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. 2025 Mar;30(11):2400309.
doi: 10.2807/1560-7917.ES.2025.30.11.2400309.

Epidemiology of Staphylococcus haemolyticus nosocomial bacteraemia in neonatal intensive care units, France, 2019 to 2023: predominance of the ST29 (CC3) multidrug-resistant lineage

Patricia Martins Simões  1   2 , Nathalie van der Mee-Marquet  3 , Benjamin Youenou  1   2 , Anne-Gaelle Ranc  1   2 , Céline Dupieux-Chabert  1   2 , Guillaume Menard  4   5 , Clarisse Dupin  6 , Marine Butin  1   2   7 , François Vandenesch  1   2 , Frédéric Laurent  1   2 , Anne Berger-Carbonne  8 , Camille Kolenda  1   2 , Anne Tristan  1   2 ; S. haemolyticus neonatal infections Study Group  9
Collaborators, Affiliations

Epidemiology of Staphylococcus haemolyticus nosocomial bacteraemia in neonatal intensive care units, France, 2019 to 2023: predominance of the ST29 (CC3) multidrug-resistant lineage

Patricia Martins Simões et al. Euro Surveill. 2025 Mar.

Abstract

BackgroundStaphylococcus haemolyticus (SH) is an opportunistic pathogen associated with nosocomial infections, particularly bacteraemia in neonates. Epidemiological trends and genetic diversity of these infections worldwide are largely unknown.AimTo investigate an increase in SH vascular catheter-related bacteraemia in neonates and describe the molecular epidemiology in France between 2019 and 2023.MethodsWe analysed clinical and microbiological surveillance data from the French national surveillance network for central catheter-related (venous and umbilical) infections between 2019 and 2023. We also performed genomic and phylogenetic analyses of 496 strains isolated both inside (n = 383 from neonates, staff and environmental samples) and outside (n = 113 from adults) the neonatal intensive care unit (NICU) settings.ResultsThe proportion of SH among the 474 reported cases of nosocomial bacteraemia increased from about 20% to 30% over 5 years, mainly affecting very low birth weight preterm neonates (≤ 1,500 g). The ST29 sequence type (ST) not prevalent in previous studies was predominant, accounting for 74% of NICU strains. ST29 was characterised by phenotypic multidrug resistance to at least six classes of antibiotics (oxacillin, quinolones, gentamicin, cotrimoxazole, clindamycin and rifampicin), which distinguished it with good sensitivity and specificity from other prevalent multidrug-resistant STs identified (ST1 and ST25). ST29 strains more frequently harboured the drfG, vga-LC and mupA genes and a triple point mutation (D471E, I527M and S532N) in the rpoB gene.ConclusionsThe present study highlights the success of a highly resistant ST29 lineage in French NICUs mainly affecting very low birth weight premature neonates.

Keywords: Staphylococcus haemolyticus; bacteraemia; bloodstream infections; epidemiology; multi-drug resistance; neonatal infections; neonatal intensive care units; outbreak.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Geographical distribution of neonatal intensive care units participating in SPIADI surveillance of nosocomial bacteraemia or sending Staphylococcus haemolyticus strains to the French National Reference Centre for Staphylococci for analysis, France, 2019–2023 (n = 39)
Figure 2
Figure 2
Multilocus sequence typing diversity of Staphylococcus haemolyticus isolates associated with nosocomial infections sent to the French National Reference Centre for Staphylococci, France, 2017–2023 (n = 496)
Figure 3
Figure 3
Phylogeography of French (n = 490) and international Staphylococcus haemolyticus isolates (n = 199), 1988–2023
Figure 4
Figure 4
Phylogeography of the Staphylococcus haemolyticus ST29 clade, France, 2017–2023 (n = 319)
Figure 5
Figure 5
Phylogeography of the Staphylococcus haemolyticus ST25 clade, France, 2017–2023 (n = 73)
See this image and copyright information in PMC

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