Risk factors and clinical impact of COVID-19-associated pulmonary aspergillosis: Multicenter retrospective cohort study

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.

Bloodstream Infections in Patients with Hematologic Diseases: Causative Organisms and Factors Associated with Resistance

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 vfancomycin-resistant Enterococcus isolates from E. faecium BSIs had increased. In addition, we found that ciprofloxacin prophylaxis was statistically significantly associated with ESBL production in Enterobacteriaceae BSIs. We conclude that, in order to avoid critical complications and to reduce the burden of antimicrobial-resistant organisms in patients with hematologic diseases, it is necessary to conduct periodic examinations evaluating changes in BSI epidemiology within a single medical center.

Pneumonia due to Schizophyllum commune in a Patient with Acute Myeloid Leukemia: Case Report and Literature Review

Schizophyllum commune is a mold in phylum Basidiomycota and is an uncommon human pathogen. Sinusitis and allergic bronchopulmonary mycosis are the two major diseases caused by S. commune. Although there have been several reports of invasive fungal diseases, most of them were invasive sinusitis. We present a case of invasive fungal pneumonia due to S. commune, developed in a patient with acute myeloid leukemia presenting neutropenic fever. The diagnosis was made by characteristic macroscopic and microscopic findings of fungal isolate and was confirmed via sequencing of internal transcribed spacer region. The patient was improved after 8 weeks of antifungal therapy based on the susceptibility result.We propose that S. commune should be considered as an emerging pathogen of invasive fungal pneumonia when a patient is under immunocompromised state. We also reviewed global literatures focused on the invasive fungal diseases caused by S. commune

Advances in prophylaxis and treatment of invasive fungal infections:perspectives on hematologic diseases

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.

Evaluation of a Newly Developed Rapid Automated Fluorescent Lateral Flow Immunoassay to Detect IgG and IgM Antibodies to Chikungunya Virus

The ichroma Chikungunya virus (CHIKV) IgG/IgM (Boditech Med Inc., Chuncheon, Korea) is a newly developed rapid lateral flow immunoassay for detection of anti- CHIKV-IgG/ IgM. This study conducted with thirty-six anti-CHIKV IgG positive sera, 57 anti-CHIKV IgM positive sera and 163 anti-CHIKV IgG/IgM negative sera which were confirmed by commercial enzyme-linked immunosorbent assays (ELISAs) (Inbios CHIKjj Detect™ IgM Capture ELISA, Inbios CHIKjj Detect™ IgG ELISA (InBios International Inc., Seattle, WA, USA), Anti-CHIKV ELISA (IgM), Anti- CHIKV ELISA (IgG) (Euroimmun, Lübeck, Germany)). The ichroma detected all 36 anti-CHIKV IgG and 57 anti-CHIKV IgM positivity (100% sensitivity). For 163 anti-CHIKV IgG/IgM negative sera, the ichroma showed one false positive for IgM (99.4% specificity). The ichroma showed no cross-reactivity and no interference. The ichroma demonstrated good diagnostic performance compared to the current ELISAs.

Evaluation of a Newly Developed Rapid Automated Fluorescent Lateral Flow Immunoassay to Detect IgG and IgM Antibodies to Chikungunya Virus

The ichroma Chikungunya virus (CHIKV) IgG/IgM (Boditech Med Inc., Chuncheon, Korea) is a newly developed rapid lateral flow immunoassay for detection of anti- CHIKV-IgG/ IgM. This study conducted with thirty-six anti-CHIKV IgG positive sera, 57 anti-CHIKV IgM positive sera and 163 anti-CHIKV IgG/IgM negative sera which were confirmed by commercial enzyme-linked immunosorbent assays (ELISAs) (Inbios CHIKjj Detect™ IgM Capture ELISA, Inbios CHIKjj Detect™ IgG ELISA (InBios International Inc., Seattle, WA, USA), Anti-CHIKV ELISA (IgM), Anti- CHIKV ELISA (IgG) (Euroimmun, Lübeck, Germany)). The ichroma detected all 36 anti-CHIKV IgG and 57 anti-CHIKV IgM positivity (100% sensitivity). For 163 anti-CHIKV IgG/IgM negative sera, the ichroma showed one false positive for IgM (99.4% specificity). The ichroma showed no cross-reactivity and no interference. The ichroma demonstrated good diagnostic performance compared to the current ELISAs.

