Antimicrobial stewardship programs (ASPs) can lower antibiotic use, decrease medical expenses, prevent the emergence of resistant bacteria, and enhance treatment for infectious diseases. This study summarizes the stepwise implementation and effects of ASPs in a single university-affiliated tertiary care hospital in Korea; it also presents future directions and challenges in resource-limited settings. At the study hospital, the core elements of the ASP such as leadership commitment, accountability, and operating system were established in 2000, then strengthened by the formation of the Antimicrobial Stewardship (AMS) Team in 2018. The actions of ASPs entail key components including a computerized restrictive antibiotic prescription system, prospective audit, post-prescription review through quantitative and qualitative intervention, and pharmacy-based interventions to optimize antibiotic usage. The AMS Team regularly tracked antibiotic use, the effects of interventions, and the resistance patterns of pathogens in the hospital. The reporting system was enhanced and standardized by participation in the Korea National Antimicrobial Use Analysis System, and educational efforts are ongoing. Stepwise implementation of the ASP and the efforts of the AMS Team have led to a substantial reduction in the overall consumption of antibiotics, particularly regarding injectables, and optimization of antibiotic use. Our experience highlights the importance of leadership, accountability, institution-specific interventions, and the AMS Team.

Invasive fungal infections (IFIs) are common causes of mortality and morbidity in patients with hematologic diseases. Delayed initiation of antifungal treatment is related to mortality. Aspergillus sp. is the leading cause of IFI followed by Candida sp. Diagnosis is often challenging owing to variable conditions related to underlying diseases. Clinical suspect and prompt management is important. Imaging, biopsy, and non-culture-based tests must be considered together. New diagnostic procedures have been improved, including antigen-based assays and molecular detection of fungal DNA. Among hematologic diseases, patients with acute myeloid leukemia, myelodysplastic syndrome, recipients of hematopoietic stem cell transplantation are at high risk for IFIs. Antifungal prophylaxis is recommended for these high-risk patients. There are continuous attempts to achieve ideal management of IFIs. Scoring system for quality control has been developed with important recommendations of current guidelines. Higher adherence to guidelines is related to decreased mortality in IFIs.

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.

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.

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: Systemic corticosteroids have become the standard of care for severe to critically ill patients with coronavirus disease 2019 (COVID-19). However, the real-world efficacy and safety outcomes associated with a higher dose of corticosteroids remain uncertain. Methods: We conducted a nationwide, population-based, matched cohort study of severe to critically ill adult patients with COVID-19 between January 2020 and June 2021 in Korea using the National Health Information Database. Patients using systemic corticosteroids were included and high-dose corticosteroid use was defined as a daily mean prescribed dose of more than 6 mg of dexamethasone. We then employed a proportional hazard regression model to identify prognostic factors for 28-day all-cause mortality and conducted a Fine and Gray regression model to assess risk factors for developing COVID-19-associated pulmonary aspergillosis (CAPA). Results: During the study period, 102,304 patients with COVID-19 were screened, 5,754 met the eligibility criteria, and 2,138 were successfully matched. The mean prescribed daily dose was 4.2 mg and 13.4 mg in the standard- and high-dose groups, respectively, and the mean duration of use was not different between the groups. High-dose corticosteroid use independently increased all-cause mortality at 28 days (adjusted hazard ratio [aHR], 1.48; 95% confidence interval [CI], 1.25–1.76) and 90 days (aHR, 1.63; CI, 1.44–1.85) after admission. Subgroup analysis revealed a statistically significant elevation in the risk of mortality among patients using low-flow or high-flow nasal cannulas, with aHRs of 1.41 and 1.46, respectively. No significant impact of high-dose steroids was observed, even in patients who underwent mechanical ventilation at 28 days (aHR, 1.17; CI, 0.79–1.72). As a safety outcome, high-dose corticosteroid use showed an association with the development of CAPA (aHR, 2.97; 95% CI, 0.94–9.43). Conclusion Among severe to critically ill patients with COVID-19, high-dose corticosteroid use was associated with increased 28-day all-cause mortality and showed a trend toward the development of CAPA.

Purpose: Hepatitis B is a major prognostic factor after hematopoietic stem cell transplantation (HSCT). Currently, no consensus exists regarding the management of various scenarios that can lead to reverse seroconversion of the hepatitis B surface antigen (HBsAg-RS). This study focused on HBsAg-RS, which serves as an indicator of active hepatitis, and aimed to obtain exploratory information on the associated patient and treatment factors. Methods: This single-center retrospective study utilized clinical data extracted from the electronic medical records of Seoul St. Mary’s Hospital, Korea. Patients who underwent HSCT between January 2013 and December 2018 and tested negative for hepatitis B surface antigen (HBsAg) before undergoing HSCT were included. The associations between HBsAg-RS and demographic information, baseline hepatitis B serological markers, and vaccination status were statistically analyzed. Results: This study included 1,344 patients, of whom 83.3% tested positive for the hepatitis B surface antibody (HBsAb) during HSCT. HBsAg-RS occurred in 2.2% of HBsAb-negative patients and 3.0% of HBsAb-positive patients, indicating no significant difference in reactivation rates according to HBsAb status. However, positivity for hepatitis B core antibody (HBcAb) was significantly associated with hepatitis B reactivation (HBsAg-RS rate: 8.0%). The vaccination rates were highest in patients who were negative for both HBsAb and HBcAb and had a transient protective effect. Conclusion The sufficient patient population enabled the identification of an association between baseline HBcAb positivity and the development of HBsAg-RS. Further prospective studies are warranted to determine optimal vac‑ cination strategies for preventing HBsAg-RS.

