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Considering patient room shortages and prevalence of other communicable diseases, reassessing the isolation of patients with Clostridioides difficile infection (CDI) is imperative. We conducted a retrospective study to investigate the secondary CDI transmission rate in a hospital in South Korea, where patients with CDI were not isolated. Using data from a real-time locating system and electronic medical records, we investigated patients who had both direct and indirect contact with CDI index patients. The primary outcome was secondary CDI transmission, identified by whole-genome sequencing. Among 909 direct and 2,711 indirect contact cases, 2 instances of secondary transmission were observed (2 [0.05%] of 3,620 cases), 1 transmission via direct contact and 1 via environmental sources. A low level of direct contact (113 minutes) was required for secondary CDI transmission. Our findings support the adoption of exhaustive standard preventive measures, including environmental decontamination, rather than contact isolation of CDI patients in nonoutbreak settings.

Objective: To determine the association between insufficient sleep in the prenatal period and postpartum depression (PPD), and whether changes in sleep patterns during pregnancy increase the risk of PPD., Methods: A prospective cohort study was conducted between March 2013 and November 2017. Participants completed a sleep questionnaire pre-pregnancy and at 12, 24 and 36 gestational weeks (GW). Depressive symptoms were assessed by the Edinburgh Postnatal Depression Scale (EPDS) at 4 weeks postpartum, and the cut-off score for PPD was 10 or more., Results: Of 2512 participants, 410 (16.3%) were identified as having PPD. Only insufficient sleep at 36 GW was significantly associated with PPD after adjusting for confounding factors (odds ratio 1.79, 95% confidence interval 1.40-2.27, P < 0.001). Both Group 1 (change from sufficient to insufficient) and Group 3 (sustained insufficient) demonstrated a significant risk of PPD at all starting time-points in the multivariate analysis, but no significant association was evident between Group 2 (change from insufficient to sufficient) and PPD., Conclusion: Insufficient sleep at 36 GW was associated with a significant risk of developing PPD. Additionally, regardless of whether women had sufficient sleep, a shift towards worsening sleep at 36 GW was highly associated with PPD., (© 2021 International Federation of Gynecology and Obstetrics.)

Background: All healthcare workers (HCWs) in Yongin Severance Hospital were allocated to receive the ChAdOx1 nCov-19 vaccine according to national policy. A report of thrombosis and thrombocytopenia syndrome (TTS) associated with ChAdOx1 nCoV-19 led to hesitancy about receiving the second dose among HCWs who had received the first dose., Methods: From 7 to 14 May, 2021, we performed a survey to identify the factors associated with hesitancy about receiving the second vaccine dose among HCWs at the hospital who had received the first dose of the vaccine. Based on survey results, a hospital-wide campaign was implemented on 18 May 2021 to improve vaccine coverage. HCWs who completed the second dose completed a self-administered questionnaire to evaluate the effect of the campaign., Findings: Of 1,171 HCWs who had received the first dose of the vaccine, 71.5% completed the online survey, of whom 3.7% refused to take the second dose and 22.3% showed hesitancy. Hesitancy to receive a second dose was significantly associated with age under 30 years and concerns about TTS, and was less common among those who trusted effectiveness and safety of the vaccine. Among HCWs who received the first dose, 96.2% completed vaccination with the second dose between 27 May and 4 June, 2021. Of those who answered the questionnaire asked about the timing of their decision to receive the second dose, 57.1% reported that they were motivated by the hospital-wide campaign., Conclusion: A tailored intervention strategy based on a survey can improve COVID-19 vaccination uptake among HCWs., Competing Interests: The authors have declared that no competing interests exist.

