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The proportion of pediatric cases with severe acute hepatitis of unknown etiology in the coronavirus disease 2019 era was higher than that in the pre-coronavirus disease 2019 era in Japan’s largest pediatric transplant center. Further research and monitoring are essential.

Information regarding effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant strains on clinical manifestations and outcomes of coronavirus disease 2019 (COVID-19) in pregnant women is limited.A retrospective observational study was conducted using the data from the nationwide COVID-19 registry in Japan. We identified pregnant patients with symptomatic COVID-19 hospitalized during the study period. The Delta and Omicron variants of concern (VOC) predominant periods were defined as August 1 to December 31, 2021 and January 1 to May 31, 2022, respectively. Clinical characteristics were compared between the patients in the Delta and Omicron VOC periods. In addition, logistic regression analysis was performed to identify risk factors for developing moderate-to-severe COVID-19.During the study period, 310 symptomatic COVID-19 cases of pregnant women were identified; 111 and 199 patients were hospitalized during the Delta and Omicron VOC periods, respectively. Runny nose and sore throat were more common, and fatigue, dysgeusia, and olfactory dysfunction were less common manifestations observed in the Omicron VOC period. In the multivariable logistic regression analysis, onset during the later stage of pregnancy (OR: 2.08 [1.24-3.71]) and onset during the Delta VOC period (OR: 2.25 [1.08-4.90]) were independently associated with moderate-to-severe COVID-19, whereas two doses of SARS-CoV-2 vaccine were protective against developing moderate-to-severe COVID-19 (OR: 0.34 [0.13-0.84]).Clinical manifestations of COVID-19 in pregnant women differed between the Delta and Omicron VOC periods. SARS-CoV-2 vaccination was still effective in preventing severe COVID-19 throughout the Delta and Omicron VOC periods.

Information regarding the clinical manifestations and outcomes of coronavirus disease 2019 (COVID-19) in children under the Omicron variant predominant period is still limited.A nationwide retrospective cohort study was conducted. Pediatric COVID-19 patients (18 years of age) hospitalized between August 1, 2021 and March 31, 2022 were enrolled. Epidemiological and clinical characteristics between the Delta variant predominant period (August 1 to December 31, 2021) and the Omicron variant predominant period (January 1 to March 31, 2022) were compared.During the study period, 458 cases in the Delta predominant period and 389 cases in the Omicron predominant period were identified. Median age was younger (6.0 vs. 8.0 years, P = 0.004) and underlying diseases were more common (n = 65, 16.7% vs. n = 53, 11.6%) in the Omicron predominant period than those in the Delta variant predominant era. For clinical manifestations, fever ≥38.0 °C at 2 to13 years old, sore throat at ≥ 13 years, and seizures at 2 to13 years old were more commonly observed, and dysgeusia and olfactory dysfunction at ≥ 6 years old were less commonly observed in the Omicron variant predominant period. The number of patients requiring noninvasive oxygen support was higher in the Omicron predominant period than that in the Delta predominant period; however, intensive care unit admission rates were similar and no patients died in both periods.In the Omicron variant predominant period, more pediatric COVID-19 patients experienced fever and seizures, although the overall outcomes were still favorable.

As there are no large-scale reports of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) mRNA vaccination in patients with nephrotic syndrome using immunosuppressive agents, we conducted the prospective study.SARS-CoV-2 mRNA vaccines were administered to patients with nephrotic syndrome receiving immunosuppressive agents. The titers of SARS-CoV-2 spike protein receptor-binding domain antibodies were measured before and after vaccination. We evaluated factors associated with antibody titers after vaccination and analyzed adverse events.We enrolled 40 patients and evaluated vaccine immunogenicity in 35 of them. Seroconversion ( 0.8 U/mL) was achieved in all patients, and the median antibody titer was 598 U/mL (interquartile range, 89-1380 U/mL). Patients using mycophenolate mofetil (MMF) showed lower antibody titers than those who were not (median: 272 U/mL vs. 2660 U/mL, p = 0.0002), and serum immunoglobulin G (IgG) levels showed a weak linear relationship with antibody titers (RThe SARS-CoV-2 mRNA vaccine was immunogenic in patients with nephrotic syndrome using immunosuppressive agents, although the use of MMF and low levels of serum IgG were associated with lower antibody titers after vaccination. Patients with high disease activity may experience a relapse of nephrotic syndrome after vaccination. A higher resolution version of the Graphical abstract is available as Supplementary information.

