Control and Prevention of MDROs


While multidrug-resistant organisms (MDROs) such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE), Clostridium difficile (C. diff) and certain Gram-negative bacilli (GNB ) continue to alarm the general public and are frequently misunderstood by patients, now theres an even better reason for healthcare professionals to not become complacent about these pathogens.

This year, a new hospital requirement related to preventing healthcare-associated infections (HAIs) due to MDROs) was added to the Joint Commissions National Patient Safety Goal 7, Reduce the risk of HAIs. This new requirement (as with two other requirements added to this goal relating to surgical site infections and catheter-related bloodstream infections) has a one-year phase-in period that includes defined milestones, with full implementation expected by Jan. 1, 2010. For the new requirement, "implement evidence-based practices to prevent HAIs due to MDROs in acute-care hospitals," Stoessel and Truscott (2009) explain that elements of performance for the hospital include:

-- Conduct periodic risk assessments for MDRO acquisition and transmission

-- Based on the results of the risk assessment, educate staff and licensed independent practitioners about HAIs, MDROs, and prevention strategies at hire and annually thereafter

-- Educate patients, and their families as needed, who are infected or colonized with a MDRO about HAI prevention strategies

-- Implement a surveillance program for MDROs based on the risk assessment

-- Measure and monitor MDRO prevention processes and outcomes

-- Provide MDRO surveillance data to key stakeholders (e.g., leaders, licensed independent practitioners, nursing staff, other clinicians)

-- Implement policies and practices aimed at reducing the risk of transmitting MDROs that meet regulatory requirements and are aligned with evidence-based standards

-- Implement a laboratory-based alert system (manual and/or electronic) that identifies new patients with MDROs, especially when indicated by risk assessment

A quick review of the clinical aspects, routes of transmission and preventive measures of MDROs is in order.

MDROS are dangerous because they are resistant to one or more classes of broad-spectrum antibiotics and other antimicrobial agents. While MRSA (not to mention vancomycin-intermediate S. aureus [VISA] and vancomycin-resistant S. aureus [VRSA]) has been the media darling of late, other MDROs of concern are Klebsiella pneumonia, Escherichia coli, Burkholderia cepacia, Acinetobacter baumannii and GNB, including those producing extended spectrum beta-lactamases (ESBLs) and others.

Different MDROs have had different patterns of emergence. While MRSA was first isolated in the late 1960s, VRE emerged in the early 1990s. Some bugs prefer intensive care units while others thrive in long-term care facilities; this has been borne out by antibiotic resistance rates that correlate with healthcare facility size, type and level of care. Data have shown that MRSA and VRE have achieved significant toeholds in inpatient facilities, with community-acquired strains gaining ground in outpatient care and other pathogens, such as Pseudomonas aeruginosa, growing in prevalence.

Siegel et al. (2006) emphasize that one of the key things for healthcare workers to remember is that MDROs persistence is frequently determined by a number of factors, including the availability of vulnerable patients; selective pressure exerted by antimicrobial use; increased potential for transmission from larger numbers of colonized or infected patients; and the impact of implementation and adherence to prevention efforts

Patients vulnerable to colonization and infection include those with compromised host defenses from underlying medical conditions, recent surgery and in-dwelling medical devices such as urinary catheters.

Siegel et al. (2006) assert that preventing infections will reduce the burden of MDROs in healthcare settings, and that prevention of antimicrobial resistance depends on appropriate clinical practices that should be incorporated into all routine patient care. These include optimal management of vascular and urinary catheters, prevention of lower respiratory tract infection in intubated patients, accurate diagnosis of infectious etiologies, and judicious antimicrobial selection and utilization. Guidance for these preventive practices include the Campaign to Reduce Antimicrobial Resistance in Healthcare Settings (, a multi-faceted, evidence-based approach with four parallel strategies: infection prevention; accurate and prompt diagnosis and treatment; prudent use of antimicrobials; and prevention of transmission.

Interventions used to control or eradicate MDROs can be grouped into seven categories. These include administrative support, judicious use of antimicrobials, surveillance (routine and enhanced), Standard and Contact Precautions, environmental measures, education and decolonization.

