Last data update: Jan 21, 2025. (Total: 48615 publications since 2009)
Records 1-30 (of 66 Records) |
Query Trace: Ham C[original query] |
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Identification and characterization of vancomycin-resistant staphylococcus aureus CC45/USA600, North Carolina, USA, 2021
MacFarquhar JK , Bajpai A , Fisher T , Barr C , Kent AG , McKay SL , Campbell D , Gargis AS , Balbuena R , Lonsway D , Karlsson M , Walters MS , Ham DC , Glover WA . Emerg Infect Dis 2025 31 (1) 194-196 Vancomycin-resistant Staphylococcus aureus (VRSA) is a rare but serious public health concern. We describe a VRSA case in North Carolina, USA. The isolate from the case belonged to the USA600 lineage and clonal complex 45. No transmission was identified. Confirmed VRSA cases should include a thorough investigation and public health response. |
Clusters of emerging multidrug-resistant organisms in United States healthcare facilities during the initial months of the SARS-CoV-2 pandemic
Ham DC , Li R , Mitsunaga T , Czaja C , Prestel C , Bhaurla S , Cumming M , Brennan B , Innes G , Carrico S , Chan A , Merengwa E , Stahl A , Ostrowsky B , de Perio MA , Walters MS . Am J Infect Control 2024 52 (12) 1390-1396 BACKGROUND: Outbreaks of emerging multidrug-resistant organisms (eMDROs), including carbapenem-resistant Enterobacterales, carbapenem-resistant Acinetobacter baumannii, and Candida auris, have been reported among severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients. We describe eMDRO clusters in SARS-CoV-2 units and associated infection control (IC) practices early in the SARS-CoV-2 pandemic. METHODS: We conducted a retrospective survey of a convenience sample of health departments in 11 states to describe clusters of eMDROs that began before November 1, 2020 and involved SARS-CoV-2 units. Cluster characteristics and IC practices during the cluster period were assessed using a standardized outbreak report form, and descriptive analyses were performed. RESULTS: Overall, 18 eMDRO clusters (10 carbapenem-resistant Enterobacterales, 6 C auris, 1 carbapenem-resistant Pseudomonas aeruginosa, and 1 carbapenem-resistant A baumannii) in 18 health care facilities involving 397 patients were reported from 10 states. During the cluster period, 60% of facilities reported a shortage of isolation gowns, 69% extended use of gowns, and 67% reported difficulty obtaining preferred disinfectants. Reduced frequency of hand hygiene audits was reported in 85% of acute care hospitals during the cluster period compared with before the pandemic. CONCLUSIONS: Changes in IC practices and supply shortages were identified in facilities with eMDRO outbreaks during the SARS-CoV-2 pandemic and might have contributed to eMDRO transmission. |
Factors affecting chlorinated product formation from sodium hypochlorite bleach and limonene reactions in the gas phase
Walsh CM , Baughman NN , Ham JE , Wells JR . ACS EST Air 2025 10 (1) 1317-1328 During use of sodium hypochlorite bleach, gas-phase hypochlorous acid (HOCl) and chlorine (Cl2) are released, which can react with organic compounds present in indoor air. Reactivity between HOCl/Cl2 and limonene, a common constituent of indoor air, has been observed. The purpose of this study was to characterize the chemical species generated from gas-phase reactions between HOCl/Cl2 and limonene. Gas-phase reactions were prepared in Teflon chambers housing HOCl, Cl2, and limonene. The resulting chemical products were analyzed using gas-phase preconcentration, followed by gas chromatography and high-resolution mass spectrometry. Several chlorinated products were detected, including limonene species containing one, two, and three chlorines and limonene chlorohydrin. Product concentrations and yields were estimated for the most abundant products, and greater than 80% of transformed limonene was represented in the detected products. Temporal sampling of the reactions allowed time courses to be plotted for limonene decay and chlorinated limonene product generation under different conditions, including the treatments of HOCl/Cl2, Cl2 only, high vs low relative humidity, and +/- ozone. These experiments add product speciation, yield estimates, and an understanding of environmental factors affecting product formation to previous studies, further highlighting the chemical transformations initiated by sodium hypochlorite bleach in indoor air. |
Candida auris in US correctional facilities
Hennessee I , Forsberg K , Erskine J , Charles A , Russell B , Reyes J , Emery C , Valencia N , Sherman A , Mehr J , Gallion H , Halleck B , Cox C , Bryant M , Nichols D , Medrzycki M , Ham DC , Hagan LM , Lyman M . Emerg Infect Dis 2024 30 (13) S36-s40 Candida auris is an emerging fungal pathogen that typically affects patients in healthcare settings. Data on C. auris cases in correctional facilities are limited but are needed to guide public health recommendations. We describe cases and challenges of providing care for 13 patients who were transferred to correctional facilities during January 2020-December 2022 after having a positive C. auris specimen. All patients had positive specimens identified while receiving inpatient care at healthcare facilities in geographic areas with high C. auris prevalence. Correctional facilities reported challenges managing patients and implementing prevention measures; those challenges varied by whether patients were housed in prison medical units or general population units. Although rarely reported, C. auris cases in persons who are incarcerated may occur, particularly in persons with known risk factors. Measures to manage cases and prevent C. auris spread in correctional facilities should address setting-specific challenges in healthcare and nonhealthcare correctional environments. |
Extensively drug-resistant pseudomonas aeruginosa outbreak associated with artificial tears
Grossman MK , Rankin DA , Maloney M , Stanton RA , Gable P , Stevens VA , Ewing T , Saunders K , Kogut S , Nazarian E , Bhaurla S , Mephors J , Mongillo J , Stonehocker S , Prignano J , Valencia N , Charles A , McNamara K , Fritsch WA , Ruelle S , Plucinski CA , Sosa L , Ostrowsky B , Ham DC , Walters MS . Clin Infect Dis 2024 BACKGROUND: Carbapenemase-producing, carbapenem-resistant Pseudomonas aeruginosa (CP-CRPA) are extensively drug resistant bacteria. We investigated the source of a multistate CP-CRPA outbreak. METHODS: Cases were defined as a U.S. patient's first isolation of P. aeruginosa sequence type 1203 with the carbapenemase gene blaVIM-80 and cephalosporinase gene blaGES-9 from any specimen source collected and reported to CDC between January 1, 2022-May 15, 2023. We conducted a 1:1 matched case-control study at the post-acute care facility with the most cases, assessed exposures associated with case status for all case-patients, and tested products for bacterial contamination. RESULTS: We identified 81 case-patients from 18 states, 27 of whom were identified through surveillance cultures. Four (7%) of 54 case-patients with clinical cultures died within 30 days of culture collection, and four (22%) of 18 with eye infections underwent enucleation. In the case-control study, case-patients had increased odds of receiving artificial tears compared to controls (crude matched OR: 5.0, 95% CI: 1.1, 22.8). Overall, artificial tears use was reported by 61 (87%) of 70 case-patients with information; 43 (77%) of 56 case-patients with brand information reported use of Brand A, an imported, preservative-free, over-the-counter (OTC) product. Bacteria isolated from opened and unopened bottles of Brand A were genetically related to patient isolates. FDA inspection of the manufacturing plant identified likely sources of contamination. CONCLUSIONS: A manufactured medical product serving as the vehicle for carbapenemase-producing organisms is unprecedented in the U.S. The clinical impacts from this outbreak underscore the need for improved requirements for U.S. OTC product importers. |
Reply to Diekema et al. "Are contact precautions "essential" for the prevention of healthcare-associated methicillin-resistant Staphylococcus aureus?"
