Factors affecting work-related non-fatal injuries among aged workers in South Korea.

Introduction: The objective of this paper is to investigate whether an aging workforce is associated with an increase in work-related non-fatal injuries and to explore the underlying reasons for this potential increase. Methods: Aged workers were defined as those who were at least 55-years-old. Work-related non-fatal injuries were assessed in aged and young workers who were registered with the workers' compensation system from 2017 to 2021 of South Korea. Results: The mean estimated rate of work-related non-fatal injuries of aged workers (0.88/100) was about 2.5-times higher than that of younger workers (0.35/100). Most work-related non-fatal injuries in the older adults were in individuals working in the "construction sector" (36.0%), those with "elementary occupations (unskilled workers)" (45.0%), and those with employment status of "daily worker" (44.0%). "Trip & slip" (28.7%) and "falling" (19.6%) were more frequent types of work-related non-fatal injuries in aged workers relative to young workers. The category of "buildings, structures, and surfaces" was a more frequent cause of work-related non-fatal injuries in aged workers than young workers. Discussion: The incidence of non-fatal work-related injuries is higher among aged workers compared to their younger counterparts. The increased occurrence of aged workers participating in precarious employment and jobs, along with the greater physical vulnerability, is likely the cause of their higher rate of work-related non-fatal injuries.

Distribution of Extended-Spectrum-ß-Lactamase-Producing Diarrheagenic Escherichia coli Clonal Complex 10 Isolates from Patients with Diarrhea in the Republic of Korea.

ESBL-producing E. coli is a public health concern in healthcare settings and the community. Between 2009 and 2018, a total of 187 ESBL-producing pathogenic E. coli isolates were identified, and clonal complex (CC) 10 was the predominant clone (n = 57). This study aimed to characterize the ESBL-producing pathogenic E. coli CC10 strains obtained from patients with diarrhea to improve our understanding of CC10 distribution in the Republic of Korea. A total of 57 CC10 strains were selected for comprehensive molecular characterization, including serotype identification, the analysis of antibiotic resistance genes, the investigation of genetic environments, the determination of plasmid profiles, and the assessment of genetic correlations among CC10 strains. Among the CC10 isolates, the most prevalent serotype was O25:H16 (n = 21, 38.9%), followed by O6:H16 (10, 19.6%). The most dominant ESBL genes were blaCTX-M-15 (n = 31, 55%) and blaCTX-M-14 (n = 15, 27%). Most blaCTXM genes (n = 45, 82.5%) were located on plasmids, and these incompatibility groups were confirmed as IncB/O/K/Z, IncF, IncI1, and IncX1. The mobile elements located upstream and downstream mainly included ISEcp1 (complete or incomplete) and IS903 or orf477. Phylogenetic analysis showed that the CC10 strains were genetically diverse and spread among several distinct lineages. The results of this study show that ESBL-producing pathogenic E. coli CC10 has been consistently isolated, with CTX-M-15-producing E. coli O25:H16 isolates being the major type associated with the distribution of CC10 clones over the past decade. The identification of ESBL-producing pathogenic E. coli CC10 isolates underscores the possible emergence of resistant isolates with epidemic potential within this CC. As a result, continuous monitoring is essential to prevent the further dissemination of resistant ESBL-producing E. coli CC10 strains.

Multiparity increases the risk of diabetes by impairing the proliferative capacity of pancreatic ß cells.

Pregnancy imposes a substantial metabolic burden on women, but little is known about whether or how multiple pregnancies increase the risk of maternal postpartum diabetes. In this study, we assessed the metabolic impact of multiple pregnancies in humans and in a rodent model. Mice that underwent multiple pregnancies had increased adiposity, but their glucose tolerance was initially improved compared to those of age-matched virgin mice. Later, however, insulin resistance developed over time, but insulin secretory function and compensatory pancreatic ß cell proliferation were impaired in multiparous mice. The ß cells of multiparous mice exhibited aging features, including telomere shortening and increased expression of Cdkn2a. Single-cell RNA-seq analysis revealed that the ß cells of multiparous mice exhibited upregulation of stress-related pathways and downregulation of cellular respiration- and oxidative phosphorylation-related pathways. In humans, women who delivered more than three times were more obese, and their plasma glucose concentrations were elevated compared to women who had delivered three or fewer times, as assessed at 2 months postpartum. The disposition index, which is a measure of the insulin secretory function of ß cells, decreased when women with higher parity gained body weight after delivery. Taken together, our findings indicate that multiple pregnancies induce cellular stress and aging features in ß cells, which impair their proliferative capacity to compensate for insulin resistance.

