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Mycobacterium abscessus is a rare but well-described pathogen that has been associated with nosocomial infections. This article reports on a nosocomial cluster of M abscessus infections in 4 cardiac surgery patients and the steps that were taken to investigate and abate the cluster. Visual Abstract. Mycobacterium abscessus Cluster in Cardiac Surgery Patients.: Mycobacterium abscessus is a rare but well-described pathogen that has been associated with nosocomial infections. This article reports on a nosocomial cluster of M abscessus infections in 4 cardiac surgery patients and the steps that were taken to investigate and abate the cluster. Background: Nontuberculous mycobacteria are water-avid pathogens that are associated with nosocomial infections. Objective: To describe the analysis and mitigation of a cluster of Mycobacterium abscessus infections in cardiac surgery patients. Design: Descriptive study. Setting: Brigham and Women's Hospital, Boston, Massachusetts. Participants: Four cardiac surgery patients. Intervention: Commonalities among cases were sought, potential sources were cultured, patient and environmental specimens were sequenced, and possible sources were abated. Measurements: Description of the cluster, investigation, and mitigation. Results: Whole-genome sequencing confirmed homology among clinical isolates. Patients were admitted during different periods to different rooms but on the same floor. There were no common operating rooms, ventilators, heater-cooler devices, or dialysis machines. Environmental cultures were notable for heavy mycobacterial growth in ice and water machines on the cluster unit but little or no growth in ice and water machines in the hospital's other 2 inpatient towers or in shower and sink faucet water in any of the hospital's 3 inpatient towers. Whole-genome sequencing confirmed the presence of a genetically identical element in ice and water machine and patient specimens. Investigation of the plumbing system revealed a commercial water purifier with charcoal filters and an ultraviolet irradiation unit leading to the ice and water machines in the cluster tower but not the hospital's other inpatient towers. Chlorine was present at normal levels in municipal source water but was undetectable downstream from the purification unit. There were no further cases after high-risk patients were switched to sterile and distilled water, ice and water machine maintenance was intensified, and the commercial purification system was decommissioned. Limitation: Transmission pathways were not clearly characterized. Conclusion: Well-intentioned efforts to modify water management systems may inadvertently increase infection risk for vulnerable patients. Primary Funding Source: National Institutes of Health. [ABSTRACT FROM AUTHOR]

Background: Little is known about clusters of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in acute care hospitals.Objective: To describe the detection, mitigation, and analysis of a large cluster of SARS-CoV-2 infections in an acute care hospital with mature infection control policies.Design: Descriptive study.Setting: Brigham and Women's Hospital, Boston, Massachusetts.Participants: Patients and staff with cluster-related SARS-CoV-2 infections.Intervention: Close contacts of infected patients and staff were identified and tested every 3 days, patients on affected units were preemptively isolated and repeatedly tested, affected units were cleaned, room ventilation was measured, and specimens were sent for whole-genome sequencing. A case-control study was done to compare clinical interactions, personal protective equipment use, and breakroom and workroom practices in SARS-CoV-2-positive versus negative staff.Measurements: Description of the cluster, mitigation activities, and risk factor analysis.Results: Fourteen patients and 38 staff members were included in the cluster per whole-genome sequencing and epidemiologic associations. The index case was a symptomatic patient in whom isolation was discontinued after 2 negative results on nasopharyngeal polymerase chain reaction testing. The patient subsequently infected multiple roommates and staff, who then infected others. Seven of 52 (13%) secondary infections were detected only on second or subsequent tests. Eight of 9 (89%) patients who shared rooms with potentially contagious patients became infected. Potential contributing factors included high viral loads, nebulization, and positive pressure in the index patient's room. Risk factors for transmission to staff included presence during nebulization, caring for patients with dyspnea or cough, lack of eye protection, at least 15 minutes of exposure to case patients, and interactions with SARS-CoV-2-positive staff in clinical areas. Whole-genome sequencing confirmed that 2 staff members were infected despite wearing surgical masks and eye protection.Limitation: Findings may not be generalizable.Conclusion: SARS-CoV-2 clusters can occur in hospitals despite robust infection control policies. Insights from this cluster may inform additional measures to protect patients and staff.Primary Funding Source: None. [ABSTRACT FROM AUTHOR]