Characteristics of population structure, antimicrobial resistance, virulence factors, and morphology of methicillin-resistant Macrococcus caseolyticus in global clades

Abstract

Macrococcus caseolyticus is an opportunistic pathogen that is frequently isolated from dairy products and veterinary infections. Recent studies have reported the possibility of methicillin resistance that be transferred among staphylococcal species in foods. The present study examined the population structure, antimicrobial resistance, virulence factors, and morphology of methicillin-resistant M. caseolyticus by investigation of 94 genomes derived from both isolates in beef (n = 7) and pork (n = 2) at Shanghai and those deposited in public domain (n = 85). Phylogenetically, M. caseolyticus were divided into four clades, which each consisted of genomes isolated from continent of European countries (82.4%, n = 78), Asian countries (11.3%, n = 10), United States (4.1%, n = 4), Australia (1%, n = 1), and Sudan (1%, n = 1). The M. caseolyticus isolated from present study formed a genetically distinguished clade, which was characterized by novel alleles in the traditional 7-gene MLST scheme. Furthermore, we identified 24 AMR genes that were associated with 10 classes of antimicrobial agents in M. caseolyticus. Most AMR genes were carried by dominant plasmids such as rep7a, rep22 and repUS56. The genomes in the global clades carried significantly less AMR genes (p < 0.05) and more virulence factors (p < 0.001) than present clade. Virulence factors were detected in methicillin resistant M. caseolyticus including genes coding hemolysin, adherence, biofilm formation, exotoxin, and capsule that associated to human health and infection. Finally, as the close relative of the genus Staphylococcus, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed for morphological comparison that M. caseolyticus has a larger diameter and thicker cell wall compared with S. aureus ATCC 25,923. Taken together, our study suggested that M. caseolyticus mediating divergent antimicrobial resistance and virulence factors could serve as the vector for methicillin resistance habitats in foodborne microorganisms.

Expanding the Landscape of Noncanonical Amino Acids in RiPP Biosynthesis

“…Future efforts to find the mature RiPP will also focus on Streptococcus oralis , an additional species that was sequenced and shown to possess the grc gene cluster after the initial generation of our RaS-RiPP network. Macrococcus caseolyticus , an opportunistic pathogen isolated from dairy products, offers an alternative strain as it encodes a homologous grc cluster on a plasmid, albeit with a different precursor peptide sequence . These strains further underline the complex secondary metabolites that are encoded in underexplored microbes, notably those with small genomes.…”

“…Macrococcus caseolyticus, an opportunistic pathogen isolated from dairy products, offers an alternative strain as it encodes a homologous grc cluster on a plasmid, albeit with a different precursor peptide sequence. 81 These strains further underline the complex secondary metabolites that are encoded in underexplored microbes, notably those with small genomes.…”

Genus-Wide Genomic Characterization ofMacrococcus: Insights into Evolution, Population Structure, and Functional Potential

“…Comparatively, some genomic elements identified here were present across multiple Macrococcus spp., indicating shared inter-species functional potential for some phenotypes. Methicillin resistance genes mecB and mecD , for example, were variably present within multiple Macrococcus species (via GTDB-Tk; Figure 3), mirroring previous studies, which have reported mecB and/or mecD in various Macrococcus spp., including M. caseolyticus (Schwendener et al, 2017; MacFadyen et al, 2018; Zhang et al, 2022), M. bohemicus (Foster and Paterson, 2020), M. canis (Chanchaithong et al, 2019), and M. goetzii (Maslanova et al, 2018). Outside of the AMR space, we further identified proteins that shared homology with virulence factors in other species.…”

“…Aureolysin is an extracellular zinc-dependent metalloprotease secreted by Staphylococcus aureus , which plays a crucial role in host immune system evasion (Thammavongsa et al, 2015; Pietrocola et al, 2017). While others have detected aureolysin homologues in Macrococcus genomes (Mazhar et al, 2019a; b; Zhang et al, 2022), the roles this protein plays in Macrococcus interactions with human or animal hosts (if any) are unknown.…”

“…Several studies have employed genomic approaches to gain insight into the evolution and population structure of Macrococcus ; however, these studies relied on a limited number of genomes (Maslanova et al, 2018; Schwendener and Perreten, 2022) and/or focused on specific taxa within the genus (e.g., M. caseolyticus ) (MacFadyen et al, 2018; Zhang et al, 2022). Furthermore, very few studies—genomic or otherwise—describing Macrococcus spp.…”