Predicting Clearance of Colonization with Vancomycin-Resistant Enterococci and Methicillin-Resistant Staphylococcus aureus by Use of Weekly Surveillance Cultures

Abstract

We analyzed surveillance cultures for vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) collected during a multicenter trial to determine if three negative cultures collected at weekly intervals would predict clearance of VRE or MRSA from colonized patients. Seventy-two percent of VRE-colonized patients and 94% of MRSA-colonized patients were culture negative after three consecutive negative cultures.Infections with oxacillin (methicillin)-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) have increased dramatically in recent years, and together, they cause 12% of all health care-associated infections (2,8,16). Patients infected with MRSA or VRE, as well as asymptomatically colonized patients, serve as a reservoir for transmission of these bacteria to other hospitalized patients. To prevent spread, national guidelines recommend that health care providers use contact precautions during care of colonized and infected patients until it can be demonstrated that they are no longer colonized (5,10,14). Colonization with VRE can be prolonged (1, 3, 7), so the current recommendation by the Hospital Infection Control Practices Advisory Committee (HICPAC) is that isolation precautions should be maintained until VRE-negative results are documented with at least three consecutive negative cultures collected a minimum of 1 week apart (6,14,15). Persistent carriage with MRSA is also well documented (11, 13). Criteria for documenting clearance of MRSA from colonized patients are not established, although the standard of three negative weekly cultures is commonly applied to this population.The National Institute of Allergy and Infectious Diseases (NIAID) supported a large, cluster-randomized trial assessing strategies to reduce transmission of VRE and MRSA in 19 intensive care units (ICUs) (W. C. Huskins, C. M. Huckabee, N. P. O'Grady, P. R. Murray, H. Kopetskie, L. Zimmer, M. E. Walker, R. L. Sinkowitz-Cochran, J. A. Jernigan, M. Samore, D. Wallace, and D. A. Goldmann, submitted for publication). Stool or perianal swabs for VRE and anterior nasal swabs for MRSA were collected at all ICU sites from patients upon admission, weekly thereafter, and on discharge and were processed at a central laboratory. More than 22,000 swabs from approximately 9,900 patients were collected for VRE culture, and a similar number was collected for MRSA, during the 18-month study period. The trial did not include any systematic effort to "decolonize" patients, and topical antimicrobial agents (e.g., mupirocin, chlorhexidine, and vancomycin) were used infrequently in the participating ICUs. The systematic collection of specimens from ICU populations at multiple geographic sites presented an opportunity to evaluate the HICPAC recommendations for VRE and their applicability for MRSA colonization.Stool or perianal swabs for VRE were inoculated into bileesculin azide broth supplemented with 8 g/ml vancomycin and incubated at 35°C for 18 to 24 h. Broths were subcultured onto bile-...

Performance Characteristics of the Cepheid Xpert vanA Assay for Rapid Identification of Patients at High Risk for Carriage of Vancomycin-Resistant Enterococci

“…The lower sensitivity of a culture, therefore, should be taken into consideration when following the HICPAC recommendation to terminate isolation following three negative cultures (2). Multiple studies have also shown that spontaneous decolonization occurs only in a limited number of patients; however, reappearance of the VRE within a few weeks of decolonization is common (12,18,19). All Xpert vanA-positive discordant results were tested by a second independent laboratory-developed real-time PCR to confirm that the false-positive results were truly due to the presence of the vanA gene.…”

Persistance du portage de bactéries multirésistantes après la réanimation

“…Ce portage indétectable se révélera problématique lorsque la BMR émergera à nouveau après une ou plusieurs lignes d'antibiothérapie. [17][18][19].…”

Duration of Contact Precautions for Acute-Care Settings

“…The SRN survey found that most institutions used 1-3 negative MRSA surveillance cultures to determine whether CP could be discontinued, though some providers report that their hospital utilizes CP indefinitely in patients with a history of MRSA. Published evidence indicates that most patients will remain negative for MRSA colonization if they have 3 consecutive negative weekly surveillance cultures, 12 though the optimal number of and interval between cultures remains unclear in the literature. Patients with chronic wounds and those from long-term care facilities may be at higher risk for persistent MRSA colonization and recolonization 13 ; thus, for these patients, hospitals may extend CP.…”

“…36 Published evidence indicates that most patients will remain negative for MRSA if they have 3 consecutive negative weekly surveillance cultures. 12 …”

“…72 Most studies investigating the duration of VRE colonization duration have used gastrointestinal tract samples, 63 stool samples, 14,19 and perirectal and perineal swabs, 20,67,68,73 or both. 12,60 Some studies have included surveillance cultures obtained from other sites including throat and urine samples. 16 While limited, data comparing the sensitivity of rectal and perirectal cultures suggest that both are comparable.…”