A neonatal patient with Herpes simplex virus type-2 meningoencephalitis was treated by high-dose intravenous acyclovir therapy. Serum and cerebrospinal fluid (CSF) concentrations were measured retrospectively, showing that the CSF-to-serum concentration ratio was 0.67-0.71, which was higher than the previously reported values in other age groups.

We describe a domestic case of retropharyngeal abscess (RPA) in a child caused by a community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolate that was genetically proven to be the USA300 clone (sequence type [ST]8-SCCmec IVa-Panton-Valentine leukocidin [PVL]). USA300 generally has a PVL gene, an epidemiologic association with severe and recurrent skin and soft tissue infection, and is the leading cause of RPA in the United States. A 1-year-old previously healthy girl visited the emergency department with fever, sore throat, and a difficulty in moving her neck. The patient had no recent medical exposure or history of travel abroad. Enhanced computed tomography revealed a bulky low-density area with ring enhancement in the retropharyngeal and right parapharyngeal spaces. MRSA was isolated from pus obtained from surgical drainage, and antibiotics were continued for a total of 21 days. MRSA was analyzed by whole genome sequencing and compared with representative USA300 isolates. The strain was typed as ST8-t9829-SCCmec IVa with PVL and arginine catabolic mobile element, and its sequence was 99.8% identical to USA300 isolates. The present case supports the possibility that USA300 is potentially spreading in the Japanese community and raises the possibility of USA300 invasive infections without a clear route of infection.

Background Several reports have suggested that routine use of anaerobic blood culture bottles together with aerobic bottles may improve blood culture positivity. However, the information is still limited regarding the utility of anaerobic blood culture bottles in the pediatric intensive care unit, where bacteremia due to anaerobic bacteria is relatively rare. Methods A retrospective observational study was conducted at a pediatric intensive care unit in a tertiary children’s hospital in Japan from May 2016 to January 2020. Patients aged ≤ 15 years old with bacteremia, for which both aerobic and anaerobic blood cultures were submitted, were included in the study. We investigated whether the positive blood culture cases were from aerobic or anaerobic bottles. We also compared the amount of blood inoculated into culture bottles to determine the effect of blood volume on the rate of detection. Results During the study period, a total of 276 positive blood cultures from 67 patients were included in this study. Among the paired blood culture bottles, 22.1% were positive only for the anaerobic bottles. Escherichia coli and Enterobacter cloacae were the most common pathogens that were detected in anaerobic bottles only. Obligate anaerobic bacteria were detected from two (0.7%) bottles. There was no significant difference in the amount of blood inoculated into aerobic and anaerobic culture bottles. Conclusions The use of anaerobic blood culture bottles in the PICU may increase the detection rate of facultative anaerobic bacteria.

Background Several studies have investigated whether pregnancy is a risk factor for developing severe coronavirus disease 2019 (COVID-19); however, the results remain controversial. In addition, the information regarding risk factors for developing severe COVID-19 in pregnant women is limited. Methods A retrospective cohort study analyzing the data from the nationwide COVID-19 registry in Japan was conducted. Propensity score–matched analysis was performed to compare COVID-19 severity between pregnant and nonpregnant women. Multivariate analysis was also conducted to evaluate risk factors for developing moderate-to-severe COVID-19 in pregnant women. Results During the study period, 254 pregnant and 3752 nonpregnant women of reproductive age were identified. After propensity score matching, 187 pregnant women and 935 nonpregnant women were selected. A composite outcome of moderate-to-severe COVID-19 was more frequently observed in pregnant women than that of nonpregnant women (n = 18 [9.6%] vs n = 46 [4.9%]; P = .0155). In multivariate analysis, the presence of underlying diseases and being in the second-to-third trimester of pregnancy were recognized as risk factors for moderate-to-severe COVID-19 in pregnant women (odds ratio [95% confidence interval]: 5.295 [1.21–23.069] and 3.871 [1.201–12.477], respectively). Conclusions Pregnancy could be a risk factor for moderate-to-severe COVID-19 for women in Japan. In addition to the presence of comorbidities, advanced pregnancy stages may contribute to greater risks for developing moderate-to-severe COVID-19 in pregnant women.

