Vancomycin-Resistant Enterococci: Again, Bad News
Abstract & Commentary
Synopsis: Monitoring of ordered clinical specimens may not be sufficient to determine the presence of VRE in a hospital. It is likely that many hospitals are infected, and there is little chance that this will change soon.
Source: Bonten MJM, et al. Epidemiology of colonization of patients and environment with vancomycin-resistant enterococci. Lancet 1996;348:1615-1619.
Bonten and coworkers describe a pretty ugly situation at Cook County Hospital, where VRE has become endemic in the medical intensive care unit. They undertook a six-week study in early 1995, during which time they collected 972 body site cultures and 1294 environmental cultures on patients admitted to the ICU. Of the 97 admissions of 92 patients, all had at least one rectal swab per week, but the 38 that ended up on ventilators were studied intensively with daily cultures of the rectum, groin, arm, oropharynx, trachea, and stomach. Daily environmental cultures included both bedrails, drawsheet, blood-pressure cuff, urine containers, and enteral feedings.
They found nine patients to be at least colonized with VRE on admission and that one of those acquired a second strain.
They were able to find 262 isolates, of which there were 20 genetically distinct strains that spanned a spectrum of resistance pattterns with genes van A, B, and C.
Of the patients who were not colonized with VRE on admission, 41% of them acquired it during their stay, with a mean acquisition time of five days. This acquisition seemed to be related to cross-colonization as the acquired strains correlated with those of other patients in the unit. Of the study patients who has positive environmental cultures, only three (23%) became colonized. The environmental cultures did, however, correlate with the number of body site cultures that were positive. Environmental cultures were most likely to be positive on the bedrails. Drawsheets were more likely to be positive for VRE than blood pressure cuffs, enteral feedings, and urine containers.
The first place patients were colonized was usually the groin or the rectum. Recovery from other sites, such as the axilla, oropharynx, and trachea, lagged and remained less likely. Once colonized, the intestinal tract had the highest concentration of VRE. It also persisted during the entire course of MICU stay once it was established. It was not unusual for a patient to have multiple VRE strains. Four had two strains, one had three types, and one had four different types of VRE.
Colonization correlated with prior use of antimicrobials, particularly cephalosporins or vancomycin.
COMMENT BY ALAN D. TICE, MD
While this is certainly a difficult situation, it is far from unique. It is clear that the intensive care units of many hospitals have become endemic foci for multiple strains of VRE. An earlier study in 1995 showed a similar situation in Baltimore, with 40 different strains of VRE firmly established in a hospital there.1 In a random sample, an average of 20% of the patients were positive in a large university medical center.
As the authors point out, monitoring ordered clinical specimens may not be sufficient to determine the presence of VRE in a hospital. It is likely that many hospitals are infected, and there is little chance that this will change soon. There is a clear dilemma in treatment decisions with the value of antibiotics in preventing and treating some infections yet a risk of acquiring VRE. This will likely increase the need for infectious diseases specialists to help on both an individual patient as well as an infection control basis.
The first approach should be to prevent a highly endemic situation such as exists at Cook County Hospital, where 55% of ventilated patients become colonized in the MICU and there is clear mortality and morbidity from the infection. The best ways to avoid an endemic situation are by periodic surveillance and effective infection control measures when it is detected.
The tools that we have against this persistent organism are few and rely primarily on our knowledge of infection control. The standards of restriction of antibiotic use, barrier precautions, routine surveillance, and segregation of known infected patients may be of some help, but the long-term outlook is bleak. Hopefully there will be new antibiotics that will be effective against VRE, but the chances do not seem great in the near future. VRE appears to be a formidable foe with its ability to cross-colonize, persist outside the body (for an hour or more on gloved or ungloved hands),2 and to persist within the body for prolonged periods of time and with multiple concomitant resistant strains. It is highly likely that the organism will easily spill over into the community because of its ability to colonize the intestinal tract.
1. Morris JG, Jr, et al. Enterococci resistant to multiple antimicrobial agents, including vancomycin: Establishment of endemicity in a University Medical Center. Ann Intern Med 1995;123:250-259.
2. Naskin CA, et al. Recovery of vancomycin-resistant enterococci on fingertips and environmental surfaces. Infect Control Hosp Epidemiol 1995;16:577-581.