Investigation of MALDI-TOF Mass Spectrometry for Assessing the Molecular Diversity of Campylobacter jejuni and Comparison with MLST and cgMLST: A Luxembourg One-Health Study.

Maureen Feucherolles,Morgane Nennig,Delphine Martiny,Catherine Ragimbeau,Christian Penny,Henry-Michel Cauchie,Sören L. Becker,Serge Losch

doi:10.3390/diagnostics11111949

Abstract

There is a need for active molecular surveillance of human and veterinary Campylobacter infections. However, sequencing of all isolates is associated with high costs and a considerable workload. Thus, there is a need for a straightforward complementary tool to prioritize isolates to sequence. In this study, we proposed to investigate the ability of MALDI-TOF MS to pre-screen C. jejuni genetic diversity in comparison to MLST and cgMLST. A panel of 126 isolates, with 10 clonal complexes (CC), 21 sequence types (ST) and 42 different complex types (CT) determined by the SeqSphere+ cgMLST, were analysed by a MALDI Biotyper, resulting into one average spectra per isolate. Concordance and discriminating ability were evaluated based on protein profiles and different cut-offs. A random forest algorithm was trained to predict STs. With a 94% similarity cut-off, an AWC of 1.000, 0.933 and 0.851 was obtained for MLSTCC, MLSTST and cgMLST profile, respectively. The random forest classifier showed a sensitivity and specificity up to 97.5% to predict four different STs. Protein profiles allowed to predict C. jejuni CCs, STs and CTs at 100%, 93% and 85%, respectively. Machine learning and MALDI-TOF MS could be a fast and inexpensive complementary tool to give an early signal of recurrent C. jejuni on a routine basis.

Highlights

A total of 1134 spectra acquired after an ethanol/acetonitrile extraction were identified by the Bruker BDAL database (n = 8468 spectra) on MBT compass explorer (v4.1)
All isolates were identified as C. jejuni with a score average ≥ 2.00 and all Bacterial Test Standard (BTS) were identified as E. coli with a score average ≥ 2.00
In the present study our results provide evidence that MALDI-TOF mass spectrometry (MS) could be a valuable tool to swiftly subtype C. jejuni

Summary

Introduction

Campylobacter spp. was recognized as an important human pathogen in the 1970s even if it had been previously described at the end of the 19th century by Escherich in the colons of children [1]. It has emerged as being the main cause of enteritis in humans and the most common foodborne bacterial zoonosis, superseding Salmonella spp. infections worldwide. Since 2005, campylobacteriosis is the most prevalent bacterial zoonosis in Europe with an underestimated incidence of 59.7 per 100,000 population in 2019 [2] It is frequently mentioned as an important health and economic burden [3], which represented

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