Whole-genome sequencing of Listeria monocytogenes from maternal and neonatal clinical isolates in Kuwait

Introduction. Listeria monocytogenes is a foodborne pathogen that poses a significant threat during pregnancy, frequently associated with adverse maternal and neonatal outcomes, including preterm birth, spontaneous abortion, stillbirth and neonatal sepsis.

Hypothesis/Gap Statement. Despite its clinical relevance, there is a lack of whole-genome sequencing (WGS)-based data describing the genomic characteristics and circulating lineages of L. monocytogenes associated with maternal and neonatal infections in Kuwait, limiting regional epidemiological understanding.

Aim. To genomically characterize L. monocytogenes isolates from maternal and neonatal clinical specimens at the Maternity Hospital, Kuwait.

Methodology. Nine clinical isolates collected between 2017 and 2022, obtained from high vaginal swabs and blood cultures of unrelated mothers and neonates, were subjected to WGS. Antimicrobial susceptibility testing was performed using the VITEK-2 system. Genomic analysis included determination of sequence types (STs), clonal complexes (CCs), genomic characterization using multi-locus sequence typing (MLST), core-genome MLST (cgMLST), antimicrobial resistance (AMR) determinants and virulence gene profiles.

Results. Seven isolates (S2–S8) were ST2 and belonged to CC2, whereas S1 and S9 were classified as ST3 and ST308 and belonged to CC3 and CC1, respectively. Phenotypic susceptibility profiles were correlated with genotypic findings, with a conserved resistome dominated by fosX (fosfomycin resistance) and vga(G ) (lincosamide resistance). All isolates harboured conserved core virulence genes associated with stress response, quorum sensing, nutrient regulation, host cell invasion and intercellular survival. The cgMLST analysis demonstrated ≥99.5% genetic similarity among ST2/CC2 isolates, which clustered together and were genetically distinct from older local isolates (S1, S9) and international reference strains.

Conclusion. This first WGS-based genomic characterization of L. monocytogenes in Kuwait demonstrates the repeated detection of ST2/CC2 across multiple maternal and neonatal cases over several years. These findings provide baseline genomic data and highlight the need for integrated, expanded genomic surveillance linking clinical, food and environmental isolates to improve source attribution, early detection and public health interventions for listeriosis.