INTRODUCTION — Prevention and control of methicillin-resistant Staphylococcus aureus (MRSA) infection is among the most important challenges of infection prevention. Factors in transmission include colonization, impaired host defenses, and contact with skin or contaminated fomites [1-3]. Worldwide, an estimated 15 percent of infections are caused by S. aureus, nearly one-third of those (31 percent) are due to MRSA [4].
The success of MRSA control has varied substantially with different strategies [5,6]. Numerous guidelines have been published from countries around the world:
●In 2023, United States guidelines were updated, entitled "SHEA/IDSA/APIC Practice recommendation: Strategies to prevent methicillin-resistant Staphylococcus aureus transmission and infection in acute care hospitals: 2022 update [5]."
●Guidelines for Europe and specific European countries can be found online: European MRSA prevention guidelines [6].
●Other guidelines have also been published [7].
Issues related to epidemiology of MRSA are discussed further separately. (See "Methicillin-resistant Staphylococcus aureus (MRSA) in adults: Epidemiology".)
Issues related to prevention and control of MRSA outside intensive care units will be reviewed here. Issues related to prevention of MRSA infection in intensive care units are discussed separately. (See "Nosocomial infections in the intensive care unit: Epidemiology and prevention".)
IN HEALTH CARE SETTINGS
Basic infection prevention principles — Principles of infection prevention for reducing spread of MRSA include attention to careful hand hygiene and adherence to contact precautions for care of patients with known MRSA infection.
Hand hygiene — Hand hygiene consists of cleaning hands with soap and water or an alcohol-based hand gel before and after clinical encounters with patients who have MRSA infection [8]. Hand hygiene is an important factor in controlling the transmission of health care-associated infection [9]. This was illustrated in a study in which implementation of a hand-hygiene campaign led to an increase in the rate of hand hygiene compliance (48 to 66 percent) with a concomitant decrease in the rate of MRSA transmission (2.16 to 0.93 episodes per 10,000 patient-days) and the overall rate of health care-associated infections (16.9 to 9.9 percent) [9]. Thus to help control MRSA, health care workers and institutions should aim to follow the Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) hand hygiene guidance recommendations [10,11].
General principles regarding hand hygiene are discussed further separately. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Hand hygiene'.)
Contact precautions — Contact precautions include use of gowns and gloves during clinical encounters with patients who have MRSA infection; multiple studies have demonstrated the efficacy of contact precautions for reducing spread of MRSA [12-14]. Patients colonized or infected with MRSA may be cohorted with other such patients. MRSA colonization status should be noted in the hospital record so that appropriate precautions can be arranged promptly if colonized patients require repeat admission [15].
General principles regarding contact precautions are discussed further separately. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Contact precautions'.)
The optimal approach for discontinuation of contact precautions for MRSA is uncertain [5]. Guidelines regarding the duration of contact precautions for acute care settings were published in 2018 by the Society for Healthcare Epidemiology of America (SHEA) [16]. For patients who have been previously colonized or infected with MRSA who are not on antibiotics with activity against MRSA, these guidelines suggest discontinuation of contact precautions after documentation of one to three negative weekly surveillance cultures; most patients remain negative for MRSA colonization after three consecutive weekly surveillance cultures [17]. The optimal sampling site is uncertain; the anterior nares are a commonly used site. For patients who may be at higher risk for persistent MRSA colonization and recolonization (such as those with chronic wounds or patients from long-term care facilities), the guidelines indicate extension of contact precautions is reasonable. The optimal duration of extension is unknown; a minimum of six months is commonly used.
This guidance is in agreement with the United States Centers for Disease Control and Prevention, which has indicated that, in general, it is reasonable to discontinue contact precautions when three or more surveillance cultures are negative over the course of a week or two in the absence of antimicrobial therapy (for several weeks), a draining wound, respiratory secretions, [18].
One randomized trial comparing active screening with passive screening among more than 600 patients with prior documented MRSA colonization noted that active screening led to more frequent discontinuation of contact precautions when they were no longer needed (relative risk 2.5; 95% CI 1.5-4.7), resulting in reduction in inappropriate isolation and cost of isolation [19].
