From the Guidelines
MALDI-TOF mass spectrometry should be used for rapid microbial identification in clinical settings, despite its higher error rates, as it allows for faster targeted therapy and improves patient outcomes, as evidenced by a reduction in hospital length of stay and antibiotic use 1. To address the limitation of higher error rates, laboratories should implement confirmatory testing for critical results, especially for organisms with high clinical impact.
- MALDI-TOF typically delivers results within minutes to hours, which is significantly faster than traditional culture methods.
- Error rates can range from 5-15% depending on the organism and database quality, with errors most commonly occurring with closely related species, rare organisms, or when using outdated databases.
- To minimize errors, laboratories should:
- Maintain updated spectral databases
- Ensure proper sample preparation
- Use quality control strains regularly
- Consider supplementary tests for certain organism groups like Streptococcus viridans or Shigella/E. coli
- Critical identifications, particularly for blood cultures or unusual resistance patterns, should be confirmed with additional methods. The use of MALDI-TOF MS has been shown to reduce the time to pathogen identification, resulting in a significant shortening of response times and improved patient outcomes, including a reduction in hospital length of stay and mortality rate 1. Additionally, a recent study demonstrated that implementation of rapid microbial identification by MALDI-TOF testing can decrease the median time to identification and reduce the median length of stay, ICU transfer rate, and mortality rate 1. Overall, the benefits of using MALDI-TOF mass spectrometry for rapid microbial identification, including improved patient outcomes and reduced antibiotic use, outweigh the limitations of higher error rates, making it a valuable tool in clinical microbiology.
From the Research
MALDI-TOF Rapid Results but High Error Rates
- The use of MALDI-TOF MS in clinical microbiology laboratories has been shown to provide rapid results, with some studies indicating a reduction in time to obtain a microbiological diagnosis by 24 hours compared to conventional biochemical automatic systems 2.
- However, despite its rapidity and accuracy, MALDI-TOF MS also has some drawbacks, including a small number of spectra in the database and inherent similarities among organisms, which can make it difficult to distinguish between different species and result in misidentifications 3.
- The quality of MALDI-TOF mass spectra in routine diagnostics has been assessed in an international external quality assessment, which found heterogeneous spectral quality between devices, considering the median number of marker masses detected, reproducibility between technical replicates, and measurement error 4.
- Simple workflow adaptations have been identified, which can improve the spectral quality of poorly performing devices, and should be considered by laboratories yielding a low spectral quality 4.
- The development of databases covering highly pathogenic bacteria, closely related bacteria, and bacteria of clinical relevance has been initiated to improve MALDI-TOF MS diagnostics of highly pathogenic bacteria 5.
- MALDI-TOF MS has been applied to various fields of clinical microbiology, including the detection of antibiotic susceptibility/resistance biomarkers, the identification of aminoacidic sequences and the chemical structure of protein terminal groups, and as an emerging method in microbial typing 2.