Popovich KJ , Aureden K , Ham DC , Harris AD , Hessels AJ , Huang SS , Maragakis LL , Milstone AM , Moody J , Yokoe D , Calfee DP . Clin Infect Dis 2023 As the authors of the 2022 update of the Society for Healthcare Epidemiology of America/Infectious Diseases Society of America/Association for Professionals in Infection Control and Epidemiology practice recommendations for prevention of methicillin-resistant Staphylococcus aureus (MRSA) infection and transmission in acute care hospitals [1], we would like to respond to the recently published Viewpoints article by Diekema and colleagues [2]. The purpose of this letter is to highlight that there is more agreement than disagreement between the recently published practice recommendations and what Diekema et al proposed as an alternative. For decades, the infection prevention community has debated the use of contact precautions for MRSA prevention. We agree that studies of contact precautions for MRSA prevention have come to conflicting conclusions and do not provide a definitive answer that applies to all settings. Current data suggest that contact precautions are an important component of a MRSA control program in many but not all hospitals. In some hospitals, a low prevalence of MRSA and/or successful implementation of other control strategies has reduced the incremental benefit of contact precautions to the point that the potential benefits may be outweighed by other considerations and priorities. |
Cluster of carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa among patients in an adult intensive care unit - Idaho, 2021-2022
Cahill ME , Jaworski M , Harcy V , Young E , Ham DC , Gable P , Carter KK . MMWR Morb Mortal Wkly Rep 2023 72 (31) 844-846 Treatment of carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa (CP-CRPA) infections is challenging because of antibiotic resistance. CP-CRPA infections are highly transmissible in health care settings because they can spread from person to person and from environmental sources such as sink drains and toilets. During September 2021-January 2022, an Idaho hospital (hospital A) isolated CP-CRPA from sputum of two patients who stayed in the same intensive care unit (ICU) room (room X), 4 months apart. Both isolates had active-on-imipenem metallo-beta-lactamase (IMP) carbapenemase gene type 84 (bla(IMP-84)) and were characterized as multilocus sequence type 235 (ST235). A health care-associated infections team from the Idaho Division of Public Health visited hospital A during March 21-22, 2022, to discuss the cluster investigation with hospital A staff members and to collect environmental samples. CP-CRPA ST235 with bla(IMP-84) was isolated from swab samples of one sink in room X, suggesting it was the likely environmental source of transmission. Recommended prevention and control measures included application of drain biofilm disinfectant, screening of future patients who stay in room X (e.g., the next 10 occupants) upon reopening, and continuing submission of carbapenem-resistant P. aeruginosa (CRPA) isolates to public health laboratories. Repeat environmental sampling did not detect any CRPA. As of December 2022, no additional CP-CRPA isolates had been reported by hospital A. Collaboration between health care facilities and public health agencies, including testing of CRPA isolates for carbapenemase genes and implementation of sink hygiene interventions, was critical in the identification of and response to this CP-CRPA cluster in a health care setting. |
SHEA/IDSA/APIC Practice Recommendation: Strategies to prevent methicillin-resistant Staphylococcus aureus transmission and infection in acute-care hospitals: 2022 Update
Popovich KJ , Aureden K , Ham DC , Harris AD , Hessels AJ , Huang SS , Maragakis LL , Milstone AM , Moody J , Yokoe D , Calfee DP . Infect Control Hosp Epidemiol 2023 44 (7) 1-29 Previously published guidelines have provided comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). The intent of this document is to highlight practical recommendations in a concise format designed to assist acute-care hospitals in implementing and prioritizing efforts to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission and infection. This document updates the "Strategies to Prevent Methicillin-Resistant Staphylococcus aureus Transmission and Infection in Acute Care Hospitals" published in 2014.(1) This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA). It is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the Association for Professionals in Infection Control and Epidemiology (APIC), the American Hospital Association (AHA), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. |
Multipathogen outbreak of bacillus cereus and clostridium perfringens among hospital workers in Alaska, August 2021
Newell K , Helfrich K , Isernhagen H , Jones M , Stickel G , McKeel H , Castrodale L , McLaughlin J . Public Health Rep 2023 333549231170220 OBJECTIVE: Clostridium perfringens and Bacillus cereus are common causes of reported foodborne illness. On August 6, 2021, the Alaska Division of Public Health identified a multipathogen gastrointestinal outbreak among hospital staff in Homer, Alaska. The objectives of this study were to identify the outbreak source and prevent future illness. METHODS: We conducted a retrospective cohort study of hospital staff who participated in luncheon events during August 5-7, 2021, and used an online survey to identify hospital staff with gastrointestinal illness. We defined case patients as people who reported new-onset gastrointestinal illness (diarrhea or abdominal cramping) after food consumption during the luncheon events. We calculated adjusted odds ratios of gastrointestinal illness associated with reported food exposures. We tested available food samples for C perfringens and B cereus and tested case patient stool specimens for C perfringens. We conducted an environmental investigation at the implicated vendor site. RESULTS: Of 202 survey responses, 66 (32.7%) people reported acute gastrointestinal illness: 64 (97.0%) reported diarrhea, 62 (94.9%) reported abdominal cramps, and none were hospitalized. Of 79 people who consumed ham and pulled pork sandwiches, 64 (81.0%) met the case definition; this food item was significantly associated with increased odds of gastrointestinal illness (adjusted odds ratio = 296.4; 95% CI, 76.7-2019.1). C perfringens and B cereus were isolated at confirmatory levels from sandwich samples. C perfringens enterotoxin was detected in all 5 stool specimens tested. Environmental investigators observed other food items at the sandwich vendor that were refrigerated outside the required temperature range (>41 °F); no clear handling deficiencies for the implicated food were identified. CONCLUSION: Quick notification and effective collaboration can help detect an outbreak, identify the responsible food vehicle, and mitigate further risk. |
Large-Format Additive Manufacturing and Machining Using High-Melt-Temperature Polymers. Part I: Real-Time Particulate and Gas-Phase Emissions
