Identifying Anaerobic Bacteria Using MALDI-TOF Mass Spectrometry: A Four-Year Experience

Frontiers in Cellular and Infection Microbiology

Maribel Zamora-Cintas¹  María Antonia Fernández-Chico¹  Luis Alcalá²  Lidia Quiroga²  Adrián Ruiz²  Belén Rodríguez-Sánchez²  Mercedes Marín³  Patricia Muñoz⁴ 

[1] Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain;Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain;Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain;Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain;Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain;CIBER de Enfermedades Respiratorias (CIBERES CB06/06/0058), Madrid, Spain;Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain;Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain;CIBER de Enfermedades Respiratorias (CIBERES CB06/06/0058), Madrid, Spain;Medicine Department, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain;

关键词: MALDI-TOF;    mass spectrometry;    protein spectrum;    anaerobic bacteria;    routine identification;   

DOI  :  10.3389/fcimb.2021.521014

来源: Frontiers

【 摘 要 】

Because of the special culture requirements of anaerobic bacteria, their low growth-rate and the difficulties to isolate them, MALDI-TOF MS has become a reliable identification tool for these microorganisms due to the little amount of bacteria required and the accuracy of MALDI-TOF MS identifications. In this study, the performance of MALDI-TOF MS for the identification of anaerobic isolates during a 4-year period is described. Biomass from colonies grown on Brucella agar was directly smeared onto the MALDI-TOF target plate and submitted to on-plate protein extraction with 1μl of 100% formic acid. Sequencing analysis of the 16S rRNA gene was used as a reference method for the identification of isolates unreliably or not identified by MALDI-TOF MS. Overall, 95.7% of the isolates were identified to the species level using the updated V6 database vs 93.8% with previous databases lacking some anaerobic species; 68.5% of the total were reliably identified with high-confidence score values (≥2.0) and 95.0% with low-confidence values (score value ≥1.7). Besides, no differences between Gram-positive and Gram-negative isolates were detected beyond a slight decrease of correct species assignment for gram positive cocci (94.1% vs 95.7% globally). MALDI-TOF MS has demonstrated its usefulness for the identification of anaerobes, with high correlation with phenotypic and conventional methods. Over the study period, only 2.1% of the isolates could not be reliably identified and required molecular methods for a final identification. Therefore, MALDI-TOF MS provided reliable identification of anaerobic isolates, allowing clinicians to streamline the most appropriate antibiotic therapy and manage patients accordingly.

【 授权许可】

CC BY