Most of us know that within six years of the introduction of penicillin, resistant hospital isolates of Staphylococcus aureus climbed from an extremely infrequent occurrence to representing more than 80 percent of the total. Epidemic strains of methicillin-resistant Staphylococcus aureus (MRSA) were present in the 1960s and early 1970s. Surprising to many is that in the 1970s, Great Britain and several European countries with expansive MRSA presence experienced such a significant decline in outbreaks, that MRSA eradication appeared imminent. However, this optimistic assessment was short-lived as a second wave began to emerge, first in Australia, then in the United States and Ireland and continues to be a global threat.1
Several early epidemiological studies concluded that MRSA appeared de novo in several regions, prior to the introduction of methicillin. Epidemic MRSA strains may have been created due to selective pressures from the extensive use of tetracycline and streptomycin at the time. Evidence to support this belief is strengthened as the period of MRSA decline correlated well with reduced use of these antibiotics. MRSA resurgence may have been fueled by increased use of cephalosporins and other newly available antibiotics asserting increased selective pressure, or possibly by an as yet unidentified transmissibility factor. Containment got away from us. Regardless of how MRSA came into being, its elevation to superbug status was heralded by the appearance of strains with reduced (intermediate) susceptibility to vancomycin (VISA) and with cases of vancomycin-resistant S. aureus (VRSA) at a time when there were NO other effective antibiotics available! Cold fear struck hospitals in the early 1990s as whole units were shut down if one case of VISA or VRSA occurred to limit transmission. Although new antibiotics were introduced just in time to avert widespread disaster, MRSA, VISA and VRSA have been terrible experiences for many infected patients and their families. Yet the lessons healthcare providers and scientists have learned (and are still learning) are incredibly valuable.
What follows is an update on MRSA statistics and epidemiological strain distinctions, a listing of syndromes caused by invasive MRSA along with their crude mortality rates and infection risk factors, followed by a listing of MRSA contamination sites in the hospital (reservoirs) and recommended transmission-prevention strategies.
MRSA in the United States
-- Invasive (serious) MRSA infections occur in approximately 94,000 persons each year and are associated with approximately 19,000 deaths: 86 percent healthcare-associated and 14 percent community-associated.2
-- According to the National Nosocomial Infectious Surveillance system (NNIS) in 2003, 64.4 percent of S. aureus infections acquired in Intensive Care Units (ICU) were MRSA.3
-- MRSA infections in the hospital are associated with extended lengths of stay, higher mortality and increased costs.
-- MRSA most often isolated from community outbreaks is the strain USA300, followed by strains USA400, USA1000, and USA1100.
-- MRSA strains most frequently isolated from HAIs are USA100, USA200 and less often, USA500.2
-- Invasive MRSA syndromes: Between July 2004 and December 2005, 8,987 cases of invasive MRSA were reported into the NNIS system. Klevens analyzed these cases as to clinical syndromes, associated mortality and associated risk factors.2
Clinical syndromes associated with invasive MRSA:
-- 76.2 percent bacteremia - crude mortality* of 10.2 percent
-- 13.3 percent pneumonia - crude mortality of 32.4 percent
-- 9.7 percent celluitis - crude mortality of 6.1 percent
-- 7.5 percent osteomyelitis (not provided)
-- 6.3 percent endocarditis crude mortality of 19.3 percent
-- 4.3 percent septic shock crude mortality of 55.6 percent
-- Overall crude mortality in the hospital 17.8 percent
-- 12.9 percent experienced recurrent invasive infections
*Crude mortality is the proportion of a population dying without distinguishing contributory causes
Risk factors for MRSA colonization or infection (note only the first four factors were identified in Klevens study of invasive MRSA in NNIS identified above). Risk identified if patient had a history of:2,4
-- Recent or frequent hospitalizations
-- Residence at a long-term care facility
-- MRSA infection or colonization
-- Severe underlying illness or co-morbid condition
-- Prolonged hospital stay
-- Exposure to broad-spectrum antibiotics
-- Presence of foreign bodies (central venous catheters, wound drains, implants, etc.)