Dissemination of the high-risk cloneST147 carbapenem-resistant klebsiella pneumoniae from a local tertiary care hospital in the Republic of Korea.

BACKGROUND: The emergence of carbapenem-resistant Enterobacterales (CRE) infections is rapidly increasing and represents a serious public threat. In 2020, a total of 16,883 carbapenemase-producing Enterobacterales strains were collected; among these isolates, 21 strains were repeatedly isolated in a local tertiary care hospital. METHODS: Antimicrobial susceptibility testing was performed using the broth microdilution method. All 21 strains of CRKP were analyzed by PFGE after XbaI digestion. The 21 CRKP strains were sequenced on the Illumina Miseq and Oxford Nanopore GridION platforms. RESULTS: These 21 CRKP isolates showed an identical antimicrobial resistance profile, including resistance to ampicillin, carbapenems, cephems, chloramphenicol, fluoroquinolone, macrolides and trimethoprim/sulfamethoxazole. Based on whole-genome analysis, these 21 CRKP isolates shared a common genetic structure (ISAba125-IS630-blaNDM-1-bleMBL) and harbored additional resistance determinants (blaOXA-1, blaCTX-M-15, blaSHV-11, blaSHV-67, aac(6')-Ib-cr, qnrS1, OqxA, OqxB, catB3, mph(A), sul1, and dfrA12) and mutations in the quinolone resistance-determining regions of gyrA (S83I) and parC (S80I). These isolates belonged to the ST147 and KL64 capsular types, which were carried on IncFIB replicon plasmids. The 21 CRKP strains collected from one hospital were divided into five PFGE patterns, and they were closely related with a minimum similarity value of 95.2%. These isolates were found to be highly related based on the presence of between 2 and 27 SNPs. CONCLUSIONS: These findings indicate that NDM-1-producing K. pneumoniae ST147 may have been introduced via a common source, implying nosocomial transmission; furthermore, continuous monitoring is necessary to prevent endemic transmission.

Decrease in Weekly Working Hours of Korean Workers From 2010 to 2020 According to Employment Status and Industrial Sector.

BACKGROUND: The present study examined changes in the working hours of Korean workers from 2010 to 2020 according to employment status and industrial sector. METHODS: This was a secondary analysis of data from the third (2010), fourth (2014), fifth (2017) and sixth (2020) Korean Working Conditions Surveys, which were conducted by the Korea Occupational Safety and Health Agency. RESULTS: During the past 10 years, workers classified as employees, self-employed, or employers experienced clear declines in average weekly working hours and in the percentages of individuals who worked more than 48 hours per week. During 2020, the largest proportion of employees (52.8%) had 40-hour work weeks, whereas the largest proportions of self-employed individuals (26.8%) and employers (25.1%) had very long work weeks (≥ 60 h/week). Also during 2020, individuals who were self-employed or employers in the sectors of 'Accommodation and food service' had the longest weekly work hours, whereas employees in the sector of 'Transportation' had the longest weekly work hours. All three groups (employees, self-employed, and employers) in all 21 industrial sectors experienced declines in average weekly working hours from 2017 to 2020. CONCLUSION: From 2010 to 2020, employees, self-employed individuals, and employers experienced clear declines in average weekly working hours, and in the percentages of individuals with long weekly working hours. However, there were also differences in the weekly working hours of those who had different employment status and who worked in different industrial sectors. The implementation of the 40-hour work-week and the 52-hour maximum work-week in Korea reduced excessive work hours by individuals who had different employment status and who worked in different industrial sectors, and probably improved worker quality-of-life. We recommend extension of these regulations to workplaces with fewer than 5 employees.

