None of the MDROs in the studies in this review showed biocide resistance at the concentrations typically used for chlorhexidine bathing; the in vitro studies compared survivability of resistant MDROs in low concentrations of chlorhexidine. An equal number of studies suppor ted or refuted the hypothesis that chlorhexidine bathing increases the prevalence of resistance genes in hospitals; however, many of these studies looked at isolates from a single hospital and may have limited generalizability. Regardless of changes in prevalence, these authors hypothesize that overdiluted concentrations or residual chlorhexidine may be selecting for resistant organisms (either resistant clones/strains or organisms less susceptible to chlorhexidine) and should be monitored for clinical impact. Clinical Implications The clinical impact of chlorhexidine resistance genes is unclear. One in vitro study of MRSA isolates in a U.S. hospital found that MRSA strains showed more resistance to chlorhexidine than methicillin- susceptible strains. Other studies found more chlorhexidine resistance in VRE than in vancomycin- susceptible Enteroccoci strains in isolates from Danish hospitals. Some evidence suggests that chlorhexidine bathing can favor chlorhexidine- resistant MDROs (particularly MDR-GNB) by eliminating the “competition” from chlorhexidine- susceptible MDROs. Importantly, no studies suggest that chlorhexidine bathing was ineffective due to resistance; at the concentrations typically used (1- 4%), chlorhexidine still kills even the most resistant organisms. However, overdiluted solutions may fail to kill organisms as intended and create unwanted transmission and infection, especially in cases where biofilms have formed. Some alternatives to chlorhexidine, such as triclosan and hydrogen peroxide, have their own risk of resistance selection. Cationic compounds show promising effectiveness against MDROs, but it will be some time before these products are commercially available. Implementation As described above, the most common frequency of chlorhexidine bathing is daily, and the most common application is a 2% chlorhexidine gluconate solution, either in prepackaged wipes or in soaked washcloths. One important aspect of chlorhexidine use is to allow long-term contact with the skin, with a recommended contact time of at least 5 minutes. No-rinse applications can further take advantage of chlorhexidine’s persistent antimicrobial effects on the skin. Chlorhexidine can be successfully used for MRSA decontamination, when combined with mupirocin and active surveillance. However, the effectiveness of decolonization for otherwise healthy populations is unclear. While some studies find successful reductions in skin and soft tissue infections in healthy populations by instituting daily bathing with 2% chlorhexidine-impregnated clothes, others did not find benefits to introducing chlorhexidine in a non-critical care hospital setting.
In general, daily chlorhexidine bathing is a low-cost strategy that is well received by staff. Chlorhexidine bathing also has the advantage of being easy and quick to implement, although compliance can wane over time. Good leadership support for an infection control program can increase regular use of chlorhexidine bathing, and when facilities implement chlorhexidine bathing, leadership support for infection preventionprograms can help sustain compliance with bathing over time. Key Findings • The strongest evidence supports using chlorhexidine bathing to reduce colonization and infection, particularly by multidrug— resistant Gram-positive bacteria (MDR-GPB) such as MRSA and VRE, and for healthcare- associated infections (HAIs) related tomedical devices that create a break in the skin (e.g., central lines). • Less evidence is available to support chlorhexidine bathing for preventing infection from MDR Gram-negative bacteria (MDR-GNB), such as carbapenem-resistant Enterobacteriaceae (CRE), and for other types of HAIs. • As an intervention, chlorhexidine is low cost to implement (especially if routine bathing is already in place) and generally well received by staff, but compliance with bathing can wane over time. • While the literature has not described any clinical effects of chlorhexidine resistance, this practice should continue to be monitored. Active Surveillance for MDROs “Active surveillance” is a broad practice that encompasses many activities, including sample collection, laboratory testing, data collection, data analysis, and reporting and feedback. Active surveillance helps prevent the spread of infection by identifying when an MDRO enters a healthcare facility and quickly triggering infection control measures. Active surveillance can also help with diagnosis and appropriate treatment of infections and antibiotic stewardship by generating data that can be used to create a local profile of antibiotic susceptibility or antibiogram. Epidemiologically, genotyping of active surveillance samples can help identify potential modes of transmission or assess need for patient bathing/deeper environmental cleaning by identifying related organisms from multiple sample sites. These genotyping data can also be used to identify whether the MDROs identified in screening are endemic to the environment or are imported by asymptomatic carriers. However, this practice requires access to labs with the capacity to do quick-turnaround, real- time genotyping. Integration of active surveillance programs into electronic medical records can help automate identification and analysis but requires facilities with those capacities or access to them. However, generating larger, regional and even global surveillance systems allows individual facilities
to identify risk factors for incoming patients (for example, knowing what areas of the world have high prevalence of certain MDROs). Many resource challenges arise in creating sophisticated laboratory and data integration systems that can identify, genotype, and share information on MDROs. At the same time, investing in these systems benefits other infection control practices by generating the data that allow facilities to take a risk-based approach to screening, isolation, and contact precautions, which represent an opportunity for cost saving. Finally, facilities must make decisions about when to stop active surveillance, balancing the costs of an active surveillance program against the possibilities of failed eradication and recolonization. Active surveillance for MDROs is necessary because routine surveillance of clinical samples will undercount colonized or infected patients. The proportion of clinically evident cases also varies by organism and susceptibility of the patient population, which means many asymptomatic carriers will go unnoticed without active surveillance. In addition, an accurate screening process will reduce the number of patients on isolation or contact precautions unnecessarily. In an outbreak of an MDRO in an otherwise low- prevalence setting, active surveillance is needed to verify that the outbreak has been successfully contained. It is recommend that surveillance always be paired with other infection prevention practices. Screening Methods for Detecting MDROs Although screening is widely used, findings are mixed as to the correct screening method (patient sites, type of swabs used), frequency, target population, and culturing of samples. The sensitivity and specificity of a sample collection site or type varies by type of MDRO. Given the costs associated with active surveillance and subsequent patient isolation, universal surveillance is recommended in facilities where the incidence of MDROs is moderate to high and for patients for whom the rate of conversion from colonization to infection is high (e.g., transplant patients). In universal surveillance, skin, blood, and respiratory samples perform better at initially identifying the presence of an MDRO than did urine samples. The CDC (2019) offers guidelines for surveillance based on different categories of organisms and resistance mechanisms, with a recommended approach for each. 68 General MDR-GNB: No consensus exists on frequency of screening or timing of screening for MDR-GNB. One review showed that screening during admission with weekly followup prevented the spread of MDR -A. baumanii . But a similar program for MDR- K. pneumoniae was not successful. In epidemic settings, targeted screening on admission for high-risk patients is recommended. Screening can also be used to reinforce other prevention practices in the outbreak response, such as hand hygiene.
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