Capsular serotyping of Haemophilus influenzae by using matrix-associated laser desorption ionization-time of flight...

Area of Science:

• Microbiology
• Clinical Diagnostics
• Analytical Chemistry

Background:

• Haemophilus influenzae is a significant pathogen responsible for invasive diseases, with various capsular serotypes (a-f) and non-typeable (NT) strains.
• Traditional serotyping methods (serological and PCR) for H. influenzae are effective but are often time-consuming and costly.

Purpose of the Study:

• To evaluate matrix-associated laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) as a rapid and cost-effective alternative for capsular serotyping of H. influenzae clinical isolates.
• To establish an in-house database for H. influenzae serotyping using MALDI-TOF MS.

Main Methods:

• An in-house MALDI-TOF MS database was created for all six H. influenzae serotypes and NT strains.
• The performance of the database was assessed using 79 previously identified clinical strains and 58 prospectively collected strains.
• Measurements were conducted on a Bruker MALDI BioTyper system, with results determined by matching spectra against the reference library.

Main Results:

• MALDI-TOF MS correctly identified all 137 tested H. influenzae strains.
• High sensitivity and specificity were observed for serotypes b, e, f, and NT strains, with values such as 100%/94.3% for type b and 85.5%/99.2% for NT strains.
• The method demonstrated excellent performance, confirming its utility for H. influenzae serotyping.

Conclusions:

• MALDI-TOF MS is a valuable alternative for the capsular serotyping of H. influenzae clinical strains.
• This technique offers significant advantages in speed and cost-effectiveness compared to conventional methods.
• MALDI-TOF MS is suitable for routine implementation in clinical diagnostic laboratories for efficient H. influenzae identification.