Outbreak of multidrug-resistant Staphylococcus haemolyticus ST29 in a French neonatal unit.

Background: Staphylococcus haemolyticus is a clinically relevant coagulase-negative staphylococcus frequently responsible for hospital-acquired infections, especially in premature newborns.

Aim: To describe an outbreak of multidrug-resistant S. haemolyticus in a neonatal department.

Methods: The outbreak was investigated using classical methods, including screening of the patients, genotyping of the isolates and environmental survey. Numerous infection control measures were implemented.

Findings: In 2022 and 2023, a clonal outbreak of multidrug-resistant S. haemolyticus ST29 (40 infections and 71 carriages) occurred in the neonatology department of a University Hospital in France. The infection control measures implemented only partially controlled the outbreak. Although our investigation did not clearly identify the source and mode of transmission, a reservoir constituted by patients and transmission by healthcare workers are the most likely. This episode occurred in a context of countrywide outbreaks of S. haemolyticus ST29 in several French neonatology departments.

Conclusion: This prolonged outbreak of S. haemolyticus ST29 accounted for the increase in the incidence of S. haemolyticus-related infections in French neonatology departments. Implementation of proactive measures is crucial to limit the spread of such pathogens in neonatal ICUs.