients were included in the pre-intervention group and 53 in the intervention group. The combination of AB identification via MALDI-TOF MS and ID PharmD intervention significantly reduced the median time to effective therapy compared to conventional identification without intervention [77.7 (95% CI: 73.1–84.8) to 36.6 (95% CI: 25.9–50.9) hours (P < 0.0001)]. Rapid organism identification along with ID PharmD intervention was also associated with a 19% increase in clinical cure (15% versus 34%, P = 0.016) and a decreased length of stay during antibiotic therapy (13 [8–18] versus 11 [7–15] days, P = 0.021). No difference in 14-day mortality was observed (20% versus 25%, P = 0.526). Median costs during infection were approximately $6500 less in the intervention group ($49,402 [35,307–86,566] versus $42,872 [26,966–74,506]; P = 0.243). AB identification via MALDI-TOF MS combined with stewardship intervention allows for timely, effective antimicrobial therapy and is associated with increased clinical cure.

Introduction

For the first time, the Centers for Disease Control and Prevention have prioritized multi-drug resistant (MDR) Acinetobacter baumannii (AB) as a serious threat to public health (Centers for Disease Control and Prevention, 2013). The attributable mortality rate associated with AB infections has been reported as high as 61.6% with excess costs of treatment ranging from $8480 to $168,648 (Jang et al., 2009, Weingarten et al., 1999). Currently approximately 63% of AB in the USA is considered MDR, making the administration of timely, effective antimicrobial therapy challenging (Centers for Disease Control and Prevention, 2013). Prompt pathogen identification is crucial for optimizing antimicrobial therapy, with delays in the initiation of effective antibiotics associated with poor patient outcomes (Barenfanger et al., 2008, Bauer et al., 2010, Forrest et al., 2008, Harbarth et al., 2003, Ibrahim et al., 2000, Lodise et al., 2003). Early appropriate antimicrobial therapy has been shown to reduce mortality by 25.5% in infections due to AB, making rapid organism identification particularly important in these patients (Erbay et al., 2009, Grupper et al., 2007, Park et al., 2013, Robenshtok et al., 2006, Sunenshine et al., 2007). Matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) uses mass spectrometry (MS) to rapidly identify organisms following isolation from clinical specimens. Integration of MALDI-TOF MS into clinical microbiology workflow decreases time to organism identification by 1.2–1.5 days compared to conventional methods (Huang et al., 2013, Perez et al., 2013, Tan et al., 2012, Vlek et al., 2012). There are limited data evaluating the use of MALDI-TOF MS and antimicrobial stewardship on patient outcomes and only one study to date focuses on patients with MDR organisms (Huang et al., 2013, Perez et al., 2013, Perez et al., 2014). This study evaluates the impact of MALDI-TOF MS in conjunction with an infectious diseases pharmacist’s (ID PharmD) intervention on clinical and economic outcomes in patients with AB pneumonia and/or bacteremia.

Section snippets

Study design

This was a retrospective, quasi-experimental single-center study conducted at The Ohio State University Wexner Medical Center (OSUWMC), a 1250-bed tertiary care academic medical center located in Columbus, Ohio. The study was approved by the Office of Responsible Research Practices Institutional Review Board with a waiver of consent granted. The OSUWMC antimicrobial stewardship program is a multidisciplinary team that includes infectious diseases (ID) physicians, ID PharmDs, an ID pharmacy

Results

During the study period, 206 patients were identified for inclusion. After exclusion criteria were applied, 119 patients were included in the final analysis. Of these, there were 66 patients in the pre-intervention group and 53 in the intervention group (Fig. 1). Demographic characteristics including age, immunosuppression and APACHE II score were similar in both groups (Table 1). Patients in the intervention group tended to have lower median Charlson Comorbidity Index values compared to the

Discussion

AB has emerged as a formidable pathogen constituting an enormous burden on the healthcare system in the U.S. and globally (Centers for Disease Control and Prevention, 2013). Antimicrobial stewardship programs are challenged with the timely effective treatment of infections due to AB, particularly in the setting of mounting antimicrobial resistance. To our knowledge, this is the first study evaluating the clinical and economic impact of MALDI-TOF MS and stewardship intervention in patients with

Acknowledgements

The authors would like to acknowledge OSUMC Microbiology Laboratory personnel for assistance with MALDI-TOF MS and Mark Korte for assistance with cost analysis.

Funding: There was no financial support for this work.

Transparency declarations:

E.W. has attended speaker’s bureau for Advandx and Nanosphere.

D.A.G has received research support to her institution from Cubist, serves as a speaker for Merck and Astellas, and has participated on advisory boards for Astellas, Bayer, Cubist, Durata, Forest,

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  • Cited by (0)

    Key points: Rapid identification of Acinetobacter baumannii via MALDI-TOF MS combined with stewardship intervention allows for timely, effective therapy and is associated with increased clinical cure.

    ☆☆

    Original abstract presented at the 24th European Congress of Clinical Microbiology and Infectious Diseases, Barcelona, Spain.

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