Sang Yop Shin

Scoring systems for prediction of mortality in patients with intensive care unit-acquired sepsis: a comparison of the Pitt bacteremia score and the Acute Physiology and Chronic Health Evaluation II scoring systems.

This study compares the effectiveness of the Pitt bacteremia score, the Charlson weighted index of comorbidity, and the Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring systems for the prediction of mortality in intensive care unit (ICU) patients with sepsis using the retrospective observational method on 134 patients with ICU-acquired sepsis. The statistical analyses show several important findings. First, Pitt bacteremia score is significantly correlated with the APACHE II scoring system (correlation coefficient = 0.738, P < 0.001). Second, the APACHE II scoring system, the Pitt bacteremia score, and the Charlson weighted index of comorbidity are independently correlated with mortality. Third, the Pitt bacteremia score and the APACHE II scores are positively related to mortality in patients with ICU-acquired sepsis. As the result of the analyses, the mortality rate in patients with sepsis in the ICU is better predicted with the Pitt bacteremia score because it provides better estimation of sensitivity and specificity than the APACHE II scoring system and the Charlson weighted index of comorbidity.

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.

Predominance of an ST11 extended-spectrum β-lactamase-producing Klebsiella pneumoniae clone causing bacteraemia and urinary tract infections in Korea.

To investigate the antimicrobial resistance, extended-spectrum beta-lactamases (ESBLs) and clones of Klebsiella pneumoniae isolates causing bacteraemia or urinary tract infection (UTI) in Korea, a total of 406 K. pneumoniae isolates from patients with bacteraemia (221 isolates) and UTI (185 isolates) were collected from 10 tertiary-care Korean hospitals from July 2006 to October 2007. In vitro antimicrobial susceptibility testing was performed for all isolates and ESBL production was tested. Multilocus sequence typing (MLST) analyses were performed to characterize genotypes of ESBL-producing K. pneumoniae isolates. PFGE was performed for sequence type 11 (ST11) isolates. Forty-seven UTI isolates (25.4 %) produced ESBLs, while 30 bacteraemia isolates (13.6 %) produced ESBLs (P=0.002). Among 77 ESBL-producing isolates, thirty-two (41.6 %) produced SHV-type ESBLs. bla(CTX-M) genes such as bla(CTX-M-14) and bla(CTX-M-15) were detected in 36.4 %. MLST and PFGE analyses showed that ST11 was dominant in ESBL-producing K. pneumoniae isolates causing UTI (57.4 %) and in those causing bacteraemia (70.0 %) and has been prevalent in Korean hospitals. ST11 isolates harbour a combination of different ESBL genes. The ST11 clone of ESBL-producing K. pneumoniae isolates prevails in Korea, but most isolates might acquire ESBL genes independently or several different clones might be distributed in Korea.

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.

Dissemination of ST131 and ST393 community-onset, ciprofloxacin-resistant Escherichia coli clones causing urinary tract infections in Korea

OBJECTIVE Ciprofloxacin-resistant Escherichia coli is growing concern in clinical settings. In this study, we investigated the distribution of virulence determinants and phylogenetic groups among community-onset, ciprofloxacin-resistant E. coli isolates causing urinary tract infections (UTIs) in Korea. In addition, the evidence of clonal spread in the community was also examined. METHODS From November 2006 to August 2007, 543 community-onset E. coli isolates causing UTIs were collected as part of a multicenter surveillance study. In vitro susceptibility testing was performed using broth microdilution method. Distribution of virulence determinants and phylogenetic groupings were examined. In addition, multilocus sequence typing (MLST) analysis was performed. RESULTS In vitro antimicrobial susceptibility testing revealed that 154 isolates (28.4%) were ciprofloxacin-resistant. Of these, 129 ciprofloxacin-resistant E. coli isolates were further characterized. As a result of phylogenetic subgrouping, we found that phylogenetic subgroup D was the most predominant (46 isolates, 35.7%), followed by B2 (44 isolates, 34.1%), A (21 isolates, 16.3%), and B1 (18 isolates, 14.0%). MLST analysis showed 48 sequence types (STs). The most prevalent ST was ST131 (32 isolates, 24.8%), followed by ST393 (23 isolates, 17.8%). While all ST131 isolates belonged to phylogenetic subgroup B2, which is known to be a highly virulent, all ST393 isolates belonged to subgroup D. ST131 and ST393 showed different profiles of virulence factors; papA, papG allele III, and traT genes were significantly more prevalent in ST131 than in ST393 (p values, <0.001). CONCLUSIONS Based on genotyping, it is suggested that epidemic and virulent ciprofloxacin-resistant E. coli clones such as ST131 and ST393 have disseminated in Korea. However, the diversity of CTX-M genes in ST131 isolates may indicate that ESBL genes have been acquired independently or several ESBL-producing, ciprofloxacin-resistant E. coli clones may have disseminated in the Korean community.

