• Pediatric Infection and Vaccine
• /
• v.31 no.1
• /
• pp.94-101
• /
• 2024

Purpose: Coronavirus disease 2019 (COVID-19) has posed a significant burden to infant and toddler's care globally, while the disease severity is generally mild in this age group. In this study, we aimed to assess epidemiological and clinical aspects of COVID-19 in infants and toddlers in Seoul, South Korea. Methods: We used Seoul Metropolitan Government's epidemiological investigation database to describe the epidemiological and clinical characteristics of COVID-19 in infants and toddlers, between March 2020 to December 2021. Results: A total of 5,025 infants and toddlers aged <5 years was diagnosed between the observed period. 2,720 (54.1%) had symptoms, and fever was the most common symptom in 1,941 (74.1%). Of the diagnosed cases, 96.4% did not have underlying diseases. In a district level, extended opening of childcare facility was associated with increased risk of COVID-19 in infants and toddlers. Conclusions: An efficient monitoring system, resembling routine clinical care, is crucial, considering the low rates of severe progression and fatality among infants and toddlers. Moreover, a well-grounded intervention based on scientific evidence, rather than unconditional closures, is necessary to establish a suitable childcare policy that ensures safety from infectious diseases while not overlooking the developmental aspects of social skills.

• Pediatric Infection and Vaccine
• /
• v.31 no.1
• /
• pp.46-54
• /
• 2024

Purpose: This study aimed to identify the pathogens of bloodstream infection in children with underlying hemato-oncologic diseases, analyze susceptibility patterns, compare temporal trends with those of previous studies, and assess empirical antimicrobial therapy. Methods: Retrospective review study of children bacteremia in hemato-oncologic diseases was conducted at Seoul National University Bundang Hospital from January 2013 to July 2023. Results: Overall, 98 episodes of bacteremia were observed in 74 patients. Among pathogens isolated, 57.1% (n=56) were Gram-positive bacteria, 38.8% (n=38) were Gram-negative bacteria, and 4.1% (n=4) were Candida spp. The most common Gram-positive bacteria were coagulase-negative staphylococci (n=21, 21.4%) and Staphylococcus aureus, (n=14, 14.3%) whereas the most common Gram-negative bacteria were Klebsiella pneumoniae (n=16, 16.3%) and Escherichia coli (n=10, 10.2%). The susceptibility of Gram-positive bacteria to penicillin, oxacillin, and vancomycin was 11.5%, 32.7%, and 94.2%, respectively and the susceptibility of Gram-negative bacteria to cefotaxime, piperacillin/tazobactam, imipenem, gentamicin, and amikacin was 68.6%, 80%, 97.1%, 82.9%, and 91.4%, respectively. Methicillin-resistant S. aureus was detected in 1 strain and among Gram-negative strains, extended spectrum β-lactamase accounted for 28.9% (12/38). When analyzing the antibiotic susceptibility and empirical antibiotics, the mismatch rate was 25.5% (n=25). The mortality rate of children within 30 days of bacteremia was 7.1% (n=7). Conclusions: Empirical antibiotic therapy for bacteremia in children with hemato-oncologic diseases should be based on the local antibiogram in each institution and continuous monitoring is necessary.

