MRSA on the rise, even in newborns

September 2006

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) is increasing both in and out of the hospital. According to the CDC, there has been an increasing incidence of MRSA in intensive care units and in the community.

Epidemiologically, the CDC defines community-associated MRSA as any diagnosis of MRSA made in an outpatient setting or within the first 48 hours of hospital admission with no history of MRSA colonization or infection, no history of permanent indwelling catheters or medical devices and no history in the past year of hospitalization, long-term care facility stay, dialysis or surgery.

Looks like a spider bite

“Community-associated MRSA is clinically an infection of the skin and soft tissue that resembles a spider bite. MRSA can cause pneumonia or other more severe infections, including but not limited to sepsis, toxic shock syndrome, osteomyelitis and necrotizing fasciitis. For a small proportion of patients, it is a life-threatening event,” Sue Gerber, MD, MPH, said at the 33rd Annual Educational Conference and International Meeting of the Association for Professionals in Infection Control and Epidemiology Inc., held in Tampa, Fla.

Recently, there have been documented outbreaks of community-associated MRSA in well-baby nurseries, according to Gerber, of the Chicago Department of Public Health.

Outbreaks in well nurseries

A Chicago nursery reported that a number of newborns were returning to the hospital within a few days after birth with MRSA skin lesions.

These reports included newborns who were younger than 30 days old and who were delivered at the hospital between May and December 2004. When they returned to the hospital, these patients had recognizable skin lesions but not colonization.

Eleven babies (nine boys and two girls) delivered between May and December were identified as having MRSA. The babies’ mean age was 7 days, with a range of 4 to 23 days. Their mean hospital stay was four days, with a range of three to 11 days. Nine of the babies were delivered by cesarean section, and one baby had onset of MRSA before discharge.

The skin lesions were documented by health care providers as looking like blisters, vesicles or pustules, and were found all over the body. Two babies had single lesions, and nine had multiple lesions affecting multiple body parts. Ten infants received topical treatment, and three of these also received oral antibiotics. None of the lesions required draining.

None of the mothers or other family members had a history of skin lesions, and there were no links to other risk factors for MRSA, such as history of hospitalization, dialysis, surgery, prison stays or living in military barracks.

As part of the investigation, 135 health care workers were cultured. One physician and one nursery nurse had nasal colonization of MRSA.

The nurse was present in the nursery during the stays of all 11 babies, while the physician was present with just a few of them.

After reinforcement of infection control measures, hand hygiene, direct observation and training and enhanced environmental cleaning, the two health care workers were successfully decolonized, and no further cases were identified.

“This is a somewhat new phenomenon,” Gerber said. “There was a similar cluster in Los Angeles and one in New York City. Many factors can be involved, such as length of hospital stay, maternal factors and cesarean vs. vaginal delivery. Additionally, there seems to be a male predominance, although in the Chicago cluster, none of the males were circumcised.”

Outbreaks in the NICU

Infection control is of utmost importance in the neonatal intensive care unit (NICU), where advanced care takes place.

“MRSA is prevalent in the NICU, and it will be difficult to ever completely eradicate MRSA from the NICU because of the prevalence in the community,” Gerber said. “However, the goal is to prevent invasive disease and morbidity. Prevention of severe infection and guaranteeing the optimal care of these babies is the key.”

In Chicago, seven hospitals reported MRSA in level-3 NICUs. Because of these reports, an investigation was designed to describe the epidemiology of MRSA in Chicago NICUs. The investigation included these seven hospitals and two other hospitals. Hospitals completed standardized surveys for each MRSA-positive patient in the NICU between June 2001 and September 2002.

A cluster was defined as two or more patients in the NICU with a positive culture for identical types of MRSA taken on collection dates within a 14-day period. An invasive case was defined as MRSA isolated from a sterile site, blood, spinal fluid or soft tissue associated with a change in a patient’s clinical status or a patient diagnosed with an abscess and MRSA isolated from the abscessed site.

A noninvasive case was MRSA isolated from nonsterile sites, such as sputum, umbilicus, rectum, device, etc.

Thirteen clusters were identified in these nine hospitals.

There were 149 total cases (118 noninvasive and 31 invasive), 24 bacteremias and seven abscesses. There were 10 deaths (six invasive cases and four noninvasive cases).

“Transmission of MRSA can be within hospitals or from community strains. The potential for this is great, as health care workers serve at many different facilities,” she said.

Recommendations for these nine hospitals included hand hygiene, isolating cohorts, neonatal surveillance cultures, screening of health care workers, decolonization, environmental cultures, molecular analysis, communication and regulation.

Preventing MRSA in the nursery

According to Gerber, following are recommendations to prevent MRSA in the well-baby nursery:

• Hand hygiene: availability of soap and water and alcohol-based waterless solutions, no artificial fingernails and compliance.
• Environmental cleaning: MRSA can exist anywhere. All equipment has the potential for contamination.
• Umbilical care: This may delay cord detachment, but reduces bacterial colonization.
• Parent and visitor education: Include education on hand hygiene and information about MRSA and other nosocomial pathogens.
• Observation of the umbilicus: Health care workers need to watch for infection.
• Limitation of visitors: Explain to families why visitors should be limited, especially those with apparent skin lesions.
• Gowns: In the outbreak setting, they can be effective, but this is not a hard-and-fast rule.
• Weigh the benefits of breast-feeding: MRSA can be passed from mother to child through breast milk, but this must be weighed against the benefits of breast milk. Breast pumps could be a reservoir for MRSA contamination, so storage and handling of pumped milk is key.

Unknown effects

Continuing surveillance efforts, such as the National Nosocomial Infection Surveillance System and European Antimicrobial Resistance Surveillance System, have shown the global increase in MRSA infections worldwide, Gerber said.

Infection is known to cause psychological and financial harm. Although direct costs include hospitalizations, additional diagnostic procedures, therapy and additional antibiotic use, indirect costs include productivity loss, long-term disability and mortality.

For more information:

• Gerber S. MRSA in the newborn. Presented at the 33rd Annual Educational Conference and International Meeting of the Association for Professionals in Infection Control and Epidemiology Inc. June 11-15, 2006. Tampa, Fla.