This study examined the impact of implementing a MALDI-TOF MS instrument on the time to identify bacteria causing bloodstream infections at a clinical microbiology laboratory. The study found that using MALDI-TOF MS reduced the mean time to identification from 38.05 hours to 26.68 hours. Every hour of delayed appropriate antibiotic treatment decreases patient survival by 7.6%. The implementation of MALDI-TOF MS significantly decreased identification times and has the potential to improve patient outcomes for the 187,500 Americans with gram-negative bloodstream infections each year.

1. UNIVERSITY OF COLORADO | COLORADO STATE UNIVERSITY | UNIVERSITY OF NORTHERN COLORADO
Reducing Time to
Bacterial Identification
in Blood Stream Infections
Veronica Ann Broslawik, MLS (ASCP)CM
MPH Candidate | Epidemiology
Colorado School of Public Health Forum
December 5, 2014
with Drs. Nancy Madinger and Bruce McCollister
University of Colorado Hospital
Clinical Microbiology Laboratory

2. Introduction
• Blood Stream Infections (BSIs)
– Frequently result in critical illness
– Associated with high morbidity and mortality rates
• Antibiotic Administration
– Adequate and appropriate
– Timely

3. Introduction
• Matrix-Assisted Laser Desorption Ionization,
Time of Flight Mass Spectrometry (MALDI-TOF MS)
– Revolutionary bacteria identification
– Easy, fast, and low-cost method for identification
– Compared to phenotypic identification techniques

4. Study Objective
• This study aimed to examine the impact of
implementation of a MALDI-TOF MS
instrument on time to identification of
bacteria causing blood stream infections in
a clinical microbiology laboratory.

5. Methods
• Retrospective, quasi-experimental, before/after study
• Culture Inclusion Criteria
• Gram negative rods in the Enterobacteriaciae group
(examples: E. coli or Salmonella species)
• Received in the lab from June 2013 to August 2014
• From inpatients at University of Colorado Hospital
• First positive culture
• Not a mixed infection
• Antibiotic sensitivity testing completed

6. Results
0
24
48
72
96
120
HourstoIdentification
Identifications Before Implementation of MALDI-TOF
BEFORE MALDI Average Time to Identification Before MALDI
n mean 95% CI
153 38.05 35.36-40.73

7. Results
0
24
48
72
96
120
HourstoIdentification
Identifications After Implementation of MALDI-TOF
AFTER MALDI Average Time to Identification After MALDI
n mean 95% CI
104 26.68 24.61-28.76

8. Results
0
24
48
72
96
120
HourstoIdentification
Identifications Before and After Implementation of MALDI-TOF MS
Before MALDI After MALDI
Mean Time to Identification Before MALDI = 38.04 hours Mean Time to Identification After MALDI = 26.68 hours

9. Results
BloodCulture
Drawn
BeforeMALDIAfterMALDI
0 12 24 36 48 60 72
Hours After Culture Positivity
CulturePositive
TimetoBacterial
Identification
TimetoAntibiotic
SusceptibilityResults
38.04
26.68

10. Results
BloodCulture
Drawn
BeforeMALDIAfterMALDI
0 12 24 36 48 60 72
Hours After Culture Positivity
CulturePositive
38.04
Time to Identification
Mean (hours) 95% CI (hours)
Before MALDI 38.04 35.56 - 40.73
After MALDI 26.68 24.61 - 28.76
26.68

11. Results
BloodCulture
Drawn
BeforeMALDIAfterMALDI
0 12 24 36 48 60 72
Hours After Culture Positivity
CulturePositive
Time to Identification
MALDI-TOF identification takes 7-15 hours less
time compared to phenotypic identification.
( α = 0.05 pvalue <0.001).
38.04
26.68

12. Results
The implementation of the MALDI-TOF MS
brought significant decreases in time to
identification of gram negative bacteria
at the University of Colorado Hospital.

13. Discussion
• MALDI-TOF improves laboratory process
identification of bacteria causing BSIs over
phenotypic identification techniques
• 750,000 blood stream infections/year in the US
- 25% gram negative bacteria  187,500 people
• MALDI-TOF MS is highly sensitive and specific
• Every hour in delay to appropriate antibiotic
treatment decreases patient survival by 7.6%

14. Public Health Context
BloodCulture
Drawn
BeforeMALDIAfterMALDI
0 12 24 36 48 60 72
Hours After Culture Positivity
CulturePositive
TimetoBacterial
Identification
TimetoAntibiotic
SusceptibilityResults

15. Public Health Context
BloodCulture
Drawn
BeforeMALDIAfterMALDI
0 12 24 36 48 60 72
Hours After Culture Positivity
CulturePositive Time to
Identification
Time to
Antibiotic
Susceptibility
Results

16. Acknowledgments
• Nancy Madinger, MD and Bruce McCollister, MD Medical
Directors, University of Colorado Hospital Clinical Microbiology Laboratory
• Deborah Havens, MLS(ASCP)
Chief Medical Technologist, University of Colorado Hospital Clinical Microbiology Laboratory
• University of Colorado Hospital Clinical Microbiology
Laboratory Staff
– Especially Mehdi Bandali and Elizabeth Matthys
• Colorado School of Public Health Capstone Classmates
and Instructors

17. Questions?