Respiratory syncytial virus (RSV) poses a significant threat to infants and young children in Korea and globally.Current preventive measures, such as palivizumab, have limitations, necessitating the exploration of new strategies.Nirsevimab, a long-acting monoclonal antibody, has emerged as a promising option for protecting all infants from RSV. Clinical trials and real-world evidence support its effectiveness in reducing RSV-related hospitalizations.The economic burden of RSV infection in Korea underscores the need for cost-effective interventions. While several RSV vaccines are under development, none are currently available in Korea. Maternal immunization programs and vaccines for older infants offer potential avenues for expanding protection. This review highlights the evolving landscape of RSV prevention, with a shift towards nirsevimab and future vaccines. Further research is crucial to understand the long-term consequences of RSV infection and develop comprehensive prevention strategies tailored to the Korean population.

Cytomegalovirus (CMV) is a significant concern for patients with allogeneic hematopoietic cell transplantation (alloHCT). CMV management differs between institutions due to the lack of local guidelines. Here, we describe a case of refractory/resistant CMV infection treated using our institution's CMV management protocol. A 59-year-old woman who underwent allo-HCT was treated for CMV reactivation. Despite 3 months of valganciclovir administration, serum CMV level surged. CMV gene mutation test revealed a ganciclovir-resistant A594V mutation in the UL97 gene.Treatment was switched to foscarnet until the drug became unavailable nationwide. During the foscarnet shortage, cidofovir was used, leading to a decline in CMV levels when foscarnet was reintroduced and used for 2 months.Following allo-HCT, CMV prophylaxis with letermovir is crucial to prevent reactivation in seropositive recipients.CMV titers should be monitored frequently after allo-HCT. The cutoff value for preemptive therapy varies across institutions, with ganciclovir/valganciclovir usually administered as first-line therapy. Maribavir is an option in cases of ganciclovir/valganciclovir resistance or intolerance. CMV gene mutations should be examined in patients with suspected resistance after 2 weeks of appropriate treatment. This case was discussed at the Clinical Grand Round of the Annual Conference of the Korean Society of Infectious Diseases on November 2, 2023.

Background: Immunocompromised patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection often have prolonged viral shedding, and some are clinically suspected of reinfection with different SARSCoV-2 variants. However, data on this issue are limited. This study investigated the SARS-CoV-2 variants in serially collected respiratory samples from immunocompromised patients with prolonged viral shedding for over 12 weeks or relapsed viral shedding after at least 2 weeks of viral clearance. Materials and Methods: From February 2022 to September 2023, we prospectively enrolled immunocompromised patients with coronavirus disease 2019 who had hematologic malignancies or had undergone transplantation and were admitted to a tertiary hospital. Weekly saliva or nasopharyngeal swabs were collected from enrolled patients for at least 12 weeks after diagnosis. Genomic RNA polymerase chain reaction (PCR) was performed on samples, and those testing positive underwent viral culture to isolate the live virus. Spike gene full sequencing via Sanger sequencing and real-time reverse transcription-PCR for detecting mutation genes were conducted to identify SARSCoV-2 variants. Results: Among 116 enrolled patients, 20 with prolonged or relapsed viral shedding were screened to identify the variants. Of these 20 patients, 7 (35%) exhibited evidence of re-infection; one of 8 patients with prolonged viral shedding and 6 of 12 with relapsed viral shedding were reinfected with SARS-CoV-2. Conclusion Our data suggest that approximately one-third of immunocompromised patients with persistent or relapsed viral shedding had reinfection with different variants of SARS-CoV-2.