Characteristics of carbapenem-resistant Enterobacteriaceae isolates from Korea

In this study, the characteristics of carbapenem-resistant Enterobacteriaceae (CRE) isolates from Korea was investigated. A total of 22 CRE isolates were investigated, and most were identified as Klebsiella pneumoniae (16 isolates). In vitro antimicrobial susceptibility testing, multilocus sequence typing, and pulsed-field gel electrophoresis were performed. Extended-spectrum β-lactamase (ESBL) and carbapenemase genes were detected using gene amplification and sequencing. Efflux pump activity and inactivating mutations in OmpK35/36 were also investigated. Among 22 CRE isolates, only 5 produced metallo-β-lactamases (3 NDM-1, one VIM-2 and one IMP-1). Four and 2 K. pneumoniae and Serratia marcescens isolates showed resistance to polymyxins, respectively, and 2 CRE isolates (1 K. pneumoniae and C. freundii) were resistant to tigecycline. The prevalent carbapenem resistance mechanism found in K. pneumoniae might be porin defects. The most prevalent clone of carbapenem-resistant K. pneumoniae was ST11 (56.3%), which is the most frequently identified clone among ESBL-producing K. pneumoniae isolates from Korea. Three NDM-1-producing K. pneumoniae isolates belonged to a single clone (ST340) despite their different antimicrobial susceptibilities. In the present study, the clonal dissemination of carbapenem-resistant K. pneumoniae isolates (ST11) and NDM-1-producing K. pneumoniae isolates (ST340) was determined. Polymyxin- and tigecycline-resistant CRE isolates were also identified, which limits treatment options for infections causes by these organisms.

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.

Clinical experience of tigecycline treatment in infections caused by extensively drug-resistant Acinetobacter spp.

BACKGROUND Tigecycline has broad spectrum antimicrobial activity and is approved for complicated intra-abdominal infections, complicated skin and soft tissue infections, and community-acquired pneumonia. There are few data on clinical experience of tigecycline in hospital-acquired pneumonia (HAP) and Acinetobacter spp. infection. METHODS A retrospective study was performed at eight hospitals in Korea from May 2009 to January 2010. Adult patients treated with tigecycline regardless of their source of infection or pathogens were enrolled. RESULTS Tigecycline was administered in 108 patients. Pneumonia was the most common infection (43.5%), followed by skin and soft tissue infections (20.4%). Acinetobacter baumannii was isolated from 83 patients (76.9%) accounting for 50.3% of isolated pathogens, showing a resistance rate of 67.5% to carbapenems. Superinfection was identified in 32 patients (29.6%). Pseudomonas aeruginosa was most common microorganism causing superinfection (46.9%). Overall 30-day mortality rate was 52.9%. Thirty-day mortality rate of HAP and Acinetobacter spp. infection was 60.5% and 59.4%, respectively. CONCLUSION Tigecycline can be considered as an alternative therapy in patients with HAP or infections caused by Acinetobacter spp., especially extensively drug-resistant A. baumannii.

Characteristics of community-onset NDM-1-producing Klebsiella pneumoniae isolates.

Multilocus sequence typing and in vitro antimicrobial susceptibility testing were performed for three community-onset New Delhi metallo-β-lactamase-1 (NDM-1)-producing Klebsiella pneumoniae isolates from Korea. The genetic structure surrounding the blaNDM-1 gene was determined in blaNDM-1-harbouring plasmids. Three NDM-1-producing K. pneumoniae isolates were found to belong to the same clone (sequence type 340). Each of these isolates showed the same genetic structure surrounding the blaNDM-1 gene. The genes blaNDM-1, bleMBL, trpF and dsbC were flanked by two intact insertion sequences, ISAba125 and IS26, which may promote horizontal gene transfer. The blaNDM-1-harbouring plasmids conferred antimicrobial resistance to carbapenems, cephalosporins, aminoglycosides and aztreonam in transconjugants. It can be speculated that either the entire blaNDM-1-harbouring plasmids or just the part of the plasmid containing the blaNDM-1 gene may have transferred between K. pneumoniae and Escherichia coli. Following the transfer, the isolate disseminated throughout Korea. This study suggests the need for monitoring the dissemination of NDM-1-producing isolates across countries or continents due to their potential transferability via ISAba125- and IS26-associated transposons.

New Erwinia-Like Organism Causing Cervical Lymphadenitis

ABSTRACT The first case of cervical lymphadenitis due to infection by a new Erwinia-like organism is reported. The organism was identified initially as Pantoea sp. by a Vitek 2-based assessment but was finally identified as a member of the genus Erwinia by 16S rRNA gene sequence analysis. The isolate displayed 98.9% 16S rRNA gene sequence similarity to that of E. tasmaniensis and showed phenotypic characteristics that were different from other Erwinia species.