Infectious diseases after transplantation account for significant morbidity and mortality in children undergoing transplantation; the importance of pediatric transplant infectious disease (TID) specialists has therefore been recognized. Although tremendous advancement continues in transplantation medicine, pediatric-specific data and evidence are limited. In Japan, the majority of TIDs had not been managed by infectious disease specialists because pediatric infectious diseases have not been recognized as a solo subspecialty until recently in Japan. However, in the last decade, there was a new movement for pediatric TID in Japan; some pediatric infectious disease specialists trained outside Japan have been playing an important role in managing pediatric TID in a few academic and pediatric institutions. In this review article, we introduce the current status of infectious complications related to pediatric hematopoietic cell and solid organ transplantation, highlighting currently available local evidence, common practice and issues in the field of pediatric TID in Japan.

Background Shiga toxin-producing Escherichia coli (STEC) may cause hemolytic uremic syndrome (STEC-HUS) and encephalopathy which possibly lead to neurological sequelae and mortality. However, the detailed epidemiology of this disease remains unclear due to its low frequency. This study aimed to describe the characteristics, demographics, and mortality of patients with STEC-HUS using a nationwide database. Methods We performed a retrospective cohort study using the Diagnosis Procedure Combination database, which includes approximately half of acute-care inpatients across Japan. We enrolled patients who were hospitalized for STEC-HUS from July 2010 to March 2020. We defined patients with unfavorable outcomes as any of the following at discharge: in-hospital death within three months, tracheostomy, mechanical ventilation, dialysis, and rehabilitation. Results This study included 655 patients with STEC-HUS (median age, 7 years). 62 patients (9.5%) were admitted to intensive care units within 2 days of admission. A total of 125 (19.1%) patients had any one of the composite unfavorable outcomes: 24 (3.7%) in-hospital death within 3 months, 9 (1.4%) tracheostomy during hospitalization, 24 (3.7%) mechanical ventilation at discharge, 22 (3.4%) dialysis at discharge, and 95 (14.5%) rehabilitation at discharge. Thirty-one patients (4.7%) developed STEC-HUS related acute encephalopathy. Conclusion Regardless of advances in multidisciplinary medicine, we found STEC-HUS remains a poor prognostic condition. Disclosures All Authors: No reported disclosures.

Clinical characteristics of bacteremic urinary tract infection due to third-generation cephalosporin-resistant Escherichia coli in children remain unclear. We conducted a case control study comparing the clinical information of the third-generation cephalosporin-susceptible group (S-E. coli group) and the third-generation cephalosporin-resistant group (R-E. coli group). The R-E. coli group included extended-spectrum beta-lactamases (ESBLs) or AmpC-producing E. coli. We identified 52 cases of bacteremic UTI due to E. coli; 42 cases were in the S-E. coli group and 10 cases were in the R-E. coli group. Empiric antibiotics were more likely to be inappropriate for pediatric patients with bacteremic urinary tract infection due to third-generation cephalosporin-resistant E. coli than those infected by susceptible E. coli (60% vs. 0%, P 0.001). However, duration of fever and rate of relapse were not significantly different. The outcomes of bacteremic UTI due to multidrug-resistant E. coli in children were satisfactory regardless of susceptibility to empiric antibiotics.