The major downside of contact precautions is increased cost [20,21]. Some studies favor elimination of contact precautions for patients with MRSA [22-24]; however, these studies are underpowered and lack controls for confounding variables such as universal gloving. A recent quasi-experimental study across all 123 VA hospitals showed some of the hazards of discontinuing contact precautions or active surveillance hospitals and the subsequent increase in MRSA infection rates among facilities discontinuing active surveillance and contact precautions [25]. Some centers have discontinued the use of contact precautions in certain situations. Guidelines suggest that sites considering moving away from contact precautions for patients with MRSA should: (a) perform a risk assessment; (b) reinstitute contact precautions with increases in MRSA rates; (c) consider using contact precautions in high-risk settings such as ICU patients, burn units, dialysis patients, transplant patients, and residents of long-term care facilities. These recommendations constitute a more customized "middle ground approach," but do not endorse abandoning all MRSA contact precautions [26]. Hospitals not using contact precautions should also have optimal programs in other areas of infection control including hand hygiene, environmental cleaning, and targeted decolonization protocols.
Principles regarding contact precautions are discussed further separately. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Contact precautions'.)
Role of active surveillance
Definitions — Active surveillance consists of performing screening cultures (of the nares, oropharynx, and/or perineum) to identify asymptomatic patients who are colonized with antibiotic-resistant bacteria, with the goal of intervening to minimize the likelihood of spread to other patients (via implementation of contact precautions) [12]. A proportion of patients with MRSA colonization develop MRSA infection, and transmission occurs from both colonized and infected patients [15,27-29]. The rate of progression from colonization to infection has been estimated to be between 9 to 33 percent [5,29-34].
The anterior nares are a frequent site of MRSA carriage (positive in 73 to 93 percent of carriers); however, nasal colonization has not been universally found among MRSA-positive patients with implanted devices, and the rectum may be an important reservoir among those with community-acquired MRSA [35-37]. Areas of skin breakdown may be colonized with MRSA, and sampling such areas is a reasonable option if other sites are not cultured or are culture-negative.
Different microbiologic methods exist for surveillance testing; these include standard microbiology methods, selective media, and polymerase chain reaction-based tests. Rapid whole-genome sequencing is an alternative method that may be useful for outbreak investigation but is not yet widely available for routine clinical use [38,39]. (See "Methicillin-resistant Staphylococcus aureus (MRSA): Microbiology and laboratory detection".)
Clinical cultures alone may underestimate the prevalence of MRSA by as much as 85 percent [37,40]. Health care settings not using active surveillance are able to identify patients with MRSA infection only via clinical cultures obtained from symptomatic patients (ie, passive surveillance).
Clinical approach — The optimal role for active surveillance is not known, and there is insufficient evidence for a single routine approach [5]. Active surveillance cultures appear to be most useful in the setting of hospital outbreaks and among patients at high risk for MRSA carriage [41]. MRSA risk factors include [41-54]:
●History of MRSA colonization (such patients should be isolated initially pending surveillance testing results)
●Intensive care unit (ICU) admission
●Severe underlying illness or comorbid conditions
●Prolonged hospital stay
●Indwelling device such as central venous catheter
●Residence in long-term care facility or exposure to correctional facilities, crowding, or unstable housing
●Patients on hemodialysis
●Patients hospitalized in the previous 12 months
●Broad-spectrum antibiotic exposure in the last three months
●Injection drug use
Advocates of active surveillance have pointed to its success in several European countries where MRSA has been contained at a low prevalence (examples include the Netherlands, Finland, and France) [55-59]. These strategies involved a multifaceted approach including surveillance, contact isolation, health care worker screening with decolonization, and closing units for comprehensive screening and cleaning when warranted [60-62]. Given this combination of interventions, it is not certain which intervention or combination of interventions is required for MRSA control. Therefore, extrapolating these experiences to other health care settings with variable MRSA prevalence and other factors is difficult and sometimes impossible.
In the United States, the Veterans Affairs has mandated active surveillance along with other infection control interventions including contact precautions that have led to a decrease in MRSA [63]. Other states have also mandated active surveillance for MRSA [64]. The 2023 United States guidelines consider active surveillance as "additional but not essential intervention" [5]. The latest US guidelines also state that hospitals choosing not to do whole-hospital active surveillance should consider instituting a more targeted policy based on high-risk patients or high-risk encounters and should use their MRSA-targeted risk assessment to decide whether they should use active surveillance.
Institutions performing surveillance cultures should establish clear policies regarding how the results will be used to make decisions about contact precautions, cohorting, and decolonization. Educational programming about adherence for patients, visitors, health care workers, environmental cleaners, and other hospital personnel is recommended.
