Too Much Too Soon or Too Little Too Late: The Challenge of Preventing Acinetobacter Transmissions*

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Multidrug-resistant Acinetobacter baumannii (MDRAB) is prone to prolonged transmission, frustrating to eradicate, and has been associated with numerous ICU outbreaks (1). A report of the detection of A. baumannii in a culture renders even the most steadfast intensivist nervous. Multiple transmissions can stimulate the implementation of costly and unproven infection prevention measures. MDRAB transmission within a facility is associated with excess mortality and healthcare expenditure (cost per infection between $33,000 and $130,000) (2). Bundle approaches to MDRAB control (3–8) include hand hygiene and isolation education, active patient and environmental surveillance for MDRAB, contact isolation of MDRAB-colonized patients, universal gowning and gloving, geographic cohorting of MDRAB-colonized and/or newly admitted (untested) patients, cohorting of staff, enhanced environmental cleaning (bleach and hydrogen peroxide vapor), isolation adherence monitors, increased staffing ratios for MDRAB patients, daily chlorhexidine bathing, and increased attention to antimicrobial stewardship. Which of these measures are most useful, and which are merely Brownian motion, requires further study. Such studies are essential to guide the allocation of limited resources.
In this issue of Critical Care Medicine, Thom et al (9) studied the frequency of cultivable Acinetobacter on the gloves or hands of healthcare workers after interactions with colonized patients. Acquisition of Acinetobacter was used as a proxy for potential transmission. The investigators detected Acinetobacter on the hands or gloves in 30% of interactions with colonized patients, which is more frequent than the 20% of interactions reported with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) (10). Contamination was associated with isolate drug resistance (though < 20% of studied patients harbored susceptible strains). Some interactions were higher risk, such as coming in contact with bedrails, wounds, or an artificial airway. In addition, certain types of healthcare providers were disproportionately at-risk for acquisition, including respiratory and physical therapists. The risk among respiratory therapists makes sense given the findings with airway care. Physical therapists typically interact closely with patients for longer periods of time than other providers (increased interaction time was also associated with acquisition). Of further concern was the observation that 20% of intended control patients (i.e., those not known to harbor Acinetobacter) were positive on sampling, despite active surveillance on admission.
How can the experience of Thom et al (9) be incorporated into practice? Hand hygiene is a bedrock of infection prevention and control. However, hand hygiene compliance, even with dedicated intervention, is less than perfect (11), and Acinetobacter is particularly persistent in the environment (12). The data by Thom et al (9) reinforce the need for improvements in hand hygiene compliance, and further suggest that universal gloving may have a role in the management of Acinetobacter despite negative results in the prevention of MRSA and VRE transmission (10). The data on the inequality of healthcare provider risk support greater inclusion of therapy providers in prevention programs. The number of therapy providers on duty may be too few to truly cohort MDRAB-colonized patient care. Alternative means of cohorting, such as providing services to these patients at the end of shift, may serve to reduce transmission risk using existing staffing. Finally, active surveillance for Acinetobacter (and other pathogens) is designed to identify patients who serve as a reservoir for transmission (3). Even with active surveillance, colonized patients are not always recognized. Universal prevention measures (such as gowning and gloving, increased environmental cleaning, and chlorhexidine bathing) may lend additional control to transmission from unknown reservoirs.
This study is small, single center, and limited by the lack of genomic typing. Nevertheless, it contributes to our understanding of MDRAB transmission by supporting components of previously reported control bundles.
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