Acinetobacter baumannii is a highly potent nosocomial pathogen that is associated with increased in-hospital mortality. Here, we investigated the changes in molecular characteristics of carbapenem-resistant A. baumannii (CRAB) isolated from the blood samples of patients admitted to a tertiary hospital in South Korea from January 2009 to July 2015. Whole genome sequencing using the Illumina MiSeq platform and multi-locus sequence typing (MLST) were performed for 98 CRAB clinical isolates. In silico analyses for the prediction of antimicrobial resistance and virulence factor genes were performed. Plasmid sequences, including complete forms, were reconstructed from the sequence reads. Epidemiologic data were collected from the hospital database. MLST using the Oxford scheme revealed 10 sequence types of CRAB, of which ST191 was the dominant type (n = 59). Although blaOXA-23 was shared by most analysed strains, the compositions of antimicrobial resistance determinants differed among sequence types. ST447 and ST451/ST1809 with a few resistance genes were isolated during the later years of the study period. The number of virulence genes increased, while that of ST191 did not change significantly over the investigation period. Intriguingly MLST types, compositions of antimicrobial resistance genes, and virulence genes had no association with clinical outcomes of CRAB bacteraemia. In conclusion, active changes in or accumulations of antimicrobial resistance determinants and virulence genes in CRAB were not observed during the research period. Molecular characteristics of CRAB had no association with clinical outcomes of CRAB bacteraemia., Competing Interests: The authors have declared that no competing interests exist.

Objective: We present a method for comparing association networks in a matched case-control design, which provides a high-level comparison of co-occurrence patterns of features after adjusting for confounding factors. We demonstrate this approach by examining the differential distribution of chronic medical conditions in patients with major depressive disorder (MDD) compared to the distribution of these conditions in their matched controls., Materials and Methods: Newly diagnosed MDD patients were matched to controls based on their demographic characteristics, socioeconomic status, place of residence, and healthcare service utilization in the Korean National Health Insurance Service's National Sample Cohort. Differences in the networks of chronic medical conditions in newly diagnosed MDD cases treated with antidepressants, and their matched controls, were prioritized with a permutation test accounting for the false discovery rate. Sensitivity analyses for the associations between prioritized pairs of chronic medical conditions and new MDD diagnosis were performed with regression modeling., Results: By comparing the association networks of chronic medical conditions in newly diagnosed depression patients and their matched controls, five pairs of such conditions were prioritized among 105 possible pairs after controlling the false discovery rate at 5%. In sensitivity analyses using regression modeling, four out of the five prioritized pairs were statistically significant for the interaction terms., Conclusion: Association networks in a matched case-control design can provide a high-level comparison of comorbid features after adjusting for confounding factors, thereby supplementing traditional clinical study approaches. We demonstrate the differential co-occurrence pattern of chronic medical conditions in patients with MDD and prioritize the chronic conditions that have statistically significant interactions in regression models for depression., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objectives: Many studies have found evidence that aspirin has protective effects against certain cancers, but quantitative dose-response data have been available only on a limited basis. This study aimed to confirm the dose-response relationship of aspirin usage and gastric cancer and to estimate the cumulative dose threshold of aspirin to achieve protective effects against gastric cancer in the general population., Methods: A total of 461,489 individuals in a population-based longitudinal cohort provided by the National Health Insurance Services (NHIS) in the Republic of Korea were observed from 2007 to 2012 to identify gastric cancer incident cases. The pharmacy claims data of these individuals from 2002 to 2006 were reviewed to assess cumulative medication exposure using the defined daily dose (DDD) system. Hazard ratios (HRs) of aspirin use for gastric cancer were estimated using multivariate Cox Proportional Hazard regression. Sensitivity analyses, including propensity-score matching and a nested case-control design, were performed to evaluate the variability caused by study design., Results: A total of 5674 incident gastric cancers were identified from 2,965,500 person-years of follow-up observation, giving an overall incidence rate of 191.00 gastric cancers per 100,000 person-years. Compared to non-users, those with aspirin use of ≥3 DDD-years showed a statistically significant protective effect of aspirin use against gastric cancer; the adjusted HR (95% confidence intervals) were 0.79 (0.63-0.98) and 0.63 (0.48-0.83) for those with aspirin use of 3-4 DDD-years and 4-5 DDD-years, respectively (P for trend < 0.001). Sensitivity analyses using propensity-score matching and a nested case-control design consistently showed a chemopreventive effect of aspirin., Conclusion: Long-term aspirin use was associated with reduced gastric cancer incidence in the general population of South Korea when the cumulative dose was >3 DDD-years.