Decolonization
Routine chlorhexidine bathing — Routine inpatient chlorhexidine bathing has been shown to be useful for reducing MRSA colonization and infection; these issues are discussed separately:
●Issues related to patient bathing in intensive care units are discussed separately. (See "Nosocomial infections in the intensive care unit: Epidemiology and prevention", section on 'Patient bathing/decolonization'.)
●Issues related to patient bathing in non-critical care units are discussed separately. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Patient bathing'.)
Targeted decolonization — Issues related to efficacy and clinical approach to targeted decolonization are discussed in the following sections. Issues related to MRSA epidemiology are discussed further separately. (See "Methicillin-resistant Staphylococcus aureus (MRSA) in adults: Epidemiology", section on 'MRSA colonization'.)
MRSA nasal colonization appears to precede infection, although asymptomatic nasal carriage is not always identifiable in the setting of MRSA infections [65]. In addition, the durability of MRSA decolonization is limited [12].
Patients with medical devices — Some expert guidelines recommend targeted decolonization of known MRSA carriers who have medical devices, such as central lines, mid-line catheters, and lumbar drains. This recommendation is based mainly on the ABATE trial, a cluster-randomized trial of 53 hospitals comparing routine bathing to decolonization with universal chlorhexidine and targeted nasal mupirocin in noncritical care units [66]. MRSA and VRE clinical culture positivity was unchanged in the study-population, but a subset of patients with medical devices appeared to benefit from decolonization.
At time of hospital discharge — For hospitalized patients with MRSA infection or MRSA colonization, we favor initiating a decolonization regimen at the time of hospital discharge to reduce the likelihood of subsequent MRSA infection.
The optimal regimen and duration of decolonization are uncertain. The best-studied regimen consists of 4% rinse-off chlorhexidine for daily bathing or showering, 0.12% chlorhexidine mouthwash twice daily, and 2% nasal mupirocin twice daily, all administered for five days twice per month for six months [30]. However, adherence to this regimen outside the context of a clinical trial has been difficult; it is uncertain whether less intensive regimens would have comparable efficacy.
The above approach is supported by a randomized trial including more than 2000 hospitalized patients with MRSA colonization managed with education with or without decolonization (chlorhexidine for daily bathing or showering, chlorhexidine mouthwash, and nasal mupirocin for five days twice per month for six months) at the time of discharge [30]. Use of postdischarge decolonization was associated with a 30 percent reduction (from 9.2 to 6.3 percent) in the rate of MRSA infection during the year after discharge (hazard ratio 0.70, 95% CI 0.52-0.96); the number needed to treat to prevent one MRSA infection was 30. About two-thirds of participants in the decolonization group were able to adhere fully to the regimen; among these individuals, there were 44 percent fewer MRSA infections and 40 percent fewer infections from any cause.
In other studies, briefer decolonization regimens (such as a single five-day course) have been associated with short-lived success for prevention of infection during temporary high-risk circumstances [67-69].
Mupirocin and chlorhexidine resistance may occur [70]. Mupirocin resistance occurred in 24 percent of MRSA isolates in one study [71-75]. The gene for high-level mupirocin resistance, mupA, has been found on a plasmid in USA300 MRSA clones, suggesting that the future utility of this drug may be limited since this clone has been implicated in many community-associated MRSA infections [76,77]. Thus far, no breakpoints have been established for mupirocin susceptibility testing, and commercial tests are limited [78].
Prior to surgery — Issues related to MRSA decolonization in patients undergoing surgery are discussed in detail separately. (See "Overview of control measures for prevention of surgical site infection in adults", section on 'S. aureus decolonization'.)
Environmental cleaning — MRSA-colonized and MRSA-infected patients readily contaminate the inanimate environment in their hospital room or home. Health care providers who come into contact with a colonized patient or their surrounding inanimate environment can in turn easily contaminate their hands, clothing, and medical equipment [14,79-82]. Meticulous cleaning of patient care surfaces is essential for control of MRSA environmental contamination [5,12,83,84]. MRSA can survive on surfaces for hours, days, or months but is killed by to routinely used hospital disinfectants. The viability of MRSA on inanimate surfaces and object depends on a variety of factors including temperature, humidity, the number of organisms present, and the type of surface.
