Area kids carry drug-resistant germ

A drug-resistant germ was found in children tested in the St. Louis metropolitan area by researchers at Washington University School of Medicine in St. Louis.

Demographic analyses showed that children carrying the superbug were associated with a low socioeconomic status, defined as enrollment in Medicaid and living in crowded households.

A research team led by Stephanie A. Fritz, M.D., investigator in infectious diseases in the School of Medicine’s Department of Pediatrics, took nasal swabs from 1,300 children. Patients were recruited from 11 pediatric practices in the Washington University Pediatric and Adolescent Ambulatory Research Consortium spread throughout the St. Louis area. Patients ranged in age from birth to 18 and came from a variety of socioeconomic backgrounds.

Of the patients tested, 32 carried methicillin-resistant Staphyhloccoccus aureus (MRSA), a type of staph that is resistant to some antibiotics, and 331 carried, or were colonized with, methicillin-sensitive Staphyhloccoccus aureus (MSSA), a type that many antibiotics can treat. Based on those results, the researchers estimate nearly 2.5 percent of children in St. Louis County and the city of St. Louis are colonized with MRSA and nearly 25 percent are colonized with MSSA. Nationally, about 1 percent of the population is colonized with MRSA, according to the Center for Disease Control and Prevention.

The results of the research were published in the June issue of the journal Pediatrics.

Of the 32 children with the MRSA isolates, nine had health-care associated MRSA types (HA-MRSA) and 21 had community-acquired MRSA types (CA-MRSA). Symptoms of an MRSA infection range from abscesses and boils, which is the most common form of this infection and may spread and become very painful, to rarely, severe sepsis, necrotizing pneumonia and death.

Health-care associated MRSA types occur most often in people with contact with health-care institutions. Community-acquired MRSA infections typically occur in otherwise healthy patients.

Risk factors for community-acquired MRSA include employment of a household member in health care, use of antibiotics within the past year, seeking care in an emergency department or urgent care center in the past six months, hospitalization or history of a prior systemic infection.

“We found that the rate of MRSA nasal colonization in black children was 4.7 percent and 1.2 percent in Caucasian children,” Fritz says. “Possible explanations for this racial disparity include environmental factors leading to greater exposure or a genetic predisposition to colonization.”

Children colonized with health-care associated MRSA were more likely to be white, to have private health insurance and to live in a household with a pet compared with children colonized with community-associated MRSA.

Prior to the late 1990s, MRSA typically only occurred in patients on dialysis, following surgery or residents of nursing homes. However, in the late ’90s MRSA began surfacing in otherwise healthy adults and children.

“We were surprised that we didn’t have a higher rate of MRSA colonization in this community based on the number children we see with MRSA abscesses,” Fritz says. “It is possible that the true prevalence in our community is even higher than demonstrated by our survey because participants were sampled only once and from only one body site.”

To prevent the spread of MRSA, Fritz said families should practice good hand hygiene and not share personal care items, such as towels or razors, since the germ is typically spread from skin-to-skin contact.

Fritz SA, Garbutt J, Elward A, Shannon W, Storch GA. Prevalence of and Risk Factors for Community-Acquired Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus Colonization in Children Seen in a Practice-Based Research Network. Pediatrics, June 2008, pp. 1090-1098.

Funding from the National Institutes of Health under Ruth L. Kirschstein National Research Service Award 5 T32 HD007507 supported this research.

Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked third in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.