-- Frequent contact with healthcare system or healthcare personnel
-- Veterinarians (MRSA from cats, dogs, horses, cows, pigs)
-- IV drug use
-- Previous MRSA infection or colonization
Studies have identified a variety of MRSA reservoirs near colonized or infected patients and determined that S. aureus can remain viable up to 56 days after contamination of common materials in the hospital.5,6 In a study by Boyce, MRSA was isolated from the rooms of 73 percent of MRSA infected patients and 69 percent of colonized patients.7 We know the pathogens are there. Far less is known about the relative contribution of these reservoirs to the clinical transmission of MRSA. MRSA has been isolated from the list of items below and protocols must be developed to address them. Is total elimination achievable? Probably not. But to not address them at all is unacceptable. The following is a list of the more commonly noted fomites that have been found to be contaminated with MRSA in the clinical setting:
-- Surfaces near patient: Bed rail, over-table, side table, pitcher, basin, telephone, gloves in open boxes, privacy curtains, monitoring instrument surfaces and leads, bathroom fixtures, tissues, food trays after patient use, light switches, call button, TV remote, door handles, waste basket
-- Patients: Skin, hair, nares (nose), mouth/teeth and patient-generated aerosols, draining wounds or other potentially contaminated body fluids, dermatitis, seborrheic lesions
-- Linens: Bed linens and patient clothes
-- Items that directly or indirectly touch patient: Stethoscopes, rectal thermometer handles, blood pressure cuff, pulse oximeters, thermometers, stethoscopes, ECG and EKG leads, specimen containers, patient records, pens, computer keyboards
-- Healthcare providers: Lab coats, warming covers, zippered fleece vests, cardigans, mens ties, watches, isolation and cover gowns, masks (on outer and inner surface often inappropriately worn as necklace), gloves, hands, artificial nails and fills (space between fill and nail where disinfectants cannot reach) forearms, nares, dermatitis, hair (longer and dirtier have higher counts)
-- Hydro-treatment tanks
MRSA infections have engendered national/global public attention. Private and public healthcare protection groups, reimbursement agencies, and the media they are all aware and concerned. Litigation for healthcare-associated MRSA infections is increasing. The Joint Commission is targeting MDROs, including MRSA, in their accreditation requirements (National Patient Safety Goals NPSG O7.03). We have to solve this threat. There have been many success stories of bundled prevention strategies that have stopped and reversed the upward trend. But they have required changes, communication and effort. Facilities cannot keep doing the same things they have been doing and expect a better result.
As infection preventionists (IPs) introduce changes from the status quo, cultural changes will inevitably be required that will meet with resistance. Discuss options with key staff members who will participate in protocol implementations. Document rationale for making program decisions. Identify champions who can bring tremendous value to you in winning the attitudes and determination of staff to execute your MRSA prevention program (pilot first, then adjust and expand). Milken once said, to every complex problem, there is a simple answer...and it is wrong. MRSA from its creation, routes of infection, pathogenesis, means of transmission and treatment presents a complex problem. No single activity can solve it. It will take a multi-pronged approacha bundle of selected strategies to which everyone in your facility is 100 percent committed. Strategy components shown to be effective in successful MRSA reduction/prevention follow:
-- Educate administration leaders, clinicians, admission personnel, lab staff, housekeeping and engineering on MRSA infections, identify and describe MRSA reservoirs and modes of transmission together with their personal roles as preventionists independent contractors MUST agree to follow facility MRSA prevention protocols! Re-educated yearly, as responsibilities change and as alterations in the program necessitate.
-- Conduct active surveillance cultures (ASC) on admission and as appropriate during hospital stay, on those individuals that fit the risk criteria appropriate to your local population assess and adjust as circumstances change; OR, you may decide to test all incoming patient.4
-- Establish an alert system (manual or electronic) to notify appropriate individuals when MRSA patients are readmitted, when culture or PCR positives are identified, etc.
-- Keep units informed on their MRSA HAI status in easy to interpret format.
-- Isolate patients under contact precautions (CP) if tested positive for MRSA; OR isolate all patients until test results show them to be negative several exceptionally rapid PCR tests for MRSA identification now cut days of waiting down to a couple of hours. Explain CP procedures to your patient so he/she can understand and participate in, rather than resent, the special treatment.
-- Use private room if possible; if not possible, cohort with other MRSA patients; if this is not possible, room with patients at low risk of acquiring MRSA or with patient that has probably already been exposed.
-- Make certain all personal protective equipment (PPE) appropriate for contact precautions is conveniently located. Waste cans must be conveniently located near room exit as must hand sanitizer or sink for sanitizing hands before donning gloves and immediately after removal. Assume used PPE has been contaminated. Remove in such a way as to prevent self contamination and reduce the risk of MRSA dispersion.
-- Monitor strict adherence to hand hygiene protocols.
-- Practice decolonization or suppression of colonized patients. Clinical trials with mupirocin have demonstrated a reduction of S. aureus in 91 percent to 97 percent of patients. Eliminating MRSA colonization of the nares prior to surgery has been shown to significantly reduce post-surgical MRSA HAIs. Chlorhexidine showers prior to surgery have also proven to reduce infection risk. Mouth rinses with CHG have been shown to reduce ventilator-associated infection (VAP). MRSA is, however, less sensitive to CHG than methicillin-sensitive Staphylococcus (MSSA). Regular frequent use of soap and water as well as alcohol hand sanitizers is recommended rather than CHG, once a patient has been successfully treated for MRSA. MRSA does build resistance to mupirocin and thus its use is appropriate for at-risk patients undergoing procedures, but not for routine use. Emphasize to the patient the importance of adherence to any prescribed systemic treatment for the duration of the regimen.
