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Universal testing program with the GeneXpert System optimizes MRSA control efforts
Most healthcare institutions in the U.S. have been watching an ominous trend of escalating proportions of methicillin-resistant Staphylococcus aureus (MRSA). The National Nosocomial Infection Survey results over the last 25 years dramatically illustrate this situation. MRSA infections, in contrast to those caused by methicillin-susceptible strains, cause more morbidity and mortality and cost dramatically more to manage2. A few years ago, more than one-quarter of all hospitals in the United States had experienced one or more outbreaks of MRSA3. Many institutions have begun selective testing of some patients believed to be at higher risk. Several commercial chromogenic agar plates have been developed to culture nasal swabs for active surveillance of MRSA. However, even with the most rapid culture turnaround time, results from cultures are not available for at least 24 hours, and the most common result in most patients, a negative, will not be known for at least 2 days. Such results could reach the unit days after a colonized patient had been sharing a room with a non-colonized patient. Moving the non-colonized patient into another room at this point is for patients and families, a social and public-relations nightmare. What do you tell someone who has shared a bathroom and blood pressure cuff for two days with an MRSA carrier? The alternative, instituting barrier precautions preemptively on every patient until their MRSA status is known, is costly and problematic.
As the rate of infections, the coverage in the news media, and predictably, the public’s fears, increase, there has been a demand for public policy to address their concerns. Dr. William Jarvis of the Centers for Disease Control and Prevention, an internationally known expert on infectious disease prevention, emphasized the urgency in a recent presentation to a group of healthcare workers from the Good Samaritan Hospital system in Phoenix. Dr. Jarvis exhorted healthcare workers to develop a “search and destroy” mentality when it comes to MRSA. If healthcare institutions fail to respond appropriately and decisively, the government will step in. Already 8 states have either enacted or are actively pursuing legislation related to testing and/or reporting of MRSA in healthcare institutions.
Reducing the time to detection is another important factor in a successful MRSA control program. In fact, the “opportunity time” during which an undiscovered colonized patient can transmit MRSA to others, a term coined by Dr. Richard Thomson at Evanston, is directly related to the turnaround time of the screening assay. Previous studies have shown that the faster a colonized patient is identified, the more effective control measures will be and the more likely the appropriate antibiotics will be selected6.
A key consideration among VA hospital laboratories in choosing the testing system is technologist time. Training and validation has to be quick; the VA wanted this program up and running ASAP. The Cepheid GeneXpert was their choice, according to many microbiologists both within the VA and at other institutions such as Loyola University Medical Center in Chicago and Washington Hospital in Fremont, California. It is a moderate complexity test so training is easy and less highly trained workers can perform the test, there is minimal hands-on time (<2 minutes), and the instrument is random access, i.e., a new sample can be added to the instrument at any time. Laboratory technicians and technologists have emphatically voiced their satisfaction with the simplicity of the GeneXpert workflow.
In a recent issue of CAP Today10, Loyola announced that they had achieved a 67 percent reduction in MRSA bacteremia in only 4 months by using the GeneXpert for pre-admissions testing. Obviously, MRSA test results are only as good as the action taken on the basis of those results, but it is becoming increasingly clear that the medical value of rapidly available, actionable results provided by the GeneXpert System can be an important ally in the “search and destroy” strategy being adopted by more and more hospitals. References
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Selective testing of patients based on some risk assessment has been shown to detect only 85% of the colonized patients in a hospital4; and the elaborate admission interview required to determine who might be at risk is counterproductive, disliked by nursing staff, and slows down admissions. Even less effective is passive detection, in which MRSA-carrying patients are discovered only if cultures sent to the clinical laboratory yield MRSA. This approach fails to identify 70% of truly colonized patients.
Evanston Northwestern Healthcare in Evanston, Illinois has taken a leadership role in MRSA control. Dr. Lance Peterson, Director of the Evanston system’s EpiCenter and Health Care Epidemiologist, has been the U.S.’s principal promoter of MRSA screening. Dr. Peterson has been preaching the value of universal nares testing by RT-PCR for colonization at time of admission for MRSA and proving that it yields both cost-benefits and patient care benefits. The group at Evanston Northwestern Healthcare recently published their results little more than a year after implementing the full program at three hospitals within their system8. Dr. Peterson and colleagues described the planning and implementation process in the journal of the Joint Commission on Accreditation of Healthcare Organizations7. Within just one year, they met the goals of the intervention, which included an 80% reduction of MRSA and a cost savings of $1.2 million, which showed that the program was at least cost-neutral and certainly a huge success for patient care. The Northwestern data also convincingly showed enhanced benefits of universal testing at admission, with a reduction of >40% of the MRSA prevalence among patients after the implementation of universal testing compared with the prevalence seen during the previous period of ICU patient testing only. 
Last year, the U.S. Department of Veterans Affairs implemented strong new MRSA “screening” mandates for incoming patients throughout the entire national system. Hospitals were not told which system to use for testing, but most have chosen the approach of the real-time, random-access, moderate complexity GeneXpert from Cepheid. Although data have not yet been analyzed, anecdotal reports suggest that numbers of hospital-acquired MRSA infections are visibly declining. 
Different medical centers have different approaches to the colonized patient once he or she is detected. Patients positive for MRSA are placed in a private room or cohorted with other MRSA-colonized patients. At some institutions, patients may be offered decolonization1,9. Current recommendations for MRSA decolonization from the Association for Professionals in Infection Control and Epidemiology (APIC) include the intranasal antibiotic mupirocin, two oral antimicrobials such as trimethoprim-sulfamethoxazole and rifampin or doxycycline and rifampin, and skin antisepsis such as chlorhexidine baths. Individual physicians choose their own prophylactic antibiotics for MRSA-colonized patients who require surgery. 