Clinical Characteristics and Antimicrobial Susceptibility Trends in Citrobacter Bacteremia: An 11-Year Single-Center Experience

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.

Erratum: Carbapenem-Resistant Enterobacteriaceae: Prevalence and Risk Factors in a Single Community-Based Hospital in Korea

The authors found errors in their published article.

Comparison of Six Commercial Diagnostic Tests for the Detection of Dengue Virus Non-Structural-1 Antigen and IgM/IgG Antibodies

ELISAs and rapid diagnostic tests (RDTs) are widely used for diagnosing dengue virus (DENV) infection. Using 138 single blood samples, we compared the ability to detect non-structural (NS)-1 antigen and anti-DENV IgM/IgG antibodies among (1) DENV Detect NS1 ELISA, DENV Detect IgM capture ELISA and DENV Detect IgG ELISA (InBios International, Inc.); (2) Anti-Dengue virus IgM Human ELISA and Anti-Dengue virus IgG Human ELISA (Abcam); (3) Dengue virus NS1 ELISA, Anti-Dengue virus ELISA (IgM) and Anti-Dengue virus ELISA (IgG) (Euroimmun); (4) Asan Easy Test Dengue NS1 Ag 100 and Asan Easy Test Dengue IgG/IgM (Asan Pharm); (5) SD BIOLINE Dengue Duo (Standard Diagnostics); and (6) Ichroma Dengue NS1 and Ichroma Dengue IgG/IgM (Boditech Med). For NS1 antigen detection, InBios and Euroimmun showed higher sensitivities (100%) than the RDTs (42.9–64.3%). All tests demonstrated variable sensitivities for IgM (38.1–90.5%) and IgG (65.7–100.0%). InBios and Boditech Med demonstrated higher sensitivity (95.6% and 88.2%, respectively) than the other tests for combined NS1 antigen and IgM antibody. Five NS1 antigen tests had good agreement (92.8–98.6%) without showing positivity for chikungunya. However, all IgG tests demonstrated potential false-positivity with variable ranges. Clinical laboratories should note performance variations across tests and potential cross-reactivity.

Cytomegalovirus Colitis during Dasatinib Treatment for Patients with Hematologic Malignancy: Case Series and Literature Review

Dasatinib, a tyrosine kinase inhibitor, is widely used for patients with chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. Although the drug has a potent immunosuppressive effect, infectious complications during dasatinib treatment have been reported rarely. We describe five patients who developed cytomegalovirus (CMV) colitis during dasatinib treatment, in whom the colitis was initially confused with other causes. The patients, three with chronic myeloid leukemia, and two with acute lymphoblastic leukemia, were diagnosed with CMV colitis based on endoscopic and histologic findings. The patients who examined blood CMV polymerase chain reaction were all positive. The patients received antiviral therapy in the form of either ganciclovir or valganciclovir, and the overall treatment outcome was fair. These cases suggest that physicians should consider the possibility of CMV reactivation when treating diarrhea and/or hematochezia in patients on dasatinib.

