The scenario describes a potential outbreak of multidrug-resistant Enterococcus faecium in an extended-care facility (ECF) wing, indicated by four positive cultures (including the current case and three prior cases from urine and a draining wound) within a month. The organism exhibits resistance to ampicillin, vancomycin, and penicillin, but sensitivity to linezolid, suggesting a possible vancomycin-resistant Enterococcus (VRE) strain, which is a significant concern in healthcare settings. The Certification Board of Infection Control and Epidemiology (CBIC) emphasizes the importance of rapid outbreak detection and response in the "Surveillance and Epidemiologic Investigation" domain, aligning with Centers for Disease Control and Prevention (CDC) guidelines for managing multidrug-resistant organisms (MDROs).

Option A, "Notify the medical director of the outbreak," is the most immediate and critical action. Identifying an outbreak—defined by the CDC as two or more cases of a similar illness linked by time and place—requires prompt notification to the facility’s leadership (e.g., medical director) to initiate a coordinated response. The presence of four Enterococcus cases, including a multidrug-resistant strain, within a single ECF wing over a month suggests a potential cluster, necessitating urgent action to assess the scope, implement control measures, and allocate resources. The CDC’s "Management of Multidrug-Resistant Organisms in Healthcare Settings" (2006) recommends immediate reporting to facility leadership as the first step to activate an outbreak investigation team, making this the priority.

Option B, "Compare the four culture reports and sensitivity patterns," is an important subsequent step in outbreak investigation. Analyzing the antibiotic susceptibility profiles and culture sources can confirm whether the cases are epidemiologically linked (e.g., clonal spread of VRE) and guide treatment and control strategies. However, this is a detailed analysis that follows initial notification and should not delay alerting the medical director. Option C, "Conduct surveillance cultures for this organism in all residents," is a proactive measure to determine the prevalence of Enterococcus faecium, especially VRE, within the wing. The CDC recommends targeted surveillance during outbreaks, but this requires prior authorization and planning by the outbreak team, making it a secondary action after notification. Option D, "Notify the nursing administrator to close the wing to new admissions," may be a control measure to prevent further spread, as suggested by the CDC for MDRO outbreaks. However, closing a unit is a significant decision that should be guided by the medical director and infection control team after assessing the situation, not an immediate independent action by the IP.

The CBIC Practice Analysis (2022) and CDC guidelines prioritize rapid communication with leadership to initiate a structured outbreak response, including resource allocation and policy adjustments. Given the multidrug-resistant nature and cluster pattern, notifying the medical director (Option A) is the most immediate and appropriate action to ensure a comprehensive response.