Stefaniak AB , Bowers LN , Martin SB Jr , Hammond DR , Ham JE , Wells JR , Fortner AR , Knepp AK , du Preez S , Pretty JR , Roberts JL , du Plessis JL , Schmidt A , Duling MG , Bader A , Virji MA . J Chem Health Saf 2021 28 (3) 190-200 The literature on emissions during material extrusion additive manufacturing with 3-D printers is expanding; however, there is a paucity of data for large-format additive manufacturing (LFAM) machines that can extrude high-melt-temperature polymers. Emissions from two LFAM machines were monitored during extrusion of six polymers: acrylonitrile butadiene styrene (ABS), polycarbonate (PC), high-melt-temperature polysulfone (PSU), poly(ether sulfone) (PESU), polyphenylene sulfide (PPS), and Ultem (poly(ether imide)). Particle number, total volatile organic compound (TVOC), carbon monoxide (CO), and carbon dioxide (CO(2)) concentrations were monitored in real-time. Particle emission rate values (no./min) were as follows: ABS (1.7 × 10(11) to 7.7 × 10(13)), PC (5.2 × 10(11) to 3.6 × 10(13)), Ultem (5.7 × 10(12) to 3.1 × 10(13)), PPS (4.6 × 10(11) to 6.2 × 10(12)), PSU (1.5 × 10(12) to 3.4 × 10(13)), and PESU (2.0 to 5.0 × 10(13)). For print jobs where the mass of extruded polymer was known, particle yield values (g(-1) extruded) were as follows: ABS (4.5 × 10(8) to 2.9 × 10(11)), PC (1.0 × 10(9) to 1.7 × 10(11)), PSU (5.1 × 10(9) to 1.2 × 10(11)), and PESU (0.8 × 10(11) to 1.7 × 10(11)). TVOC emission yields ranged from 0.005 mg/g extruded (PESU) to 0.7 mg/g extruded (ABS). The use of wall-mounted exhaust ventilation fans was insufficient to completely remove airborne particulate and TVOC from the print room. Real-time CO monitoring was not a useful marker of particulate and TVOC emission profiles for Ultem, PPS, or PSU. Average CO(2) and particle concentrations were moderately correlated (r (s) = 0.76) for PC polymer. Extrusion of ABS, PC, and four high-melt-temperature polymers by LFAM machines released particulate and TVOC at levels that could warrant consideration of engineering controls. LFAM particle emission yields for some polymers were similar to those of common desktop-scale 3-D printers. |
Large-Format Additive Manufacturing and Machining Using High-Melt-Temperature Polymers. Part II: Characterization of Particles and Gases
Stefaniak AB , Bowers LN , Martin SB Jr , Hammond DR , Ham JE , Wells JR , Fortner AR , Knepp AK , du Preez S , Pretty JR , Roberts JL , du Plessis JL , Schmidt A , Duling MG , Bader A , Virji MA . J Chem Health Saf 2021 28 (4) 268-278 Extrusion of high-melt-temperature polymers on large-format additive manufacturing (LFAM) machines releases particles and gases, though there is no data describing their physical and chemical characteristics. Emissions from two LFAM machines were monitored during extrusion of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) polymers as well as high-melt-temperature Ultem (poly(ether imide)), polysulfone (PSU), poly(ether sulfone) (PESU), and polyphenylene sulfide (PPS) polymers. Filter samples of particles were collected for quantification of elements and bisphenol A and S (BPA, BPS) and visualization of morphology. Individual gases were quantified on substance-specific media. Aerosol sampling demonstrated that concentrations of elements were generally low for all polymers, with a maximum of 1.6 mg/m(3) for iron during extrusion of Ultem. BPA, an endocrine disruptor, was released into air during extrusion of PC (range: 0.4 ± 0.1 to 21.3 ± 5.3 μg/m(3)). BPA and BPS (also an endocrine disruptor) were released into air during extrusion of PESU (BPA, 2.0-8.7 μg/m(3); BPS, 0.03-0.07 μg/m(3)). Work surfaces and printed parts were contaminated with BPA (<8-587 ng/100 cm(2)) and BPS (<0.22-2.5 ng/100 cm(2)). Gas-phase sampling quantified low levels of respiratory irritants (phenol, SO(2), toluene, xylenes), possible or known asthmagens (caprolactam, methyl methacrylate, 4-oxopentanal, styrene), and possible occupational carcinogens (benzene, formaldehyde, acetaldehyde) in air. Characteristics of particles and gases released by high-melt-temperature polymers during LFAM varied, which indicated the need for polymer-specific exposure and risk assessments. The presence of BPA and BPS on surfaces revealed a previously unrecognized source of dermal exposure for additive manufacturing workers using PC and PESU polymers. |
Vital Signs: Health disparities in hemodialysis-associated staphylococcus aureus bloodstream infections - United States, 2017-2020
Rha B , See I , Dunham L , Kutty PK , Moccia L , Apata IW , Ahern J , Jung S , Li R , Nadle J , Petit S , Ray SM , Harrison LH , Bernu C , Lynfield R , Dumyati G , Tracy M , Schaffner W , Ham DC , Magill SS , O'Leary EN , Bell J , Srinivasan A , McDonald LC , Edwards JR , Novosad S . MMWR Morb Mortal Wkly Rep 2023 72 (6) 153-159 INTRODUCTION: Racial and ethnic minorities are disproportionately affected by end-stage kidney disease (ESKD). ESKD patients on dialysis are at increased risk for Staphylococcus aureus bloodstream infections, but racial, ethnic, and socioeconomic disparities associated with this outcome are not well described. METHODS: Surveillance data from the 2020 National Healthcare Safety Network (NHSN) and the 2017-2020 Emerging Infections Program (EIP) were used to describe bloodstream infections among patients on hemodialysis (hemodialysis patients) and were linked to population-based data sources (CDC/Agency for Toxic Substances and Disease Registry [ATSDR] Social Vulnerability Index [SVI], United States Renal Data System [USRDS], and U.S. Census Bureau) to examine associations with race, ethnicity, and social determinants of health. RESULTS: In 2020, 4,840 dialysis facilities reported 14,822 bloodstream infections to NHSN; 34.2% were attributable to S. aureus. Among seven EIP sites, the S. aureus bloodstream infection rate during 2017-2020 was 100 times higher among hemodialysis patients (4,248 of 100,000 person-years) than among adults not on hemodialysis (42 of 100,000 person-years). Unadjusted S. aureus bloodstream infection rates were highest among non-Hispanic Black or African American (Black) and Hispanic or Latino (Hispanic) hemodialysis patients. Vascular access via central venous catheter was strongly associated with S. aureus bloodstream infections (NHSN: adjusted rate ratio [aRR] = 6.2; 95% CI = 5.7-6.7 versus fistula; EIP: aRR = 4.3; 95% CI = 3.9-4.8 versus fistula or graft). Adjusting for EIP site of residence, sex, and vascular access type, S. aureus bloodstream infection risk in EIP was highest in Hispanic patients (aRR = 1.4; 95% CI = 1.2-1.7 versus non-Hispanic White [White] patients), and patients aged 18-49 years (aRR = 1.7; 95% CI = 1.5-1.9 versus patients aged ≥65 years). Areas with higher poverty levels, crowding, and lower education levels accounted for disproportionately higher proportions of hemodialysis-associated S. aureus bloodstream infections. CONCLUSIONS AND IMPLICATIONS FOR PUBLIC HEALTH PRACTICE: Disparities exist in hemodialysis-associated S. aureus infections. Health care providers and public health professionals should prioritize prevention and optimized treatment of ESKD, identify and address barriers to lower-risk vascular access placement, and implement established best practices to prevent bloodstream infections. |