Therapeutic drug monitoring guided by the area under the concentration-time curve (AUC-guided TDM) is recommended for vancomycin. However, validated efficient software remains elusive to popularize AUC-guided TDM in Japan. The aim of this study was to validate a newly developed web application, PAT, for AUC estimation. PAT was developed on the R ver. 3.6.2 platform for use with mobile phones and personal computers. AUC estimated by PAT (AUCPAT) was evaluated against the reference AUC (AUCREF) calculated with the log-linear trapezoidal rule using eight measured concentrations, or against AUC (AUCBM-P) calculated using an evaluated available software with clinical data. Investigating the best sampling points with limited sampling, PAT produced the least bias using two concentrations at 1 h and 11 h after the end of infusion (slope 1.18, intercept −15.57, median AUCPAT/AUCREF 0.93 [range 0.81–1.24]), where only one estimation (6%) was out of the predetermined acceptable range of 0.8–1.2. Employment of only a trough concentration was more biased (AUCPAT/AUCREF range 0.73–1.30 for 11 h, AUCPAT/AUCREF range 0.62–1.40 for 23 h). In comparison with the evaluated software, AUCPAT was not biased against the AUCBM-P (slope 1.04, intercept −15.80, median AUCPAT/AUCBM-P 1.00 [range 0.86–1.10]). The new application using two concentrations was appropriately validated and might be efficient in popularizing the AUC-guided TDM of vancomycin.

Pharmacologic knowledge is important for pediatricians conducting feasible pharmacokinetic or pharmacodynamic (PK/PD) studies or applying effective antimicrobial therapies in children. Because of the difficulties in conducting PK/PD studies in children, antimicrobial PK/PD data in children are still limited. To fill in the lack of knowledge, promotion of population PK/PD analysis, which allows us to handle sparse sampling data from individual patients, is important because it is considered a suitable methodology to conduct PK/PD studies in children with limited blood drug concentration data for PK/PD analysis. Population PK/PD analysis is also useful in the clinical setting to provide individualized optimal dosage for each patient with various conditions. Here we summarized the current aspects of pediatric PK/PD studies of antimicrobials in Japan from clinical and research perspectives, specifically focusing on the importance of population PK/PD analysis.

Data are limited regarding the safety of and antibody response to the BNT162b2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger ribonucleic acid vaccine in adolescents and young adults with underlying disease.This prospective observational study enrolled patients age 12-25 years with chronic underlying disease who received 2 doses of BNT162b2. A 18-item questionnaire was used to assess adverse events within 7 days post-vaccination, and data regarding severe adverse events were collected from electronic medical records. An antibody titer for the receptor-binding domain of the spike protein in SARS-CoV-2 was used to assess antibody response after the second vaccine dose.Study participants were 429 patients (241 [56.2%] age 12-15 years; 188 [43.8%] age 16-25 years). The most common underlying diseases were genetic or chromosomal abnormalities and/or congenital anomalies, followed by endocrine or metabolic diseases; 32% of participants were immunocompromised. Severe adverse events were observed after the second dose in 1 (0.4%) patient age 12-15 years and in 2 (1.1%) patients age 16-25 years; all patients recovered. Seropositivity after the second vaccine dose was 99.0%. The geometric mean antibody titer was higher in patients age 12-15 years versus 16-25 years (1603.3 [1321.8-1944.7] U/mL vs. 949.4 [744.2-1211.0] U/mL). Compared with immunocompetent patients, immunocompromised patients had a lower antibody titer (2106.8 [1917.5-2314.7] U/mL vs. 467.9 [324.4-674.8] U/mL).Vaccination with BNT162b2 was acceptably safe and immunogenic for adolescents and young adults with underlying disease.