Medical equipment should be dedicated to a single patient when possible to avoid transfer of pathogens via fomites. Equipment that must be shared should be cleaned and disinfected before use for another patient [12].
Environmental services personnel should be included as an integral part of the infection prevention team. Checklists for cleaning frequently touched patient care surfaces (such as bed controls, light switches, doorknobs, etc) can be useful for reinforcing consistency [41]. Ultraviolet markers may be useful for monitoring thoroughness of room cleaning [85-87].
Issues related to environmental cleaning are discussed further separately. (See "Infection prevention: General principles".)
Antibiotic stewardship — Inappropriate or excessive antibiotic use can lead to selection of resistant organisms [88,89]. The risk of MRSA colonization has been correlated with the frequency and duration of prior antimicrobial therapy [90,91]. Several studies have documented a higher risk of MRSA colonization following therapy with fluoroquinolones and other antibiotics that do not have MRSA coverage [92-95]. Reductions in the use of certain antibiotics within hospital systems can reduce the incidence of MRSA infection [96-98]. However, altering an antibiotic formulary can in turn lead to emergence of other resistant pathogens [88,97]. Two out of three systematic reviews and/or meta-analyses found an association between implementation of antimicrobial stewardship interventions and a decreased incidence of MRSA infection and/or colonization [99-101]. These data led the SHEA/IDSA/APIC MRSA compendium to change antibiotic stewardship from an additional practice to an essential practice in the latest 2023 guidelines.
IN THE COMMUNITY — Risk factors for MRSA infection are summarized in the table (table 1). Tools for preventing MRSA spread in the community include hand hygiene, minimizing transmission risk, decolonization and reducing broad-spectrum antibiotic use [54].
Minimizing transmission risk
Hand hygiene — Hand hygiene is as important in the community as in the hospital. Hands should be cleaned thoroughly with soap and water or an alcohol-based hand sanitizer, immediately after touching the skin or any item that has come in direct contact with a draining wound. (See 'Hand hygiene' above.)
Other measures — Wounds that are draining should be kept covered with clean, dry bandages. Patients with open wounds should not participate in activities involving skin-to-skin contact with others until wounds are fully healed. Individuals should avoid sharing personal items that may become contaminated with wound drainage, such as towels, clothing, bedding, bar soap, razors, or athletic equipment that touches the skin. Clothing that comes into contact with wound drainage should be laundered and dried thoroughly. Environmental surfaces with which multiple individuals have bare skin contact should be cleaned with an over-the-counter cleaner with activity against S. aureus. Cross-transmission of MRSA between humans and their pets has been described [2,102-104].
Decolonization
Clinical approach — In the outpatient setting, decolonization is reasonable for patients with recurrent MRSA infection despite hygiene optimization and/or if ongoing transmission is occurring among household members or other close contacts [8,105].
The optimal approach to decolonization is uncertain; we favor one of the following regimens (administered to the patient as well as household members) [8,105]:
●Nasal decolonization with mupirocin ointment (2%) applied to nares twice daily for 5 to 10 days, and
●Topical body decolonization (one of the following):
•Chlorhexidine gluconate (2% or 4% solution): daily washes or use of a disposable impregnated cloth for 5 to 14 days, or
•Dilute bleach baths (one teaspoon bleach per gallon of water, or one-fourth cup bleach per one-fourth tub [approximately 13 gallons of water] for 15 minutes twice weekly) for approximately three months
Following decolonization, surveillance cultures are not necessary in the absence of active infection [8].
The efficacy of decolonization in outpatient settings is limited. Based on available data, the above approach may temporarily eradicate MRSA colonization, but there is no definitive evidence that it reduces the likelihood of subsequent infection [71,106-114]. Given the observed reduction in MRSA infection rate associated with a longer (six-month) decolonization regimen at the time of hospital discharge [30], further study of longer decolonization regimens among patients in community settings is warranted. (See 'At time of hospital discharge' above.)
In one randomized trial including 300 adults and children with community-onset skin and soft tissue infection (SSTI) and S. aureus colonization randomized to no therapeutic intervention (control group) or one of three five-day decolonization regimens (regimen 1: 2% mupirocin ointment applied to the nares twice daily, regimen 2: intranasal mupirocin plus daily 4% chlorhexidine body washes, or regimen 3: intranasal mupirocin plus daily dilute bleach water baths), eradication rates were 48, 56, 54, and 71 percent, respectively [107]. In a retrospective study including more than 900 patients with MRSA colonization who underwent decolonization and follow-up for subsequent MRSA infection (five-day course of nasal mupirocin ointment [2%] plus chlorhexidine gluconate [4%] every second day), decolonization did not affect the risk of infection but there was a trend toward delayed infection in patients following decolonization (median time to infection 50.0 versus 15.5 days; p = .06) [114].
