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.

Although venetoclax (VEN)-based combination chemotherapy in patients with acute myeloid leukemia (AML) results in prolonged and profound neutropenia, data regarding infectious complications and antimicrobial prophylaxis are lacking. We investigated the infectious complications in 122 adult patients with AML under the same standard of care for prevention. The prophylaxis protocol was fluconazole 400 mg/d without antibacterial agents. The incidence of proven or probable invasive fungal infections (IFIs) was 6.6/100 cycles, and 22 patients (18.0%) were diagnosed (median, second cycle; interquartile range, 1–2). All IFIs were caused by Aspergillus and significantly influenced the overall mortality (odds ratio (OR), 2.737; 95% confidence interval (CI), 1.051–7.128; p = 0.034). In the multivariate analysis, secondary or therapy-related AML was an independent risk factor for IFIs (OR, 3.859; 95% CI, 1.344–11.048, p = 0.012). A total of 39 bloodstream infection (BSIs) episodes occurred in 35 patients (28.7%), with an incidence of 12.7/100 cycles. High-dose steroid administration within 90 days was associated with the occurrence of BSIs (OR, 7.474; 95% CI; 1.661–3.631, p = 0.008), although BSIs themselves did not have an impact on the outcomes. Our findings suggest evidence for the need for mold-active antifungal agents as antifungal prophylaxis, rather than fluconazole, especially in patients with secondary or therapy-related AML.

Background/Aims: The risk factors and clinical impacts of coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) remain controversial, and no data have been reported in Korea. This study aimed to investigate the epidemiology and importance of CAPA diagnostic efforts and to identify the predictors of CAPA and the impacts on clinical outcomes.Methods: Between January 2020 and May 2021, data of severely to critically ill COVID-19 patients were extracted from seven hospitals of the Catholic Medical Center through a clinical data warehouse. Corticosteroid use was subcategorized into total cumulative dose, early 7-day dose, mean daily dose, and duration of use.Results: A total of 2,427 patients were screened, and 218 patients were included. CAPA was diagnosed in 4.6% (10/218) of all hospitalized and 11.2% (10/89) of intensive care unit patients. Total cumulative dose (over 1,000 mg as methylprednisolone) and daily high-dose corticosteroid use (over 60 mg/day) were independent predictors but not early 7-day high-dose corticosteroid use (over 420 mg/week) (odds ratio [OR], 1.731; 95% confidence interval [CI], 0.350 to 8.571) nor prolonged use (OR, 2.794; 95% CI, 0.635 to 13.928). In-hospital overall mortality was 11.9% (26 of 218). CAPA itself did not affect the outcome; rather, daily high-dose steroid use significantly increased the 30-day mortality (hazard ratio, 5.645; 95% CI, 1.225 to 26.091).Conclusions: CAPA was not uncommon, especially in critically ill patients. Daily high-dose corticosteroid use was the predictor of CAPA and associated with high mortality rates. High-dose corticosteroids use after early inflammatory phase should be avoided, and active surveillance methods for CAPA are essential for those high-risk patients.

Background Patients with hematologic diseases are at high risk of bloodstream infections (BSIs). This study aimed to analyze clinical features and distributions of microorganisms in patients with hematologic diseases presenting at a tertiary care university-affiliated hospital in Korea. Materials and Methods We retrospectively reviewed all BSI episodes recorded in patient medical records at two hematologic wards of the Catholic Hematology Hospital from January to December 2020. Our aim was to analyze demographic and clinical characteristics relevant to BSIs. We also described the antimicrobial resistance patterns of the major pathogens identified in this study, and evaluated risk factors for extended-spectrum beta-lactamase (ESBL) production in Enterobacteriaceae isolates and for vancomycin resistance in enterococcal isolates. Results A total of 380 BSI episodes were identified in 334 patients over the course of 1 year (monomicrobial BSI episodes, 86.1%; polymicrobial BSI episodes, 13.9%). Gram-negative bacteria accounted for 242 isolates (54.8%). The most frequently isolated Gram-negative bacteria isolates were Escherichia coli (107 [24.2%]) followed by Klebsiella spp. (72 [16.3%]), Pseudomonas spp. (21 [4.8%]), and Enterobacter spp. (12 [2.7%]). The most commonly identified Gram-positive bacteria were Enterococcus spp. (72 [16.3%]) followed by viridans streptococci (54 [12.2%]), coagulase-negative staphylococci (CoNS) (24 [5.4%]), and Corynebacterium spp. (22 [5.0%]). ESBL-producing Enterobacteriaceae accounted for 25.1% of the total distribution. Among 54 Enterococcus faecium isolates, 100.0% were resistant to ampicillin and 55.6% showed resistance to vancomycin, while 100.0% (n = 12) of Enterococcus faecalis isolates were susceptible to ampicillin and vancomycin, respectively. Use of ciprofloxacin prophylaxis (odds ratio: 5.20; 95% confidence interval: 1.11 - 24.34; P = 0.04) was an independent risk factor for ESBL production in Enterobacteriaceae BSIs. Conclusion Compared with the results of a previous study conducted at the same institution, our findings demonstrated that Gram-negative bacteria remained dominant pathogens in BSIs occurring in patients with hematologic diseases. Our findings also demonstrated a comparatively decreased prevalence of ESBL-producing Enterobacteriaceae in the evaluated BSIs. However, the prevalence of enterococcal BSIs had not decreased, and the proportion of vancomycin-resistant Enterococcus isolates from E. faecium BSIs had increased. In addition, we found that ciprofloxacin p...