Live attenuated vaccines are contraindicated for patients on immunosuppressive agents or biological agent, except for live attenuated varicella vaccine, although previous reports showed their effectiveness and safety. This study is the nationwide cross-sectional research about the current utilization of live attenuated vaccines for patients on immunosuppressive agents or biological agents in Japan. We sent questionnaires to pediatric centers and examined whether each institution offered live attenuated vaccines to patients with immunosuppressive agents or biological agents (institutional research). We also examined adverse events associated with live attenuated vaccines between 2013 and 2017 (patient research). In the institutional research, 46 out of 334 institutions (13.8%) administered live attenuated vaccines to patients receiving immunosuppressive agents. In contrast, only six out of 270 institutions (2.2%) administered live attenuated vaccines to patients receiving biological agents. However, 66.3% of physicians answered that patients receiving immunosuppressive agents should be immunized with live attenuated vaccines, and only 7.0% disagreed with them. In the patient research, data for 781 patients were collected. Vaccine-associated infections were observed in only two patients (0.3%), both of whom had varicella, although they recovered promptly. No life-threatening adverse events were noted.In pediatric centers, the demand for live attenuated vaccines in patients receiving immunosuppressive agents was high and most physicians think they should be immunized. Immunization with live attenuated vaccines appeared safe in patients receiving immunosuppressive agents, although further studies are needed for patients receiving biological agents What is known: • Live attenuated vaccines (LAV) are generally contraindicated for patients on immunosuppressive agents (IS) or biological agents (BA), except for live attenuated varicella vaccine, as immunocompromised patients are at greater risk for serious viral infection from the vaccine strains. • Viral infections, such as measles and varicella, cause serious complications in children receiving IS. • Several previous reports showed that LAV is relatively effective and safe for patients receiving IS. What is new: • In Japan, the demand for LAV in patients receiving IS was high, and most physicians hoped they should be immunized. • Vaccine-associated infection is rarely observed in patients with IS after LAV administration. • Immunization with LAV appeared safe in patients receiving IS.University Hospital Medical Information Network (UMIN).UMIN000029176.Date of registration: 2017/09/19.

Objectives Pharmacokinetic (PK) parameters can change significantly during extracorporeal membrane oxygenation (ECMO) and continuous haemodialysis. This case report describes the pharmacokinetics of a 3-h meropenem infusion in an infantile anuric patient on ECMO with continuous haemodialysis. Case A 19-month-old female patient with asplenia syndrome was admitted to the paediatric intensive care unit for postoperative management of an extracardiac total cavopulmonary connection procedure. Veno-arterial ECMO and continuous haemodialysis were initiated on postoperative Day 2 for circulatory insufficiency due to septic shock and thrombosis of the inferior vena cava extending to the pulmonary artery. Blood and ascites cultures were positive for extended-spectrum β-lactamase-producing Escherichia coli, and 3-h meropenem infusions [120–300 mg/kg/day divided every 8 h (q8h)] were commenced. Following dose escalation to 300 mg/kg/day q8h, sustained negative blood cultures were confirmed. The estimated meropenem clearance and volume of distribution (Vd) were 2.21 mL/kg/min and 0.59 L/kg, respectively. These patient-specific PK parameters were used to predict the PK profile of various dosing regimens. Both 1-h and 3-h infusions of meropenem at 60, 120 and 200 mg/kg/day q8h predicted that the free drug concentration would remain above the minimum inhibitory concentration (fT>MIC) at an MIC of 1 μg/mL for >40% of the dosing interval. However, when the target was set at 100% fT>MIC, only a 3-h infusion of 200 mg/kg/day q8h could achieve the target in this patient despite the presence of anuria. Conclusion To optimise meropenem dosing in paediatric patients on ECMO and continuous haemodialysis, further study and PK monitoring are warranted.

