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Why Every Hospital Microbiology Laboratory Should Buy a MALDI-TOF

Microbiology is undergoing a revolution due to the rapid introduction of molecular and proteonomic technology. ClinLabNavigator has published many articles on microbial PCR tests. Now, Microbiology is poised to undergo an even more radical innovative disruption with the introduction of Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry, which is commonly referred to as MALDI-TOF.

Cost data published by the Agency for Healthcare Research and Quality indicates the national annual expenditure for sepsis represents 15% of Medicare inpatient coverage and that sepsis is currently the most expensive condition to treat. Part of the sepsis treatment protocol is early initiation of broad-spectrum antibiotics. Additionally, preliminary culture results reported to physicians often result in use of empiric broad-spectrum antibiotic therapy. However, up to 38% of initially prescribed antibiotics for bloodstream infections are inappropriate. Inappropriate therapy leads to increased antibiotic resistance unnecessary cost, and poor outcomes. Therefore the goal of the microbiology laboratory is to provide faster, more accurate bacterial identifications and antimicrobial susceptibility results.

Traditional bacterial identification from cultures is complex, requiring observation of colony growth, classification by staining, and biochemical testing by manual or semi-automated methods. Less than 10% of bacteria causing infections are identified by conventional methods by 24 hours after growth is observed. Less than 90% of bacteria can be identified correctly to species level by conventional methods. The accuracy of MALDI-TOF identification is 98.3% and can be performed from a single bacterial colony, the same day culture growth is observed.

A recent publication from Methodist Hospital in Houston, Texas reported that the use of MALDI-TOF decreased the mean hospital length of stay for gram-negative sepsis from 11.9 to 9.3 days and decreased the mean hospital inpatient cost by $19,547 (Musser, et al. Arch Pathol Lab Med, 2013, 137; 1247-1254).

Another study from the University of Michigan showed that MALDI-TOF decreased the time to bacterial identification from 84 to 55.9 hours and the time to optimal therapy from 90.3 to 47.3 hours. This improvement in laboratory turnaround time significantly impacted patient care and patient safety by decreasing mortality from 20.3% to 14.5% and length of ICU stay from 14.9 to 8.3 days (Huang AM, et al.. Clin Infect Dis 2013, 57; 1237-1245).

MALDI-TOF allows reporting of accurate, inexpensive microbiology results to the treating physician the same day a bacterial culture turns positive, which is at least 2 days sooner than traditional methods. This rapid turnaround time facilitates correct, targeted antibiotic therapy and significantly improved patient outcomes. Every hospital laboratory with a microbiology laboratory should seriously consider implementing MALDI-TOF in the near future.

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