Background: Mycoplasma pneumoniae is a major cause of community-acquired pneumonia (CAP) in children, with a rising incidence of macrolide resistance. Early diagnosis is crucial for reducing the disease burden; however, current diagnostic tools have limitations.We evaluated the diagnostic accuracy of serological assays and their performance based on symptom onset in children with CAP. Methods: From September 2023 to September 2024, we prospectively enrolled children with CAP, classified as M. pneumoniae pneumonia (MPP) or non-MPP, from 16 hospitals in Korea. Serological testing included chemiluminescence immunoassay (CLIA) and ELISA for detecting IgM and IgG, along with particle agglutination (PA) for total antibody measurements. Serological responses were analyzed at different times after symptom onset (0–4, 5–9, and 10–21 days). Results: Among 472 children with CAP (362 MPP, 110 non-MPP), 138 (29.2%) underwent PA testing, and 334 (70.8%) underwent IgM testing. PA at a 1:640 cutoff showed 48.0% sensitivity and 100% specificity. CLIA and ELISA showed comparable sensitivities (69.1% vs. 69.2%) and specificities (76.9% vs. 66.7%) for IgM testing. Seropositivity increased significantly with time since symptom onset (P for trend < 0.001), reaching 97.9% for IgM, 62.5% for IgG, and 94.7% for PA at 10–21 days. Conclusions The time post-symptom onset significantly influenced the diagnostic utility of serological tests for pediatric MPP, which showed limited value during the early stage of illness. These findings emphasize the importance of symptom onset-based interpretation of serological test results and their utility in complementing PCR when optimizing MPP diagnosis in children.

Background: There are no clear guidelines to determine whether to perform D1 or D1+ lymph node dissection in early gastric cancer (EGC). This study aimed to develop a nomogram for estimating the risk of extraperigastric lymph node metastasis (LNM). Materials and Methods: Between 2009 and 2019, a total of 4,482 patients with pathologically confirmed T1 disease at 6 affiliated hospitals were included in this study. The basic clinicopathological characteristics of the positive and negative extraperigastric LNM groups were compared. The possible risk factors were evaluated using univariate and multivariate analyses. Based on these results, a risk prediction model was developed. A nomogram predicting extraperigastric LNM was used for internal validation. Results: Multivariate analyses showed that tumor size (cut-off value 3.0 cm, odds ratio [OR]=1.886, P=0.030), tumor depth (OR=1.853 for tumors with sm2 and sm3 invasion, P=0.010), cross-sectional location (OR=0.490 for tumors located on the greater curvature, P=0.0303), differentiation (OR=0.584 for differentiated tumors, P=0.0070), and lymphovascular invasion (OR=11.125, P<0.001) are possible risk factors for extraperigastric LNM. An equation for estimating the risk of extraperigastric LNM was derived from these risk factors. The equation was internally validated by comparing the actual metastatic rate with the predicted rate, which showed good agreement. Conclusions A nomogram for estimating the risk of extraperigastric LNM in EGC was successfully developed. Although there are some limitations to applying this model because it was developed based on pathological data, it can be optimally adapted for patients who require curative gastrectomy after endoscopic submucosal dissection.

Purpose: We investigated the clinicopathological features and management for superficial nonampullary duodenal tumors (SNADTs). The safety and feasibility of laparoscopic management, especially laparoscopic endoscopic cooperative surgery (LECS), were evaluated. Methods: A total of 59 patients with SNADTs who underwent operations from January 2009 to December 2018 at all 8 institutions of the Catholic Medical Center were identified in our comprehensive multi-institutional database. Clinicopathological and surgical data on the 4 anatomical regions of the duodenum were collected and compared.Characteristics of laparoscopic procedure (laparoscopy-only) and LECS procedures were also compared. Results: There were significantly more asymptomatic patients with tumors in the first and second vs. third and fourth duodenal regions. Gastrointestinal stromal tumors (GISTs), carcinoids, and ectopic pancreatic tumors were identified in 32, 12, and 5 cases, respectively. Forty-two patients (71.2%) underwent laparoscopy. Of patients undergoing laparoscopy, the LECS group exhibited significantly more endophytic features and smaller tumor sizes (P < 0.001 and P < 0.001, respectively). Although no significant difference in the wedge resection or postoperative complication rate was seen between the 2 groups (P = 0.096 and P = 0.227, respectively), the wedge resection rate was higher, and the complication rate lower, in the LECS group than the conventional laparoscopic surgery group. Conclusion Most of the SNADTs located in proximal duodenum were detected incidentally. GISTs were the most common diagnoses of SNADTs in all locations. In treating these tumors, laparoscopic resection is safe and feasible. Especially, LECS may be ideal for treating small endophytic tumors, minimizing over-resection and postoperative complications.