-- Dispose of, or thoroughly disinfect before use, any items used for caring for the MRSA patient or that were present in their room. Use dedicated items wherever possible.
-- Try not to transport patient, but if it is necessary, cover all open wounds. If a patient has a MRSA respiratory infection, placing a mask on the patient reduces risk of aerosol dispersion. The transporter should remove contaminated PPE and practice appropriate hand hygiene prior to patient transport and don clean PPE after arrival at destination if appropriate
-- Remove linens in such a way as to limit MRSA dispersal
-- In addition to MRSA education for housekeeping (environmental services), make certain appropriate fresh cleaning solutions are prepared and used at the correct concentrations, pH, etc., that cleaning is performed before disinfection, and that that all areas are adequately processed and allowed to dry according to manufacturers instructions. Surfaces close to the patient, or often touched by the patient or individuals entering the room, should be disinfected with increased frequency. Make certain this exceptionally important part of your infection-prevention team understands and feels he/she is a critical member. (See the APIC Guide to the elimination of MRSA Transmission in Hospital settings 2007; or Institute for Healthcare Improvement (IHI) 5 Million Lives Campaign How-to-Guide: Reduce MRSA Infection for suggestions and checklist aids addressing this increasingly important area of infection prevention)
-- Inform staff that they may be contaminated (hair, exposed portions of face, scrub pants, etc.) and could bring MRSA to break rooms, waiting rooms, naïve patient rooms, homes, athletic equipment, etc.
-- Educate MRSA patients and their families helping them to prevent MRSA spread in the hospital and at home (keep personal items dedicated, dont share towels, keep things clean, etc.). Prepare them for the significant possibility of recurrent MRSA infections and what to do if they occur8.9
-- Monitor MRSA prevention program compliance and address non-compliance issues, remove barriers to compliance or adjust as program appropriate. Document outcomes. Communicate status for each unit and celebrate success. Adjust prevention program as appropriate
-- Antibiotic stewardship extremely important part of preventing the emergence and sustained presence of multidrug-resistant organisms (MDROs)
Lessons Learned (And Still learning)
MRSA is a formidable enemy. It has also provided powerful experiences with many important lessons. The outbreaks of VISA and the minimal but terrifying confrontations with VRSA have been significant wake up calls. Conquering MRSA, though necessary, will not be the end. Next time, or the time after that, a rogue pathogen fighting for its own survival could be more virulent than MRSA and possess even greater antibiotic resistance. Hopefully, we will have incorporated our substantive learning from the rise and spread of MRSA to better contain and obliterate the next aggressive superbug before it wields out of control and we are left defenseless. We have experienced in the war against emerging new pathogens that, History is a race between education and catastrophe (H.G. Wells), and that Those who cannot learn from history are doomed to repeat it. (George Santayana).
Wava Truscott, PhD, is director of scientific affairs and clinical education in the Department of Medical Sciences at Kimberly-Clark Health Care.
Ayliffe G. and English M. Hospital Infection: From Miasma to MRSA (Cambridge UK: Cambridge University Press, 2003), 215-218.
Klevens RM, Morrison MA, Nadle J. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA. 2007;298(15):1763-1771.
Klevens RM, Edwards JR, Tenover FC, et. al. Changes in the epidemiology of methicillin-resistant Staphylococcus aureus in intensive care units in U.S. hospitals. Clin Infect Dis. 2006;42:389-391
Muto CA, Jernigan JA, Ostrowsky BE, Richet HM, Jarvis WR, Boyce JM, et al. SHEA guideline for preventing nosocomial transmission of multidrug-resistant strains of Staphylococcus aureus and enterococcus. Infect Control Hosp Epidemiol 2003;24:362-86.
Neely AN, Maley MP. Survival of enterococcus and staphylococcus on hospital fabrics and plastics. J Clin Microbiol. 2000;38:724-726.
Huang R, Mehta S, Weed D, et. al. Methicillin-resistant Staphylococcus aureus survival on hospital fomites. Infect Control Hosp Epidemiol 2006;27:1267-1269.
Boyce JM, Potter-Bynoe G, Chenevert C, et. al. Environmental contamination due to methicillin-resistant Staphylococcus aureus; possible infection control implications. Infect Control Hosp Epidemiol. 1997;18:622-627.
Huang SS, Platt R, Risk of Methicillin-resistant Staphylococcus aureus infection after previous infection or colonization. Clin Infect Dis. 2003;36:281-285.
Buckingham SC. Prevention of recurrent MRSA skin infections: what you need to know. Consultant 2008;481.