Studies have documented that administrative support and involvement were crucial for the successful control of MDROs. Interventions that require administrative support include: prompt and effective communications to identify patients previously known to be colonized/infected with MDROs; providing handwashing facilities and dispensers; maintaining staffing levels appropriate to the level of care required; enforcing adherence to recommended infection control practices such as hand hygiene and Standard and Contact Precautions; direct observation of adherence to precautions with feedback to healthcare providers; and keeping staff informed about changes in transmission rates.

Educational campaigns, including facility-wide, unit-targeted, and informal educational interventions, to enhance adherence to infection prevention and control can decrease MDRO transmission. In studies of educations impact on MDRO control, the focus was to encourage a behavior change through improved understanding of the problem MDRO that the facility was trying to control. Whether the desired change involved hand hygiene, antimicrobial prescribing patterns, or something else, enhancing understanding and creating a culture that supported the desired behavior were viewed as essential to success.

Antibiotic stewardship is a key component of MDRO control and prevention, and includes the following elements: effective antimicrobial treatment of infections; use of narrow spectrum agents; treatment of infections and not contaminants; avoiding excessive duration of therapy; and restricting use of broad-spectrum or more potent antimicrobials to treatment of serious infections when the pathogen is not known or when other effective agents are unavailable.

Surveillance is a critically important component of any MDRO control program, allowing detection of newly emerging pathogens, monitoring epidemiologic trends, and measuring the effectiveness of interventions. Multiple MDRO surveillance strategies have been employed, ranging from surveillance of clinical microbiology laboratory results obtained as part of routine clinical care, to use of active surveillance cultures (ASC) to detect asymptomatic colonization.

The 2008 SHEA/HICPAC position paper, Recommendations for Metrics for Multidrug-Resistant Organisms in Healthcare Settings, suggests that healthcare facilities use the following routine metrics to monitor MDROs and the infections they cause:

1. An MDRO-specific line list for tracking patients who have acquired an MDRO.

2. An antibiogram for monitoring susceptibility patterns of isolates recovered from patients.

3. The incidence of hospital-onset MDRO bacteremia, which is an objective, laboratory-based metric that is highly associated with invasive disease and does not require chart review to estimate infection burden.

4. Clinical culture results to measure incidence of infection or colonization, to quantify the number of people whose MDRO acquisition is healthcare-associated.

In addition, the SHEA/HICPAC paper suggests that healthcare facilities may want to calculate both the overall prevalence of carriage and the prevalence of carriage at admission, the latter of which can be useful in detecting importation of methicillin-resistant S. aureus into healthcare facilities, to estimate the exposure burden. Active surveillance testing can augment and increase the accuracy of some metrics. Healthcare facilities not performing active surveillance testing might wish to consider point-prevalence screening, to help assess how much the number of positive clinical culture results underestimates the hidden reservoir of MDROs.

Conducting active surveillance requires a commitment of time and resources. Siegel et al. (2006) say that for successful implementation, these additional elements must be secured:

1. Personnel to obtain the appropriate cultures

2. Microbiology laboratory personnel to process the cultures

3. Mechanism for communicating results to caregivers

4. Concurrent decisions about use of additional isolation measures triggered by a positive culture, e.g., Contact Precautions

5. Mechanism for assuring adherence to the additional isolation measures

The challenges of conducting active surveillance are numerous. First, Siegel et al. (2006) point out that the most effective timing and interval is not well defined; some studies indicate the time of admission to the hospital or at the time of transfer to or from designated units, while others indicate obtaining cultures on a periodic basis or based on the presence of specific risk factors for MDRO carriage. Second, Siegel et al. (2006) say that methods of obtaining the culture should be appropriate to the particular resistant organism; for example, the nares are best for MRSA, while stool swabs are indicated for VRE.

Since 1996, the Centers for Disease Control and Prevention (CDC) has recommended the use of Standard and Contact Precautions for MDROs judged by an infection control be of special clinical and epidemiologic significance. Siegel et al. (2006) say that this recommendation was based on general consensus and was not necessarily evidence-based. No studies have directly compared the efficacy of Standard Precautions alone versus Standard Precautions and Contact Precautions, with or without ASC, for control of MDROs. Some reports mention the use of one or both sets of precautions as part of successful MDRO control efforts; however, the precautions were not the primary focus of the study intervention.