• Korean Journal of Radiology
• /
• v.25 no.5
• /
• pp.481-492
• /
• 2024

Objective: To evaluate the clinical and imaging characteristics of SARS-CoV-2 breakthrough infection in hospitalized immunocompromised patients in comparison with immunocompetent patients. Materials and Methods: This retrospective study analyzed consecutive adult patients hospitalized for COVID-19 who received at least one dose of the SARS-CoV-2 vaccine at two academic medical centers between June 2021 and December 2022. Immunocompromised patients (with active solid organ cancer, active hematologic cancer, active immune-mediated inflammatory disease, status post solid organ transplantation, or acquired immune deficiency syndrome) were compared with immunocompetent patients. Multivariable logistic regression analysis was performed to evaluate the effect of immune status on severe clinical outcomes (in-hospital death, mechanical ventilation, or intensive care unit admission), severe radiologic pneumonia (≥ 25% of lung involvement), and typical CT pneumonia. Results: Of 2218 patients (mean age, 69.5 ± 16.1 years), 274 (12.4%), and 1944 (87.6%) were immunocompromised an immunocompetent, respectively. Patients with active solid organ cancer and patients status post solid organ transplantation had significantly higher risks for severe clinical outcomes (adjusted odds ratio = 1.58 [95% confidence interval {CI}, 1.01-2.47], P = 0.042; and 3.12 [95% CI, 1.47-6.60], P = 0.003, respectively). Patient status post solid organ transplantation and patients with active hematologic cancer were associated with increased risks for severe pneumonia based on chest radiographs (2.96 [95% CI, 1.54-5.67], P = 0.001; and 2.87 [95% CI, 1.50-5.49], P = 0.001, respectively) and for typical CT pneumonia (9.03 [95% CI, 2.49-32.66], P < 0.001; and 4.18 [95% CI, 1.70-10.25], P = 0.002, respectively). Conclusion: Immunocompromised patients with COVID-19 breakthrough infection showed an increased risk of severe clinical outcome, severe pneumonia based on chest radiographs, and typical CT pneumonia. In particular, patients status post solid organ transplantation was specifically found to be associated with a higher risk of all three outcomes than hospitalized immunocompetent patients.

• IMMUNE NETWORK
• /
• v.21 no.2
• /
• pp.14.1-14.17
• /
• 2021

Scrub typhus develops after the individual is bitten by a trombiculid mite infected with Orientia tsutsugamushi. Since it has been reported that pneumonia is frequently observed in patients with scrub typhus, we investigated whether intranasal (i.n.) vaccination with the outer membrane protein of O. tsutsugamushi (OMPOT) would induce a protective immunity against O. tsutsugamushi infection. It was particular interest that when mice were infected with O. tsutsugamushi, the bacteria disseminated into the lungs, causing pneumonia. The i.n. vaccination with OMPOT induced IgG responses in serum and bronchoalveolar lavage (BAL) fluid. The anti-O. tsutsugamushi IgA Abs in BAL fluid after the vaccination showed a high correlation of the protection against O. tsutsugamushi. The vaccination induced strong Ag-specific Th1 and Th17 responses in the both spleen and lungs. In conclusion, the current study demonstrated that i.n. vaccination with OMPOT elicited protective immunity against scrub typhus in mouse with O. tsutsugamushi infection causing subsequent pneumonia.

• IMMUNE NETWORK
• /
• v.21 no.5
• /
• pp.33.1-33.19
• /
• 2021

IL-1β plays critical roles in the priming and effector phases of immune responses such as the differentiation, commitment, and memory formation of T cells. In this context, several reports have suggested that the IL-1β signal is crucial for CTL-mediated immune responses to viral infections and tumors. However, little is known regarding whether IL-1β acts directly on CD8⁺ T cells and what the molecular mechanisms underlying expression of IL-1 receptors (IL-1Rs) on CD8⁺ T cells and features of IL-1R⁺ CD8⁺ T cells are. Here, we provide evidence that the expression of IL-1R type I (IL-1RI), the functional receptor of IL-1β, is preferentially induced by IL-21 on TCR-stimulated CD8⁺ T cells. Further, IL-1β enhances the effector function of CD8⁺ T cells expressing IL-21-induced IL-1RI by increasing cytokine production and release of cytotoxic granules containing granzyme B. The IL-21-IL-1RI-IL-1β axis is involved in an augmented effector function through regulation of transcription factors BATF, Blimp-1, and IRF4. Moreover, this axis confers a unique effector function to CD8⁺ T cells compared to conventional type 1 cytotoxic T cells differentiated with IL-12. Chemical inhibitor and immunoprecipitation assay demonstrated that IL-21 induces a unique pattern of STAT activation with the formation of both STAT1:STAT3 and STAT3:STAT5 heterodimers, which are critical for the induction of IL-1RI on TCR-stimulated CD8⁺ T cells. Taken together, we propose that induction of a novel subset of IL-1RI-expressing CD8⁺ T cells by IL-21 may be beneficial to the protective immune response against viral infections and is therefore important to consider for vaccine design.

