Abstract
Matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows the identification of microorganisms directly from positive blood culture broths. Use of the MALDI-TOF MS for rapid identification of microorganisms from blood culture broths can reduce the turnaround time to identification and may lead to earlier appropriate treatment of bacteremia. During February and April 2010, direct MALDI-TOF MS was routinely performed on all positive blood cultures. During December 2009 and March 2010 no direct MALDI-TOF MS was used. Information on antibiotic therapy was collected from the hospital and intensive care units' information systems from all positive blood cultures during the study period. In total, 253 episodes of bacteremia were included of which 89 during the intervention period and 164 during the control period. Direct performance of MALDI-TOF MS on positive blood culture broths reduced the time till species identification by 28.8-h and was associated with an 11.3% increase in the proportion of patients receiving appropriate antibiotic treatment 24 hours after blood culture positivity (64.0% in the control period versus 75.3% in the intervention period (p0.01)). Routine implementation of this technique increased the proportion of patients on adequate antimicrobial treatment within 24 hours.
Highlights
Bloodstream infections are associated with high rates of morbidity and mortality and microbiological identification of causative pathogens is crucial for optimal management[1]
Conventional identification is based on time-consuming procedures, and species identification and susceptibility testing usually requires at least 48 hours after blood cultures become positive
Antibiotic treatment could be adjusted based on the results of direct MALDI-TOF MS analysis in addition to the information that was available from Gram staining, culturing results and results of susceptibility testing
Summary
Bloodstream infections are associated with high rates of morbidity and mortality and microbiological identification of causative pathogens is crucial for optimal management[1]. Conventional identification is based on time-consuming procedures, and species identification and susceptibility testing usually requires at least 48 hours after blood cultures become positive. Developed in the 1980s [2,3], the MALDI technique is an ionization technique that allows the analysis of biomolecules. The method is used for detection and characterization of biomolecules with molecular masses between 400 and 350,000 Da. The feasibility of MALDI-TOF MS identification of bacterial colonies from solid media has been assessed on a wide array of clinically relevant bacterial strains as well as yeast isolates. Correct identification at the species level is obtained in 80–95% of bacterial isolates [4], and in 66–87% when applied directly on positive blood culture broths [5,6,7,8]
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