Seong Yeol Ryu

Risk factors and treatment outcomes of community-onset bacteraemia caused by extended-spectrum β-lactamase-producing Escherichia coli

The purpose of this study was to identify risk factors for extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli amongst community-onset bacteraemia and to evaluate treatment outcomes. From the database of a nationwide surveillance programme for bacteraemia, data from patients with community-onset E. coli bacteraemia were analysed. Patients with ESBL-producing E. coli bacteraemia were compared with those with non-ESBL-producing bacteraemia. The overall proportion of ESBL-producers was 9.5% (82/865) amongst community-onset E. coli bacteraemia cases. Healthcare-associated infection, underlying liver disease and primary bacteraemia were significant independent factors associated with ESBL-producing E. coli bacteraemia (P<0.05). There was a trend toward mortality being higher in the ESBL group compared with the non-ESBL group (15.0% vs. 7.6%; P=0.096). ESBL production was found to be an independent factor associated with mortality after adjusting for confounding variables (odds ratio=2.99, 95% confidence interval 1.01-8.84; P=0.048), along with severe sepsis, higher Pitt bacteraemia score, primary bacteraemia, pneumonia and underlying liver disease (P<0.05). ESBL-producing E. coli is a significant cause of bacteraemia, even in patients with community-onset infections, predicting higher mortality, particularly in patients with primary bacteraemia, underlying liver disease or healthcare-associated infection.

Bloodstream Infections and Clinical Significance of Healthcare-associated Bacteremia: A Multicenter Surveillance Study in Korean Hospitals

Recent changes in healthcare systems have changed the epidemiologic paradigms in many infectious fields including bloodstream infection (BSI). We compared clinical characteristics of community-acquired (CA), hospital-acquired (HA), and healthcare-associated (HCA) BSI. We performed a prospective nationwide multicenter surveillance study from 9 university hospitals in Korea. Total 1,605 blood isolates were collected from 2006 to 2007, and 1,144 isolates were considered true pathogens. HA-BSI accounted for 48.8%, CA-BSI for 33.2%, and HCA-BSI for 18.0%. HA-BSI and HCA-BSI were more likely to have severe comorbidities. Escherichia coli was the most common isolate in CA-BSI (47.1%) and HCA-BSI (27.2%). In contrast, Staphylococcus aureus (15.2%), coagulase-negative Staphylococcus (15.1%) were the common isolates in HA-BSI. The rate of appropriate empiric antimicrobial therapy was the highest in CA-BSI (89.0%) followed by HCA-BSI (76.4%), and HA-BSI (75.0%). The 30-day mortality rate was the highest in HA-BSI (23.0%) followed by HCA-BSI (18.4%), and CA-BSI (10.2%). High Pitt score and inappropriate empirical antibiotic therapy were the independent risk factors for mortality by multivariate analysis. In conclusion, the present data suggest that clinical features, outcome, and microbiologic features of causative pathogens vary by origin of BSI. Especially, HCA-BSI shows unique clinical characteristics, which should be considered a distinct category for more appropriate antibiotic treatment.

Fluoroquinolone Resistance in Uncomplicated Acute Pyelonephritis: Epidemiology and Clinical Impact

The objectives of this study were to investigate antibiotic resistance in urinary pathogens from Korean patients with uncomplicated acute pyelonephritis (UAPN), and to determine the effect of fluoroquinolone (FQ) resistance on clinical outcome in those patients with UAPN initially treated with FQ. Clinical and microbiologic data for all the APN patients attending 14 hospitals in South Korea in 2008 were collected retrospectively. Urinary pathogens were identified in 719 cases, and Escherichia coli was the most common pathogen (661/719, 91.9%). Antibiotic susceptibilities to several E. coli antibiotics were as follows: ciprofloxacin, 84.1%; trimethoprim-sulfamethoxazola (TMP-SMX), 67.2%; and extended-spectrum beta-lactamase-negative, 92.4%. FQ was the most frequent antibiotic prescribed for UAPN (45.3% intravenously and 53.9% by mouth). We compared clinical outcomes and hospital days in patients with FQ-resistant (32) and FQ-sensitive E. coli (173) who received FQ as initial empirical therapy. Clinical cure was higher in the FQ-sensitive group (78% vs. 91%, p=0.027), and hospital days were longer in the FQ-resistant group (9.6±5.5 days vs. 7±3.5 days, p=0.001). In conclusion, FQ-sensitivity of E. coli from UAPN was 84.1%. FQ treatment of UAPN caused by FQ-resistant E. coli has a lower cure rate and involves longer hospital stay than FQ treatment of cases caused by FQ-sensitive E. coli.

