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Objectives: It is unclear whether the poor outcome of patients with severe vancomycin-resistant enterococci (VRE) infection is attributable to vancomycin resistance or to Enterococcus faecium (Efm), which predominates among VRE., Methods: Retrospective study of a prospectively identified cohort from nationwide surveillance. A cohort of consecutive, nonduplicate episodes of monomicrobial bloodstream infections (BSIs) caused by Efm in 2016 was selected. The primary outcome was all-cause, 30-day, in-hospital mortality. Inverse probability weighting was applied using the propensity score for vancomycin-resistant Efm (VREfm) BSI., Results: A total of 241 Efm BSI episodes were included, of which 59 (24.5%) were VREfm. Patients with VREfm BSI were younger but had similar comorbidities to those with vancomycin-sensitive Efm (VSEfm) BSI. Multivariable logistic regression revealed that younger age, previous piperacillin-tazobactam use, and steroid use were significant risk factors for VREfm BSI, but 30-day in-hospital mortality did not differ significantly between groups (35.6% and 23.6% for VREfm and VSEfm, respectively; odds ratio, 1.79; 95% confidence interval, 0.95-3.37; P = 0.101). However, Cox regression with inverse probability weighting revealed that vancomycin resistance was independently associated with an increased risk of mortality (adjusted hazard ratio, 2.18; 95% confidence interval, 1.03-4.62; P = 0.041)., Conclusion: In patients with Efm BSI, vancomycin resistance was independently associated with mortality., Competing Interests: Declarations of competing interest The authors have no competing interests to declare., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Patients with uncomplicated Staphylococcus aureus primary bacteremia and catheter-related bloodstream infection (CRBSI) should be treated for at least 14 days. However, evidence for oral step-down therapy is lacking in these patients. A retrospective cohort was identified from 2013 to 2018 in a 1,950-bed tertiary hospital. An oral antimicrobial therapy (OAT) group was defined as patients treated with oral antibiotics following less than 10 days of intravenous antimicrobial therapy (IAT). Treatment failure was defined as any case of recurrence or death within 90 days. A total of 103 patients were included in the analysis, including 32 patients treated with OAT. Rates of treatment failure were 3.2% and 12.7% in the OAT and IAT groups ( P  = 0.113). The length of hospital stay was shorter in the OAT group. OAT was not an independent risk factor for treatment failure. OAT may reduce the duration of hospitalization without adverse effects in these patients.

Objectives: Vancomycin and teicoplanin are glycopeptides with activity against Enterococcus faecium. However, studies on the clinical efficacy of teicoplanin are limited. This study aimed to compare the therapeutic efficacy of teicoplanin and vancomycin in E. faecium bacteremia., Methods: We identified patients with bloodstream infections prospectively from July 2015 to December 2016 in 14 hospitals as part of a multicenter nationwide surveillance. Patients with E. faecium monomicrobial bacteremia were selected. Teicoplanin and vancomycin groups included patients treated with either agent for ≥48 hours. The primary outcome was 30-day all-cause in-hospital mortality. The Cox proportional hazards model with inverse probability weighting was used to account for the imbalance in baseline characteristics between the two groups., Results: Among 97 patients with E. faecium bacteremia, 33 (34%) were treated with teicoplanin and 64 (66%) with vancomycin. There were no significant differences in 30-day in-hospital mortality (18.2% vs 26.6%, P = 0.358) and 7-day mortality (6.1% vs 15.6%, P = 0.212). Furthermore, multivariable analysis confirmed that the use of teicoplanin was not significantly associated with mortality (adjusted odds ratio, 0.72; 95% confidence interval, 0.28-1.86; P = 0.494)., Conclusion: We found no significant differences in the clinical outcomes. These findings suggest teicoplanin as a useful alternative to vancomycin., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Purpose: To find pharmacokinetic/pharmacodynamic parameters of vancomycin associated with the optimal outcome of severe infection due to Enterococcus species., Methods: We retrospectively reviewed enterococcal bacteremia cases treated with vancomycin from January 2015 to December 2020. The primary outcome was 30-day mortality. We calculated cutoff values of the ratio of vancomycin area under the concentration-time curve over 24 h to the minimum inhibitory concentration (AUC 24 /MIC) and trough concentration (C trough ) during the initial 72 h of treatment. The optimal cutoff value was determined using the Youden index. Binary variables created based on these cutoffs were further assessed using multivariable analysis., Results: A total of 65 patients were included. The majority (87.7%) had solid or hematologic malignancies. Thirty-day mortality and nephrotoxicity occurred in nine (13.4%) and 14 (21.5%) patients, respectively. Both vancomycin AUC 24 /MIC and C trough showed fair performance in predicting 30-day mortality (AUC of receiver-operator curve for AUC 24 /MIC, 0.712; 95% confidence interval [CI] 0.539-0.886; AUC for C trough , 0.760; 95% CI 0.627-0.892; pairwise AUC comparison: p = 0.570). C trough  ≥ 13.94 μg/mL, but not AUC 24 /MIC ≥ 504, had a significant association with 30-day mortality after adjusting for confounders (odds ratio, 8.40; 95% CI 1.60-86.62; p = 0.010)., Conclusion: Mean C trough  ≥ 13.94 μg/mL during the initial 72 h was associated with higher 30-day mortality in enterococcal bacteremia. Further studies are warranted to elucidate optimal pharmacokinetic targets for enterococcal bacteremia., (© 2022. The Author(s).)