Background: Phylogenetic studies are essential for understanding the virulence and resistance factors of bacteria, especially in evaluating their distribution within specific populations for effective infection control. Urinary tract infections (UTIs) caused by Escherichia coli are highly prevalent and pose significant health challenges from childhood to adulthood. The rising incidence of multidrug-resistant (MDR) strains highlights the urgent need for research aimed at developing preventive measures and epidemiological control strategies. This study aimed to analyze phylogenetically uropathogenic E. coli strains and their resistance phenotypes in children. Materials and Methods: A retrospective analysis was conducted on 111 urine culture samples collected from June 2023 to February 2024 at the Pediatric Emergency Hospital (PEH) in Lima, Peru. The phylogroups of E. coli were identified using Clermont's protocol based on polymerase chain reaction. Results: UTIs were predominantly observed in females (85.6%) and infants under two years old (42.3%). The most frequent uropathogenic E. coli phylogroups were B2 (30.6%), D (29.7%), and A (25.2%). These phylogroups showed significant correlation with MDR and the production of extended spectrum beta-lactamases (ESBL). Conclusion At PEH, UTIs in children are primarily caused by uropathogenic E. coli from the B2 and D phylogroups, which demonstrate high virulence and resistance factors. The correlation between these phylogroups, MDR, and ESBL production, along with the increasing infection rates associated with phylogroup A, suggests a potential for horizontal gene transfer. This underscores the urgent need for vigilant control measures.

Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments. Materials and Methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19. Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00–1.09; P=0.04) showed a significant association with long COVID after 12–18 months in a multivariable logistic regression analysis. Conclusion Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.

Pneumocystis jirovecii pneumonia (PJP) is a life-threatening infection commonly observed in immunocompromised patients, necessitating prompt diagnosis and treatment. This review evaluates the diagnostic performance of various tests used for PJP diagnosis through a comprehensive literature review. Additionally, we propose a diagnostic algorithm tailored to non-human immunodeficiency virus immunocompromised patients, considering the specific characteristics of current medical resources in Korea.

Background: This study compared the mortality rates within 30 days of 2 different doses of sulbactam (6 g and 9–12 g daily) when used in colistin (COL)-based treatment regimens and COL monotherapy for carbapenem-resistant Acinetobacter baumannii (CRAB). Materials and Methods: This retrospective cohort study included 234 participants diagnosed with severe pneumonia due to CRAB infection at Phramongkutklao Hospital, Thailand, from July 1, 2011, to April 30, 2023. Participants were categorized into three groups: COL monotherapy, COL with 6 g of sulbactam daily (COL+S6g), and COL with 9–12 g of sulbactam daily (COL+SHD). Following the exclusion of patients with renal impairment (serum creatinine ≥1.5 mg/dl), a 1:2 propensity score (PS) matching was used to ensure comparable groups, with the COL group designated as the control. The matching variables included age, APACHE II scores, serum creatinine, intensive care units admission, and bacteremia. The number of participants in each group was as follows: 19 in COL, 32 in COL+S6g, and 38 in COL+SHD.The primary outcomes assessed were all-cause mortality rates at 7, 14, and 30 days. Kaplan–Meier survival curves and the Log-rank test were used to evaluate differences between groups, while multivariate Cox regression models were applied to determine the impact of treatment regimens. Results: The unmatching PS analysis indicated that the COL+SHD regimen significantly reduces mortality compared to the COL regimen; hazard ratios (HR) were 0.18 (95% confidence interval [CI], 0.06–0.55) for 7-day mortality and 0.53 (95% CI,-0.29–0.97) for 30-day mortality. In addition, the COL+SHD regimen also lowered mortality more than the COL+S6g regimen within 7 days (HR, 0.29; 95% CI, 0.11–0.75). After PS matching, the COL+SHD regimen significantly reduced 7-day mortality compared to the COL regimen (adjusted HR, 0.24; 95% CI, -0.07–0.82). However, COL+S6g did not differ in mortality from either COL+SHD or COL for 7-day mortality. At 14 days and 30 days, there were no significant regimens to reduce mortality. Conclusion Combining COL+SHD effectively reduced death in 7 days from severe pneumonia in CRAB infection treatment.