Coronavirus disease 2019 (COVID-19) is usually less severe in children and adolescents than in adults. However, it can cause severe respiratory illness in a small proportion of children with risk factors. Here, we report a rare case of a 10-year-old boy with postinfectious bronchiolitis obliterans that developed after pneumonia caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This patient was previously healthy apart from a high body mass index (BMI, 30.13; 99.6th percentile for the age bracket), history of preterm birth (35 weeks), and low birth weight (1,850 g). He had persistent exertional dyspnea after recovering from SARS-CoV-2-related pneumonia. Spirometry revealed obstructive lung disease with the following results: predicted forced vital capacity (FVC% pred ), 71%; forced expiratory volume in 1 second (FEV 1 % pred ), 63%; FEV 1 /FVC, 0.81; and forced expiratory flow 25-75 % pred , 55%. Chest computed tomography showed multifocal areas of parenchymal hyperlucency and mosaic attenuation in both lungs. This case suggests that careful observation of children with obesity and low birth weight is necessary after recovery from SARS-CoV-2-related pneumonia.

Culture tests are very important in choosing the appropriate antibiotics for bacterial infections. In some cases, bacteria that could not be identified in standard culture bottles could be detected using blood culture bottles. A previously healthy 13-year-old boy visited our emergency room. He experienced pain, redness, and hardness of periumbilical skin and a fever for five days. There was no history of abdominal surgery and penetrating trauma.Computed tomography showed abscess with cellulitis at the periumbilical soft tissue with no congenital anomaly. Ultrasonography-guided aspiration was performed, and about 8.5 mL of the purulent abscess was aspirated. The abscess was cultured using blood culture bottle. The pus grew Actinomyces radingae and Clostridium ramosum. When performing the pus culture, using blood culture bottles can be more effective and rapid than the standard culture method for the detection of bacterial pathogens.

Culture tests are very important in choosing the appropriate antibiotics for bacterial infections. In some cases, bacteria that could not be identified in standard culture bottles could be detected using blood culture bottles. A previously healthy 13-year-old boy visited our emergency room. He experienced pain, redness, and hardness of periumbilical skin and a fever for five days. There was no history of abdominal surgery and penetrating trauma.Computed tomography showed abscess with cellulitis at the periumbilical soft tissue with no congenital anomaly. Ultrasonography-guided aspiration was performed, and about 8.5 mL of the purulent abscess was aspirated. The abscess was cultured using blood culture bottle. The pus grew Actinomyces radingae and Clostridium ramosum. When performing the pus culture, using blood culture bottles can be more effective and rapid than the standard culture method for the detection of bacterial pathogens.

Background: Coronavirus disease 2019 (COVID-19) vaccination is necessary to reach herd immunity and essential for mitigating the spread of the pandemic. In May 2021, the US FDA and the EU have expanded the emergency use authorization for a COVID-19 vaccine to children aged 12 to 15. The aim of this study was to investigate parental acceptability of COVID-19 vaccination for their children, factors affecting their acceptability, and children's perceptions of COVID-19 vaccines in Republic of Korea. Methods: We conducted a questionnaire survey at two tertiary hospitals from May 25, 2021 to June 3, 2021. Subjects were parents having children under 18 years and children aged 10–18 years. Results: Two hundred twenty-six parents and 117 children aged 10–18 years were included in the final analysis. Overall, 76.5% and 64.2% of parents intended to get vaccinated against COVID-19 and intended to have their children vaccinated, respectively. However, only 49.6% of children responded that they would get COVID-19 vaccination. In the multivariate analysis, high confidence in the safety of COVID-19 vaccines (adjusted odds ratio [AOR], 4.87; 95% confidence interval [CI], 1.32–24.12), parents' willingness to vaccinate themselves (AOR, 19.42; 95% CI, 6.85–64.00), and awareness of the need to vaccinate children against COVID-19 (AOR, 13.15; 95% CI, 4.77–41.27) were associated with positive factors intention to vaccinate their children. Conclusion This study provides insight into how parents think about the COVID-19 vaccine for their children in South Korea. Our findings could be referenced in establishing a policy for childhood COVID-19 vaccination in the future.