Less costly but still accurate methods for monitoring HIV treatment response are needed. We prospectively evaluated if a qualitative polymerase chain reaction (PCR) amplification assay for virologic monitoring could maintain accuracy while reducing costs in Seoul, South Korea. We conducted the first prospective study comparing a qualitative PCR amplification of HIV-1 reverse transcriptase (RT) versus a commercial real time PCR assay (i.e., viral load) for virologic monitoring of 150 patients receiving antiretroviral therapy (ART) between November 2011 and August 2012 at an urban hospital in Seoul, South Korea. A total of 215 blood plasma samples from 150 patients receiving ART for more than 6 months were evaluated. Using the individual viral load assay, 12 of 215 (5.6%) plasma samples had more than 500 HIV RNA copies/ml. The qualitative PCR amplification assay detected individual samples with ≥500 HIV RNA copies/ml with 100% sensitivity. The specificities of the qualitative PCR amplification of the HIV-1 RT assay were 94.1%, 93.6%, and 93.2% compared to the real time PCR at 500, 1,000, and 5,000 threshold of HIV RNA copies/ml, respectively, and $24,940 USD would have been saved for 150 patients during 10 months. The qualitative PCR amplification of the HIV-1 RT assay might be a useful approach to effectively monitor patients receiving ART and save resources.

Background: Carbapenem resistance among gram-negative bacilli is an emerging threat worldwide. The objective of this study was to identify risk factors for the acquisition of carbapenem-resistant Escherichia coli (CRE)., Methods: We conducted a matched case-control study comprising 57 cases of acquisition of CRE and 114 controls (1:2 matched) selected from patients with a culture of carbapenem-susceptible E coli between January 2006 and December 2010 at a 2000-bed tertiary care center in South Korea., Results: On univariate analysis, previous use of carbapenem (P < .01), fluoroquinolone (P < .01), and glycopeptide (P < .01), as well as length of hospital stay (P < .05), were significantly associated with CRE acquisition. On multivariate analysis, previous use of carbapenem (odds ratio [OR], 4.56; 95% confidence interval [CI] 1.44-14.46; P = .01) and previous use of fluoroquinolone (OR, 2.81; 95% CI, 1.14-6.99; P = .03) were independent risk factors., Conclusions: At this institute, the antibiotic selective pressure of carbapenems and fluoroquinolones was shown to be an important risk factor for the acquisition of CRE., (Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.)

Background: Multiple prevention measures have the possibility of impacting HIV incidence in South Korea, including early diagnosis, early treatment, and pre-exposure prophylaxis (PrEP). We investigated how each of these interventions could impact the local HIV epidemic, especially among men who have sex with men (MSM), who have become the major risk group in South Korea. A mathematical model was used to estimate the effects of each these interventions on the HIV epidemic in South Korea over the next 40 years, as compared to the current situation., Methods: We constructed a mathematical model of HIV infection among MSM in South Korea, dividing the MSM population into seven groups, and simulated the effects of early antiretroviral therapy (ART), early diagnosis, PrEP, and combination interventions on the incidence and prevalence of HIV infection, as compared to the current situation that would be expected without any new prevention measures., Results: Overall, the model suggested that the most effective prevention measure would be PrEP. Even though PrEP effectiveness could be lessened by increased unsafe sex behavior, PrEP use was still more beneficial than the current situation. In the model, early diagnosis of HIV infection was also effectively decreased HIV incidence. However, early ART did not show considerable effectiveness. As expected, it would be most effective if all interventions (PrEP, early diagnosis and early treatment) were implemented together., Conclusions: This model suggests that PrEP and early diagnosis could be a very effective way to reduce HIV incidence in South Korea among MSM.

Background: There have been various efforts to identify less costly but still accurate methods for monitoring the response to HIV treatment. We evaluated a pooling method to determine if this could improve screening efficiency and reduce costs while maintaining accuracy in Seoul, South Korea., Methods: We conducted the first prospective study of pooled nucleic acid testing (NAT) using a 5 minipool + algorithm strategy versus individual viral load testing for patients receiving antiretroviral therapy (ART) between November 2011 and August 2012 at an urban hospital in Seoul, South Korea. The viral load assay used has a lower level of detection of 20 HIV RNA copies/ml, and the cost per assay is US$ 136. The 5 minipool +algorithm strategy was applied and 43 pooled samples were evaluated. The relative efficiency and accuracy of the pooled NAT were compared with those of individual testing., Results: Using the individual viral load assay, 15 of 215 (7%) plasma samples had more than 200 HIV RNA copies/ml. The pooled NAT using the 5 minipool + algorithm strategy was applied to 43 pooled samples; 111 tests were needed to test all samples when virologic failure was defined at HIV RNA ≥ 200 copies/ml. Therefore, 104 tests were saved over individual testing, with a relative efficiency of 0.48. When evaluating costs, a total of US$ 14,144 was saved for 215 individual samples during 10 months. The negative predictive value was 99.5% for all samples with HIV RNA ≥ 200 copies/ml., Conclusions: The pooled NAT with 5 minipool + algorithm strategy seems to be a very promising approach to effectively monitor patients receiving ART and to save resources.