• Pediatric Infection and Vaccine
• /
• v.30 no.3
• /
• pp.139-144
• /
• 2023

Purpose: Children with incomplete Kawasaki disease (KD) and pyuria may be misdiagnosed with urinary tract infection (UTI) during the early phase of the prodrome. We investigated the percentage of UTI diagnoses preceding a KD diagnosis. Methods: Using the National Health Insurance data of South Korea, we assessed differences in UTI diagnoses made during the week preceding a KD diagnosis, according to demographic and geographic factors from November 2007-October 2019. Results: A total of 53,822 KD cases were identified, including 304 patients (0.56%) diagnosed with a UTI during the week preceding a KD diagnosis. The younger age group (0-11 months) showed the highest percentage of preceding UTI diagnoses (0.95%), with higher odds than 4-year-old children (3.12; 95% confidence interval, 2.05-4.77). Conclusions: These findings suggest a potentially misleading presentation of incomplete KD, a clinical conundrum requiring further investigation and validation, particularly in infants.

• Pediatric Infection and Vaccine
• /
• v.30 no.3
• /
• pp.152-158
• /
• 2023

Staphylococcus aureus (SA) is a common cause of skin and soft tissue infections. Panton-Valentine leukocidin (PVL) toxin-producing strain of SA has been discovered worldwide and is known to cause serious infections. However, reports of neonatal infections caused by PVL-positive SA are rare. Here, we report a case of severe skin and soft tissue infection caused by PVL-positive SA in a 7-day-old neonate. The patient was admitted to the emergency room with a history of fever for one day, tenderness, and sensation of buttocks heating. The infant presented with fever, tachycardia, poor general health, progressive tenderness, and edema of the buttocks on the day of admission. Ultrasonography and magnetic resonance imaging revealed necrotizing fasciitis involving the skin, soft tissue, and muscles. Specimens drained from the buttock lesions confirmed the presence of PVL-positive methicillin-resistant SA (MRSA), and there was no bacteremia. She recovered after one month of intravenous antibiotics and surgical drainages. One month after discharge, she was rehospitalized for otitis externa and was infected with MRSA again. Considering the PVL-positive strain, the patient was treated with intravenous linezolid and dressing. The patient underwent decolonization therapy in a 0.5% chlorhexidine bath and recovered completely without sequelae. This case suggests that aggressive drainage and antibiotic treatment are essential for PVL-producing MRSA infections, and additional decolonization is needed to prevent recurrence and community spread.

• Annals of Occupational and Environmental Medicine
• /
• v.34
• /
• pp.3.1-3.12
• /
• 2022

Background: Influenza illness causes several disruptions to the workforce. The absenteeism that often ensues has economic implications for employers. This study aimed to estimate the cost-benefit of influenza vaccination in a healthcare setting from the employer's perspective. Methods: A cross-sectional questionnaire survey was conducted in a private hospital in 2018-2019 comparing voluntary vaccinated with non-vaccinated employees with influenza vaccine. The analyses were made based on self-reporting on absenteeism and presenteeism from Influenza-like illnesses (ILIs). The costs incurred, both direct and indirect costs, were included in the study. A cost-benefit analysis was performed by measuring the cost of the vaccination program. The costs of absenteeism and reduced productivity were calculated using 3 hypothesised levels of effectiveness in the following percentage of productivity of 30%, 50%, and 70%. The costs were also calculated based on four scenarios: with and without operating income and with and without replacement. The benefits of the influenza vaccination from the employer's perspective were analysed. The benefit to cost ratio was determined. Results: A total of four hundred and twenty-one respondents participated. The influenza vaccination rate was 63.0%. The rate of ILI of 38.1% was significantly lower among vaccinated. The ILI-related absenteeism reported was also significantly lower amongst vaccinated employees at 30% compared to 70% non-vaccinated. Employers could save up to USD 18.95 per vaccinated employee when only labour cost was included or 54.0% of cost savings. The cost-saving rose to USD 155.56 when the operating income per employee was also included. The benefit to cost ratio confirmed that the net cost-benefit gained from the vaccination was more than the net cost of vaccination. Conclusions: Influenza vaccination for working adults was cost-saving and cost-beneficial when translated into financial investments for the employer. A workplace vaccination demonstrates a significant cost-benefit strategy to be applied in any institutional setting.

