OBJECTIVE: To investigate the
pathogenesis of
bloodstream infection by
Staphylococcus epidermidis , using the
molecular epidemiology , in high-
risk neonates .
METHODS: We conducted a
prospective study of a cohort of
neonates with
bloodstream infection using
central venous catheters for more than 24 h. "National
Healthcare Safety Network"
surveillance was conducted. Genotyping was performed by
DNA fingerprinting and mecA
genes and icaAD were detected by multiplex-
PCR .
RESULTS: From April 2006 to April 2008, the
incidence of
bloodstream infection and
central venous catheter -associated
bloodstream infection was 15.1 and 13.0/1000
catheter days, respectively, with S. epidermidis
accounting for 42.9% of episodes. Molecular
analysis was used to
document the similarity among six isolates of
bloodstream infection by S. epidermidis from cases with positive
blood and
central venous catheter tip
cultures . Fifty percent of
neonates had
bloodstream infection not identified as definite or probable
central venous catheter -related
bloodstream infection . Only one case was considered as definite
central venous catheter -related
bloodstream infection and was extraluminally acquired; the remaining were considered probable
central venous catheter -related
bloodstream infections , with one probable extraluminally and another probable intraluminally acquired
bloodstream infection . Additionally, among mecA+ and icaAD+ samples, one
clone (A) was predominant (80%). A polyclonal profile was found among sensitive samples that were not carriers of the icaAD
gene .
CONCLUSIONS: The majority of
infections caused by S. epidermidis in
neonates had an unknown origin, although 33.3% appeared to have been acquired intraluminally and extraluminally. We observed a polyclonal profile between sensitive samples and a prevalent
clone (A) between resistant samples. .