Dutch "Search and Destroy" Policy Keeps Community-Acquired MRSA in Check

Paula Moyer, MA

September 29, 2006

September 29, 2006 (San Francisco) — A rigorous screening method can help keep the prevalence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) low among hospitalized patients, according to a team of Dutch investigators who presented their findings here at the 46th Interscience Conference on Antimicrobial Agents and Chemotherapy.

"We definitely have community-acquired MRSA in the Netherlands, but rigorous screening in hospitalized patients reduces spread and prevents cross-fertilization of community-acquired strains with nosocomial MRSA," said principal investigator Christina M. Vandenbroucke-Grauls, MD, PhD, during her presentation.

"At this point about 8% to 10% of MRSA cases in our hospitals are community-acquired." Dr. Vandenbroucke-Grauls, an infection control specialist at the Vrije University Medical Center in Amsterdam, Netherlands, added that MRSA constitutes less than 1% of all hospital-acquired S aureus strains in the Netherlands . Community-acquired MRSA is defined as such if the patients' symptoms of infection began within 48 hours of being hospitalized and the patient has had no evidence of exposure to nosocomial MRSA.

The country began a rigorous program in 2002, dubbed "search and destroy," after having seen a slow increase in MRSA that started 20 years ago. The infection control policies that were introduced in Dutch hospitals to contain MRSA consist of the following measures:

  • isolating and screening high-risk patient groups,

  • screening low-risk groups,

  • strict isolation of carriers, and

  • treatment of people carrying MRSA.

The policy identifies 4 risk groups. The group at highest risk, group 1, consists of known carriers or those who have a positive culture sample from any body site. The next high-risk group, group 2, is made up of patients who have been transferred to Dutch hospitals from other countries, typically outside western Europe, patients who have had carriers as roommates or have been on wards where transmission of MRSA has occurred, either in a hospital or a nursing home. Group 3 consists of hospital staff who were involved in caring for known carriers, hospital staff who have worked in hospitals abroad, and dialysis patients who received such treatment abroad. The last group, Group 4, has no known risk factors. For example, healthcare workers who immigrate to the Netherlands are required to be tested, and must present for that test 1 week before they can start work, Dr. Vandenbroucke-Grauls said during her presentation.

Patients and staff in who are known carriers, group 1, are always strictly isolated. Employees who care for carriers are gowned, masked, and gloved, and they sanitize their hands by a set protocol when they leave the carrier patient's room. Employees who are carriers are not allowed to care for patients until their cultures are negative.

Patients in groups 2 and 3 are isolated until their MRSA status is confirmed by cultures, as are employees. Patients who would presumably be in group 4 are cultured. The approach was instituted after MRSA cases had increased from 5 cases per year 10 years previously to 1500 cases per year in 2002. A reanalysis of S aureus strains showed that certain MRSA were falling below the radar: MRSA with low levels of methicillin resistance. Identifying these strains and improving screening methods was the impetus for developing the isolation and screening policies. "Even so, we still had1500 cases per year, but the intrusion of community-acquired MRSA has dropped," Dr. Vandenbroucke-Grauls said.

She added that gauging the proportion of community-acquired MRSA in the total MRSA pool is difficult, but the community-acquired strains have different genetic features from the nosocomial strains. For example, community-acquired strains typically have Panton-Valentine Leucocidin (PVL) genes, and the presence of the genes can be used as a surrogate marker. A random sample of in-hospital strains in 2002 showed that 15% of MRSA-strains were shown to be PVL-positive.

Guidelines for controlling MRSA in hospitals, issued by the Workingparty on Infection Prevention (WIP), are currently being updated to include the new risk groups for community-acquired MRSA, Dr. Vandenbroucke-Grauls said. This update is timely because certain occupational groups in the community have risks for community-acquired MRSA: soccer players, who share close quarters and have historically shared towels and had other skin-to-skin contact in the locker room, and hog farmers. A porcine strain of community-acquired MRSA has been identified in hogs, which live in close quarters on industrial farms and are often fed high doses of antibiotics in their feed. This strain of MRSA has been transferred to humans, and 23% of hog farmers have been infected.

"We now screen pig farmers when they are hospitalized," Dr. Vandenbroucke-Grauls said. "We ask about pig exposure in a number of questions and if any question gets a 'yes' answer, the patient is isolated."

"The overall Dutch approach and the new information about MRSA in pigs are fascinating and have implications for other countries beyond the Netherlands," said Robert Spencer, DSc. Dr. Spencer is a consultant microbiologist and regional director of the Health Protection Agency at the Bristol Royal Infirmary in the United Kingdom. He stressed that he was speaking on his own and not representing the Infirmary's views.

"However, the main cause of community-acquired MRSA is still selective antibiotic pressure. Patients and parents still pressure physicians to give an antibiotic when it isn't an appropriate choice," Dr. Spencer pointed out. "Physicians still need to educate patients and families that most illnesses are self-limiting and probably viral in nature, and therefore, they shouldn't go to the doctor expecting an antibiotic." This strategy will help prevent further mutation of S aureus strains into MRSA, he said.

46th ICAAC: Abstract K-563. Presented September 28, 2006.

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