Cytomegalovirus Colitis during Dasatinib Treatment for Patients with Hematologic Malignancy: Case Series and Literature Review

Dasatinib, a tyrosine kinase inhibitor, is widely used for patients with chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. Although the drug has a potent immunosuppressive effect, infectious complications during dasatinib treatment have been reported rarely. We describe five patients who developed cytomegalovirus (CMV) colitis during dasatinib treatment, in whom the colitis was initially confused with other causes. The patients, three with chronic myeloid leukemia, and two with acute lymphoblastic leukemia, were diagnosed with CMV colitis based on endoscopic and histologic findings. The patients who examined blood CMV polymerase chain reaction were all positive. The patients received antiviral therapy in the form of either ganciclovir or valganciclovir, and the overall treatment outcome was fair. These cases suggest that physicians should consider the possibility of CMV reactivation when treating diarrhea and/or hematochezia in patients on dasatinib.

Comparison of Enterococcus faecium Bacteremic Isolates from Hematologic and Non-hematologic Patients: Differences in Antimicrobial Resistance and Molecular Characteristics

BACKGROUND: Enterococcus faecium, especially vancomycin-resistant E. faecium (VREfm), is a major concern for patients with hematologic diseases. Exposure to antibiotics including fluoroquinolone, which is used as a routine prophylaxis for patients with hematologic (MH) diseases, has been reported to be a risk factor for infection with vancomycin-resistant eneterocci. We compared the characteristics of E. faecium isolates according to their vancomycin susceptibility and patient group (MH vs non-MH patients). METHODS: A total of 120 E. faecium bacteremic isolates (84 from MH and 36 from non-MH patients) were collected consecutively, and their characteristics (susceptibility, multilocus sequence type [MLST], Tn1546 type, and the presence of virulence genes and plasmids) were determined. RESULTS: Among the vancomycin-susceptible E. faecium (VSEfm) isolates, resistance to ampicillin (97.6% vs 61.1%) and high-level gentamicin (71.4% vs 38.9%) was significantly higher in isolates from MH patients than in those from non-MH patients. Notably, hyl, esp, and pEF1071 were present only in isolates with ampicillin resistance. Among the VREfm isolates, ST230 (33.3%) and ST17 (26.2%) were predominant in MH patients, while ST17 (61.1%) was predominant in non-MH patients. Plasmid pLG1 was more prevalent in E. faecium isolates from MH patients than in those from non-MH patients, regardless of vancomycin resistance. Transposon analysis revealed five types across all VREfm isolates. CONCLUSIONS: The antimicrobial resistance profiles and molecular characteristics of E. faecium isolates differed according to the underlying diseases of patients within the same hospital. We hypothesize that the prophylactic use of fluoroquinolone might have an effect on these differences.

Infectious complications after hematopoietic stem cell transplantation: current status and future perspectives in Korea

Hematopoietic stem cell transplantation (HSCT) is a treatment for hematologic malignancies, immune deficiencies, or genetic diseases, ect. Recently, the number of HSCTs performed in Korea has increased and the outcomes have improved. However, infectious complications account for most of the morbidity and mortality after HSCT. Post-HSCT infectious complications are usually classified according to the time after HSCT: pre-engraftment, immediate post-engraftment, and late post-engraftment period. In addition, the types and risk factors of infectious complications differ according to the stem cell source, donor type, conditioning intensity, region, prophylaxis strategy, and comorbidities, such as graft-versushost disease and invasive fungal infection. In this review, we summarize infectious complications after HSCT, focusing on the Korean perspectives.

Primary Sternal Osteomyelitis caused by Staphylococcus aureus in an Immunocompetent Adult

Primary sternal osteomyelitis (PSO) is a rare condition that may develop without any contiguous focus of infection. Due to the rarity of the disease, early diagnosis and appropriate treatment are often delayed. Herein, we describe a patient with PSO caused by Staphylococcus aureus that presented with chest pain and fever. The patient had no predisposing factors for sternal osteomyelitis. The chest pain was thought to be non-cardiogenic, as electrocardiography and cardiac enzyme did not reveal ischemic changes when he visited the emergency room. After blood culture revealed the presence of S. aureus, every effort was made to identify the primary focus of infection. Bone scan and magnetic resonance imaging revealed osteomyelitis with soft tissue inflammation around the sternum. After 8 weeks of antibiotics treatment, the patient recovered without any complications.