Background: The incidence of Gram-negative bacteraemia is rising globally and remains a major cause of morbidity and mortality. The majority of patients with Gram-negative bacteraemia initially receive intravenous (IV) antibiotic therapy. However, it remains unclear whether patients can step down to oral antibiotics after appropriate clinical response has been observed without compromising outcomes. Compared with IV therapy, oral therapy eliminates the risk of catheter-associated adverse events, enhances patient quality of life and reduces healthcare costs. As current management of Gram-negative bacteraemia entails a duration of IV therapy with limited evidence to guide oral conversion, we aim to evaluate the clinical efficacy and economic impact of early stepdown to oral antibiotics., Methods: This is an international, multicentre, randomised controlled, open-label, phase III, non-inferiority trial. To be eligible, adult participants must be clinically stable / non-critically ill inpatients with uncomplicated Gram-negative bacteraemia. Randomisation to the intervention or standard arms will be performed with 1:1 allocation ratio. Participants randomised to the intervention arm (within 72 h from index blood culture collection) will be immediately switched to an oral fluoroquinolone or trimethoprim-sulfamethoxazole. Participants randomised to the standard arm will continue to receive IV therapy for at least 24 h post-randomisation before clinical re-assessment and decision-making by the treating doctor. The recommended treatment duration is 7 days of active antibiotics (including empiric therapy), although treatment regimen may be longer than 7 days if clinically indicated. Primary outcome is 30-day all-cause mortality, and the key secondary outcome is health economic evaluation, including estimation of total healthcare cost as well as assessment of patient quality of life and number of quality-adjusted life years saved. Assuming a 30-day mortality of 8% in the standard and intervention arms, with 6% non-inferiority margin, the target sample size is 720 participants which provides 80% power with a one-sided 0.025 α-level after adjustment for 5% drop-out., Discussion: A finding of non-inferiority in efficacy of oral fluoroquinolones or trimethoprim-sulfamethoxazole versus IV standard of care antibiotics may hypothetically translate to wider adoption of a more cost-effective treatment strategy with better quality of life outcomes., Trial Registration: ClinicalTrials.gov NCT05199324 . Registered 20 January 2022., (© 2022. The Author(s).)