Phylogenetic Analysis of Severe Fever with Thrombocytopenia Syndrome Virus in South Korea and Migratory Bird Routes Between China, South Korea, and Japan

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne viral disease. The SFTS virus (SFTSV) has been detected in the Haemaphysalis longicornis, which acts as a transmission host between animals and humans. SFTSV was first confirmed in China in 2009 and has also been circulating in Japan and South Korea. However, it is not known if a genetic connection exists between the viruses in these regions and, if so, how SFTSV is transmitted across China, South Korea, and Japan. We therefore hypothesize that the SFTSV in South Korea share common phylogenetic origins with samples from China and Japan. Further, we postulate that migratory birds, well-known carriers of the tick H. longicornis, are a potential source of SFTSV transmission across countries. Our phylogenetic analysis results show that the SFTSV isolates in South Korea were similar to isolates from Japan and China. We connect this with previous work showing that SFTSV-infected H. longicornis were found in China, South Korea, and Japan. In addition, H. longicornis were found on migratory birds. The migratory bird routes and the distribution of H. longicornis are concurrent with the occurrence of SFTSV. Therefore, we suggest that migratory birds play an important role in dispersing H. longicornis-borne SFTSV.

Severe Fever with Thrombocytopenia Syndrome in South Korea, 2013-2015

Background Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that was recently identified in China, South Korea and Japan. The objective of the study was to evaluate the epidemiologic and clinical characteristics of SFTS in South Korea. Methods/Principal Findings SFTS is a reportable disease in South Korea. We included all SFTS cases reported to the Korea Centers for Disease Control and Prevention (KCDC) from January 2013 to December 2015. Clinical information was gathered by reviewing medical records, and epidemiologic characteristics were analyzed using both KCDC surveillance data and patient medical records. Risk factors for mortality in patients with SFTS were assessed. A total of 172 SFTS cases were reported during the study period. SFTS occurred throughout the country, except in urban areas. Hilly areas in the eastern and southeastern regions and Jeju island (incidence, 1.26 cases /105 person-years) were the main endemic areas. The yearly incidence increased from 36 cases in 2013 to 81 cases in 2015. Most cases occurred from May to October. The overall case fatality ratio was 32.6%. The clinical progression was similar to the 3 phases reported in China: fever, multi-organ dysfunction, and convalescence. Confusion, elevated C-reactive protein, and prolonged activated partial thromboplastin times were associated with mortality in patients with SFTS. Two outbreaks of nosocomial SFTS transmission were observed. Conclusions SFTS is an endemic disease in South Korea, with a nationwide distribution and a high case-fatality ratio. Confusion, elevated levels of C-reactive protein, and prolonged activated partial thromboplastin times were associated with mortality in patients with SFTS.

Multicenter Prospective Observational Study of the Comparative Efficacy and Safety of Vancomycin versus Teicoplanin in Patients with Health Care-Associated Methicillin-Resistant Staphylococcus aureus Bacteremia

ABSTRACT The purpose of this study was to compare the clinical efficacy and safety of vancomycin to those of teicoplanin for the treatment of adult patients with health care-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) bacteremia. A multicenter observational study was prospectively conducted in 15 teaching hospitals in Korea between February 2010 and July 2011. Adult patients (≥18 years old) with HA-MRSA bacteremia who were initially treated with vancomycin (VAN) (n = 134) or teicoplanin (TEC) (n = 56) were enrolled. Clinical and microbiological responses and drug-related adverse events were compared between the two treatment groups using univariate and multivariate logistic regression analyses. The vancomycin and teicoplanin MICs were determined by Etest. The MRSA-related mortality, duration of fever, and duration of MRSA bacteremia in the treatment groups were not significantly different. There was no significant difference in the occurrence of drug-related adverse events. Among the 190 MRSA isolates, the VAN MICs ranged from 0.5 to 2 μg/ml (MIC50 and MIC90, 1.5 μg/ml), and the TEC MIC ranged from 0.5 to 8 μg/ml (MIC50, 3 μg/ml; MIC90, 6 μg/ml). In multivariate analyses, the antibiotic type (vancomycin or teicoplanin) was not associated with treatment outcomes. This study indicates that teicoplanin is an effective and safe alternative to vancomycin for the treatment of HA-MRSA bacteremia.

Catheter-associated bacteremia by Mycobacterium senegalense in Korea

BackgroundRapidly growing mycobacteria is recognized as one of the causative agents of catheter-related infections, especially in immunocompromised hosts. To date, however, Mycobacterium senegalense, which was known as the principal pathogen of bovine farcy, has not been reported in human infection.Case presentationWe describe the first case of human infection by M. senegalense, which has caused catheter-related bloodstream infection in a cancer patient in Korea. The microorganism was identified by the 16S rRNA gene, rpoB, and 16S-23S rRNA gene internal transcribed spacer (ITS) sequence analyses.ConclusionOur first report of catheter-associated bacteremia caused by M. senegalense suggests the zoonotic nature of this species and indicates the expansion of mycobacterial species relating to human infection. M. senegalense should be considered as one of the causes of human infections in the clinical practice.