Feasibility of a selective epoxidation technique for use in quantification of peracetic acid in air samples collected on sorbent tubes
Walsh CM , Jackson SR , Baughman NN , Ham JE , Wells JR . J Chem Health Saf 2022 29 (4) 378-386 Peracetic acid is a disinfection agent used in medical and food processing facilities, and occupational exposures have been documented. To facilitate characterization of daily occupational exposures, the current work describes the development of a personal sampling technique to quantify the peracetic acid concentration in air samples. Peracetic acid atmospheres were generated in 100 L Teflon chambers, and samples were collected on 350 mg XAD-7 solid sorbent tubes for 4 h at a flow rate of 250 mL/min using a personal sampling pump. Indirect measurement of peracetic acid was achieved by desorption from the sorbent and subsequent treatment with cyclohexene to initiate an epoxidation reaction, formally known as the Prilezhaev reaction. The epoxidation product, cyclohexene oxide, was quantified by gas chromatography-mass spectrometry. The reaction enabled quantification of peracetic acid with high specificity over the common co-contaminants hydrogen peroxide and acetic acid, which were introduced in 10-fold and 100-fold excess to challenge the reaction. The technique also demonstrated an overall estimate of bias and precision of 11 and 8%, respectively, and a limit of detection of 60 ppbv was estimated. Preliminary storage experiments indicate that unreacted peracetic acid is stable on the sorbent tubes for 72 h when stored at -20 °C following collection. Overall, the specificity of the reaction and capability to sample for longer time periods than current methods, in addition to the use of safer personal sampling materials, demonstrate the utility of this technique for peracetic acid measurement in air. © 2022 Elsevier Inc.. All rights reserved. |
Potential misclassification of diabetes and prediabetes in the U.S.:Mismatched hba1c and glucose in NHANES 2005-2016
Staimez LR , Kipling LM , Nina Ham J , Legvold BT , Jackson SL , Wilson PWF , Rhee MK , Phillips LS . Diabetes Res Clin Pract 2022 189 109935 AIMS: To assess the prevalence and clinical implications of "mismatches" between HbA1c and glucose levels in the United States across the life course. METHODS: Participants ages 12-79 years from U.S. National Health and Nutrition Examination Survey (NHANES) 2005-2016 without known diagnosis of diabetes and who had a 75g oral glucose tolerance test were included. Previously undiagnosed diabetes (DM), prediabetes, and normal glucose metabolism (NGM) were defined using American Diabetes Association cut-points. Mismatches were defined by the hemoglobin glycation index (HGI). RESULTS: In 10,361 participants, 5% and 41% had diabetes and prediabetes, respectively, by fasting or 2-hour glucose criteria. By HbA1c criteria, the high HGI tertile consisted of mostly abnormal classification (3% DM, 52% prediabetes) and the low HGI tertile contained mostly normal classification (78% NGM). Across all ages, 15% (weighted: 30 million individuals) had clinically significant mismatches of HGI magnitude ≥+0.5% (i.e., high mismatch) or ≤-0.5% (low mismatch). Mismatch was most common in older adults and non-Hispanic Black participants. CONCLUSIONS: Mismatches of clinically significant magnitude could lead to HbA1c-related misdiagnosis or inappropriate management in up to 30 million Americans. Older adults, non-Hispanic Black individuals, and others with high mismatches may benefit from complementing HbA1c with additional diagnostic and management strategies. |
Trimethoprim-sulfamethoxazole resistance patterns among Staphylococcus aureus in the United States, 2012-2018
Ham DC , Fike L , Wolford H , Lastinger L , Soe M , Baggs J , Walters MS . Infect Control Hosp Epidemiol 2022 44 (5) 1-4 We reviewed trimethoprim-sulfamethoxazole antibiotic susceptibility testing data among Staphylococcus aureus using 3 national inpatient databases. In all 3 databases, we observed an increases in the percentage of methicillin-resistant Staphylococcus aureus that were not susceptible to trimethoprim-sulfamethoxazole. Providers should select antibiotic regimens based on local resistance patterns and should report changes to the public health department. |
Chemical emissions from heated vitamin e acetate-insights to respiratory risks from electronic cigarette liquid oil diluents used in the aerosolization of (9)-thc-containing products
LeBouf RF , Ranpara A , Ham J , Aldridge M , Fernandez E , Williams K , Burns DA , Stefaniak AB . Front Public Health 2021 9 765168 As of February 18, 2020, the e-cigarette, or vaping, product use associated lung injury (EVALI) outbreak caused the hospitalization of a total of 2,807 patients and claimed 68 lives in the United States. Though investigations have reported a strong association with vitamin E acetate (VEA), evidence from reported EVALI cases is not sufficient to rule out the contribution of other chemicals of concern, including chemicals in either THC or non-THC products. This study characterized chemicals evolved when diluent oils were heated to temperatures that mimic e-cigarette, or vaping, products (EVPs) to investigate production of potentially toxic chemicals that might have caused lung injury. VEA, vitamin E, coconut, and medium chain triglyceride (MCT) oil were each diluted with ethanol and then tested for constituents and impurities using a gas chromatograph mass spectrometer (GC/MS). Undiluted oils were heated at 25°C (control), 150°C, and 250°C in an inert chamber to mimic a range of temperatures indicative of aerosolization from EVPs. Volatilized chemicals were collected using thermal desorption tubes, analyzed using a GC/MS, and identified. Presence of identified chemicals was confirmed using retention time and ion spectra matching with analytic standards. Direct analysis of oils, as received, revealed that VEA and vitamin E were the main constituents of their oils, and coconut and MCT oils were nearly identical having two main constituents: glycerol tricaprylate and 2-(decanoyloxy) propane-1,3-diyl dioctanoate. More chemicals were measured and with greater intensities when diluent oils were heated at 250°C compared to 150°C and 25°C. Vitamin E and coconut/MCT oils produced different chemical emissions. The presence of some identified chemicals is of potential health consequence because many are known respiratory irritants and acute respiratory toxins. Exposure to a mixture of hazardous chemicals may be relevant to the development or exacerbation of EVALI, especially when in concert with physical damage caused by lung deposition of aerosols produced by aerosolizing diluent oils. |
Extensively Drug-Resistant Carbapenemase-Producing Pseudomonas aeruginosa and Medical Tourism from the United States to Mexico, 2018-2019.