Objective: To evaluate the impact of a vancomycin-resistant Enterococcus (VRE) screening policy change on the incidence of healthcare-associated (HA)-VRE bacteremia in an endemic hospital setting., Design: A quasi-experimental before-and-after study., Setting: A 1,989-bed tertiary-care referral center in Seoul, Republic of Korea., Methods: Since May 2010, our hospital has diminished VRE screening for admitted patients transferred from other healthcare facilities. We assessed the impact of this policy change on the incidence of HA-VRE bacteremia using segmented autoregression analysis of interrupted time series from January 2006 to December 2014 at the hospital and unit levels. In addition, we compared the molecular characteristics of VRE blood isolates collected before and after the screening policy change using multilocus sequence typing and pulsed-field gel electrophoresis., Results: After the VRE screening policy change, the incidence of hospital-wide HA-VRE bacteremia increased, although no significant changes of level or slope were observed. In addition, a significant slope change in the incidence of HA-VRE bacteremia (change in slope, 0.007; 95% CI, 0.001-0.013; P = .02) was observed in the hemato-oncology department. Molecular analysis revealed that various VRE sequence types appeared after the policy change and that clonally related strains became more predominant (increasing from 26.1% to 59.3%)., Conclusions: The incidence of HA-VRE bacteremia increased significantly after VRE screening policy change, and this increase was mainly driven by high-risk patient populations. When planning VRE control programs in hospitals, different approaches that consider risk for severe VRE infection in patients may be required.

Background: Sequence type (ST) 17 vancomycin-resistant Enterococcus faecium (VREF) is frequently isolated in nosocomial settings. The aim of this study was to identify whether ST17 contributes to subsequent bacteremia more often than other STs among hospitalized patients carrying VREF., Methods: A retrospective cohort study was conducted in patients carrying ST17 VREF and those with non-ST17 VREF. Rectal screening according to hospital policy was used to identify patients with VREF. Subsequent VREF bacteremia events within a year of detection of colonization were recorded. Cox regression analysis was used to adjust the covariates involved in determining the association between ST17 and subsequent bacteremia events., Results: The cohorts comprised 52 patients with ST17 and 169 patients with non-ST17 VREF. One-year VREF bacteremia-free rates were 85.9% and 90.2%, respectively. In multivariate analysis, ST17 was associated with subsequent bacteremia at an adjusted hazard risk (aHR) of 4.02 (95% confidence interval [CI], 1.32-12.29). Liver transplantation (aHR, 40.08; 95% CI, 4.87-329.76) and hematologic malignancy (aHR, 20.97; 95% CI, 4.87-87.82) were also significant. All cases of subsequent bacteremia in ST17 VREF carriers were caused by ST17; however, subsequent bacteremia in non-ST17 carriers was often caused by ST17 or another ST variant., Conclusions: A specific genotype, ST17 is a predictor of subsequent bacteremia in hospitalized patients carrying VREF. Patients with a hematologic malignancy and those receiving a liver transplant are also at high risk. More targeted strategies may be needed to prevent VREF infection in hospitals., (© 2021. The Author(s).)

