Antimicrobial resistance dynamics of Listeria monocytogenes in France: where we are and what we need?

Abstract

Listeriosis, caused by Listeria monocytogenes, is a significant global foodborne illness with high mortality rate (20%-30%), 1 especially affecting vulnerable populations. 2The primary approach for treating listeriosis involves the use of aminopenicillins alone or in combination with aminoglycosides. 2 However, the persistent rise in antimicrobial resistance (AMR) has jeopardized current treatments.Therefore, global surveillance systems employing in-depth and accurate methods are crucial for comprehending the AMR mechanisms and, consequently, limiting the spread of antimicrobialresistant strains, to safeguard the effectiveness of both current and future treatments.In this issue of The Lancet Regional Health-Europe, Moura and colleagues 3 have used massive sequencing data coupled with phenotypic AMR assessment of L. monocytogenes isolated from clinical (n = 2908) and food (n = 2431) samples in France and overseas territories.The findings indicate that there is no increase in AMR, and all isolates (100%) demonstrated susceptibility to ampicillin and amoxicillin, the first-line treatments for listeriosis.Additionally, the authors illustrated a high accuracy (>99%) of whole genome sequencing (WGS) in predicting AMR, along with the associated genetic elements such as transposons, prophages, or plasmids.Furthermore, the study revealed that while acquired resistance was infrequent (2.23%), it was more prevalent in food (3.74%) than clinical isolates (0.98%) (p < 0.0001).Notably, isolates exhibiting disinfectant or stress resistance traits (bcrABC and emrC genes encoding resistance to benzalkonium chloride) showed a higher prevalence of acquired resistance (20.20% vs. 7.20%) (p < 0.0001).Interestingly, these findings provide evidence for the efficacy of the current listeriosis treatments.However, recent worldwide studies have indicated a rise in AMR, especially toward aminopenicillins, 4-6 presenting another facet of a controversial picture.Significantly, the high accuracy observed in predicting AMR underscores the potential utility of WGS for routine surveillance of AMR in L. monocytogenes.Thus far, WGS has demonstrated high accuracy in predicting AMR in foodborne pathogens.Notably, Nguyen et al. have shown that MICs