Outbreak Intervention for Bloodstream Infections Caused by Methicillin Resistant Coagulase-Negative Staphylococci in Neonatal Intensive Care Unit

Abstract

Coagulase-negative staphylococci (CoNS) may cause severe infections in newborns hospitalised in Neonatal Intensive Care Units (NICU). The present study aimed to investigate the outbreak of bloodstream infections (BSI) caused by CoNS among 18 neonates in Polish NICU, including the implementation of preventive strategies. The outbreak period was observed from June to September 2009 in a group of 1016 newborns. To terminate the outbreak, an independent audit was performed in October 2009 by a team of experts. The post-intervention time lasted from January to March 2010. The genotype characteristics of CoNS derived from the blood samples and strains isolated from the NICU environment and staff hands were analysed by PCR (Polymerase Chain Reaction) and PFGE (Pulsed Field Gel Electrophoresis). In the outbreak period, the incidence density of BSI was 4.5/1000 patient days (pds), whereas that of CoNS BSI was 3.3/1000 pds. Generally, in the outbreak period, 18 cases of BSI caused by CoNS were registered with a large number of new cases in the 34th week of 2009, associated with a four-day-long public holiday. Both monomicrobial infections, as well as polymicrobial ones caused by multi-drug resistant Staphylococcus haemolyticus and Staphylococcus epidermidis, were noted. The result indicated high epidemic level of resistance genes among the CNS strains as well as horizontal spread of selected clones. After the intervention, when the preventive procedures had been standardized, a twofold decrease was recorded in the incidence rate of BSI from 4.5/1000 pds in the outbreak time comparing to 2.4/1000 pds in the post-intervention time. Our data support the view that CoNS are significant nosocomial pathogens in NICU and that some clones are transmitted between babies, through the hands of the staff. The research shows a failure to prepare Polish Infection Control Teams f