Abstract: Uncomplicated bacteremia and catheter-related bloodstream infection (CRBSI) are frequently suggested as factors associated with low risk of infective endocarditis in Staphylococcus aureus bacteremia (SAB). Nevertheless, guidelines recommend that echocardiography in all patients with SAB. We evaluated the effects of echocardiography on patient outcomes. Patients with uncomplicated S. aureus CRBSI were retrospectively identified between January 2013 and June 2018 at a 1950-bed, tertiary-care university hospital. Treatment failure was defined as any case of relapse or all-cause death within 90 days. Of 890 SAB patients, 95 with uncomplicated S. aureus CRBSI were included. Thirty-two patients underwent echocardiography within 30 days of their first positive blood culture. Two patients who underwent echocardiography revealed right-sided infective endocarditis. One patient who did not undergo echocardiography experienced recurrent SAB (peripheral CRBSI) 85 days after his first positive blood culture. There were no SAB-related deaths. The Kaplan-Meier curves of treatment failure showed no significant differences between patients who did and did not undergo echocardiography (P = .77). In multivariable analysis, risk factors for treatment failure were liver cirrhosis (hazard ratio: 9.60; 95% confidence interval: 2.13-43.33; P = .003) and other prostheses (hazard ratio: 63.79; 95% confidence interval: 5.05-805.40; P = .001). This study did not verify the putative association between treatment failure and implementation of echocardiography in patients with uncomplicated S. aureus CRBSI. Given the low observed rates of adverse outcomes, routine echocardiography might not be obligatory and could be performed on an individual basis., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Bloodstream infection (BSI) is a common complication after living-donor liver transplantation (LDLT). Some patients develop recurrent BSIs. We evaluated the impacts of early recurrent BSIs (ER-BSIs) on outcomes in LDLT recipients. LDLT cases between 2008 and 2016 were included. Early BSI (E-BSI) was defined as a BSI event that occurred within 2 months after LDLT. ER-BSIs were defined as new-onset BSIs within 2 months due to another pathogen at a ≥ 48-h interval or a relapse of BSIs by the same pathogen at a ≥ 1-week interval, with negative cultures in between. The primary objective was evaluating the all-cause mortality of each group of LDLT recipients (90 days and 1 year). The secondary objectives were analyzing associated factors of each all-cause mortality and risk factors for early single BSI and ER-BSI. Among 727 LDLT recipients, 108 patients experienced 149 events of E-BSI with 170 isolated pathogens. Twenty-eight patients (25.9%, 28/108) experienced ER-BSI. The 1-year survival rates of patients without BSI, with early single BSI event, and with ER-BSIs were 92.4%, 81.3%, and 28.6%, respectively. ER-BSI was the most significant risk factor for 1-year mortality (adjusted HR = 5.31; 95% CI = 2.27-12.40). Intra-abdominal and/or biliary complications and early allograft dysfunction were risk factors for both early single BSI and ER-BSI. Interestingly, longer cold ischemic time and recipient operative time were associated with ER-BSI. LDLT recipients with ER-BSI showed very low survival rates accompanied by intra-abdominal complications. Clinicians should prevent BSI recurrence by being aware of intra-abdominal complications.

Background: Clinically relevant categorization of antimicrobial resistance is critical to mitigating the threat it poses. Difficult-to-treat resistance (DTR) is a recently proposed category defined as nonsusceptibility to all first-line antibiotic agents., Methods: A retrospective study was conducted with nonduplicate cases of gram-negative bloodstream infection (GNBSI) caused by 4 major taxa (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter species) identified from a nationwide surveillance database. DTR was defined as nonsusceptibility to all the β-lactams and fluoroquinolones tested. Patient characteristics and mortality were compared between DTR GNBSI and GNBSI caused by carbapenem-resistant but not DTR and extended-spectrum cephalosporin-resistant but not DTR isolates using Centers for Disease Control and Prevention definitions. Adjusted odds ratios (aORs) for 30-day in-hospital mortality were examined for DTR in overall and in propensity score-matched cohorts., Results: A total of 1167 episodes of monomicrobial GNBSI were identified, and 147 (12.6%) of the isolates were DTR. The majority of DTR isolates were Acinetobacter species (79.6%) and P. aeruginosa (17.7%). DTR infections were associated with previous antibiotic use, healthcare contact, ventilator use, and lower respiratory tract infection. Crude mortality for GNBSI caused by DTR was 50.3%. A multivariable model showed that only DTR, but not other categories, was significantly associated with mortality (adjusted odds ratio [aOR], 3.58 [95% confidence interval {CI}, 1.27-10.19]). DTR was also a significant predictor for mortality in the analysis of propensity score-matched cohorts (aOR, 3.48 [95% CI, 1.82-6.79])., Conclusions: In patients with GNBSI, DTR was associated with higher mortality than those in other resistance categories. Our findings suggest that DTR could be useful for surveillance and prognostication., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background/aims: Methicillin-resistant Staphylococcus aureus (MRSA) is highly prevalent in hospitals, and has recently emerged in the community. The impact of methicillin-resistance on mortality and medical costs for patients with S. aureus bacteremia (SAB) requires reevaluation., Methods: We searched studies with SAB or endocarditis using electronic databases including Ovid-Medline, Embase-Medline, and Cochrane Library, as well as five local databases for published studies during the period January 2000 to September 2011., Results: A total of 2,841 studies were identified, 62 of which involved 17,563 adult subjects and were selected as eligible. A significant increase in overall mortality associated with MRSA, compared to that with methicillin-susceptible S. aureus (MSSA), was evidenced by an odds ratio (OR) of 1.95 (95% confidence interval [CI], 1.73 to 2.21; p < 0.01). In 13 endocarditis studies, MRSA increased the risk of mortality, with an OR of 2.65 (95% CI, 1.46 to 4.80). When three studies, which compared mortality rates between CA-MRSA and CA-MSSA, were combined, the risk of methicillin-resistance increased 3.23-fold compared to MSSA (95% CI, 1.25 to 8.34). The length of hospital stay in the MRSA group was 10 days longer than that in the MSSA group (95% CI, 3.36 to 16.70). Of six studies that reported medical costs, two were included in the analysis, which estimated medical costs to be $9,954.58 (95% CI, 8,951.99 to 10,957.17)., Conclusion: MRSA is still associated with increased mortality, longer hospital stays and medical costs, compared with MSSA in SAB in studies published since the year 2000.

