An atypical pattern of coagulase-negative staphylococcal (CoNS) sepsis, characterized by persistence despite aggressive antibiotic therapy, has been described in neonates cared for in neonatal intensive-care units. Our aim was to analyse the clinical, microbiological and molecular determinants of this persistent CoNS bacteraemia. Neonates with late-onset CoNS bacteraemia were studied for a 2-year period. Demographic, clinical, laboratory, microbiological and molecular data were compared between neonates with persistent (≥3 consecutive positive blood cultures) and non-persistent CoNS bacteraemia. Twenty-nine infants with persistent and 43 with non-persistent bacteraemia were identified, with no significant differences regarding demographic and clinical characteristics between the two groups. Of a total of 170 CoNS isolates, 80 showed biofilm production (54 persistent and 26 non-persistent; p 0.013), whereas 127 were positive for the icaA and icaD genes (74 persistent and 53 non-persistent; p 0.598). Sixty ica-positive isolates did not produce slime, whereas 13 ica-negative isolates showed biofilm production. Endotracheal intubation and the presence of central vascular catheters were significant risk factors for persistent bacteraemia, but, in a logistic regression model, only biofilm production was significantly related to the persistent form of the disease (p 0.005). In this study, persistent CoNS sepsis in neonates requiring intensive care was not related to most of the known clinical risk factors, and it was associated with severe thrombocytopenia. Isolates associated with persistent bacteraemia were more likely to produce biofilm, independently of the presence of the ica operon.
© 2011 The Authors. Clinical Microbiology and Infection © 2011 European Society of Clinical Microbiology and Infectious Diseases.