Kracalik I , Ham DC , McAllister G , Smith AR , Vowles M , Kauber K , Zambrano M , Rodriguez G , Garner K , Chorbi K , Cassidy PM , McBee S , Stoney RJ , Moser K , Villarino ME , Zazueta OE , Bhatnagar A , Sula E , Stanton RA , Brown AC , Halpin AL , Epstein L , Walters MS . Emerg Infect Dis 2022 28 (1) 51-61 Carbapenem-resistant Pseudomonas aeruginosa (CRPA) producing the Verona integron‒encoded metallo-β-lactamase (VIM) are highly antimicrobial drug-resistant pathogens that are uncommon in the United States. We investigated the source of VIM-CRPA among US medical tourists who underwent bariatric surgery in Tijuana, Mexico. Cases were defined as isolation of VIM-CRPA or CRPA from a patient who had an elective invasive medical procedure in Mexico during January 2018‒December 2019 and within 45 days before specimen collection. Whole-genome sequencing of isolates was performed. Thirty-eight case-patients were identified in 18 states; 31 were operated on by surgeon 1, most frequently at facility A (27/31 patients). Whole-genome sequencing identified isolates linked to surgeon 1 were closely related and distinct from isolates linked to other surgeons in Tijuana. Facility A closed in March 2019. US patients and providers should acknowledge the risk for colonization or infection after medical tourism with highly drug-resistant pathogens uncommon in the United States. |
Gram-negative bacteria harboring multiple carbapenemase genes, United States, 2012-2019
Ham DC , Mahon G , Bhaurla SK , Horwich-Scholefield S , Klein L , Dotson N , Rasheed JK , McAllister G , Stanton RA , Karlsson M , Lonsway D , Huang JY , Brown AC , Walters MS . Emerg Infect Dis 2021 27 (9) 2475-2479 Reports of organisms harboring multiple carbapenemase genes have increased since 2010. During October 2012-April 2019, the Centers for Disease Control and Prevention documented 151 of these isolates from 100 patients in the United States. Possible risk factors included recent history of international travel, international inpatient healthcare, and solid organ or bone marrow transplantation. |
A Comprehensive Approach to Ending an Outbreak of Rare bla OXA-72 gene-positive Carbapenem-resistant Acinetobacter baumannii at a Community Hospital, Kansas City, MO, 2018
McKinsey DS , Gasser C , McKinsey JP , Ditto G , Agard A , Zellmer B , Poteete C , Vagnone PS , Dale JL , Bos J , Hahn R , Turabelidze G , Poiry M , Franklin P , Vlachos N , McAllister GA , Halpin AL , Glowicz J , Ham DC , Epstein L . Am J Infect Control 2021 49 (9) 1183-1185 We identified a cluster of extensively drug-resistant, carbapenemase gene-positive, carbapenem-resistant Acinetobacter baumannii (CP-CRAB) at a teaching hospital in Kansas City. Extensively drug-resistant CRAB was identified from eight patients and 3% of environmental cultures. We used patient cohorting and targeted environmental disinfection to stop transmission. After implementation of these measures, no additional cases were identified. |
Mass SARS-CoV-2 Testing in a Dormitory-Style Correctional Facility in Arkansas.
Tompkins LK , Gunn JKL , Cherney B , Ham JE , Horth R , Rossetti R , Bower WA , Benson K , Hagan LM , Crist MB , Mettee Zarecki SL , Dixon MG , Dillaha JA , Patil N , Dusseau C , Ross T , Matthews HS , Garner K , Starks AM , Weiner Z , Bowen MD , Bankamp B , Newton AE , Logan N , Schuh AJ , Trimble S , Pfeiffer H , James AE , Tian N , Jacobs JR , Ruiz F , McDonald K , Thompson M , Cooley L , Honein MA , Rose DA . Am J Public Health 2021 111 (5) e1-e10 Objectives. To assess SARS-CoV-2 transmission within a correctional facility and recommend mitigation strategies.Methods. From April 29 to May 15, 2020, we established the point prevalence of COVID-19 among incarcerated persons and staff within a correctional facility in Arkansas. Participants provided respiratory specimens for SARS-CoV-2 testing and completed questionnaires on symptoms and factors associated with transmission.Results. Of 1647 incarcerated persons and 128 staff tested, 30.5% of incarcerated persons (range by housing unit = 0.0%-58.2%) and 2.3% of staff tested positive for SARS-CoV-2. Among those who tested positive and responded to symptom questions (431 incarcerated persons, 3 staff), 81.2% and 33.3% were asymptomatic, respectively. Most incarcerated persons (58.0%) reported wearing cloth face coverings 8 hours or less per day, and 63.3% reported close contact with someone other than their bunkmate.Conclusions. If testing remained limited to symptomatic individuals, fewer cases would have been detected or detection would have been delayed, allowing transmission to continue. Rapid implementation of mass testing and strict enforcement of infection prevention and control measures may be needed to mitigate spread of SARS-CoV-2 in this setting. (Am J Public Health. Published online ahead of print March 18, 2021: e1-e10. https://doi.org/10.2105/AJPH.2020.306117). |
Amino Acid Substitutions in Positions 385 and 393 of the Hydrophobic Region of VP4 May Be Associated with Rotavirus Attenuation and Cell Culture Adaptation.
