Community MRSA on the rise in kids

Staphylococcus aureus bacteria
Staphylococcus aureus bacteria

HealthDay News -- Incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections among children has not decreased as it has in adults, and community-acquired forms of the disease are actually on the rise in pediatric populations, CDC data indicate.

The incidence of invasive community-associated MRSA infection showed a modeled yearly increase of 10.2%, from 1.1 to 1.7 infections per 100,000 from 2005 to 2010, Martha Iwamoto, MD, MPH, of the CDC in Atlanta, and colleagues reported in Pediatrics.

During the same time period, healthcare-associated and hospital-onset MRSA infection rates in children have remained the same.

In contrast, recent studies of adult populations have shown healthcare-associated MRSA rates have decreased 54.2% and hospital-onset rates have decreased 5% from 2005 to 2011. Among children the largest proportion of cases were community-associated and not associated with healthcare or a hospital stay (42%), whereas most adult cases were healthcare-associated community onset (60%), the researchers pointed out.

"Current prevention strategies for community-associated MRSA focus on education and behavior change aimed at improving hygiene, and it is unknown whether these strategies are effective or have been widely adopted," they wrote. "Additionally, some interventions recommended for adults may not be recommended in children because of the lack of data about risks versus benefits for young children."

Other differences between the two populations include a much higher prevalence of the typically community-acquired USA300 MRSA strain in healthcare-associated and hospital-onset pediatric MRSA cases compared with adults.

In the current study, USA300 accounted for 72% of invasive MRSA overall, 54% of hospital-onset cases and 63% of healthcare-associated cases, whereas in adult studies the USA300 strain was responsible for only one quarter of hospital onset invasive MRSA and one-third of healthcare associated cases. 

The only significant decreases in MRSA within the pediatric population occurred in infants aged 3 to 89 days -- incidence decreased 9.8% per year from 2005 through 2010, and was significant for hospital-onset cases and larger among nonblack infants.

"The observed decline is likely due in part to progress in infection prevention practices in NICUs, especially improvements in central line insertion and maintenance practices," the researchers wrote.

The MRSA incident rate was highest in infants aged 90 days and younger at 43.9 per 100,000 in 2010. Black children were disproportionately affected compared with other races, accounting for 59% of cases with an incidence rate of 6.7 vs. 1.6 per 100,000 among other children.

The data comprised 876 pediatric MRSA cases reported to the CDC's Active Bacterial Core Surveillance (ABCs), an active population-based surveillance system for laboratory-confirmed MRSA that spans nine metropolitan areas across the United States.

Overall, 35% of the reported MRSA cases were hospital onset, 23% were healthcare-associated community onset and 42% were community-associated.

The majority had an underlying medical condition (68%) -- most commonly prematurity (19%) or a skin condition such as eczema or abscesses (18%) -- and most resulted in hospitalization (91%). Overall, 6% of cases were fatal.

"These findings underscore the need for defining optimal strategies to prevent MRSA infections among children, especially children without health care risk factors, hospitalized children outside of the ICU, and children with recent exposure to health care," the researchers wrote.


References

  1. Iwamoto M et al. Pediatrics 2013; 132: e817–e824.
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