Susceptibility of Escherichia coli from Community-Acquired Urinary Tract Infection to Fosfomycin, Nitrofurantoin, and Temocillin in Korea

With increase of multi-drug resistant Escherichia coli in community-acquired urinary tract infections (CA-UTI), other treatment option with a therapeutic efficacy and a low antibiotic selective pressure is necessary. In this study, we evaluated in vitro susceptibility of E. coli isolates from CA-UTI to fosfomycin (FM), nitrofurantoin (NI), temocillin (TMO) as well as trimethoprim-sulfamethoxazole (SMX), ciprofloxacin (CIP) and cefepime (FEP). The minimal inhibitory concentrations were determined by E-test or agar dilution method according to the Clinical and Laboratory Standards Institute guidelines, using 346 E. coli collected in 12 Korean hospitals from March 2010 to February 2011. FM, NI and TMO showed an excellent susceptibility profile; FM 100% (346/346), TMO 96.8% (335/346), and NI 99.4% (344/346). Conversely, resistance rates of CIP and SMX were 22% (76/346) and 29.2% (101/349), respectively. FEP still retained an activity of 98.5%. In Korea, NI and TMO in addition to FM are a good therapeutic option for uncomplicated CA-UTI, especially for lower UTI. Graphical Abstract

Comparison of the clinical characteristics of diabetic and non-diabetic women with community-acquired acute pyelonephritis: A multicenter study

OBJECTIVES Purpose of this study was to compare clinical characteristics and treatment outcomes in diabetic and non-diabetic women with community-acquired APN (CA-APN). METHODS We prospectively collected and analyzed clinical data of women with CA-APN who attended 11 hospitals in South Korea from March 2010 to February 2012. RESULTS Of a total of 775 patients, 246 (31.7%) were diabetic and 529 (68.3%) non-diabetic. Fewer of the diabetic patients had flank pain (27.6% vs. 37.2% P = 0.009), symptoms of lower urinary tract infection (57.3% vs. 69.6% P = 0.001) and costovertebral angle tenderness (54.9% vs. 72.2% P < 0.001). However, more of them had C-reactive protein ≥20 mg/dL (40.7% vs. 27.4% P < 0.001), azotemia (29.3% vs. 13.4% P < 0.001) and bacteremia (53.7% vs. 38.2% P < 0.001). Final clinical failure rates and deaths did not differ between the two groups: 6.9% vs. 4.5%, P = 0.169; 2.0% vs. 1.7%, P = 0.747. However, hospitalization was longer in the diabetics than the non-diabetics (median 9.0 days vs. 7.0 days, P < 0.001). In logistic regression, diabetes was independently associated with longer hospitalization (OR 1.7, CI 1.1-2.7, P = 0.011), together with nausea/vomiting, history of admission within 1 year, bacteremia, azotemia, and dementia, as well as extended-spectrum β-lactamase (ESBL)-positivity and fluoroquinolone resistance of uropathogens. CONCLUSIONS CA-APN patients with diabetes have more severe disease manifestations and require longer hospitalization than non-diabetic patients although their clinical findings are less clear than those of non-diabetic patients.

The protective effect of ischemic preconditioning against hepatic ischemic-reperfusion injury under isoflurane anesthesia in rats.

PURPOSE Apoptosis is a central mechanism of ischemic-reperfusion injury (IRI) to the liver. Among the methods to reduce IRI, ischemic preconditioning (IP) has been shown to confer protection. Therefore, the aim of this study was to determine if IP conferred protection against hepatic IRI under isoflurane anesthesia in rats and to investigate underlying protective mechanisms. MATERIALS AND METHODS Twenty-three rats weighing 270 to 300 grams were randomly divided into three groups: (1) the sham operated group (n = 5); (2) the non-IP group (n = 9; 45 minutes of hepatic ischemia followed by 2 hours of reperfusion); and (3) the IP group (n = 9); IP induced by 10 minutes of hepatic ischemia followed by 15 minutes of reperfusion before 45 minutes of prolonged hepatic ischemia). Anesthesia was maintained with isoflurane (1.5%). We compared the degrees of hepatic injury and expressions of B cell lymphoma 2 (Bcl-2) and caspase 3 and 8 mRNAs. RESULTS The IP group showed significantly lower levels of aspartate transaminase and alanine transaminase as well as reduced histological grades of hepatocyte injury compared with the non-IP group at 2 hours after reperfusion. At the corresponding time, the Bcl-2 mRNA level was 2-fold higher in the IP group. Caspase 3 mRNA levels were highest in the non-IP group significantly compared with the sham cohort. Similarly, caspase 8 mRNA levels were highest in the Non_IP group albeit not significancely. CONCLUSION IP protected against hepatic IRI under isoflurane anesthesia in rats. The mechanism of protection appeared to involve upregulation of Bcl-2 expression resulting in inhibited apoptosis.