Synthesis and biological evaluation of tyrosine derivatives as peripheral 5HT2A receptor antagonists for nonalcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD), attributed to excessive fat accumulation in the liver, is reportedly prevalent worldwide. NAFLD is one of the leading causes of chronic liver disease, including non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatic cellular carcinoma (HCC). The peripheral roles of serotonin (5-hydroxytryptamine, 5HT) were found to regulate hepatic lipid metabolism. Among serotonin receptor subtypes, 5HT2A receptor is known to regulate hepatic lipid metabolism. Hepatic lipid accumulation and hepatic triglyceride (TG) were reduced in liver-specific 5HT2A receptor knockout (5HT2A receptor LKO) mice upon high-fat diet (HFD) feeding. In the present study, we explored a series of new peripherally acting 5HT2A receptor antagonists. Compound 14a displayed good in vitro activity, with an IC50 value of 0.17 nM. Compound 14a exhibited good microsomal stability, no significant CYP and hERG inhibition, and 5HT receptor subtype selectivity. The brain-to-plasma ratio of 14a was below the lower limit of quantification, indicating limited blood-brain barrier (BBB) penetration. HFD-fed 14a treated mice showed decreased liver steatosis and lobular inflammation. These results demonstrate the potential of newly synthesized peripheral 5HT2A receptor antagonists for treating NAFLD.

Cardiovascular age of workers with different employment categories.

INTRODUCTION: We compared the cardiovascular age (an indicator of cardiovascular disease risk) in workers with different employment status after adjustment for demographic and socioeconomic factors. METHODS: This cross-sectional study used data collected from 2007 to 2017 for the Korea National Health and Nutrition Examination Survey (KNHANES). Study participants were placed into different employment categories based on employment status and work schedule: regular full-time, regular part-time, temporary full-time, temporary part-time, daily full-time, and daily part-time. RESULTS: Analysis of women indicated that regular part-time, temporary full-time, temporary part-time, daily full-time, and daily part-time workers were more likely to have an older cardiovascular age (OR = 1.180, 1.238, 1.297, 1.493, and 1.408, respectively) after adjustment for age, marriage, education, income, residence, region, and drinking status. Analysis of men indicated employment status was unrelated to cardiovascular age. CONCLUSION: Female nonstandard Korean workers were more likely to have an increased cardiovascular age. However, most of these workers, especially daily workers, are not currently protected by the Occupational Safety and Health Act (OSHA) of Korea. Collaboration or networking with community-based health care services in Korea is essential to better manage the health of these vulnerable female workers.

Factors related to depressive symptoms in Korean self-employed workers.

BACKGROUND: We examined factors related to depressive symptoms in Korean self-employed workers. METHODS: This secondary analysis examined data of 14,454 self-employed individuals from the fifth Korean Working Conditions Survey (2017). Multiple logistic regression analysis was used to assess the relationship of depressive symptoms with different variables. RESULTS: Self-employed workers who had a good work-life balance, a good subjective health, and worked 40 to 48 hours or 48 to 60 hours/week were less likely to report depressive symptoms (all p < 0.05). However, those who always interacted with angry clients, had severe exposure to ergonomic risk factors, and were exposed to moderate or severe abusive behaviors were more likely to report depressive symptoms (all p < 0.05). Age, gender, weekly work days, and working at very fast speed were unrelated to depressive symptoms. CONCLUSIONS: Several factors known to be related to depressive symptoms do not lead to depression in self-employed individuals. Different interventions may therefore be needed to prevent depression in self-employed workers.

Dissemination of an international high-risk clone of Escherichia coli ST410 co-producing NDM-5 and OXA-181 carbapenemases in Seoul, Republic of Korea.