Background: The global resurgence of mpox, formerly monkeypox, poses an emerging threat to pregnant women due to immunological changes and potential vertical transmission, yet its impact on pregnancy remains underexplored. This study aims to pioneer a comprehensive assessment of pregnancy outcomes and the risks of vertical transmission associated with mpox infection during pregnancy. Materials and Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we searched three databases up to September 2024 for studies on pregnant women with mpox confirmed by quantitative polymerase chain reaction. Primary outcomes were composite adverse pregnancy outcomes:miscarriage or fetal death, congenital anomalies, and chorioamnionitis; the secondary outcome was vertical transmission. Study quality was assessed using Joanna Briggs Institute tools. Statistical analysis employed R software using a one-proportion model with Freeman-Tukey transformation and random-effects meta-analysis (restricted maximum-likelihood estimator, Knapp-Hartung adjustment), presenting estimated proportions with 95% confidence intervals (CIs). Results: Six studies (three case series, three case reports) comprising 11 singleton pregnancies were included.Diagnoses occurred in the first (27.3%), second (45.4%), and third trimesters (27.3%). Among the five genotypically identified Mpox cases, 20.0% were classified Clade I and 80.0% as Clade II. Meta-analysis indicated that an estimated 63% (95% CI, 43–83%) of pregnancies experienced composite adverse pregnancy outcomes. Specifically, miscarriage or fetal death occurred in 62% (95% CI, 21–102%), congenital anomalies in 50% (95% CI, 21–80%), and chorioamnionitis in 78% (95% CI, 44–96%). Vertical transmission was observed in 79% (95% CI, 6–151%). Despite small sample sizes leading to wide confidence intervals, high estimated proportions suggest that mpox severely impacts pregnancy outcomes, likely linked to maternal inflammation, placental invasion, and significant fetal risks from vertical transmission. Conclusion Mpox infection during pregnancy appears to be associated with high rates of adverse pregnancy outcomes and vertical transmission. Further large-scale studies are warranted to confirm these findings and develop preventive and management strategies mitigating this emerging threat.

The impact of Streptococcus pneumoniae coinfection on coronavirus disease 2019 (COVID-19) prognosis remains uncertain. We conducted a retrospective analysis of patients hospitalized with COVID-19 who underwent a pneumococcal urinary antigen (PUA) test to assess its clinical utility. Results showed that PUA-positive patients required more oxygen support, high-flow nasal cannula, and dexamethasone compared to PUA-negative patients.Furthermore, the significantly higher incidence of a National Early Warning Score ≥5 in the PUA-positive group (P<0.001) suggests that a positive PUA test is associated with a severe disease course. However, no significant difference in mortality was observed between the two groups, and antibiotics were used in almost all patients (96.2%). While the PUA test may help guide antibiotic use in COVID-19 patients, its interpretation should be approached with caution.

Pertussis is endemic worldwide, with epidemics occurring every 2 to 5 years despite a high vaccination coverage.After limited circulation during the coronavirus disease 2019 (COVID-19) pandemic, pertussis cases have increased rapidly worldwide since mid-late 2023, returning to pre-pandemic patterns. In Korea, 90 cases of pertussis were reported from April 2020 to May 2023, with elderly individuals aged ≥65 years accounting for 48.9%. Pertussis cases have increased sharply since June 2024, showing a nationwide epidemic, with a large increase among adolescents aged 13–15 years. As of August 2024, the national incidence rate of pertussis was estimated to be 37.75 per 100,000 population, with the highest incidence of 526.2 per 100,000 population in 13-year-olds. In Europe, during 2023–2024, an increase in pertussis incidence among infants was observed, along with large increases in 10–19-yearolds. In China, the number of reported cases of pertussis has increased rapidly since late 2023, with an age shift to older children, increase of vaccine escape, and a marked increase in the prevalence of macrolide-resistant Bordetella pertussis. The recent global resurgence of pertussis is due to decreased opportunities for boosting immunity by natural infection during the COVID-19 pandemic in combination with waning of immunity-induced pertussis vaccines.