Standard Precautions have an essential role in preventing MDRO transmission, even in facilities that use Contact Precautions for patients with an identified MDRO. Colonization with MDROs is frequently undetected; even surveillance cultures may fail to identify colonized persons due to lack of sensitivity, laboratory deficiencies, or intermittent colonization due to antimicrobial therapy. Therefore, Siegel et al. (2006) recommend that Standard Precautions be used in order to prevent transmission from potentially colonized patients. Hand hygiene is an important component of Standard Precautions; the authors of the Guideline for Hand Hygiene in Healthcare Settings cited numerous studies that demonstrated a temporal relationship between improved adherence to recommended hand hygiene practices and control of MDROs. Some facilities also preemptively used Contact Precautions, in conjunction with ASC, for all new admissions or for all patients admitted to a specific unit until a negative screening culture for the target MDRO was reported.

Contact Precautions are intended to prevent transmission of infectious agents, including epidemiologically important microorganisms, which are transmitted by direct or indirect contact with the patient or the patients environment. A single-patient room is preferred for patients who require Contact Precautions. When a single-patient room is not available, consultation with infection control is necessary to assess the various risks associated with other patient placement options (e.g., cohorting, keeping the patient with an existing roommate). Healthcare workers caring for patients on Contact Precautions should wear a gown and gloves for all interactions that may involve contact with the patient or potentially contaminated areas in the patients environment. Donning gown and gloves upon room entry and discarding before exiting the patient room is done to contain pathogens, especially those that have been implicated in transmission through environmental contamination, such as VRE, C. difficile and noroviruses.

The potential role of environmental reservoirs, such as surfaces and medical equipment, in the transmission of VRE and other MDROs has been the subject of numerous studies. While environmental cultures are not routinely recommended, environmental cultures were used in several studies to document contamination, and led to interventions that included the use of dedicated noncritical medical equipment, assignment of dedicated cleaning personnel to the affected patient care unit, and increased cleaning and disinfection of frequently-touched surfaces, according to Siegel et al. (2006). A common reason given for finding environmental contamination with an MDRO was the lack of adherence to facility procedures for cleaning and disinfection. In an educational and observational intervention, which targeted a defined group of housekeeping personnel, there was a persistent decrease in the acquisition of VRE in a medical ICU. Therefore, monitoring for adherence to recommended environmental cleaning practices is an important determinant for success in controlling transmission of MDROs and other pathogens in the environment.

Decolonization entails treatment of persons colonized with a specific MDRO, usually MRSA, to eradicate carriage of that organism. Although some investigators have attempted to decolonize patients harboring VRE, few have achieved success, according to Siegel et al. (2006). However, decolonization of persons carrying MRSA in their nares has proved possible with several regimens that include topical mupirocin alone or in combination with orally administered antibiotics plus the use of an antimicrobial soap for bathing. Siegel et al. (2006) add that decolonization regimens are not sufficiently effective to warrant routine use; therefore, most healthcare facilities have limited the use of decolonization to MRSA outbreaks, or other high prevalence situations, especially those affecting special-care units. Several factors limit the utility of this control measure on a widespread basis: identification of candidates for decolonization requires surveillance cultures; candidates receiving decolonization treatment must receive follow-up cultures to ensure eradication; and recolonization with the same strain, initial colonization with a mupirocin-resistant strain, and emergence of resistance to mupirocin duringtreatment can occur. Healthcare workers implicated in transmission of MRSA are candidates for decolonization and should be treated and culture negative before returning to direct patient care. In contrast, healthcare workers who are colonized with MRSA, but are asymptomatic, and have not been linked epidemiologically to transmission, do not require decolonization.