The rapid increase in carbapenemase-producing Enterobacterales is a global health concern. During 2017-2020, a total of 44 Escherichia coli isolates co-harbouring blaNDM-5 and blaOXA-181 were collected from patients at 17 hospitals in Seoul and characterized based on antimicrobial susceptibility, resistance genes and plasmid replicons detected using polymerase chain reaction (PCR). Clonal relatedness was estimated using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). All isolates had an identical multidrug resistance profile, including resistance to carbapenems, cephalosporins, ciprofloxacin, tetracycline, and trimethoprim/sulfamethoxazole, and susceptibility to amikacin, colistin, and tigecycline. Resistance genes (blaCTX-M-15, blaCMY-2, blaTEM-1B, blaOXA-1, aac(6')-Ib-cr, and qnrS) and plasmid replicons (IncFIA, IncFIB, and IncX3) was observed in almost all isolates. All isolates belonged to ST410 and were genetically similar (>88% similarity), with some PFGE types shared among isolates from different hospitals. Analysis of the whole genome revealed that the isolates clustered together with other strains of the international high-risk clone ST410 B4/H24RxC from other countries. These findings underline the ongoing spread of the high-risk clone of NDM-5- and OXA-181-producing E. coli ST410 B4/H24RxC among hospitals in Seoul. Continuous monitoring and implementation of infection control measures are crucial to track and prevent further spread of these resistant strains.

Association of weekly working hours with poor psychological well-being and moderation by employment status in Korean workers.

We examined the association of weekly working hours with poor psychological wellbeing in Korean workers and the moderating effect of employment status. This secondary analysis examined data from the fifth Korean Working Conditions Survey (2017). There were 30,108 waged employees and 14,459 self-employed individuals. The two groups were compared using a moderated regression model with Hayes' PROCESS macro for SPSS. The self-employed had a greater mean age than the waged employees. Higher percentages of the self-employed had short weekly working hours (<40), excessively long weekly working hours (≥60), and poor psychological well-being. After controlling for age, gender, education, monthly income, and occupational class, the interaction between weekly working hours and employment status on psychological well-being was significant (p<0.001). Among the self-employed, the well-being score was lowest in the short working hour group (<40 h/week), highest in the long working hour (48-59 h/week) groups, and intermediate in the excessively long working hours (≥60 h/week) group. For waged employees, psychological wellbeing was the greatest in the short working hour group and decreased continuously as the number of weekly working hours increased. In conclusion, employment status (employee vs. self-employed) moderated the relationship between weekly working hours and psychological well-being.

Factors that Affect Depression and Anxiety in Service and Sales Workers Who Interact With Angry Clients.

INTRODUCTION: We evaluated depression and anxiety in service and sales workers from Korea who interacted with angry clients to identify factors that mediated and moderated depression and anxiety in these workers. METHODS: This was a secondary analysis of data from the fifth Korean Working Conditions Survey conducted in 2017. A structural equation model was used for mediation and moderation analysis. RESULTS: Service and sales workers who had more interactions with angry clients had increased risk for depression and anxiety. Experiencing clients' adverse behaviors (acute episodes) mediated the relationship between interacting with angry clients (a chronic situation) on depression and anxiety. Job satisfaction and managers' support moderated the relationship between interacting with angry clients and mental health problems. CONCLUSION: We suggest that employers of service and sales workers should recruit staff based on their aptitude for such work, thus ensuring job satisfaction, and train them to deal with angry clients in such a way that they experience less emotional burden. Employers should also make bylaws requiring managers to directly take care of adverse social behavior by clients. Furthermore, a sociocultural campaign to prevent adverse social behavior by clients is also needed.

Factors related to psychological well-being in unskilled manual workers.