Gram-negative bacteremia is common in elderly patients and, compared with younger patients, mortality rates in bacteremic elderly patients are high. ESBL-producing organisms were one of the most important risk factors associated with mortality. In addition, older age is one of risk factors for colonization or infection with ESBL-producing organisms. We conducted a retrospective cohort study to evaluate risk factors of all-cause 28-day mortality in elderly patients with ESBL-producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) bacteremia. Patients aged 65 years or older, who had one or more blood cultures positive for E. coli and K. pneumoniae and who were hospitalized between January 2006 and December 2010 at a tertiary-care teaching hospital, were included. 191 bacteremic elderly patients were eligible for the study. The all-cause 28-day mortality rate was 24.6% (47/191). In multivariate analysis, prior antimicrobial therapy (p=0.014) and an elevated SOFA score (p<0.001) were independent risk factors for increased mortality, while urinary tract infection (UTI) was an independent determinant for non-mortality (p=0.011). In the current study, prior antimicrobial therapy within 30 days, an elevated SOFA score and nonurinary source of infection were significantly associated with adverse outcomes in elderly patients with ESBL-producing gram-negative bacteremia., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

The purpose of this study was to assess the prevalence and characteristics of HIV drug resistance mutations among antiretroviral therapy (ART)-naive and ART-experienced patients in South Korea. A total of 50 ART-naive and 34 ART-experienced Korean HIV-1-infected patients who visited an urban hospital from February 2007 to March 2011 were included. Most patients (86.9%) were infected with clade B HIV-1. Six (12%) ART-naive and 22 (64.7%) ART-experienced patients had HIV strains with resistance mutations. Among ART-naive patients, V179D was the most common mutation, being found in five ART-naive patients. Among ART-experienced patients, M184V was the most common mutation. Eight of 34 ART-experienced patients had thymidine analogue mutations (TAMs). The prevalence of drug-resistant HIV-1 in ART-naive patients was higher than in previous reports, and 50% of patients with virologic failure harbored strains with multiple resistance mutations. HIV drug resistance testing should be recommended to guide therapy of ART-naive patients in South Korea.

Background: The introduction of highly active antiretroviral therapy (HAART) has extended the life expectancy of persons infected with the human immunodeficiency virus type 1 (HIV-1). However, cardiovascular disease (CVD) is currently an increasing concern for HIV-infected persons., Methods: We conducted a cross-sectional case-control study to evaluate and compare the 10-y cardiovascular risk of HIV-infected Koreans who had been receiving HAART for over 6 months and age- and sex-matched uninfected persons who visited a health promotion center, by calculating Framingham risk scores (FRS)., Results: The average 10-y risk for cardiovascular events (FRS) was 7.07% (2-45) in the HIV group and 6.87% (1-37) in the control group (p = 0.77), corresponding to the very low risk group. Among HIV patients, the FRS was above 10% (low to moderate cardiovascular risk) in 19.9% of the patients, and above 20% (high risk) in 1.7% of the patients. In the healthy control group, the FRS was above 10% in 16.8% and above 20% in 2.7% (p = 0.57). The FRS was not significantly different for HIV-infected patients treated with protease inhibitor (PI)-based HAART and those treated with non-nucleoside reverse transcriptase inhibitor (NNRTI)-based HAART (7.26 ± 6.3 and 6.81 ± 4.4, respectively, p = 0.69)., Conclusions: The predicted cardiovascular risk of HIV-infected Koreans on HAART by FRS equation was low and similar to that of age- and sex-matched healthy control persons. However, the possibility remains that actual cardiovascular events could be underestimated. The next step for predicting the cardiovascular risk is to calculate the Data Collection of Adverse Events of Anti-HIV Drugs (D:A:D) equation risks.