Enhanced surveillance of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in children in the UK and Ireland.
ABSTRACT To determine the incidence and demographic features of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in children in the UK and Ireland and to characterise MRSA isolated from cases.
Prospective surveillance study.
Children aged <16 years hospitalised with bacteraemia due to MRSA.
Cases were ascertained by active surveillance involving paediatricians reporting to the British Paediatric Surveillance Unit and by routine laboratory surveillance. Patient characteristics were obtained using questionnaires sent to reporting paediatricians. MRSA isolates were characterised using molecular and phenotypic techniques including antimicrobial susceptibility testing.
265 episodes of MRSA bacteraemia were ascertained, involving 252 children. The overall incidence rate was 1.1 per 100 000 child population per year (95% CI 0.9 to 1.2): 61% of the children were aged <1 year (a rate of 9.7 cases per 100 000 population per year (95% CI 8.2 to 11.4)) and 35% were <1 month. Clinical data were obtained from 115 cases. The clinical presentation varied, with fever present in only 16% of neonates compared with 72% of older children. A history of invasive procedure was common, with 32% having had intravascular lines and 13% having undergone surgery. 62% of patients for whom data were available were receiving high-dependency care (46% in SCBU/NICU and 16% in PICU). Of 93 MRSA isolates studied, 73% belonged to epidemic strains widely associated with nosocomial infection in the UK and Ireland.
MRSA bacteraemia in children was relatively uncommon and was predominantly seen in very young children, often those receiving neonatal or paediatric intensive care. Bacteraemia predominantly involved well-documented epidemic strains of MRSA associated with nosocomial infection.
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ABSTRACT: An important determinant of a pathogen's success is the rate at which it is transmitted from infected to susceptible hosts. Although there are anecdotal reports that methicillin-resistant Staphylococcus aureus (MRSA) clones vary in their transmissibility in hospital settings, attempts to quantify such variation are lacking for common subtypes, as are methods for addressing this question using routinely-collected MRSA screening data in endemic settings. Here we present a method to quantify the time-varying transmissibility of different subtypes of common bacterial nosocomial pathogens using routine surveillance data. The method adapts approaches for estimating reproduction numbers based on the probabilistic reconstruction of epidemic trees, but uses relative hazards rather than serial intervals to assign probabilities to different sources for observed transmission events. The method is applied to data collected as part of a retrospective observational study of a concurrent MRSA outbreak in the United Kingdom with dominant endemic MRSA clones (ST22 and ST36) and an Asian ST239 MRSA strain (ST239-TW) in two linked adult intensive care units, and compared with an approach based on a fully parametric transmission model. The results provide support for the hypothesis that the clones responded differently to an infection control measure based on the use of topical antiseptics, which was more effective at reducing transmission of endemic clones. They also suggest that in one of the two ICUs patients colonized or infected with the ST239-TW MRSA clone had consistently higher risks of transmitting MRSA to patients free of MRSA. These findings represent some of the first quantitative evidence of enhanced transmissibility of a pandemic MRSA lineage, and highlight the potential value of tailoring hospital infection control measures to specific pathogen subtypes.PLoS Computational Biology 04/2012; 8(4):e1002454. · 4.87 Impact Factor