OBJECTIVES: The authors characterized the demographic, socioeconomic, and psychosocial work factors associated with performance of unskilled manual work, and then identified the modifiable psychosocial work factors that affected the psychological well-being of these workers. MATERIAL AND METHODS: This study analyzed data from the fifth Korean Working Condition Survey conducted in 2017. The study subjects were 37 081 Korean employees. The occupational classes investigated were: managers, professionals, and clerks; service and sales workers; and skilled or unskilled manual workers. RESULTS: Unskilled manual workers were more likely to be elderly and less educated, to have low income, to work fewer hours weekly, to have a shorter work duration, to perform temporary or daily jobs, and to report poor subjective health and well-being. Unskilled manual workers were also more likely to experience psychosocial hazards, such adverse social behaviors, a lack of job satisfaction, a lack of support from managers, and a poor social climate. However, with statistical adjustment for demographic, socioeconomic, and psychosocial work factors, unskilled manual work was no longer associated with poor psychological well-being, but psychosocial work factors were associated with poor psychological well-being. CONCLUSIONS: The poor psychological well-being of unskilled manual workers cannot be explained by the intrinsic nature of this type of work. Instead, the poor psychological well-being of these workers is associated with unfavorable psychosocial work factors, such as a poor employment status, a lack of job satisfaction, a lack of support from managers, and a bad social climate. These results thus suggest that the modification of psychosocial work factors may improve the psychological well-being of unskilled manual workers. Int J Occup Med Environ Health. 2021;34(6):789-804.

Emerging high-level ciprofloxacin-resistant Salmonella enterica serovar typhi haplotype H58 in travelers returning to the Republic of Korea from India.

In Korea, typhoid fever is a rare disease due to improved living standards. However, typhoid fever remains a major burden in developing countries and regions, such as India and Southeast Asia. In this study, we isolated Salmonella Typhi (S. Typhi) from eight patients with typhoid fever who were travelers returning from India. The strains isolated were characterized by antimicrobial susceptibility profiling and whole-genome sequencing (WGS) analysis. All strains were resistant to nalidixic acid and azithromycin. Among them, four isolates were highly resistant to ciprofloxacin (MIC ≥32 µg/ml); these strains have not been confirmed in Korea PulseNet DB. According to WGS, the ciprofloxacin-resistant strains belong to the global dominant multidrug-resistant (MDR) haplotype H58 (SNP glpA C1047T, SptP protein Q185* (premature stop codon)) and do not harbor the MDR plasmid. H58-associated SNPs in membrane and metabolism genes, including yhdA, yajI, hyaE, tryE, rlpB and metH, are present. Additionally, phylogenetic analysis assigned the H58 strains to sublineage II, whereas the non-H58 strains are closely related to haplotype H50. The presence of high-level ciprofloxacin-resistant S. Typhi haplotype H58 in Korea was first confirmed as due to influx from overseas via travelers. This study provides information about intercontinental drug-resistant transmission between countries and suggests that travelers need to be careful about personal hygiene.

Allergic rhinitis is associated with atmospheric SO2: Follow-up study of children from elementary schools in Ulsan, Korea.

OBJECTIVES: The purpose of this study was to examine the association of allergic rhinitis with air pollutant concentrations using the follow-up data of elementary school children in Ulsan, Korea. METHODS: All students of four elementary schools in Ulsan, South Korea were surveyed at two-year intervals. The survey used data collected five times, over a nine-year period from June 2009 to April 2018. The questionnaire used in the survey was a modified version of the ISAAC (International society of asthma and allergy of children) questionnaire. A skin prick test (SPT) was performed with 24 standard antigens. To estimate the levels of exposure to outdoor air pollution, the concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and particulate matter 10 µm or less in diameter (PM10) were used. As a dependent variable, a history of allergic rhinitis diagnosed by a doctor during the last 1-year was considered. Logistic regression analysis was used to select variables suitable for the statistical model. The selected variables were then used to assess their association with the dependent variable using the generalized estimation equation. RESULTS: Among environmental factors, SO2 was associated with a high risk and PM10 was associated with a low risk of allergic rhinitis. The risk of allergic rhinitis from living in a house built within the last year was high, and the risk from living in a multi-family house or apartment was higher than that from living in a segregated house. History of allergic diseases in the family was a high-risk factor for allergic rhinitis. There was a relationship between a history of bronchiolitis at less than 2 years of age and a high risk of allergic rhinitis. Boys were at a higher risk than girls. CONCLUSION: From the follow-up data of elementary school students in Ulsan, Korea, the concentration of SO2, which is an indicator of the degree of industrialization, was related to the prevalence of allergic rhinitis. Among all the risk factors, history of allergic disease in the parents was the most important factor, and the study reconfirmed the results of the previous studies.