Lower Respiratory Tract Diseases Caused by Common Respiratory Viruses among Stem Cell Transplantation Recipients: A Single Center Experience in Korea

PURPOSE: To describe the incidence, clinical courses, and risk factors for mortality of lower respiratory tract diseases (LRDs) caused by common respiratory viruses (CRVs) in stem cell transplantation (SCT) recipients. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 1038 patients who received SCT between January 2007 and August 2011 at a single center in Korea. RESULTS: Seventy-one CRV-LRDs were identified in 67 (6.5%) patients. The human parainfluenza virus (HPIV) was the most common causative pathogen of CRV-LRDs at 100 days [cumulative incidence estimate, 23.5%; 95% confidence interval (CI), 3.3–43.7] and 1 year (cumulative incidence estimate, 69.2%; 95% CI, 45.9–92.5) following SCT. The 30-day overall mortality rates due to influenza-LRDs, respiratory syncytial virus-LRDs, HPIV-LRDs, and human rhinovirus-LRDs were 35.7, 25.8, 31.6, and 42.8%, respectively. Co-pathogens in respiratory specimens were detected in 23 (33.8%) patients. The overall mortality at day 30 after CRV-LRD diagnosis was 32.8% (22/67). High-dose steroid usage (p=0.025), a severe state of immunodeficiency (p=0.033), and lymphopenia (p=0.006) were significantly associated with death within 30 days following CRV-LRD diagnosis in a univariate analysis. Multivariate logistic regression analysis revealed that high-dose steroid usage [odds ratio (OR), 4.05; 95% CI, 1.12–14.61; p=0.033] and lymphopenia (OR, 6.57; 95% CI, 1.80–24.03; p=0.004) were independent risk factors for mortality within 30 days of CRV-LRDs. CONCLUSION: CRV-LRDs among SCT recipients showed substantially high morbidity and mortality rates. Therefore, the implement of an active diagnostic approaches for CRV infections is required for SCT recipients with respiratory symptoms, especially those receiving high-dose steroids or with lymphopenia.

Establishment of Experimental Murine Peritonitis Model with Hog Gastric Mucin for Carbapenem-Resistant Gram-Negative Bacteria

Animal models are essential to studies of infectious diseases. The use of mice to test bacterial infection has been extensively reported. However, methods applied to clinical isolates, particularly for carbapenem-resistant bacteria, must be tailored according to the infection models and bacteria used. In this study, we infected 6-week-old female BALB/c mice intraperitoneally with different strains of resistant bacteria plus 3% hog gastric mucin. This method was found to be efficient and readily applicable for investigation of carbapenem-resisant Gram-negative pathogens (e.g., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii) detected in Korea.

Mycobacterium kansasii Pneumonia with Mediastinal Lymphadenitis in a Patient with Acute Myeloid Leukemia: Successful Treatment to Stem Cell Transplantation

Non-tuberculous mycobacterial (NTM) disease is a relatively rare cause of neutropenic fever in patients with hematologic malignancies. During the neutropenic period, performing invasive procedures for microbiological or pathological confirmation is difficult. In addition, the optimal treatment duration for NTM disease in patients with leukemia, especially prior to stem cell transplantation (SCT), has not been documented. Therefore, we report a case of pneumonia with necrotizing lymphadenitis caused by Mycobacterium kansasii diagnosed during chemotherapy being performed for acute myeloid leukemia. The radiologic findings were similar to those of invasive fungal pneumonia; however, a bronchoalveolar washing fluid culture confirmed that the pathogen was M. kansasii. After 70 days from starting NTM treatment, allogeneic SCT was performed without any complications. The patient fully recovered after 12 months of NTM treatment, and neither reactivation of M. kansasii infection nor related complications were reported.

