Actualités sur la prise en charge des infections néonatales nosocomiales tardives à staphylocoque à coagulase négative

Abstract

Coagulase-negative staphylococci (CoNS) are the most frequent cause of late-onset sepsis (LOS) in neonatal intensive care units (NICUs). Staphylococcus epidermidis is usually considered the most prevalent CoNS in this setting. However, recent reports have identified Staphylococcus capitis, another CoNS, as an emerging cause of bacteremia in NICU wards. S. capitis is the main cause of LOS in several NICUs in France, whereas this species is rarely found in adult patients from the same hospitals. S. capitis isolates from NICU infants share several striking features: they all belong to the same pulsed-field gel electrophoresis type, designated as NRCS-A, which indicates their clonal relatedness; their resistance profile reflects adaptation to antimicrobial agents specifically used in NICUs, including resistance to beta-lactams and aminoglycosides but not to fluoroquinolones, and reduced susceptibility to vancomycin; and they are associated with more severe LOS than those caused by other CoNS. The molecular characterization of NICU S. capitis isolates from several countries has shown that S. capitis NRCS-A strains have disseminated in both Western Europe (France, the United Kingdom, and Belgium) and Australia. The dissemination of such multiresistant strains imposes difficult therapeutic choices on pediatricians. As a consequence of the recent strengthening of the French and European guidelines that regulate the interpretation of clinical vancomycin susceptibility in staphylococci, a non-negligible proportion of NICU CoNS isolates (including S. capitis as well as other CoNS species) that were usually reported as vancomycin-susceptible are now categorized as vancomycin-resistant. In such cases, practitioners are faced with uncomfortable alternatives: the continued use of vancomycin in spite of the pathogen being unambiguously reported as resistant to this molecule and the use of antimicrobial agents such as linezolid or daptomycin that retain an in vitro efficacy against CoNS but whose use in neonates has not received approval by the healthcare authorities. To cope with this emerging challenge, clinical investigations of the relative tolerance and efficacy of vancomycin, linezolid, and daptomycin in NICU infants infected with these newly reported vancomycin-resistant CoNS are urgently needed.