Guo Y , Wentworth DE , Stucker KM , Halpin RA , Lam HC , Marthaler D , Saif LJ , Vlasova AN . Viruses 2020 12 (4) Rotaviruses (RVs) are the leading cause of the acute viral gastroenteritis in young children and livestock animals worldwide. Although live attenuated vaccines have been applied to control RV infection for many years, the underlying mechanisms of RV attenuation following cell culture adaption are unknown. To study these mechanisms at the genomic level, we have sequenced and conducted a comparative analysis of two virulent human (Wa, G1P[8] and M, G3P[8]) and two virulent porcine (Gottfried, G4P[6] and OSU, G5P[7]) RV strains maintained in gnotobiotic piglets for 22, 11, 12 and 9 serial passages, respectively, with their attenuated counterparts serially passaged in MA-104 cell cultures for 25, 43, 54 and 43 passages, respectively. We showed that most of the mutations were clustered in the VP4 gene, with a relatively high nonsynonymous substitution rate (81.2%). Moreover, two amino acid substitutions observed in the VP4 gene were conserved between two or more strain pairs. D385N substitution was found in M, Wa and Gottfried strains, and another one, S471H/L was present in Wa and Gottfried strains. Importantly, D385 was reported previously in another study and may be involved in regulation of virus entry. Of interest, although no 385 substitution was found in OSU strains, the attenuated OSU strain contained a unique D393H substitution within the same VP4 hydrophobic domain. Collectively, our data suggest that the VP4 hydrophobic region may play an important role in RV attenuation and aa385 and aa393 may represent potential targets for RV vaccine development using reverse genetics and site-specific mutagenesis. |
Investigation of hospital-onset methicillin-resistant Staphylococcus aureus bloodstream infections at eight high burden acute care facilities in the United States, 2016
Ham DC , See I , Novosad S , Crist M , Mahon G , Fike L , Spicer K , Talley P , Flinchum A , Kainer M , Kallen AJ , Walters MS . J Hosp Infect 2020 BACKGROUND: Despite large reductions from 2005-2012, hospital-onset methicillin-resistant Staphylococcus aureus bloodstream infections (HO MRSA BSIs) continue be a major source of morbidity and mortality. AIM: To describe risk factors for and underlying sources of HO MRSA BSIs. METHODS: We investigated HO MRSA BSIs at eight high-burden short-stay acute care hospitals. A case was defined as first isolation of MRSA from a blood specimen collected in 2016 on hospital day >/=4 from a patient without an MRSA-positive blood culture in the 14 days prior. We reviewed case-patient demographics and risk factors by medical record abstraction. The potential clinical source(s) of infection were determined by consensus by a clinician panel. FINDINGS: Of the 195 eligible cases, 186 were investigated. Case-patients were predominantly male (63%); median age was 57 years (range 0-92). In the two weeks prior to the BSI, 88% of case-patients had indwelling devices, 31% underwent a surgical procedure, and 18% underwent dialysis. The most common locations of attribution were intensive care units (ICUs) (46%) and step-down units (19%). The most commonly identified non-mutually exclusive clinical sources were CVCs (46%), non-surgical wounds (17%), surgical site infections (16%), non-ventilator healthcare-associated pneumonia (13%), and ventilator-associated pneumonia (11%). CONCLUSIONS: Device-and procedure-related infections were common sources of HO MRSA BSIs. Prevention strategies focused on improving adherence to existing prevention bundles for device-and procedure-associated infections and on source control for ICU patients, patients with certain indwelling devices, and patients undergoing certain high-risk surgeries are being pursued to decrease HO MRSA BSI burden at these facilities. |
Francisella tularensis transmission by solid organ transplantation, 2017
Nelson CA , Murua C , Jones JM , Mohler K , Zhang Y , Wiggins L , Kwit NA , Respicio-Kingry L , Kingry LC , Petersen JM , Brown J , Aslam S , Krafft M , Asad S , Dagher HN , Ham J , Medina-Garcia LH , Burns K , Kelley WE , Hinckley AF , Annambhotla P , Carifo K , Gonzalez A , Helsel E , Iser J , Johnson M , Fritz CL , Basavaraju SV . Emerg Infect Dis 2019 25 (4) 767-775 In July 2017, fever and sepsis developed in 3 recipients of solid organs (1 heart and 2 kidneys) from a common donor in the United States; 1 of the kidney recipients died. Tularemia was suspected only after blood cultures from the surviving kidney recipient grew Francisella species. The organ donor, a middle-aged man from the southwestern United States, had been hospitalized for acute alcohol withdrawal syndrome, pneumonia, and multiorgan failure. F. tularensis subsp. tularensis (clade A2) was cultured from archived spleen tissue from the donor and blood from both kidney recipients. Whole-genome multilocus sequence typing indicated that the isolated strains were indistinguishable. The heart recipient remained seronegative with negative blood cultures but had been receiving antimicrobial drugs for a medical device infection before transplant. Two lagomorph carcasses collected near the donor's residence were positive by PCR for F. tularensis subsp. tularensis (clade A2). This investigation documents F. tularensis transmission by solid organ transplantation. |
Public health importance of invasive methicillin-sensitive Staphylococcus aureus infections: Surveillance in 8 US counties, 2016
Jackson KA , Gokhale RH , Nadle J , Ray SM , Dumyati G , Schaffner W , Ham DC , Magill SS , Lynfield R , See I . Clin Infect Dis 2019 70 (6) 1021-1028 BACKGROUND: Public health and infection control prevention and surveillance efforts in the United States have primarily focused on methicillin-resistant Staphylococcus aureus (MRSA). We describe the public health importance of methicillin-susceptible S. aureus (MSSA) in selected communities. METHODS: We analyzed Emerging Infections Program surveillance data for invasive S. aureus (SA) infections (isolated from a normally sterile body site) in 8 counties in 5 states during 2016. Cases were considered healthcare-associated if culture was obtained >3 days after hospital admission; if associated with dialysis, hospitalization, surgery, or long-term care facility (LTCF) residence within 1 year prior; or if a central venous catheter was present </=2 days prior. Incidence per 100 000 census population was calculated, and a multivariate logistic regression model with random intercepts was used to compare MSSA risk factors with those of MRSA. RESULTS: Invasive MSSA incidence (31.3/100 000) was 1.8 times higher than MRSA (17.5/100 000). Persons with MSSA were more likely than those with MRSA to have no underlying medical conditions (adjusted odds ratio [aOR], 2.06; 95% confidence interval [CI], 1.26-3.39) and less likely to have prior hospitalization (aOR, 0.70; 95% CI, 0.60-0.82) or LTCF residence (aOR, 0.37; 95% CI, 0.29-0.47). MSSA accounted for 59.7% of healthcare-associated cases and 60.1% of deaths. CONCLUSIONS: Although MRSA tended to be more closely associated with healthcare exposures, invasive MSSA is a substantial public health problem in the areas studied. Public health and infection control prevention efforts should consider MSSA prevention in addition to MRSA. |
