Changing Etiology of Bacteremia in Kids Poses New Challenges

Diana Phillips

March 09, 2015

The number of children presenting to the emergency department with bacteremia has decreased significantly over time, but when it does occur, the serious bacterial infection is increasingly healthcare-associated and resistant to empirical antibiotics, and healthcare-associated bacteremia is associated with increased length of stay, according to a new study.

The changing etiology of childhood bacteremia, particularly an observed decrease in vaccine-preventable infections and an increase in Gram-negative illness, have important clinical implications with respect to timely, appropriate treatment, Adam D. Irwin, MRCPCH, from the Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, United Kingdom, and colleagues write in an article published online March 9 in Pediatrics.

"Timely, effective antimicrobial therapy is fundamental to the management of serious infections in children," the authors write. "Delayed recognition of meningococcal disease, and suboptimal resuscitation of septic shock, contribute to mortality in children. The Surviving Sepsis Campaign recommends administration of antibiotics within 1 hour of recognition of severe sepsis."

Using data from children presenting to the emergency department (ED) of a children's hospital between 2001 and 2011, the investigators conducted a retrospective time series analysis of clinically significant episodes of bacteremia to describe the etiology of the illness in the pediatric emergency care setting and to explore the effect of the timeliness of appropriate treatment on outcomes.

During the study period, 692 blood cultures were identified in children who were sampled within 48 hours of presentation to the ED. The cultures represented 575 episodes of bacteremia in 525 children, the authors report.

Of the 575 clinical episodes of bacteremia, the most common isolates were Streptococcus pneumoniae (n = 109), Neisseria meningitidis (n = 96), and Staphylococcus aureus (n = 89). The isolated organisms varied by age, with the most common organisms in early infancy being Escherichia coli and group B streptococcus.

There were 47 cases of neonatal sepsis, including one case of group B streptococcus that began shortly after birth. Overall, S pneumoniae was the most frequently reported. S pneumoniae and N meningitidis were seem most often in children between ages 1 and 5 years, whereas S aureus was seen most frequently in children older than 5 years.

There were 96 meningococcal isolates, 87 of which were group B, five were group C, three were W135, and one was Y, the authors report. During the 11-year period, there were two episodes of methicillin-resistant S aureus, including one episode in a child with a ventriculoperitoneal shunt and one in a previously well child.

During the 11-year period, vaccine-preventable infections saw an annual reduction of 10.6% (95% confidence interval [CI], 6.6% - 14.5%), whereas Gram-negative infections increased 6.7% (95% CI, 1.2% - 12.5%) annually. Importantly, the rate of pneumococcal bacteremia was reduced by 49% (95% CI, 32% - 74%) after the introduction of the pneumococcal conjugate vaccine to the UK immunization schedule in September 2006.

The rate of healthcare-associated bacteremia during the period of study increased from 0.17 to 0.43 per 1000 ED visits and was associated with an increased length of stay of 3.9 days (95% CI, 2.3 - 5.8 days; P = .002), and susceptibility to empirical antibiotics was significantly reduced, going from 96.3% to 82.6% (P < .001).

Significant comorbidities, most commonly gastrointestinal-related, were documented in 151 of the children. In addition, many of the children with gastrointestinal comorbidities had an indwelling central venous line for parenteral nutrition.

The median time to antibiotic administration was approximately 3 hours and varied by type of organism. "Children with vaccine-preventable infections received empirical antibiotics more quickly than children with other types of infection," the authors write. In a multivariable model of time to antibiotics adjusted for other potential contributors, "time to antibiotics was increased by 57 minutes for Gram-negative infections compared with vaccine-preventable infections," they report, noting that older children received antibiotics later than younger children.

Considering the evolving etiology of children with bacteremia presenting to the ED, and specifically the increased likelihood of healthcare-associated infections, resistance to empirical therapy, longer time to treatment, and prolonged length of stay, the authors call for continued etiologic surveillance and improved diagnostic tools to facilitate prompt and effective antimicrobial treatment.

This research was funded by the National Institute for Health Research's Research for Innovation, Speculation and Creativity Programme. The authors have disclosed no relevant financial relationships.

Pediatrics. Published online March 9, 2015.


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