Association of Participation in Health Check-ups with Risk Factors for Cardiovascular Diseases.

BACKGROUND: We compared the risk factors for cardiovascular diseases (CVDs) among Koreans who did and did not participate in national periodic health check-ups, after adjustment for demographic factors, socioeconomic status, and lifestyle factors. METHODS: This cross-sectional study used data from the Korea National Health and Nutrition Examination Survey (KNHANES) from 2007 to 2018. Study subjects were classified as participants or non-participants in health check-ups, based on attendance at national periodic health check-ups during the previous two years. RESULTS: Comparison of participants and non-participants in health check-ups indicated statistically significant differences in age, gender, region, education level, monthly income, employment status, obesity, smoking, alcohol consumption, exercise, and marital status. After adjustment for demographic, socioeconomic factors, and health-related behaviors, woman non-participants were more likely to have metabolic syndrome, pre-hypertension, hypertension, prediabetes, and diabetes, and man non-participants were more likely to have pre-diabetes and diabetes. CONCLUSION: Subjects who participated in periodic health check-ups had fewer CVD-related risk factors than non-participants. Thus, health care providers should encourage non-participants to attend periodic health check-ups so that appropriate interventions can be implemented and decrease the risk for CVDs in these individuals.

Factors Related to Psychological Well-Being as Moderated by Occupational Class in Korean Self-Employed Workers.

We examined factors related to the psychological well-being of self-employed workers in Korea, and the moderation of these effects by occupational class. This secondary analysis examined the data of 14,454 self-employed individuals from the fifth Korean Working Conditions Survey (2017). In all occupational classes, psychological well-being score was greater in women, and increased with monthly income and the frequency of working at very high speed; there were lower mean scores in those who became self-employed out of necessity rather than personal choice; in addition, the score decreased as the number of musculoskeletal symptoms increased. The relationship of work factors with the psychological well-being of self-employed individuals also differed according to occupational class. In conclusion, our analysis indicated that self-employed workers in different occupational classes respond differently to identical stressors.

Associations of Blood Heavy Metals with Uric Acid in the Korean General Population: Analysis of Data from the 2016-2017 Korean National Health and Nutrition Examination Survey.

We hypothesized that blood heavy metal levels such as lead, cadmium, and mercury were associated with uric acid level and hyperuricemia, and that this association remains significant after adjustment for other metals. We tested this hypothesis using the Korean National Health and Nutrition Examination Survey data. Beta coefficients and 95% confidence intervals (95% CIs) were calculated using multiple linear regression, and odds ratios (ORs) and 95% CIs were calculated using logistic regression in the cross-sectional study design. Relative to women, men had a higher geometric mean (GM) of lead (1.95 vs. 1.50 µg/dL) and mercury (3.94 vs. 2.77 µg/L), a lower GM of cadmium (0.80 vs. 1.04 µg/L), and a higher arithmetic mean (AM) of uric acid (5.84 vs. 4.40 mg/dL). Women had significant positive associations of log uric acid level with doubling of lead and mercury, and negative association with cadmium. Logistic regression analysis indicated the inverse association of serum hyperuricemia with doubling of blood metals was only significant for cadmium in women (OR = 0.641, 95% CI = 0.463 to 0.886) and the associations of serum hyperuricemia in the highest versus lowest quartiles of heavy metals were only significant for cadmium in women (OR = 0.495, 95% CI = 0.246 to 0.998). For both genders, age and estimated glomerular filtration rate (e-GFR) had negative associations with uric acid, but hypertension and triglycerides had positive associations with uric acid. In conclusion, blood lead and mercury levels were positively associated with uric acid level, but blood cadmium level was inversely associated with uric acid level and hyperuricemia in women.