So, having reviewed strategies for controlling and preventing MDROs, we come back to recommendations for compliance to National Patient Safety Goal 7. Stoessel and Truscott (2009) observe, A culture of safety is central to complying with the HAI elements of performance as detailed in NPSG 7. Given this culture within the healthcare facility, accountability, infrastructure and performance measures are effective tools to achieve and maintain compliance.

Compliance tips are as follows:

Patient Safety Culture

Active executive leadership: An effective patient safety culture must come from the top to attain and maintain the level of infection prevention required

Of paramount importance is a verbal, mental and emotional mindset that rejects the statement: it is acceptable to be at or below national infection rate averages, and instead marches to a zero tolerance of avoidable HAIs

Accept reminders from monitors, colleagues, patients and patient advocates who identify potential errors or oversights in the spirit of HAI prevention

Infrastructure Requirements

Active, effective, dedicated infection prevention and control program

User-friendly information technology (IT) systems must be in place and capable of providing necessary records maintenance, patient surveillance activities, infection rate calculations, trending analysis, correlation comparisons and required alerts

When multiple facilities are affiliated, IT systems should be integrated and compatible; or at a minimum produce comparable outputs based on standardized definitions and means of classification

Personnel must be adequately trained for effective use of applicable IT programs

Sufficient quantities of appropriate, quality supplies and devices strategically placed to ensure convenient compliance to best practices (e.g., line carts with all appropriate supplies and a procedure checklist increases compliance with best practices for aseptic central line placement; supplies readily available for donning prior to entering MRSA, VRE, C. difficile or any other contact isolation patient room increase PPE compliance)

Resources available for providing documented education and training to healthcare personnel addressing HAI-specific risk factors, frequent pathogens, consequences, means of transmission and prevention strategies are essential

Educate at-risk patients, their families and visitors on their role in prevention and detection of HAIs presented at the right level in an understandable format including the appropriate language and font size for written materials (e.g., elderly patients in stressful situations need written instructions in large print as verbal explanations are often forgotten or remembered incorrectly)

Adequate laboratory capability, and support with alert-communications systems are essential

Best practice strategies have been most successful when incorporated into a bundled approach incorporating zero tolerance for failure to meet 100 percent compliance with each bundle component

Conduct risk assessments to determine most vulnerable areas to be addressed and rank in priority order

Run pilot protocols to identify gaps and correct problems

Performance Measures

Document adherence to relevant guidelines and best practices (e.g. CDC guidelines, SHEA and APIC best practices) either by automated means, or on frequent unscheduled audits

Internal reporting: Provide unit staff, clinicians, and hospital administrators an accounting of:

Process measures: staff adherence to standardized protocols developed in compliance with guidelines or best practices such as rates of adherence to recommended practices

Outcome measures: HAI incidence rate trending such as CLABSI or SSI rates adjusted for patient risk factors as appropriate

Correlation of outcome measures with process measures provide a useful means of identifying areas for improvement

Patient risk factors as indicated


Facilitys chief executive officer and senior management are responsible for providing resources necessary to maintain adequate personnel, training, equipment ; ensuring sufficient, supplies are in place to enable compliance; and assigning responsibility for each component to competent individuals

Administrative strategies include standing orders and admittance based alert systems

All facility personnel must recognize they are an integral part of the infection prevention team and that they share responsibility for patient infections and for ensuring that appropriate infection prevention practices are used at all times

Each employee and contracted professional should know their facilitys major HAI rates and the specific HAI rates and causative pathogens in their own area of responsibility

Each employee and contracted professional must be able to describe how performance of their responsibilities impact HAI risk

Hospital and unit leaders are responsible for holding personnel accountable for their actions and informed of potential and actual consequences of non-compliance to facility protocols.


Stoessel K and Truscott W. National Patient Safety Goal 7: Recommendations for Compliance. Infection Control Today. July 2009.

Siegel JD, et al. Centers for Disease Control and Prevention, National Center for Infectious Diseases. Management of Multidrug-Resistant Organisms in Healthcare Settings. 2006.

Cohen AL, et al. Recommendations for Metrics for Multidrug-Resistant Organisms in Healthcare Settings: SHEA/HICPAC Position Paper. Infect Control Hospital Epidem. Vol. 29, No. 10. October 2008.

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