MRSA Combined With H1N1 Dangerous To Healthy Kids
November 7, 2011

MRSA Combined With H1N1 Dangerous To Healthy Kids

A new study shows how influenza can quickly become deadly, even among healthy children. An example was seen in the 2009 H1N1 influenza pandemic, when many previously healthy children became critically ill, developing severe pneumonia and respiratory failure, potentially fatal.

Now, the Children´s Hospital Boston has conducted the largest nationwide investigation of influenza in critically ill children and found a simultaneous infection with Staphylococcus aureus (MRSA) increased the risk of flu-related mortality 8-fold among previously healthy kids.

Roughly 1 in 3 children hospitalized in pediatric intensive care units for H1N1 during the first year of the 2009 pandemic were previously healthy, according to the study published in the journal Pediatrics. Nearly one in ten of all children sent to intensive care for the flu that year died, according to the study, which analyzed data from 838 of these children from 2009-10.

A total of 282 children died of flu during the 2009-10 flu season, according to the Centers for Disease Control and Prevention (CDC). During the 2010-11 season, 116 children died. From 3,000 to 49,000 Americans of all ages die of the flu each year, according to the CDC.

Nearly all of the children who had MRSA were rapidly treated with vancomycin. The fact that they died despite having the treatment is quite alarming given the rising rates of MRSA carriage among children in the community.

While doctors know that certain chronic illnesses put children at higher risk, such as asthma, heart disease or mental retardation, they cannot predict which healthy children will die from the flu, said study author Adrienne Randolph of Children´s Hospital Boston.

“There´s more risk for MRSA to become invasive in the presence of flu or other viruses,” said Randolph. “These deaths in co-infected children are a warning sign.”

Many people carry some form of staph bacteria on their skin and in their noses, without becoming ill, Niranjan Bhat, an assistant professor at the Johns Hopkins Children's Center, who wasn't involved in the new study, told USA Today reporter Liz Szabo. Under certain circumstances, however, the bacteria can break out and cause a serious infection, he noted. Still, in most cases, doctors can successfully treat these infections with antibiotics.

Aggressive types of the bacteria – which cannot be killed by antibiotics – can be life-threatening, he said.

The study underscores the need for everyone over the age of 6 months to get an annual flu shot, said co-author Timothy Uyeki, of the CDC℠s Influenza Division. People who become ill with a suspected case of flu also should get antiviral drugs immediately. “The 2009 H1N1 virus has not changed significantly to date,” he noted.

“Infections of children in the U.S. with 2009 H1N1 virus are expected this season and need to be prevented and treated appropriately. Influenza vaccination protects against 2009 H1N1 illness,” he said.

The average age of the children critically ill with H1N1 was 6 years. Most had respiratory failure, two-thirds needed a ventilator, and some required extracorporeal membrane oxygenation (ECMO) for advanced cardiac and respiratory support. Their disease progressed rapidly, and 9 percent died, two thirds of them within two weeks of ICU admission.

“Some children were quickly overwhelmed, and many died despite centers doing everything to save them,” said Randolph. “Early in the pandemic, centers were worried that they would run out of ventilators, that they would run out of ICU beds.”

While most of the children critically ill with H1N1 had one or more chronic health conditions that increased their risk, 30 percent were previously healthy.

“It is not common in the US to lose a previously healthy child to pneumonia,” said Randolph. “Unfortunately, these children had necrotizing pneumonia — eating away at their tissue and killing off whole areas of the lung. They looked like immuno-compromised patients in the way MRSA went through their body. It´s not that flu alone can´t kill — it can — but in most cases children with flu alone survived.”

Other studies have found similar results. A 2010 study, also published in Pediatrics, found that the number of children hospitalized for MRSA infection increased from 2 in 1,000 admissions in 199 to 21 in 1,000 in 2008. The rise was attributed mostly to community-acquired cases, and not cases acquired in the hospital.

Many attribute the rise to increased use of antibiotics in both people and animals. “The more antibiotics we take, the more we colonize ourselves with antibiotic-resistant organisms such as MRSA,” Randolph noted.

“Previously, MRSA has not been considered a common cause of pneumonia in kids but this may be changing,” Randolph said. “It´s likely that flu and other viral infections let MRSA invade and that there´s some synergistic reaction between flu and these bacteria.”

While recent data show an increase in MRSA co-infection in children dying from seasonal influenza, this is the first study to collect data on a large number of children with no risk factors for severe flu.


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  • Pediatrics
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