A study today in Pediatrics indicates that MRSA bloodstream infections affect children differently than adults, and that without early and aggressive treatment, children are at risk of developing serious complications.
In a retrospective study of more than 200 children diagnosed as having methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, researchers found that while mortality was low and the median duration of MRSA bacteremia is much shorter in children than in adults, nearly a third experienced treatment failure. And with each additional day the blood infections linger in children, the increased risk of developing complications rose by 50%.
"It really highlights differences in what we know about epidemiology of infections in children compared to in adults," study author Rana Hamdy, MD, MPH, director of the antimicrobial stewardship program at Children's National Health System, said in an interview.
The findings also suggests further research is needed to pinpoint the proper amount of vancomycin—the antibiotic of choice for MRSA infections—needed in children with MRSA bacteremia
Treatment failure common
Of the 278 children with MRSA bacteremia identified by the researchers in three children's hospitals in Pennsylvania, Maryland, and Utah, 232 met the criteria for inclusion in the study. The median age of the children was 5.3 years. The primary sources of the infection in the children were osteomyelitis, or bone infections (31%), catheter-related bloodstream infections (22%), and skin and soft-tissue infections (16%).
Bone infections tend to be common in children because their growing bones require a greater blood supply.
While MRSA bloodstream infections in adults are generally healthcare-associated, 78% of the children's were community-onset, meaning they occurred in the home or in another non-healthcare setting, such as a school or daycare center.
Of the 232 children with MRSA bacteremia, 31% experienced treatment failure, which was defined as 30-day MRSA-attributable mortality, recurrence of bacteremia within 30 days, and persistence of bacteremia for more than 3 days. Twenty-three percent of the children developed complications, including blood clots and the spread of the initial infection to another site in the body.
Five of the patients (2%) died within 30 days. The median duration of bacteremia was 2 days.
In adults, by comparison, mortality from MRSA bacteremia can be as high as 30%, and the pathogen remains in the bloodstream for an average of 8 to 9 days.
To determine the criteria for treatment failure, Hamdy and her colleagues did a secondary analysis of the outcomes. From that analysis they determined that endovascular infections (odds ratio [OR], 4.45), musculoskeletal infections (OR, 2.4), and critical illness (OR, 2.77) were all associated with increased odds of treatment failure.
Hamdy explained that the duration of bacteremia will generally be longer when there is a greater burden of bacteria in the blood, and that occurs when the main sources of infection are large bones or the heart. "It seemed that those were the infections that were harder to clear, and those children ended up having the bacteria detected in their blood for longer periods," she said.
Also, further analysis showed that for those children who had bacteremia for longer periods, every 1-day increase in duration was associated with a 50% increase in the odds of developing complications.
Early, aggressive treatment
For Hamdy, this in an indication that clinicians need to administer appropriate antibiotic therapy and make sure they drain any abscesses—which frequently occur in MRSA infections—early on in the infection. "For patients who have MRSA bloodstream infections, early and aggressive therapy with both antibiotics and appropriate source control, with drainage of any abscesses, is going to be very important to reduce the risk of complications," Hamdy said.
But Hamdy and her colleagues found that appropriate antibiotic therapy for children with MRSA bacteremia may also look different than it does for adults. Unlike in adults, who are more likely to experience treatment failure when they have low concentrations of vancomycin in the blood, treatment failure in children was not linked to vancomycin concentrations.
This finding could be important, the study notes, because the high doses of vancomycin recommended for adults with invasive MRSA infections have been linked to nephrotoxicity (toxic damage of the kidneys) in children. "Additional studies are needed to better understand what the target dose or concentration should be in children," Hamdy said.
Beyond the implications for treatment of MRSA bacteremia in children, Hamdy thinks the study shows that bacterial infections in children may need to be managed differently than they are in adults.
"A lot of our management practices, even when it comes to doses of antibiotics in children, have been extrapolated from adults," Hamdy said. "I think this is one of many examples that show we really can't do that, because the epidemiology, the outcomes, the characteristics of these infections are very different in children than they are in adults."
"We need to understand how these infections affect children distinct from how they affect adults, and I don't think we can make any assumptions about the way that diseases play out in children based on what they do in adults," she added.
See also:
May 5 Pediatrics study