• Korean Journal of Veterinary Research
• /
• v.35 no.2
• /
• pp.337-345
• /
• 1995

To evaluate the pathogenicity and immunogenicity of Eimeria tenella to the chicken treated with dexamethasone(DEX) and testosterone propionate (TES), we administered 0.1ml/chicken of dexamethasone and 40mg/chicken of testosterone propionate at 1-, 2-, and 7-days old, respectively. We also immunized with ND oil-emulsion vaccine at 2 weeks old. After that, we immunized and challenged with 100 and $1{\times}10^5$ oocysts/chicken of E tenella at 2 and 4 weeks old, respectively. And then we investigated the HI titers for ND virus, survival rate, body weight gain, lesion score and the weight of the bursa of Fabricius and thymus. The titers for ND virus in the groups treated with TES were higher than those in the groups treated with DEX and CON during 3 to 6 weeks. After challenge, the survival rate of testosterone propionate treated-challenged(TES-CHA) and TES-immunized and challenged(TES-V&C) groups were 61.5 and 83.3% and those of the other groups were all 100%. At 1 week after challenge, the lesion scores of TES-CHA group(4.0) was the highest of all experimental groups. Those of DEX and controlchallenged( CON-CHA) groups were 2.8, and those of all V&C groups were 2.4. During 1 and 2 weeks after immunization, the body weight gains of TES groups were severe low(61.6-82.2g and 189.6-260.4g). During 1 and 2 weeks after challenge, the body weight gains of all CHA groups were lower than those of not challenged groups. But, those of all V AC groups were not different from those of not immunized groups. At 4- and 6-weeks old, the weight of the bursa of Fabricius and thymus in the chicken of all TES groups were lower than those of all control (CON) and DEX groups. Therefore, testosterone propionate acted as immunosuppressive drug. Also, it was thought that the chicken affected a little humoral immunity to E tenella.

• Pediatric Infection and Vaccine
• /
• v.6 no.2
• /
• pp.210-218
• /
• 1999

Purpose : As several epidemics of aseptic meningitis had been reported in Korea since 1990, the need of epidemiologic study about enteroviral infections was recognized. We studied epidemiologic and clinical features of enteroviral infections in children. Methods : We analyzed the seasonal occurrence of enteroviral infections and age, sex and clinical diagnosis of the children admitted to five branch hospitals of Hallym University and diagnosed to have enteroviral infections by culture from January 1996 to December 1998. Results : Enterovirus was isolated in 126 out of 245(51.4%) stools, 15 out of 89(16.8%) nasopharyngeal aspirates and 195 out of 1,835(10.6%) cerebrospinal fluids. There were 273 echoviruses(Echo)(197 Echo 30, 46 Echo 9, 17 Echo 6, 13 unclassified), 24 coxsackieviruses B(CB)(11 CB 2, 2 CB 5, 11 unclassified), 7 coxsackieviruses A 24 and 32 unclassified enteroviruses. Yearly number of isolates was 65(46 Echo 9) in 1996, 239(197 Echo 30) in 1997 and 32(15 CB: 9 CB 2) in 1998. Epidemics of enteroviruses occurred mainly during the months May to October. The mean age of the infected children was $62.1{\pm}38.0$ months and 74.6% of the patients were younger than 7 years of age. There were 203 boys and 100 girls and 79.3% of the patients were diagnosed as aseptic meningitis. Conclusions : We confirmed that enteroviral infections occurred in epidemics from late spring to fall during the study period. Enteroviral infections occurred predominantly in boys and the preschool children. Aseptic meningitis was the main illness in the hospitalized children.