title: Nosocomial spread of a Staphylococcus capitis strain with heteroresistance to vancomycin in a neonatal intensive care unit.
abstract: A premature infant in a neonatal intensive care unit (NICU) developed a bloodstream infection caused by coagulase-negative staphylococci (CoNS) sensitive to vancomycin. The infection persisted for 3 weeks, despite therapy with vancomycin and replacement of all intravenous catheters. The neonate died due to necrotizing enterocolitis which developed during the ongoing sepsis. We screened this strain and 216 other strains of CoNS from cultures of blood obtained from neonates between 1997 and 2000 for heteroresistance to vancomycin. Forty-eight isolates, including the strain that caused ongoing sepsis, proved heteroresistant. All isolates were identified as Staphylococcus capitis and were identical, just as their resistant stable subcolonies were, when they were genetically fingerprinted by amplified-fragment length polymorphism analysis. The heteroresistant phenotype of this endemic strain was confirmed by population analysis. We conclude that heteroresistance to vancomycin occurs in S. capitis and might be the cause of therapeutic failures in NICUs. Moreover, heteroresistant strains can become endemic in such units.
authors.affiliation: Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands. w.zwet@vumc.nl
authors.forename: Wil C
authors.initials: WC
authors.lastname: Van Der Zwet
authors.forename: Yvette J
authors.initials: YJ
authors.lastname: Debets-Ossenkopp
authors.forename: Erik
authors.initials: E
authors.lastname: Reinders
authors.forename: Maria
authors.initials: M
authors.lastname: Kapi
authors.forename: Paul H M
authors.initials: PH
authors.lastname: Savelkoul
authors.forename: Ruurd M
authors.initials: RM
authors.lastname: Van Elburg
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramatsu
authors.forename: Christina M J E
authors.initials: CM
authors.lastname: Vandenbroucke-Grauls
mesh_terms: D003428:Cross Infection / Q000382:microbiology* / Q000635:transmission; D016172:DNA Fingerprinting; D017809:Fatal Outcome; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D010641:Phenotype; D013203:Staphylococcal Infections / Q000382:microbiology* / Q000635:transmission; D013210:Staphylococcus / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification*; D020713:Vancomycin Resistance