VRE admission culturing, isolation end transmission

Identification of colonization triggers isolation

Culturing transferred patients for vancomycin-resistant enterococci (VRE) is a cost-effective infection control measure that warrants wider consideration, report infectious disease clinicians at the University of Virginia Health System in Charlottesville.

VRE had remained under control at the facility since Centers for Disease Control and Prevention guidelines were implemented in 1994. However, prevalence of VRE colonization (0.73%) and infection (22 infections [0.08%]) increased in 1997 and in the first half of 1998 (1.1% colonized, 17 infections [0.12%]).¹ To investigate sources for the increases, which occurred with no change in infection control policies, patients admitted as transfers from other institutions were cultured on admission.

"If they are infected, we usually know about it, because they are transferred here with that infection," says Carlene Muto, MD, a fellow in infectious disease and epidemiology at the hospital. "The real problem is most people don’t check for [VRE] colonization. So it’s not as if the nursing homes are keeping information from us; it’s that they are not aware of it themselves."

Clinicians reasoned that the increase could be stopped if incoming colonized patients were identified and promptly placed under VRE isolation.

"We think a lot of the spread at our hospital is from people who are not identified," Muto notes.

Under the program, all patients admitted to three high-risk units were cultured, even if admitted from the community. The hospital computer was programmed to identify patients meeting culture criteria and to instruct the admitting nurse to perform a perirectal swab culture. During the first 47 days of the evaluation, 747 patients met criteria for culture. Of those, 606 patients had cultures obtained, resulting in a compliance rate of 81.1%. Of the cultures obtained, 306 (50.5%) represented admissions from other institutions and 300 (49.5%) represented admission from the community. Seven (2.29%) of 306 patients admitted from other institutions were VRE culture-positive, as compared with 0.67% (2/300) admitted from home. VRE colonization and infection rates fell as patients were identified and placed in isolation. As part of the program, patients were educated about VRE and their need to be in isolation. (See handout, p. 37.)

"It was creeping up despite no change in infection control methods," says Barry Farr, MD, hospital epidemiologist and professor of medicine and epidemiology at UVA. "It implied to us that they were starting to come through the front door, and our cultures showed we were right. No hospital is an island, and we all share each other’s problems."

While a cost-benefit analysis was not available, Farr says data to be released in a second phase of the study underscore the efficacy of the practice.

"When you know who has it and they are in isolation, they are tremendously less likely to transmit it to nearby patients," he explains. "We don’t view the costs of doing the cultures as that large. We don’t send the cultures out to a group that is doing them for profit. We do them here locally [and] we buy all of our materials. It has not ended up being that costly."

Moreover, data from a previous study suggest that there is a 16-fold higher risk of spread if colonized or infected patients are left undetected and not placed in isolation.²

"To know if that is cost-effective, first you have to know how effective it is," he says, "how much it lowers the risk of spread to other patients, which is basically what we are buying’ by [culturing]."

Many hospitals have fought VRE less aggressively, and a 1997 Centers for Disease Control and Prevention teleconference warned of a prevailing sense of apathy toward the pathogen. The CDC estimates that VRE prevalence has increased 5,000-fold since its emergence in hospitals in the eastern United States in 1989. (See Hospital Infection Control, November 1997, pp. 161-164.) In that regard, Farr disagrees with accepting endemic levels of VRE, even if there is evidence of multiple strains rather than a single clonal outbreak.

"I don’t think it is a rationale to give up," he says. "I come from a basic belief that the original infection control idea — the idea of keeping these things from being handed to patients as a casual contagion — is a good idea. And we work at that."

References

1. Muto CA, Cage EG, Durbin LJ, et al. The utility of culturing patients transferred from other hospitals or nursing homes on admission for vancomycin resistant enterococcus. Abstract 595 Fr. Presented at the annual meeting of the Infectious Disease Society of America. Denver; Nov. 12-15, 1998.

2. Jernigan JA, Titus MG, Dieter H, et al. Effectiveness of contact isolation during a hospital outbreak of methicillin-resistant Staphylococcus aureus. Am J Epidemiol 1996; 143: 496-504.