Decolonization of the patient and household (rather than the decolonization of the patient only) is supported by a randomized trial including more than 180 patients with MRSA SSTI randomized to decolonization of all household members (household group) or decolonization of the patient alone (index group); during the 12-month followup, recurrent SSTI was observed less frequently in the household group than the index group (52 versus 72 percent) [115].
Emergence of S. aureus strains tolerant or resistant to topical antimicrobial agents used for decolonization is well described; however, the clinical impact of reduced susceptibility is not clear [78].
Recurrent infection despite decolonization — Following a failed initial decolonization attempt, the likelihood of successful decolonization is relatively low. If repeat infection occurs, repeat decolonization may be attempted with the topical agents as outlined above [8]. In addition, some clinicians favor concomitant administration of oral antibiotic therapy; this decision should be made based on individual circumstances. The optimal regimen and duration of oral antibiotic therapy are uncertain; data are limited. Options include rifampin (600 mg orally once daily) administered in combination with either doxycycline (100 mg orally twice daily) or trimethoprim-sulfamethoxazole (one double-strength tab orally twice daily) for a 5- to 10-day course.
In one prospective study including 31 patients with recurrent MRSA SSTI who underwent decolonization with nasal and topical body decolonization as well as oral antibiotic therapy; during the six-month followup period, the mean number of MRSA infections per month was reduced from baseline (0.84 to 0.03 infections/month) [116].
Reducing broad-spectrum antibiotic use — Referral of patients who are labeled as penicillin-allergic for skin testing and evaluation may help mitigate the risk of developing MRSA infections by reducing overall exposure to broad-spectrum antibiotics [117]. In a large cohort study of ambulatory adults, those labeled as penicillin-allergic were more likely to receive broad-spectrum antibiotics, including fluoroquinolones, and were at significantly higher risk for the development of MRSA than those without this label [118]. Approximately 95 percent of patients with a history of penicillin allergy will be found to tolerate penicillins following an allergy evaluation [119,120]. (See "Choice of antibiotics in penicillin-allergic hospitalized patients", section on 'Impact of penicillin allergy on care'.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Management of Staphylococcus aureus infection" and "Society guideline links: Infection control".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Beyond the Basics topic (see "Patient education: Methicillin-resistant Staphylococcus aureus (MRSA) (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Basic principles – Basic infection prevention principles include attention to careful hand hygiene, environmental cleaning, prudent antibiotic use, and, in some centers, adherence to contact precautions for care of patients with known methicillin-resistant Staphylococcus aureus (MRSA) infection. (See 'Basic infection prevention principles' above.)
●Active surveillance – Active surveillance cultures identify asymptomatic individuals with MRSA colonization to be placed on contact precautions with the goal of minimizing MRSA spread to other patients. This practice is appropriate in the setting of an outbreak; its role for routine screening is a question of ongoing debate. (See 'Role of active surveillance' above.)
●Decolonization programs – For hospitalized patients with MRSA infection or MRSA colonization, we suggest initiating a decolonization regimen at the time of hospital discharge (Grade 2B). If possible, we favor the best studied regimen which consists of 4% rinse-off chlorhexidine for daily bathing or showering, 0.12% chlorhexidine mouthwash twice daily, and 2% nasal mupirocin twice daily, all administered for five days twice per month for six months. However, adherence to this regimen outside the context of a clinical trial may be difficult; it is uncertain whether less intensive regimens would have comparable efficacy. (See 'Targeted decolonization' above.)
●Preventing community spread – Tools for preventing MRSA spread in the community include minimizing transmission risk, decolonization, and reducing broad-spectrum antibiotic use. (See 'In the community' above.)
●Outpatient decolonization – In the outpatient setting, we suggest decolonization for patients with recurrent MRSA infection despite hygiene optimization and/or if ongoing transmission is occurring among household members or other close contacts (Grade 2C). (See 'Decolonization' above.)
Do you want to add Medilib to your home screen?