The need for mandatory confirmation of negative conversion in bacteremic urinary tract infection (UTI) has not been adequately addressed, even though follow-up blood cultures (FUBCs) are still prescribed liberally. The purpose of this study was to identify possible risk factors associated with positive FUBCs. We retrospectively collected data on adult cases of bacteremic UTI with at least one FUBC. Patients were divided into the negative FUBCs and the positive FUBC group, and data of both groups were compared. Of 306 cases of bacteremic UTI, 251 had a negative result from an FUBC and 55 had a positive result. Diabetes mellitus, malignancy, complicated UTI, and initial intensive care unit (ICU) admission were significantly more common in the positive FUBC group than in the negative group (all-P < 0.05). Time to defervescence was significantly longer in the positive FUBC group than in the negative group (52.2 h vs. 25.3 h, P < 0.05). A multivariate analysis showed that malignancy, initial ICU admission, CRP > 16 (mg/dL), and a time to defervescence of more than 48 h were significant factors associated with a positive FUBC. No subsequent cases of bacteremia developed in patients without risk factors associated with a positive FUBC. In bacteremic UTIs, patients with positive FUBCs usually present with higher initial inflammatory markers, longer time to defervescence, more frequent ICU admission rates, and an elevated chance of having cancer. More careful clinical assessment before drawing FUBCs would reduce costs and inconvenience to patients.

We investigated the antimicrobial susceptibility, the genotypic distributions of extended-spectrum β-lactamase (ESBL) and AmpC genes, and the molecular epidemiology of AmpC-producing Klebsiella pneumoniae (AmpC-KP) isolates causing bacteremia. Among 260 K. pneumoniae clinical isolates included in this study, plasmid-mediated AmpC β-lactamases were found in 20.7% (54/260), which included DHA-1 (96.3%, 52/54), CMY-2 (3.7%, 2/54), and CMY-10 (1.9%, 1/54). One isolate also produced DHA-1 along with CMY-2. Of the 54 AmpC-KP isolates, 31 isolates (57.4%) showed ESBL positivity. Of these 31 isolates with coproduction of ESBL and AmpC β-lactamases, 25 isolates (80.6%) produced CTX-M-15 in addition to DHA-1. Nine isolates (29.0%) were nonsusceptible to imipenem. The most prevalent sequence type (ST) was ST11 (n = 31, 57.4%), followed by ST2361 (n = 5, 9.3%), which was newly identified in this study, and ST48 (n = 4, 7.4%). K. pneumoniae isolates coproducing DHA-1 and CTX-M-15 have emerged and disseminated in Korean hospitals, even in blood isolates causing bacteremia. Such infections may become a challenge for clinicians because there is a severely restricted range of available therapeutic options for these pathogens.