Evaluation of emissions and exposures at workplaces using desktop 3-dimensional printers
Stefaniak AB , Johnson AR , du Preez S , Hammond DR , Wells JR , Ham JE , LeBouf RF , Menchaca KW , Martin SBJr , Duling MG , Bowers LN , Knepp AK , Su FC , de Beer DJ , du Plessis JL . J Chem Health Saf 2019 26 (2) 19-30 There is a paucity of data on additive manufacturing process emissions and personal exposures in real-world workplaces. Hence, we evaluated atmospheres in four workplaces utilizing desktop "3-dimensional" (3-d) printers [fused filament fabrication (FFF) and sheer] for production, prototyping, or research. Airborne particle diameter and number concentration and total volatile organic compound concentrations were measured using real-time instruments. Airborne particles and volatile organic compounds were collected using time-integrated sampling techniques for off-line analysis. Personal exposures for metals and volatile organic compounds were measured in the breathing zone of operators. All 3-d printers that were monitored released ultrafine and fine particles and organic vapors into workplace air. Particle number-based emission rates (#/min) ranged from 9.4 times 109 to 4.4 times 1011 (n = 9 samples) for FFF 3-d printers and from 1.9 to 3.8 times 109 (n = 2 samples) for a sheer 3-d printer. The large variability in emission rate values reflected variability from the printers as well as differences in printer design, operating conditions, and feedstock materials among printers. A custom-built ventilated enclosure evaluated at one facility was capable of reducing particle number and total organic chemical concentrations by 99.7% and 53.2%, respectively. Carbonyl compounds were detected in room air; however, none were specifically attributed to the 3-d printing process. Personal exposure to metals (aluminum, iron) and 12 different organic chemicals were all below applicable NIOSH Recommended Exposure Limit values, but results are not reflective of all possible exposure scenarios. More research is needed to understand 3- d printer emissions, exposures, and efficacy of engineering controls in occupational settings. |
Notes from the Field: Verona integron-encoded metallo-beta-lactamase-producing carbapenem-resistant Pseudomonas aeruginosa infections in U.S. residents associated with invasive medical procedures in Mexico, 2015-2018
Kracalik I , Ham C , Smith AR , Vowles M , Kauber K , Zambrano M , Rodriguez G , Garner K , Chorbi K , Cassidy PM , McBee S , Stoney R , Brown AC , Moser K , Villarino ME , Walters MS . MMWR Morb Mortal Wkly Rep 2019 68 (20) 463-464 Verona integron-encoded metallo-β-lactamase–producing carbapenem-resistant Pseudomonas aeruginosa (VIM-CRPA) and other carbapenemase-producing organisms represent an emerging U.S. public health threat because of high levels of antibiotic resistance and the potential for rapid spread in health care facilities (1,2). During September 18–November 19, 2018, CDC received 31 reports of VIM-CRPA through the Antibiotic Resistance Laboratory Network. Six cases (19%) occurred in U.S. patients who had recently undergone invasive medical procedures in Mexico. To identify additional cases (defined as isolation of VIM-CRPA from a patient who had an invasive procedure in Mexico in the month preceding specimen collection), CDC and state partners posted an Epi-X alert on November 19, 2018, and issued notifications through the Emerging Infections Network and to medical professional societies. As of January 18, 2019, a total of 12 cases had been identified in seven states, including four in Utah, three in Washington, and one each in Arizona, Arkansas, Oregon, Texas, and West Virginia; specimen collection months ranged from November 2015 through December 2018 (Figure). |
Particle and vapor emissions from vat polymerization desktop-scale 3-dimensional printers
Stefaniak AB , Bowers LN , Knepp AK , Luxton TP , Peloquin DM , Baumann EJ , Ham JE , Wells JR , Johnson AR , LeBouf RF , Su FC , Martin SB , Virji MA . J Occup Environ Hyg 2019 16 (8) 1-13 Little is known about emissions and exposure potential from vat polymerization additive manufacturing, a process that uses light-activated polymerization of a resin to build an object. Five vat polymerization printers (three stereolithography (SLA) and two digital light processing (DLP) were evaluated individually in a 12.85 m(3) chamber. Aerosols (number, size) and total volatile organic compounds (TVOC) were measured using real-time monitors. Carbonyl vapors and particulate matter were collected for offline analysis using impingers and filters, respectively. During printing, particle emission yields (#/g printed) ranged from 1.3 +/- 0.3 to 2.8 +/- 2.6 x 10(8) (SLA printers) and from 3.3 +/- 1.5 to 9.2 +/- 3.0 x 10(8) (DLP printers). Yields for number of particles with sizes 5.6 to 560 nm (#/g printed) were 0.8 +/- 0.1 to 2.1 +/- 0.9 x 10(10) and from 1.1 +/- 0.3 to 4.0 +/- 1.2 x 10(10) for SLA and DLP printers, respectively. TVOC yield values (microg/g printed) ranged from 161 +/- 47 to 322 +/- 229 (SLA printers) and from 1281 +/- 313 to 1931 +/- 234 (DLP printers). Geometric mean mobility particle sizes were 41.1-45.1 nm for SLA printers and 15.3-28.8 nm for DLP printers. Mean particle and TVOC yields were statistically significantly higher and mean particle sizes were significantly smaller for DLP printers compared with SLA printers (p < 0.05). Energy dispersive X-ray analysis of individual particles qualitatively identified potential occupational carcinogens (chromium, nickel) as well as reactive metals implicated in generation of reactive oxygen species (iron, zinc). Lung deposition modeling indicates that about 15-37% of emitted particles would deposit in the pulmonary region (alveoli). Benzaldehyde (1.0-2.3 ppb) and acetone (0.7-18.0 ppb) were quantified in emissions from four of the printers and 4-oxopentanal (0.07 ppb) was detectable in the emissions from one printer. Vat polymerization printers emitted nanoscale particles that contained potential carcinogens, sensitizers, and reactive metals as well as carbonyl compound vapors. Differences in emissions between SLA and DLP printers indicate that the underlying technology is an important factor when considering exposure reduction strategies such as engineering controls. |
