A cluster of three extrapulmonary Mycobacterium abscessus infections linked to well-maintained water-based heater-cooler devices

BACKGROUND

Various water-based heater-cooler devices (HCDs) have been implicated in nontuberculous mycobacteria outbreaks. Ongoing rigorous surveillance for healthcare-associated M. abscessus (HA-Mab) put in place following a prior institutional outbreak of M. abscessus alerted investigators to a cluster of 3 extrapulmonary M. abscessus infections among patients who had undergone cardiothoracic surgery.

METHODS

Investigators convened a multidisciplinary team and launched a comprehensive investigation to identify potential sources of M. abscessus in the healthcare setting. Adherence to tap water avoidance protocols during patient care and HCD cleaning, disinfection, and maintenance practices were reviewed. Relevant environmental samples were obtained. Patient and environmental M. abscessus isolates were compared using multilocus-sequence typing and pulsed-field gel electrophoresis. Smoke testing was performed to evaluate the potential for aerosol generation and dispersion during HCD use. The entire HCD fleet was replaced to mitigate continued transmission.

RESULTS

Clinical presentations of case patients and epidemiologic data supported intraoperative acquisition. M. abscessus was isolated from HCDs used on patients and molecular comparison with patient isolates demonstrated clonality. Smoke testing simulated aerosolization of M. abscessus from HCDs during device operation. Because the HCD fleet was replaced, no additional extrapulmonary HA-Mab infections due to the unique clone identified in this cluster have been detected.

CONCLUSIONS

Despite adhering to HCD cleaning and disinfection strategies beyond manufacturer instructions for use, HCDs became colonized with and ultimately transmitted M. abscessus to 3 patients. Design modifications to better contain aerosols or filter exhaust during device operation are needed to prevent NTM transmission events from water-based HCDs.

378. Descriptive Analysis of SARS-CoV-2 Infections Among Health System and University Employees

Background

We aimed to describe SARS-CoV-2 (COVID-19) infections among employees in a large, academic institution.

Table 1. COVID-19 Attribution Definitions

Methods

We prospectively tracked and traced COVID-19 infections among employees across our health system and university. Each employee with a confirmed positive test and 3 presumed positive cases were interviewed with a standard contact tracing template that included descriptive variables such as high-risk behaviors and contacts, dates worked while infectious, and initial symptoms. Using this information, the most likely location of infection acquisition was adjudicated (Table 1). We compared behavior frequency between community and unknown, likely community and community and unknown cases using descriptive statistics.

Table 3. Risk Factors for Community, Likely Community, and Unknown Cases

Results

From 3/2020 to 4/2021 we identified 3,140 COVID-19 infections in 3,119 employees out of a total of 34,562 employees (9.0%) (Figure 1). Of those 3,119 employees 1,685 (54.0%) were clinical employees working in the health system, 916 (29.4%) were non-clinical employees working in the health system, and 518 (16.6%) were university employees. Descriptive characteristics for the COVID-19 infections and adjudications are outlined in Table 2. Severe disease among employees was significantly less frequent compared to patients in the health system (15.3% vs 2.2%, p< 0.01). The frequency of travel within 14 days, masked gatherings and unmasked gatherings/activities was not significantly different between the community and unknown, likely community groups or the community and unknown groups (Table 3).

Conclusion

The majority of COVID-19 infections were linked to acquisition in the community, and few were attributed to workplace exposures. Employees with unknown sources of COVID-19 participated in higher-risk activities at approximately the same frequency as employees with community sources of COVID-19. The most frequently reported initial symptoms were mild and non-specific and rarely included fever. Despite a comprehensive testing and benefit program, a large proportion of COVID-positive employees worked with symptoms, highlighting ongoing challenges with presenteeism in healthcare.

Disclosures

Rebekah W. Moehring, MD, MPH, UpToDate, Inc. (Other Financial or Material Support, Author Royalties)

418. Low Frequency of Healthcare Worker Infections Following Occupational Exposures to COVID-19

Background

Data on occupational acquisition of COVID-19 in healthcare settings are limited. Contact tracing efforts are high resource investments.

Methods

Duke Health developed robust COVID-19 contact tracing methods as part of a comprehensive prevention program. We prospectively collected data on HCW exposures and monitored for development of symptomatic (SYX) and asymptomatic (ASYX) COVID-19 infection after documented high-, medium, and low-risk exposures. HCWs were required to self-report exposures or were identified through contact tracing as potentially exposed to COVID-19 positive HCWs, patients or visitors. Contact tracers interviewed exposed HCWs and assessed the risk of exposure as high-, medium-, or low-risk based on CDC guidance (Table 1). Testing was recommended at 6 days after high- or medium-risk exposures and was provided upon HCW request following low-risk exposures. Our vaccination campaign began in 12/2020.