Introduction: During recent decades, the rates of multidrug resistance, including resistance to carbapenems, have increased dramatically among Acinetobacter species. Tigecycline has activity against multidrug-resistant Acinetobacter spp, including carbapenem-resistant isolates. However, reports of tigecycline-resistant Acinetobacter spp are emerging from different parts of the world. The purpose of this study was to evaluate potential risk factors associated with tigecycline non-susceptible Acinetobacter bacteremia., Methods: The medical records of 152 patients with Acinetobacter bacteremia attending Samsung Medical Center between January 2010 and December 2014 were reviewed. Non-susceptibility to tigecycline was defined as a minimum inhibitory concentration (MIC) of tigecycline ≥4μg/ml. Cases were patients with tigecycline non-susceptible Acinetobacter bacteremia and controls were those with tigecycline-susceptible Acinetobacter bacteremia., Results: Of the 152 patients included in the study, 61 (40.1%) had tigecycline non-susceptible Acinetobacter bacteremia (case group). These patients were compared to 91 patients with tigecycline-susceptible Acinetobacter bacteremia (control group). The case group showed high resistance to other antibiotics (>90%) except colistin (6.6%) and minocycline (9.8%) when compared to the control group, which exhibited relatively low resistance to other antibiotics (<50%). Multivariate analysis showed that recent exposure to corticosteroids (minimum 20mg per day for more than 5 days within 2 weeks) (adjusted odds ratio (OR) 2.887, 95% confidence interval (CI) 1.170-7.126) and carbapenems (within 2 weeks) (adjusted OR 4.437, 95% CI 1.970-9.991) were significantly associated with tigecycline non-susceptible Acinetobacter bacteremia. Although prior exposure to tigecycline was more common in the case group than in the control group (9.8%, 6/61 vs. 2.2%, 2/91; p=0.046), this variable was found not to be a significant factor associated with tigecycline non-susceptibility after adjustment for other variables (adjusted OR 1.884, 95% CI 0.298-11.920; p=0.501)., Conclusions: These data suggest that tigecycline non-susceptible Acinetobacter spp have emerged and disseminated in the hospital in association with a recent exposure to carbapenems and an immunosuppressed state. This indicates that the rational use of antibiotics through a comprehensive antimicrobial stewardship program, especially in immunosuppressed patients, may be essential in limiting the emergence and spread of multidrug-resistant organisms such as tigecycline-resistant Acinetobacter spp, which are difficult to treat., (Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

With the increasing use of carbapenems, carbapenem-resistant Gram-negative bacteria have become a major concern in health care-associated infections. The present study was performed to evaluate the clinical and microbiological features of breakthrough Gram-negative bacteremia (GNB) during carbapenem therapy and to assess risk factors for development of breakthrough GNB. A case-control study was performed at a tertiary hospital from 2005 to 2014. Case patients were defined as individuals whose blood cultures grew Gram-negative bacteria while the patients were receiving carbapenems for at least 48 h before breakthrough GNB. Age-, sex-, and date-matched controls were selected from patients who received carbapenem for at least 48 h and did not develop breakthrough GNB during carbapenem treatment. A total of 101 cases of breakthrough GNB were identified and compared to 100 controls. The causative microorganisms for breakthrough GNB were Stenotrophomonas maltophilia (n = 33), Acinetobacter baumannii (n = 32), Pseudomonas aeruginosa (n = 21), and others (n = 15). Approximately 90% of S. maltophilia isolates were susceptible to levofloxacin and trimethoprim-sulfamethoxazole. The most common infection types were primary bacteremia (38.6%) and respiratory infections (35.6%). More than half of the patients died within a week after bacteremia, and the 30-day mortality rate was 70.3%. In a multivariate analysis, a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization by causative microorganisms were significantly associated with breakthrough GNB. Our data suggest that S. maltophilia, A. baumannii, and P. aeruginosa are the major pathogens of breakthrough GNB during carbapenem therapy, in association with a longer hospital stay, hematologic malignancy, persistent neutropenia, immunosuppressant use, and previous colonization., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Among 127 Stenotrophomonas maltophilia isolates causing bacteremia, 41 (32.3%) were nonsusceptible to levofloxacin, in which four sequence types and 24 diverse allelic profiles were detected. The most prevalent ST was ST77 (n = 8, 19.5%), followed by ST28 (n = 3, 7.3%). Amino acid substitutions were found in the gyrB and parC genes of 10 and 1 isolates, respectively. No amino acid substitutions were identified in gyrA. Twenty-three (56.1%) isolates showed amino acid substitutions in the parE gene. These results suggest that quinolone resistance-determining regions of parE may not be the primary targets, but an important determining factor of high levels of fluoroquinolone resistance., (Copyright © 2016 Elsevier Inc. All rights reserved.)

