Journal of Global Antimicrobial Resistance (Dec 2024)
Antimicrobial Resistance in Coagulase Negative Staphylococci: Genome Analysis and Role of Horizontal Gene Transfer
Abstract
AIM: To investigate the genetic diversity and antimicrobial resistance mechanisms in multidrug-resistant coagulase-negative staphylococci (CNS) isolated from blood cultures. BACKGROUND: CNS are increasingly recognized for their role in antimicrobial resistance, yet comprehensive genomic studies remain limited. This study focuses on understanding species-level diversity and resistance mechanisms in CNS strains. METHODS: We conducted whole-genome sequencing on 12 CNS strains from Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus hominis. We analyzed multi-locus sequence types, phylogenetic relationships, and genetic determinants of resistance, including resistance genes, plasmids, mobile genetic elements, and horizontal gene transfer (HGT) mechanisms. RESULTS: Our genomic analysis identified 22 unique resistance genes associated with 11 antimicrobial classes and quaternary ammonium compounds. Notably, we discovered the ISSha1 element in S. hominis for the first time. Novel resistance-carrying plasmids, such as pGO1 and VRSAp in S. haemolyticus, and Enterococcal pAMalpha1 in S. hominis, were also detected. While level-3 and level-4 Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) sequences were found in S. hominis, suggesting potential HGT barriers, comprehensive HGT barrier systems were not identified. Despite extensive genetic characterization, certain phenotypic resistance phenomena remained unexplained, indicating the presence of additional, unidentified mechanisms. CONCLUSIONS: Our findings highlight the genetic diversity and resistance mechanisms within CNS species, emphasizing their role as reservoirs for resistance genes. The detection of species-specific resistance genes and plasmids with cross-species transfer potential underscores the importance of vigilant surveillance and species-level screening. This study advocates for expanded genomic surveillance and collaborative efforts to combat antimicrobial resistance, emphasizing the need for CNS-specific resistance databases.