Results

12,916 HCWs registered in the contact tracing database. From March 2020-May 2021, we identified 6,606 occupational exposures (0.51 exposures/HCW). The highest incidence of workplace exposures per number of HCWs in each job category was among respiratory therapists (RT) (0.95 exposures/RT), nursing assistants (NA) (0.79 exposures/NA), and physicians (0.64 exposures/physician). The most common exposure risk level was medium (51.4%), followed by low (35.5%), and then high (13.1%). A total of 260 (2%) HCW had positive tests/conversions; 28 (10.8%) were ASYX at the time of testing. High-risk exposures had a significantly greater number of post-exposure infections compared to medium- and low-risk exposures (12.5% vs. 4.2%, vs. 0.4%; p < 0.001). The rate of SYX infection following exposure to a fellow HCW (179/3,198; 5.6%) was higher than that following exposure to a patient (81/3,408; 2.4%; p< 0.001).

Conclusion

Conversion following exposure to COVID-19 in the healthcare setting with appropriate protective equipment was low. Incomplete testing of all exposed individuals was a limitation and our data may under-estimate the true conversion rate. Our findings support our local practice of not quarantining HCWs following non-household exposures. Limiting contact tracing to only high or medium risk exposures may best utilize limited personnel resources.

Disclosures

Rebekah W. Moehring, MD, MPH, UpToDate, Inc. (Other Financial or Material Support, Author Royalties)

1262. Investigation and Mitigation of a Multi-Species Outbreak of Invasive Fungal Infections on Two Oncology Wards

Background

We investigated an increase in hospital-acquired invasive fungal infections (HA-IFI) among patients admitted to adjacent hematopoietic stem cell transplant (HSCT) and hematologic malignancy (HM) wards in the setting of a large construction project adjacent to the hospital.

Methods

We defined cases of HA-IFI as HSCT or HM patients who met criteria for probable or proven IFI with suspected inpatient acquisition. We hypothesized that outside construction increased internal particle/spore counts despite preconstruction prevention efforts. The environmental investigation included an evaluation of storage/distribution of supplies, air handler inspections, air particulate counts, and bioaerosol sampling of airborne fungal spores.

Results

From October 2017 to January 2018, 11 cases of probable/proven HA-IFI occurred (Figure 1). Infections caused by multiple pathogens (Figure 2) ranged from pneumonia and sinusitis to disseminated disease. Bioaerosol sampling and particulate counts were taken from unit corridors and rooms on both wards. Fungal species identified via bioaerosol sampling were primarily Penicillium and Cladosporium species, with rare Aspergillus identified. Geometric mean particulate counts of 1 μm aerodynamic size were reduced by 88% and 75% on the HM and HSCT wards, respectively (Figure 3). Interventions on these units occurred from January to February 2018 and included: limiting the frequency of outdoor air exchanges on air handler units, reinforcing seals around entrance doors, adjusting room pressurizations to be positive or neutral on HM ward (HSCT ward is already a positive pressure environment), eliminating cardboard associated with supplies, and requiring N95 respirators for HSCT patients when off unit. After implementing these environmental control measures, we have not identified additional cases of HA-IFI on these wards.

Conclusion

We describe a multispecies outbreak of IFI in HM and HSCT patients potentially associated with new building construction that occurred despite implementation of multiple pre-construction control efforts. A multifaceted strategy to improve air quality and protect patients on and off high-risk units was needed to mitigate the outbreak.

Disclosures

All authors: No reported disclosures.

Left ventricular rupture following coronary occlusion treated by streptokinase infusion: successful surgical repair

A 68-year-old man suffered a myocardial infarction and was treated initially with streptokinase infusion, followed by coronary balloon angioplasty. Six hours later he suffered rupture of the free wall of the left ventricle, pericardial tamponade, and cardiac arrest. He was treated successfully by cardiac resuscitation, patch closure of the perforation, and coronary bypass grafting.

The relation of serum calcium and immunoparathormone levels to parathyroid size and weight in primary hyperparathyroidism

This study was designed to determine whether the serum calcium or immunoparathormone (iPTH) level would be of value in predicting the size or weight of the parathyroid gland in patients with single-gland enlargement caused by primary hyperparathyroidism. Ninety-two patients who underwent parathyroidectomy with removal of a single enlarged gland at the North Carolina Memorial Hospital (1974 to 1984) were reviewed. The preoperative calcium and immunoparathormone levels were correlated to the weight and calculated volume of the removed gland. The calcium level was found to be significantly associated with parathyroid gland weight and volume (p less than 0.001), as determined by linear regression analysis. Despite the statistical association, the correlation coefficient (calculated with the Pearson correlation matrix) was low, 0.16 for the relation of calcium to gland weight and 0.25 for the relation of calcium to calculated gland volume. The calculated coefficients of correlation of iPTH (three different assays) to gland weight and volume were similarly low. These findings demonstrate a variable relationship between the preoperative serum calcium level or the iPTH level to the weight or volume of the enlarged hyperfunctioning parathyroid gland. Identification of the pathologic parathyroid gland(s) in primary hyperparathyroidism cannot be based on a perceived relation of preoperative calcium or iPTH levels to the size of the enlarged glands.