Background: Coronavirus disease 2019 (COVID-19) vaccination is necessary to reach herd immunity and essential for mitigating the spread of the pandemic. In May 2021, the US FDA and the EU have expanded the emergency use authorization for a COVID-19 vaccine to children aged 12 to 15. The aim of this study was to investigate parental acceptability of COVID-19 vaccination for their children, factors affecting their acceptability, and children's perceptions of COVID-19 vaccines in Republic of Korea. Methods: We conducted a questionnaire survey at two tertiary hospitals from May 25, 2021 to June 3, 2021. Subjects were parents having children under 18 years and children aged 10–18 years. Results: Two hundred twenty-six parents and 117 children aged 10–18 years were included in the final analysis. Overall, 76.5% and 64.2% of parents intended to get vaccinated against COVID-19 and intended to have their children vaccinated, respectively. However, only 49.6% of children responded that they would get COVID-19 vaccination. In the multivariate analysis, high confidence in the safety of COVID-19 vaccines (adjusted odds ratio [AOR], 4.87; 95% confidence interval [CI], 1.32–24.12), parents' willingness to vaccinate themselves (AOR, 19.42; 95% CI, 6.85–64.00), and awareness of the need to vaccinate children against COVID-19 (AOR, 13.15; 95% CI, 4.77–41.27) were associated with positive factors intention to vaccinate their children. Conclusion This study provides insight into how parents think about the COVID-19 vaccine for their children in South Korea. Our findings could be referenced in establishing a policy for childhood COVID-19 vaccination in the future.

Purpose: Human parvovirus B19 infection is widespread and has a heterogeneous clinical spectrum, ranging from asymptomatic infection to potentially life-threatening complications. We investigated the various clinical features of human parvovirus B19 infection during an outbreak of the virus in our community. Methods: A retrospective chart review study was conducted at the Pusan National University Children's Hospital from December 2017 to April 2019. We investigated the clinical features of children with parvovirus B19 immunoglobulin M or parvovirus B19 DNA detected using polymerase chain reaction. Results: A total of 24 children were diagnosed with parvovirus B19 infection. Twelve (50%) had lace form rashes, and four (16.7%) had petechial rashes. Two (8.3%) were diagnosed with fever without a focus. Six (25%) developed aplastic crisis as a complication of infection, of whom three were previously diagnosed with hereditary spherocytosis and three with acute lymphoblastic leukemia. Conclusions In addition to erythema infectiosum, the parvovirus B19 infection can present clinically with various types of rashes and fever without a focus. Furthermore, hematologic manifestations such as neutropenia and aplastic crisis can occur during infection.

Background: In February 2020, a coronavirus disease 2019 (COVID-19) outbreak was reported in fitness centers in Cheonan, Korea. Methods: From February 24 to March 13, an epidemiological investigation was conducted on the fitness center outbreak. All those who were screened were tested for severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) using real-time reverse transcriptase polymerase chain reaction. Contacts were traced and self-isolated for 14 days. We determined the epidemiological characteristics of confirmed cases of SARS-CoV-2 infection, and estimated the time-dependent reproduction number to assess the transmission dynamics of the infection. Results: A total of 116 cases were confirmed, and 1,687 contacts were traced. The source cases were 8 Zumba instructors who led aerobics classes in 10 fitness centers, and had the largest average number of contacts. A total of 57 Zumba class participants, 37 of their family members, and 14 other contacts were confirmed as cases. The attack rate was 7.3%. The contacts at Zumba classes and homes had a higher attack rate than other contacts. The mean serial interval (± standard deviation) were estimated to be 5.2 (± 3.8) days. The time-dependent reproduction number was estimated to be 6.1 at the beginning of the outbreak, but it dropped to less than 1, 2 days after the epidemiological investigation was launched. Conclusion The results suggest that the COVID-19 outbreak was effectively contained with rigorous contact tracing, isolating, and testing in combination with social distancing without a lock-down.