Background Hospital-acquired infections are associated with significant morbidity and mortality because they are often caused by multi-resistant pathogens and usually affect children with serious underlying medical conditions.

Objectives To describe trends in hospital-acquired bacteraemia (HAB) among children aged <16 years admitted to a London tertiary hospital between 2001 and 2009 inclusive.

Methods A standard proforma is used by clinical microbiologists for the management of significant bacteraemia in patients admitted to St. George's Hospital, London. Bacteraemia was considered to be hospital-acquired if the blood culture was taken at least 72 h after hospital admission in a child with clinical symptoms, signs and/or laboratory markers consistent with infection.

Results There were 478 episodes of HAB over the 9-year period, including 254 episodes (53.1%) in the Neonatal Intensive Care Unit (NICU). Gram-positive pathogens were responsible for 71 and 76% of episodes in NICU and the paediatric wards, respectively. HAB fell by 71% in NICU from 8.7 to 2.6 episodes/100 discharges (p<0.0001) and by 61% in the paediatric medical wards, from 0.70 to 0.27 episodes/100 discharges (p<0.0001) in 2001–2005 and 2006–2009, respectively. These reductions were mainly related to a decline in line-related staphylococcal bacteraemia following the introduction of guidance on safer insertion and handling of central and peripheral catheters aimed at reducing the burden of methicillin-resistant Staphylococcus aureus infections.

Conclusions The vast majority of HAB in children are associated with line infections, which can be prevented through implementation of appropriate infection control strategies. Rates of HAB are relatively easy to obtain and, after adjustment for case-mix, could be used as part of a national neonatal and paediatric nosocomial infection surveillance programme.