Evaluation of a rapid syphilis test in an emergency department setting in Detroit, Michigan
Fakile YF , Markowitz N , Zhu W , Mumby K , Dankerlui D , McCormick JK , Ham DC , Hopkins A , Manteuffel J , Sun Y , Huang YA , Peters PJ , Hoover KW . Sex Transm Dis 2019 46 (7) 429-433 BACKGROUND: Syphilis transmission can be prevented by prompt diagnosis and treatment of primary and secondary infection. We evaluated the performance of a point-of-care rapid syphilis treponemal test (RST) in an emergency department (ED) setting. METHODS: Between June 2015 and April 2016, men aged 18-34 years seeking services in a Detroit ED, and with no history of syphilis, were screened for syphilis with the RST, rapid plasma reagin (RPR) test, and Treponema pallidum particle agglutination assay (TP-PA). A positive reference standard was both a reactive RPR and a reactive TP-PA. We compared test results in self-reported MSM to non-MSM. RESULTS: Among 965 participants, 10.9% of RSTs were reactive in MSM and only 1.5% in non-MSM (p<0.001). Sensitivity of the RST was 76.9% and specificity was 99.0% (PPV 50.0%) compared to the positive reference standard. Three discordant specimens found negative with the RST but positive with the reference standard had an RPR titer of 1:1, compared with 10 specimens with concordant positive results that had a median RPR titer of 1:16. The RST sensitivity was 50.0% (PPV 68.4%) compared to the TP-PA test alone. Among men seeking care in an ED, the RST detected 76.9% of participants with a reactive RPR and TP-PA. CONCLUSIONS: The RST detected all of the participants with an RPR titer > 1:2 but less than 20% of participants with a positive TP-PA and negative RPR. The RST was useful to detect a high proportion of participants with an active syphilis in an urban ED.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. |
Vital Signs: Epidemiology and recent trends in methicillin-resistant and in methicillin-susceptible Staphylococcus aureus bloodstream infections - United States
Kourtis AP , Hatfield K , Baggs J , Mu Y , See I , Epson E , Nadle J , Kainer MA , Dumyati G , Petit S , Ray SM , Ham D , Capers C , Ewing H , Coffin N , McDonald LC , Jernigan J , Cardo D . MMWR Morb Mortal Wkly Rep 2019 68 (9) 214-219 INTRODUCTION: Staphylococcus aureus is one of the most common pathogens in health care facilities and in the community, and can cause invasive infections, sepsis, and death. Despite progress in preventing methicillin-resistant S. aureus (MRSA) infections in health care settings, assessment of the problem in both health care and community settings is needed. Further, the epidemiology of methicillin-susceptible S. aureus (MSSA) infections is not well described at the national level. METHODS: Data from the Emerging Infections Program (EIP) MRSA population surveillance (2005-2016) and from the Premier and Cerner Electronic Health Record databases (2012-2017) were analyzed to describe trends in incidence of hospital-onset and community-onset MRSA and MSSA bloodstream infections and to estimate the overall incidence of S. aureus bloodstream infections in the United States and associated in-hospital mortality. RESULTS: In 2017, an estimated 119,247 S. aureus bloodstream infections with 19,832 associated deaths occurred. During 2005-2012 rates of hospital-onset MRSA bloodstream infection decreased by 17.1% annually, but the decline slowed during 2013-2016. Community-onset MRSA declined less markedly (6.9% annually during 2005-2016), mostly related to declines in health care-associated infections. Hospital-onset MSSA has not significantly changed (p = 0.11), and community-onset MSSA infections have slightly increased (3.9% per year, p<0.0001) from 2012 to 2017. CONCLUSIONS AND IMPLICATIONS FOR PUBLIC HEALTH PRACTICE: Despite reductions in incidence of MRSA bloodstream infections since 2005, S. aureus infections account for significant morbidity and mortality in the United States. To reduce the incidence of these infections further, health care facilities should take steps to fully implement CDC recommendations for prevention of device- and procedure-associated infections and for interruption of transmission. New and novel prevention strategies are also needed. |
Insights into emissions and exposures from use of industrial-scale additive manufacturing machines
Stefaniak AB , Johnson AR , du Preez S , Hammond DR , Wells JR , Ham JE , LeBouf RF , Martin SB , Duling MG , Bowers LN , Knepp AK , de Beer DJ , du Plessis JL . Saf Health Work 2018 10 (2) 229-236 Background Emerging reports suggest the potential for adverse health effects from exposure to emissions from some additive manufacturing (AM) processes. There is a paucity of real-world data on emissions from AM machines in industrial workplaces and personal exposures among AM operators. Methods Airborne particle and organic chemical emissions and personal exposures were characterized using real-time and time-integrated sampling techniques in four manufacturing facilities using industrial-scale material extrusion and material jetting AM processes. Results Using a condensation nuclei counter, number-based particle emission rates (ERs) (number/min) from material extrusion AM machines ranged from 4.1 x 1010 (Ultem filament) to 2.2 x 1011 [acrylonitrile butadiene styrene and polycarbonate filaments). For these same machines, total volatile organic compound ERs (microg/min) ranged from 1.9 x 104 (acrylonitrile butadiene styrene and polycarbonate) to 9.4 x 104 (Ultem). For the material jetting machines, the number-based particle ER was higher when the lid was open (2.3 x 1010 number/min) than when the lid was closed (1.5-5.5 x 109 number/min); total volatile organic compound ERs were similar regardless of the lid position. Low levels of acetone, benzene, toluene, and m,p-xylene were common to both AM processes. Carbonyl compounds were detected; however, none were specifically attributed to the AM processes. Personal exposures to metals (aluminum and iron) and eight volatile organic compounds were all below National Institute for Occupational Safety and Health (NIOSH)-recommended exposure levels. Conclusion Industrial-scale AM machines using thermoplastics and resins released particles and organic vapors into workplace air. More research is needed to understand factors influencing real-world industrial-scale AM process emissions and exposures. |
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