1882. Clinical outcomes of a MALDI-TOF-tied antimicrobial stewardship intervention compared to MALDI-TOF reporting without intervention: a quasi-experimental study
Session: Poster Abstract Session: Antibiotic Stewardship: Diagnostics
Saturday, October 29, 2016
Room: Poster Hall

Background: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) has been shown to improve outcomes when used with related antimicrobial stewardship interventions. However, data are lacking regarding the impact of a MALDI-TOF-tied antimicrobial stewardship intervention in a setting where MALDI-TOF is already the standard of care.

Methods: A retrospective quasi-experimental study was conducted at a 495 bed hospital.  The pre-intervention arm (10/1/14-4/1/15) had MALDI-TOF in place with no interventions related to results. The intervention arm (11/1/2015-3/1/2016) included real-time notification of MALDI-TOF results to a stewardship team for all adult patients with bacteremia or fungemia Monday-Friday from 08:00–17:00. The medical chart was reviewed and recommendations made to the primary team, with a second review when susceptibilities were available.  The primary endpoint was time to optimal therapy in patients with bloodstream infections.

Results: 160 patients with bloodstream infections were included:  116 in the pre-intervention arm and 44 in the intervention arm. Demographics: 50% female, mean age 54 years, 53% immunocompromised, 28% admitted to the ICU.  A mean decrease of 18 hours for time to optimal therapy (P=0.007) was seen in the intervention arm (Table 1).

Conclusion: Antimicrobial stewardship intervention in response to MALDI-TOF results for bloodstream infections is associated with a decreased time to optimal therapy compared to routine MALDI-TOF result reporting.  This suggests that although MALDI-TOF can provide rapid species identification, implementation must include stewardship structure to respond to these results and improve patient outcomes.

Table 1: Outcomes


MALDI-TOF without Intervention


 MALDI-TOF with Stewardship Intervention



Mean Time to Optimal Therapy (hrs)




Mean Time to Active Therapy (hrs)




Patients Given Optimal Therapy

104 (89.7%)

44 (100%)


Patients Given Active Therapy

109 (94%)

44 (100%)


Mean Length of Stay Post Infection


9.04 (7.53)

12.87 (11.89)


30 day all-cause mortality

11 (9.5%)

7 (15.9%)


30 day infection-related readmission

10 (8.6%)

6 (14.3%)


Maressa Santarossa, PharmD1, Susan C. Bleasdale, MD2,3, Amanda Harrington, PhD, D(ABMM)4, Scott T. Benken, PharmD, BCPS-AQ CV1,2, Maria C. Merrick, DO5, Daniel S Murrell, MD6, Ellen Stolar, MD5, Amber Williams, PharmD Candidate1 and Alan E. Gross, PharmD, BCPS-AQ ID1,2, (1)Pharmacy Practice, University of Illinois at Chicago, Chicago, IL, (2)University of Illinois Hospital and Health Sciences System, Chicago, IL, (3)Medicine, University of Illinois at Chicago, Chicago, IL, (4)Clinical Microbiology Service, University of Illinois at Chicago, Chicago, IL, (5)Infectious Diseases, University of Illinois at Chicago, Chicago, IL, (6)Internal Medicine, University of Illinois at Chicago, Chicago, IL


M. Santarossa, None

S. C. Bleasdale, None

A. Harrington, None

S. T. Benken, None

M. C. Merrick, None

D. S. Murrell, None

E. Stolar, None

A. Williams, None

A. E. Gross, None

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