We evaluated the molecular epidemiology and microbiological characteristics of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) isolates that cause bacteremia in Korean hospitals, focusing especially on ST131. Our data suggest that ST131 isolates possessed more virulence traits and showed more multidrug resistance patterns than non-ST131 isolates. Among CTX-M-15 producers, the frequency of serum resistance was significantly higher in ST131 than in non-ST131. As in other parts of the world, the ESBL-EC ST131 clone has emerged and disseminated in both community and hospital settings in Korea, including in blood isolates in patients with bacteremia., (Copyright © 2016 Elsevier Inc. All rights reserved.)

We evaluated the in vitro activity of various antimicrobials alone and in combination against 291 extended-spectrum-β-lactamase-producing Escherichia coli (ESBL-EC) isolates causing bacteremia in South Korean hospitals. Ceftazidime, cefepime, and piperacillin-tazobactam in combination with amikacin showed greater activity than found in combination with ciprofloxacin. In settings with a high prevalence of ESBL-producing pathogens, combination aminoglycoside antimicrobial therapy, especially with amikacin, may be considered for empirical therapy against suspected Gram-negative sepsis as a carbapenem-saving strategy., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

A 61-year-old man with chronic hepatitis B and dyslipidemia visited the emergency department with a fever and severe headache. He was diagnosed with bacterial meningitis after a lumbar puncture, and blood culture revealed Parvimonas micra bacteremia. Although he had a history of extraction of a molar two weeks before symptom onset, there was no evidence of abscess formation on physical examination or imaging studies. He was successfully treated with oral metronidazole for 12 days after 9 days of treatment with IV ceftriaxone and vancomcycin. This is the first report of primary bacterial meningitis caused by this organism, which indicates that this organism is capable of being a bacterial meningitis pathogen., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Despite the remarkable emergence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli sequence type 131 (ST131), the clinical features and outcomes of infections caused by ST131 remain poorly described. From 2011 to 2012, we collected ESBL-producing E. coli isolates from patients with bloodstream infections in 13 hospitals in Korea and compared clinical characteristics and outcomes between ST131 and non-ST131 clones. Of the 110 ESBL-producing isolates, the most common ST was ST131 (30.9%). Multivariate analysis showed that recent operation was the only variable associated with the ST131 clone; other comorbid conditions and clinical features were similar between ST131 and non-ST131 clones. CTX-M-14 and CTX-M-15 were the predominant types of ESBLs, and CTX-M-15 was significantly associated with ST131. The rate of nonsusceptibility to ciprofloxacin was higher in ST131 than in non-ST131 clones (94.1% vs. 75.0%). No significant differences in 30-day mortality rates were found between ST131 and non-ST131 clones. Multivariate analysis revealed that older age (odds ratio [OR]=5.39, 95% confidence interval [CI] 1.22-23.89; p=0.027), nosocomial infection (OR=4.81, 95% CI 1.15-20.15; p=0.032), and higher Pitt bacteremia score (OR=7.26, 95% CI 1.41-37.42; p=0.018) were independent risk factors for 30-day mortality. The ESBL-producing E. coli ST131 clone has emerged and disseminated in Korea. Our findings reveal similarities in clinical and demographic characteristics between ST131 and non-ST131 clones. Although a more resistant profile has been detected in ST131, patients with the ST131 clone did not exhibit a higher mortality rate.