Amikacin therapy for urinary tract infections caused by extended-spectrum beta-lactamase-producing Escherichia coli

BACKGROUND/AIMS: The number of urinary tract infections (UTIs) caused by extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) is increasing. In an outpatient setting, there are limited therapeutic options to treat ESBL-producing pathogens. We evaluated the outcomes of amikacin outpatient parenteral antibiotic therapy (OPAT) for UTIs caused by ESBL-EC in patients not pre-treated with carbapenem. METHODS: We retrospectively evaluated the outcomes of amikacin OPAT for UTIs caused by ESBL-EC. RESULTS: From November 2011 to October 2012, eight females, who could not be hospitalized for carbapenem treatment, were treated with amikacin OPAT for nine episodes of non-bacteremic ESBL-EC UTIs. Seven of the eight patients had one or more comorbidities. Of the nine UTI cases, three had symptomatic lower UTIs and six had non-bacteremic upper UTIs. In all of the cases, symptomatic and laboratory improvements were observed following amikacin OPAT. One patient showed a delayed relapse with bilateral microabscesses 3 weeks after treatment cessation; however, a clinical and microbiological cure was eventually reached. All of the patients were able to tolerate amikacin OPAT without any significant nephrotoxicity or ototoxicity. CONCLUSIONS: Amikacin OPAT represents a feasible therapeutic option for non-bacteremic UTIs caused by ESBL-EC in settings with limited resources.

Budding Yeast Cells in Peripheral Blood Smear: Clue to Candidemia

No abstract available.

Carbapenem-resistant Enterobacteriaceae: Prevalence and Risk Factors in a Single Community-Based Hospital in Korea

BACKGROUND: Carbapenemase-producing Enterobacteriaceae (CPE) are Gram-negative bacteria with increasing prevalence of infection worldwide. In Korea, 25 cases of CPE isolates were reported by the Korea Centers for Disease Control and Prevention in 2011. Most CPE cases were detected mainly at tertiary referral hospitals. We analyzed the prevalence and risk factors for carbapenem-resistant Enterobacteriaceae (CRE) in a mid-sized community-based hospital in Korea. MATERIALS AND METHODS: We retrospectively analyzed all consecutive episodes of Enterobacteriaceae in a mid-sized community-based hospital from January 2013 to February 2014. CRE was defined as organisms of Enterobacteriaceae showing decreased susceptibility to carbapenems. Risk factors for CRE were evaluated by a case–double control design. Carbapenemase was confirmed for CRE using a combined disc test. RESULTS: During 229,710 patient-days, 2,510 Enterobacteriaceae isolates were obtained. A total of 41 (1.6%) CRE isolates were enrolled in the study period. Thirteen species (31.7%) were Enterobacter aerogenes, 8 (19.5%) Klebsiella pneumoniae, 5 (12.2%) Enterobacter cloacae, and 15 other species of Enterobacteriaceae, respectively. Among the 41 isolates, only one (2.4%) E. aerogenes isolate belonged to CPE. For evaluation of risk factors, a total of 111 patients were enrolled and this included 37 patients in the CRE group, 37 in control group I (identical species), and 37 in control group II (different species). Based on multivariate analysis, regularly visiting the outpatient clinic was a risk factor for CRE acquisition in the control group I (P = 0.003), while vascular catheter and Charlson comorbidity index score ≥ 3 were risk factors in control group II (P = 0.010 and 0.011, each). Patients with CRE were more likely to experience a reduced level of consciousness, use a vasopressor, be under intensive care, and suffer from acute kidney injury. However, CRE was not an independent predictor of mortality compared with both control groups. CONCLUSION: In conclusion, the prevalence of CRE was higher than expected in a mid-sized community-based hospital in Korea. CRE should be considered when patients have a vascular catheter, high comorbidity score, and regular visits to the outpatient clinic. This study suggests the need for appropriate prevention efforts and constant attention to CRE infection control in a mid-sized community-based hospital.