VRE infection spells higher costs, increased mortality
Clinicians: Culture all sites, be wary of stethoscopes
Infections with vancomycin-resistant enterococci (VRE) are nearly one-third more costly to treat than infections with susceptible strains, and are more likely to exact the ultimate price from patients, researchers reported recently in New Orleans at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).
On average, treating vancomycin-resistant enterococcal infections was 30% more costly than treating enterococcal infections that respond to vancomycin, and patients infected with VRE had roughly twice the mortality rate, reports Valentina Stosor, MD, researcher and professor of medicine at Northwestern University Medical School in Chicago.
In a study of 53 patients with E. faecium infections, Stosor and colleagues found that all 21 cases of VRE infection were acquired in the hospital and all VRE patients had received treatment with vancomycin previously. Likewise, 25 of the 32 patients in whom E. faecium was susceptible to vancomycin also were infected nosocomially. However, 59% of those patients survived, as opposed to only 24% infected with VRE.
Both groups of patients were quite immunosuppressed due to organ transplantation, cancer, HIV infection, and other causes prior to developing infection. All patients had received broad-spectrum antibiotics before developing the bacteria in their blood. There were no differences between the groups with respect to the source of the infection, although an intra-abdominal source was the most common source in both. Indwelling bladder catheters were responsible for 13 of the cases of VRE.
The average cost of treating patients with bloodstream infections due to VRE was about $83,000, as compared with $58,000 for those with strains susceptible to vancomycin. Patients infected with VRE also were in the hospital more than twice as long as those with vancomycin-susceptible E. faecium.
Heighten lab surveillance
In a separate study presented at ICAAC, clinical researchers warned that hospital laboratories that only test enterococci recovered from sterile body fluids or sites resistant to vancomycin may only be detecting a fraction of their true incidence of VRE. Once VRE has been detected in a hospital, all enterococci from all body sites should be screened for resistance to vancomycin in order to implement infection control measures and prevent further transmission, recommended Kwan Kew Lai, MD, associate professor of medicine in the division of infectious diseases and immunology at the University of Massachusetts Medical Center in Worcester.
VRE was first detected at the medical center in 1993. As a safeguard the lab began testing all enterococci, regardless of clinical significance. The infection control department checked rectal swabs of patients in close proximity to patients who were known to carry VRE. Patients with VRE were placed in private rooms and only essential personnel were allowed into patients’ rooms. Staff members were required to wear gloves and gowns when administering care to those patients.
In taking the measures, researchers realized that testing of enterococci recovered from non-sterile sites is useful when VRE has been detected in the hospital. Protective measures to control further spread of VRE in a hospital can be initiated promptly when patients who unknowingly harbor such organisms are discovered by such testing.
From May 1993 through January 1996, a total of 307 patients at the medical center had enterococcal organisms recovered from clinical specimens or from rectal swabs. In all, 85 patients had specimens from non-sterile fluids or sites submitted. If the hospital microbiology laboratory only tested enterococci from sterile body fluids or sites for susceptibility to vancomycin, those 85 patients would not have been known to harbor VRE, Lai reported at ICAAC. For example, the researchers determined if the microbiology laboratory only tested enterococci recovered from urine that was deemed infected, 80% of the patients with urinary enterococci would not be known to have VRE.
The heartbeat of infection
Complicating control efforts, VRE and other resistant organisms may be spread to patients via stethoscopes, another researcher reported at ICAAC. Indeed, of all medical devices used in patient care, the stethoscope may have the greatest potential for amplifying cross-infection of resistant nosocomial organisms in the hospital, warns Dennis Maki, MD, chief of infectious diseases at the University of Wisconsin Hospital and Clinics in Madison.
While many clinicians carry their own personal stethoscope, few clean or disinfect them on a regular basis, opening the possibility of contact spread from patient-to-patient. As evidence of that, Maki and colleagues examined contamination of stethoscopes used by workers at the hospital in a prospective ongoing study. Of 50 stethoscopes studied thus far, resistant bacteria were recovered from more than half, including 6% with VRE and 12% with methicillin-resistant Staphylococcus aureus. Stethoscopes of nurses and physicians were equally likely to be contaminated by resistant organisms.
Of greatest concern was the finding that in eight cases (16%) in which contamination by MRSA, VRE, or resistant gram-negative rods were found, the nursing unit did not have a patient known to be colonized or infected by that resistant organism. That finding reaffirms the potential for wide transmission within the hospital once stethoscopes are contaminated. To prevent transmission of VRE and other pathogens, personal stethoscopes should not be used on patients in isolation or the intensive care unit, Maki recommended. Rather, a dedicated stethoscope for each patient should be used and decontaminated after the patient is discharged. Clinicians’ personal stethoscopes should be regularly decontaminated with alcohol or an antiseptic soap at the time of handwashing before patient contact, he advised.
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