A proposed cost-saving alternative to universal screening is selective screening based on risk factor assessment [141]. The effectiveness of this type of program depends on creating a clinical decision-making tool capable of accurately identifying high-risk individuals while also accounting for the different risk factor profiles between HA-MRSA and CA-MRSA [142]. It has been proposed that targeted screening protocols may be more cost-effective in settings with < 5% prevalence of MRSA colonization on admission [143].
Many studies [61,144–149] have shown that active surveillance against VRE is cost-effective. For example, Calfee et al [144] showed that an established active surveillance program results in control of endemic VRE in high-risk patients. The infection control program was established in response to a hospital-wide VRE outbreak, and was sustained after the outbreak was controlled. The study by Calfee et al spanned 5 years and was performed at a tertiary-level university hospital, where cultures from perirectal areas were used to identify high-risk patients who were asymptomatically colonized with VRE. During the latter 2 years, 768 new cases of VRE colonization were detected among 69,672 admissions (1.1% of admissions), of which 730 (95.1%) were identified by active surveillance methods. This implies that routine clinical cultures would probably have missed the majority of colonized patients. During this period, the incidence of VRE infection was likewise extremely low at 0.12/1000 patient days (ie, 90 nosocomial VRE infections were identified in 83 patients during 743,956 days of patient care). Sixty-nine of the 83 patients (83%) who developed nosocomial VRE infections were found to be colonized with VRE by surveillance culture before the onset of infection.
Patient Decolonization
Chlorhexidine gluconate has been used in several settings to control outbreaks and infections related to MRSA and VRE due to its broad-spectrum activity against these pathogens. Chlorhexidine-based solutions reduce the density of skin colonization with pathogens such as MRSA and VRE (skin asepsis), thus lowering the risk for horizontal transmission between health care workers and patients.
Decolonization with chlorhexidine as an MRSA infection reduction technique has demonstrated benefit in the ICU setting [150]. The previously mentioned large, cluster-randomized ICU trial by Huang and colleagues found universal decolonization with twice-daily intranasal mupirocin for 5 days and daily bathing with chlorhexidine-impregnated cloths for the entire ICU stay was superior to targeted decolonization of known MRSA carriers in preventing overall MRSA isolates. However, universal decolonization failed to show a reduction in MRSA bacteremia [151], and concerns about mupirocin resistance may limit the applicability of this approach.
There are now several studies [152–154] that show decreased acquisition of VRE with use of daily chlorhexidine bathing. In a study including 1787 ICU patients, Vernon et al found [154] that the reducing microbial density of VRE on patient’s skin by using chlorhexidine led to decreased transmission. In another study by Climo et al [153] that involved 6 ICUs at 4 academic centers and measured the incidence of MRSA and VRE colonization and blood stream infections (BSI) during a period of bathing with routine soap for 6 months compared with a 6-month period where all admitted patients received daily bathing with a chlorhexidine solution, results found decreased acquisition of VRE by 50% (4.35 vs. 2.19 cases/1000 patient days, P < 0.008) following the introduction of daily chlorhexidine bathing. Furthermore, compared with 16 of 270 patients colonized with VRE who subsequently developed VRE bacteremia at baseline, only 4 of 226 VRE-colonized patients bathed with chlorhexidine in the intervention period developed a BSI, translating into a relative risk reduction of 3.35 (95% CI, 1.13–9.87; P < 0.035). Patients colonized with VRE were 3 times less likely to develop VRE bacteremia when bathed with chlorhexidine compared with regular bathing. Despite the success of this protocol for VRE, when analyzed by individual organism no significant reductions in MRSA acquisition or BSI were reported. This finding is similarly corroborated by a trial conducted in the pediatric ICU setting which found an overall reduction in bacteremia with daily chlorhexidine washes but no significant decrease in cases due to S. aureus [155].