Purpose: Hepatitis B is a major prognostic factor after hematopoietic stem cell transplantation (HSCT). Currently, no consensus exists regarding the management of various scenarios that can lead to reverse seroconversion of the hepatitis B surface antigen (HBsAg-RS). This study focused on HBsAg-RS, which serves as an indicator of active hepatitis, and aimed to obtain exploratory information on the associated patient and treatment factors. Methods: This single-center retrospective study utilized clinical data extracted from the electronic medical records of Seoul St. Mary’s Hospital, Korea. Patients who underwent HSCT between January 2013 and December 2018 and tested negative for hepatitis B surface antigen (HBsAg) before undergoing HSCT were included. The associations between HBsAg-RS and demographic information, baseline hepatitis B serological markers, and vaccination status were statistically analyzed. Results: This study included 1,344 patients, of whom 83.3% tested positive for the hepatitis B surface antibody (HBsAb) during HSCT. HBsAg-RS occurred in 2.2% of HBsAb-negative patients and 3.0% of HBsAb-positive patients, indicating no significant difference in reactivation rates according to HBsAb status. However, positivity for hepatitis B core antibody (HBcAb) was significantly associated with hepatitis B reactivation (HBsAg-RS rate: 8.0%). The vaccination rates were highest in patients who were negative for both HBsAb and HBcAb and had a transient protective effect. Conclusion The sufficient patient population enabled the identification of an association between baseline HBcAb positivity and the development of HBsAg-RS. Further prospective studies are warranted to determine optimal vac‑ cination strategies for preventing HBsAg-RS.

Purpose: Hepatitis B is a major prognostic factor after hematopoietic stem cell transplantation (HSCT). Currently, no consensus exists regarding the management of various scenarios that can lead to reverse seroconversion of the hepatitis B surface antigen (HBsAg-RS). This study focused on HBsAg-RS, which serves as an indicator of active hepatitis, and aimed to obtain exploratory information on the associated patient and treatment factors. Methods: This single-center retrospective study utilized clinical data extracted from the electronic medical records of Seoul St. Mary’s Hospital, Korea. Patients who underwent HSCT between January 2013 and December 2018 and tested negative for hepatitis B surface antigen (HBsAg) before undergoing HSCT were included. The associations between HBsAg-RS and demographic information, baseline hepatitis B serological markers, and vaccination status were statistically analyzed. Results: This study included 1,344 patients, of whom 83.3% tested positive for the hepatitis B surface antibody (HBsAb) during HSCT. HBsAg-RS occurred in 2.2% of HBsAb-negative patients and 3.0% of HBsAb-positive patients, indicating no significant difference in reactivation rates according to HBsAb status. However, positivity for hepatitis B core antibody (HBcAb) was significantly associated with hepatitis B reactivation (HBsAg-RS rate: 8.0%). The vaccination rates were highest in patients who were negative for both HBsAb and HBcAb and had a transient protective effect. Conclusion The sufficient patient population enabled the identification of an association between baseline HBcAb positivity and the development of HBsAg-RS. Further prospective studies are warranted to determine optimal vac‑ cination strategies for preventing HBsAg-RS.

BACKGROUND: Recently, Citrobacter freundii bacteremia outbreak in a neonatal intensive care unit has attracted public attention in Korea. However, Citrobacter bacteremia is uncommon and usually occurs in patients with underlying diseases such as malignancy and hepatobiliary diseases. Increase in resistance and emerging of multidrug resistance among Citrobacter species have gradually been reported. The aim of this study was to investigate the clinical characteristics and outcome of C. freundii and non-freundii bacteremia and antimicrobial susceptibility trends. MATERIALS AND METHODS: We reviewed the medical records of patients with Citrobacter bacteremia at St. Mary's Hospital, from 2007 to 2017. RESULTS: A total of 43 patients with a median age of 72 (24-93) years was identified and 90.7% of them had comorbidities. Twenty-nine (67.4%) patients had C. freundii bacteremia while 14 had non-freundii bacteremia (six of C. braakii, five of C. koseri, two of C. amalonaticus and one of C. youngae). A total of 26 (51.2%) patients had community-acquired infection and intra-abdominal infection including hepatobiliary tract was the most common portal of entry (24/43, 55.8%). Moreover, hepatobiliary tract was the leading primary site of nosocomial infection (9/17, 52.9%). Polymicrobial bacteremia was observed in 21 (48.8%) patients. The percentages of Citrobacter species susceptible to ampicillin, amikacin, aztreonam, cefazolin, cefoxitin, cefotaxime, cefepime, piperacillin-tazobactam, ciprofloxacin, and imipenem were 9.5%, 97.6%, 73.8%, 9.5%, 14.3%, 71.4%, 92.9%, 83.3%, 83.3% and 100%, respectively. The resistance rate did not increase during the study period. Of 39 patients treated with antibiotics, 36 (92.3%) received appropriate empirical antibiotics. Overall mortality was 18.6%. High Charlson comorbidity index and Pitt bacteremia score were significant risk factors for death in univariate analysis and showed trends in the multivariate analysis. No significant difference in clinical features and antimicrobial susceptibility rate was observed between C. freundii and non-freundii bacteremia. CONCLUSION Citrobacter bacteremia was predominant in the elderly with comorbidities, while no pediatric case was observed. Hepatobiliary tract is the leading primary focus of bacteremia both in community-acquired and nosocomial infection. The rate of susceptibility to antibiotics has not changed in the last 11 years.