1399 A Comparison of Colonising Organisms with Those Causing Acquired Neonatal Septicaemia

Abstract

Aims: To compare organisms colonising infants in a tertiary level neonatal unit with those subsequently causing acquired nosocomial septicaemia. Methods: We performed a retrospective audit of cases of culture-positive septicaemia in the Grantley Stable Neonatal Unit (GSNU) between January 2005 and December 2009. Cases were identified using the unit's database. We excluded those with onset of septicaemia before admission to the unit. Relevant data were extracted from the unit database and from patients' pathology reports. Specimens analysed included gastric aspirates, surface swabs, ETT aspirates, catheter tip cultures, and other clinically indicated swabs or specimens. Results: During the study period there were 7572 admissions, with 116 episodes of septicaemia, acquired in the GSNU, in 105 patients. Two episodes involved co-infection with two organisms. The most common organisms causing septicaemia were enteric Gram-negative bacilli (n=33), coagulasenegative Staphylococcus (CONS) species (n=30) and Staphylococcus aureus (n=23). Colonising organisms isolated most commonly were ‘normal respiratory flora’ not further specified (62 patients) and coagulase-negative staphylococci (44 patients). Septicaemia-causing and prior colonising organisms matched in 39/118 episodes (33%). Another 17 (14%) had possible matches (eg, Staphylococcus aureus versus ‘mixed skin flora’). In 47 episodes (40%) the organisms did not correlate. The remainder had no colonising organisms identified. Septicaemia-causing organisms were most likely to have been previously isolated from ETT aspirates (n=17), post-admission surface swabs (n=9), and umbilical catheter tips (n=8). Conclusions: There is relatively little correlation between acquired septicaemia and prior colonising organisms. Non-targeted surveillance may be of little clinical usefulness. Well-designed prospective studies are needed.