We conducted a prospective study of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccination in children and adolescents who were taking immunosuppressive agents.Two doses of SARS-CoV-2 mRNA vaccine were administered to patients taking immunosuppressive agents. Titers of SARS-CoV-2 spike protein receptor-binding domain antibodies were measured before and after vaccination. Vaccine failure was defined as a postvaccination antibody titer of0.8 U/mL. Seroconversion rates, factors associated with antibody titers after vaccination, clinical effectiveness against breakthrough infection, and adverse events were evaluated.A total of 42 patients (median age, 18.1 years) were enrolled. Immunogenicity was measured in 34 patients. The median SARS-CoV-2 spike antibody titer was 329 U/mL (interquartile range [IQR] 50-812 U/mL). Seroconversion (≥0.8 U/mL) was achieved in 29 patients (85%), whereas vaccine failure was diagnosed in five (15%). All patients with vaccine failure were recipients of solid organ transplants (SOTs) and were taking two immunosuppressants. The median antibody titer in SOT recipients (57 U/mL) was significantly lower than that in non-recipients (653 U/mL, P = 0.0002); that of patients taking two immunosuppressive agents (93 U/mL) was lower than that of patients taking one (506 U/mL, P = 0.003). Breakthrough infection occurred in three patients (7%). Adverse events were non-specific, and no flares of primary disease or acute rejection in SOT recipients occurred.SARS-CoV-2 mRNA vaccine was immunogenic in children and adolescents taking immunosuppressive agents, although SOT recipients and patients taking two immunosuppressive agents tended to show lower postvaccination antibody titers.

Delta variant of concern (VOC) is the current predominant severe acute respiratory coronavirus type 2 strain causing coronavirus disease 2019 (COVID-19); however, information regarding the impact of the Delta VOC on clinical features and outcomes in pediatric patients with COVID-19 is limited. We conducted a retrospective observational study using the data of patients

The WU polyomavirus (WUPyV) was detected by real-time PCR in the sputum of a pediatric liver transplant recipient with interstitial pneumonitis. A lower viral load was observed seven months after the initial detection. The case provides circumstantial evidence suggesting a potential role for WUPyV as a respiratory pathogen in immunocompromised children.

A total of 1038 pediatric patients with COVID-19 were identified. Among these, 308 (30%) had asymptomatic COVID-19. The overall outcome was good, and no patients died. A significant rate of patients aged

We encountered a case of Bacillus Calmette-Guérin (BCG) cervical lymphadenitis in a patient undergoing infliximab after 6 years from BCG vaccination. Tumor necrosis factor-α inhibitors may be a risk for reactivation of BCG and serious infection even several years after vaccination.

We report on an 8‐year‐old girl with Wilson disease who developed three episodes of peritonitis due to extended‐spectrum beta‐lactamase‐producing Escherichia coli after liver transplantation. Massive ascites were thought to account for low meropenem concentrations with standard dosing. Extending the infusion achieved higher troughs, greater time above minimum inhibitory concentration.

Background LT is an elective treatment choice for children diagnosed with GSD1b that can improve their quality of life and stabilize their glucose intolerance. However, careful attention should be paid to immunosuppression after LT due to the susceptibility to infection because of neutropenia and neutrophil dysfunction in GSD1b patients. This study revealed the immunological features and complications in the early post-LT period. Methods We compared findings between 11 (1.9%) children with GSD1b and 273 children with BA. Analyses using the PSM were performed to overcome selection bias. Results Despite persistent low tacrolimus trough levels in GSD1b patients, none of these children developed TCMR within 1 month after LDLT (GSD1b: 0/11 [0%] vs. BA: 86/273 [31.5%], p = .038). This result was also confirmed in PSM. The incidence of bloodstream infections was higher in GSD1b patients than in BA patients in the early phase of the post-transplant period (GSD1b: 4/11 [36.4%] vs. BA: 33/273 [12.1%], p = .041), but not reach statistical significance in PSM. In a phenotypic analysis, the ratio of CD8+ T cells in GSD1b recipients' peripheral blood mononuclear cell samples was lower than in recipients with BA through the first month after LDLT. Conclusions We found that GSD1b recipients were more likely to develop postoperative bloodstream infection than recipients with BA but did not experience TCMR despite low tacrolimus levels in the early post-LDLT period. A tailored immunosuppression protocol should be prepared for GSD1b recipients after LDLT.

Background: Vaccination hesitancy is a global public health threat. Pediatric emergency department (ED) practitioners often encounter patients who have not received adequate vaccinations due to hesitant parents. However, it is difficult to secure enough time in the ED to perform vaccination education. The National Center for Child Health and Development, a tertiary children’s hospital in Japan, initiated cooperation between the ED and the pediatric infectious diseases (ID) division to counter vaccination hesitancy. When ED …