Changes to an intensive care unit Acinetobacter baumannii population following COVID-19 disruptions and targeted infection prevention interventions. (preprint)

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a persistent nosocomial pathogen that poses a significant threat to global public health. A three-month cross-sectional observational study was conducted in a 28-bed ICU in Hangzhou, China. The same ICU was sampled for the same duration and with a similar methodology in 2019, 20 months prior to the outset of this study. Following COVID-19-associated delays, a series of IPC measures targeting patients, staff and the ICU environment were implemented for 8 months prior to and throughout this study. A total of 5,341 samples were collected from the ICU environment (n = 4450) and patients (n = 891). A. baumannii isolates were obtained from 9.5% of these samples (n = 505). Most A. baumannii isolated in this ICU were CRAB (419/518; 80.9%). Fewer CRAB were isolated here (407 from 363 sampling occasions) than in 2019 (502 from 336 sampling occasions). However, MIC50/MIC90 values for imipenem increased from 32/64 mg/L in the 2019 study to 64/128 mg/L here. This was accompanied by the proportion of global clone 2 (GC2) isolates falling from 99.5% in 2019 to 50.8% (213/419) in 2021. The phylogenetic diversity of GC2 increased, apparently driven by regular introductions of distinct clusters in association with patients. The remaining CRAB (40.2%; 206/419) were a highly clonal population of ST164, which appears to have persisted in the ICU since an introduction in mid-2020. We found clusters of GC2 and ST164 isolates with identical core genomes in different room or bed unit environments, and in multiple patients, indicative of transmission in the ICU. Changes to IPC procedures in this ICU were associated with a reduction in the total prevalence of CRAB, and in the number of CRAB isolated from clinical specimens. At the phenotypic level, the CRAB population exhibited increased resistance to carbapenems, and this may be the result of increased antibiotic prescribing over the COVID-19 period. The increased diversity of this CRAB population appears to have been the result of repeated introductions to the ICU with patients, which have continued despite interventions.

De novo Powered Air-Purifying Respirator Design and Fabrication for Pandemic Response (preprint)

Importance: The rapid spread of COVID-19 and disruption of normal supply chains resulted in severe shortages of personal protective equipment (PPE), particularly devices with few suppliers such as powered air-purifying respirators (PAPRs). A scarcity of information describing design and performance criteria represents a substantial barrier to new approaches. Objective: We sought to apply open-source product development to PAPRs to enable alternative sources of supply and further innovation. Design: We describe the design, prototyping, validation, and user testing of locally manufactured, modular, PAPR components, including filter cartridges and blower units, developed by the Greater Boston Pandemic Fabrication Team (PanFab). Two designs, one with a fully custom-made filter and housing, and the other with commercially available variants (the "Custom" and "Commercial: designs) were developed. Prototype testing was conducted at academic laboratories using equipment available during COVID-19. The designs and software are in the common domain for use or further modification. Setting: User feedback on the functionality and comfort of the design was obtained at a major US academic medical center. Participants: Feedback on designs was obtained from four individuals, including two clinicians working in an ambulatory clinical setting and two research technical staff for whom PAPR use is a standard part of occupational PPE. Main Outcomes and Measures: Engineering performance was measured using NIOSH-equivalent tests on an apparatus available in university laboratories. Clinical feedback was assessed by (1) comparison to existing PPE; (2) sense of security in a clinical setting; and (3) comfort. Results: Custom and Commercial Designs were developed for filter cartridges and blower units. The two PAPR variants passed testing for PAPR certification using an apparatus available under pandemic shortages. Respondents rated the PanFab Custom PAPR a 4 to 5 on a 5 Likert-scale across every survey question. The three other versions of the designs (with a commercial blower unit, filter, or both) also performed favorably, with survey scores of 3-5. Conclusions and Relevance: Engineering testing and clinical feedback demonstrate that the PanFab design represents a favorable alternative PAPR in terms of user comfort, mobility, and sense of security. A nonrestrictive license promotes innovation in respiratory protection for current and future medical emergencies.