Microbial Colonization of Electrocardiographic Telemetry Systems Before and After Cleaning

Nosocomial infections, especially those due to Gram-negative rod bacteria, are associated with increased hospital stays of up to 12-18 days longer than usual hospital stays in which a nosocomial infection does not occur (1). These infections result in an estimated $5.7 to 6.8 billion dollars per year in unnecessary healthcare costs in the United States (2, 3). Overall, the annual direct medical cost of nosocomial infections for hospitals is estimated to be $28.4 to 33.8 billion (2, 4-7). These rising costs and concerns for patient safety in the acute care setting have given rise to numerous questions concerning the factors associated with risk for infection, mechanisms of transmission of nosocomial infections and strategies to better protect patients through prevention of nosocomial infection. A wide variety of risk factors for nosocomial infections have been identified. These factors range from patient-linked factors such as severity of illness, prolonged hospitalization, antecedent antibiotic therapy (8, 9), and older age with its associated increased susceptibility to infection (10-12), to equipment-linked factors such as pacemakers, implantable defibrillators and ventricular assist devices (13-15). In addition, multiple studies have shown provider and patient behaviors that result in cross-contamination to be a risk factor in nosocomial infections. Hospital personnel, surfaces and equipment have all been identified as common sources of nosocomial infections through cross-contamination (8, 13, 16-19). Among these risk factors and identified mechanisms for transmission of hospital acquired infection, reusable EKG leads and telemetry boxes are particularly high risk as they represent healthcare equipment that is transferred between patients, touched by many hospital personnel during the patient stay, not traditionally cleaned on a daily basis, and often used by particularly high risk patients, such as those with open thoracic incisions who are elderly and possibly immune-compromised. The transmission of high risk surface contaminants that is difficult to combat due to the life span of many common and potentially dangerous microbes. A literature review (20) found survival rates of nosocomial microbes ranging from hours to months for common pathogens such as Staphylococcus aureus, Escherichia coli and Enterococcus subspecies. Of these, the organisms of concern include methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), certain gram-negative bacilli, and coagulase-negative staphylococci (21, 22). In particular, staphylococcus has been shown to pose an infectious risk to the patients on cardiac wards as a leading cause of major infection following cardiac surgery (23). Studies have shown both direct and indirect correlations between environmental contamination with these long-lived organisms and patient acquisition of both methicillin-resistant and vancomycin-resistant organisms (24, 25). Strategies to combat nosocomial infections have been established by multicenter trials (26), endorsed by the Centers for Disease Control (CDC), and are followed by hospital infection control departments. These strategies include improving the time to identification and isolation of infected patients, increasing the use of disposable patient care items and equipment, and improving the effective identification and disinfection of non-disposables. In 2008 the CDC published guidelines for cleaning and sterilization of hospital and patient care items using the Spaulding classification scheme, which categorizes instruments and equipment to be cleaned and reprocessed according to the level of risk associated with their intended use (27). Items and equipment for patient care are identified as belonging to one of three categories: 1) critical, 2) semi-critical and 3) non-critical, based on the degree of risk of infection involved in the use of that particular item. With these classifications, it is now easier to determine what type of disinfectant to use to clean patient care surfaces (28). Critical items are those associated with a high risk of infection if the item is contaminated. These items include surgical equipment, cardiac and urinary catheters, implants, and ultrasound probes used in sterile body cavities. Semi-critical items are those that come in contact with mucous membranes or non-intact skin. Respiratory therapy, anesthesia equipment, and esophageal probes are examples of these. Non-critical items are those that come in contact with intact skin but not mucous membranes. Examples of non-critical items are blood pressure cuffs, bed rails, linens, patient furniture, and floors (29). Cardiac telemetry systems are items that fall between the classifications of semi-critical and noncritical items for disinfection. Skin integrity and implantable hardware determine the level of risk and susceptibility. For this reason telemetry systems on surgical and medical patient care areas may require different cleaning protocols; however evidence to substantiate this hypothesis is lacking. While non-critical surfaces are not commonly associated with transmission of infections to patients (24), two studies found electrocardiography wires do have potential to be a source of colonization for organisms and nosocomial infections. An outbreak of vancomycin-resistant enterocci on a burn unit was traced to a lead wire as a potential source of cross-contamination (30). In addition, Maki & Brookmeyer presented an abstract of a study at the Interscience Conference of Antimicrobial Agents Chemotheraputics in 2003, revealing that one third of cultured lead wires were reservoirs for resistant organisms. These two studies have been cited as the basis and the rationale for using disposable cardiac telemetry lead wires (31, 32), however the complete results of the preliminary data from these studies were not published. More research is needed to build on the body of evidence related to the role of telemetry systems as a source of nosocomial infections. Although the Spalding classification scheme is helpful for prioritizing cleaning and sterilization of hospital and patient care items, little independent research has been done to demonstrate the most effective strategy for minimizing colonization of microbial flora on EKG electrodes and telemetry boxes. The purpose of this study was to evaluate the effectiveness of a new cleaning protocol on telemetry systems in four cardiovascular step-down units, two surgical and two medical units. The study aims were: to determine the effect of current cleaning practice on numbers and types of surface contaminants on telemetry systems, to determine if a difference exists in pathogen growth between two medical and two surgical units, and to evaluate the cost-comparison for a cleaning strategy as compared to use of disposable EKG electrodes.