[Show abstract][Hide abstract] ABSTRACT: Early identification of an outbreak is one of the main advantages of routine epidemiological surveillance. Enterococcus spp. used to be regarded as microorganisms of low pathogenicity, because they are part of the normal microbial flora of the gastrointestinal and genitourinary tract. Recently, they have emerged as important pathogenic agents, sometimes causing infections with high mortality rates. We studied a clustering of primary bloodstream infections caused by Enterococcus faecalis in a cardiology hospital neonatal intensive care unit (NICU). Four cases of primary bloodstream infection by E. faecalis were detected from April 15 to May 13, 2004, during active infection surveillance. The isolates were sensitive to glycopeptides. Some aspects of the management of these patients, including the date of insertion and placement of a central venous catheter, prescription of a specific medication, contiguity of beds, personnel attending the patients, and occurrence of diarrhea were analyzed to look for factors that might affect the spread of the microorganisms. Measures taken to hamper the spread included contact precautions throughout the unit, cleansing and disinfection of equipment and surfaces, bathing children with 2% chlorhexidine-gluconate-containing soap, professional reeducation, and reinforcement of all measures to prevent infections. We suggest that there is a need to re-evaluate preventive infection measures and to review the strategies aimed at decreasing the nosocomial infection rate in the NICU.