Purpose: Bacillus species have been frequently reported in recent decades as true pathogens among cancer patients. The purpose of this study was to evaluate the clinical features and risk factors of Bacillus bacteremia among adult patients with cancer., Methods: A case-control study was performed to identify the risk factors of Bacillus bacteremia among adult patients with cancer at a 1,950-bed tertiary care university hospital. Electronic medical records were reviewed for individuals who were diagnosed with Bacillus bacteremia during the period of January 1995 through December 2012. Each case was matched to two controls with cancer and non-Bacillus bacteremia. Logistic regression model was used to identify independent risk factors for Bacillus bacteremia development., Results: A total of 86 patients with Bacillus bacteremia were included and compared with 172 control patients. The presence of a central venous catheter and use of extended-spectrum cephalosporin within 1 month were identified to be independent risk factors for the development of Bacillus bacteremia. Hospital stays longer than 14 days, a history of hematopoietic stem cell transplantation, and prior use of glycopeptides had a negative association., Conclusions: The presence of a central venous catheter and prior use of extended-spectrum cephalosporin within 1 month were independent risk factors for the development of Bacillus bacteremia in adult cancer patients.

Treatment of Enterobacter infection is complicated due to its intrinsic resistance to cephalosporins. Medical records of 192 adults with cancer who had Enterobacter bacteremia were analyzed retrospectively to evaluate the risk factors for and the treatment outcomes in extended-spectrum cephalosporin (ESC)-resistant Enterobacter bacteremia in adults with cancer. The main outcome measure was 30-day mortality. Of the 192 patients, 53 (27.6%) had bloodstream infections caused by ESC-resistant Enterobacter species. Recent use of a third-generation cephalosporin, older age, tumor progression at last evaluation, recent surgery, and nosocomial acquisition were associated with ESC-resistant Enterobacter bacteremia. The 30-day mortality rate was significantly higher in the resistant group. Multivariate analysis showed that respiratory tract infection, tumor progression, septic shock at presentation, Enterobacter aerogenes as the culprit pathogen, and diabetes mellitus were independent risk factors for mortality. ESC resistance was significantly associated with mortality in patients with E. aerogenes bacteremia, although not in the overall patient population., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Patients with cancer can be vulnerable to infection with antimicrobial-resistant pathogens such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. A cohort study was performed to evaluate the epidemiology and impact of ESBL-producing Escherichia coli (ESBL-EC) bacteraemia on the outcomes of adult patients with cancer. During the 2.5-year study period, a total of 350 cases of E. coli bacteraemia were documented in cancer patients, of which 95 (27.1%) were due to ESBL-EC. Significant factors associated with ESBL-EC bacteraemia were liver disease, immunosuppressant use, recent surgery, and prior use of cephalosporins or fluoroquinolones. The overall 30-day mortality rate was 14.9% (52/350), and the mortality rate was higher in patients with ESBL-EC than in those without ESBL-EC (22.1% vs.12.2%; P=0.02). Multivariate analysis showed that ESBL-EC was an independent risk factor for mortality (odds ratio=3.01, 95% confidence interval 1.45-6.28; P=0.003), along with the presence of septic shock, mechanical ventilation, the severity of underlying diseases, and pneumonia as a source of bacteraemia. Of the 69 isolates in which ESBLs and their molecular relationships were studied, 68 (98.6%) produced CTX-M-type and 51 (73.9%) produced CTX-M-14 and/or CTX-M-15. Twenty-four sequence types (STs) were identified among CTX-M-14- and CTX-M-15-producing E. coli isolates, with ST131 being the most prevalent (12/51; 23.5%). In conclusion, this study confirms that CTX-M-producing E. coli and ST131, which have been shown to be an emerging public health threat, are widely prevalent in cancer patients and can adversely affect the outcome of E. coli bacteraemia in these patients., (Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)

Background: Acute pyelonephritis (APN) is one of the most common community-acquired infections and frequently accompanies bacteremia. The purpose of this study was to investigate the diagnostic role of procalcitonin in predicting bacteremia in patients with APN., Methods: We conducted a retrospective study of patients with APN who visited the emergency department (ED) at Samsung Medical Center, Seoul. Predictors of bacteremia were analyzed and receiver operating characteristics (ROC) curves were plotted for procalcitonin, C-reactive protein (CRP), and leukocytes., Results: During the study period, a total of 147 patients who had microbiologically proven APN and available initial procalcitonin concentrations were identified. Of these, bacteremia was present in 84 patients. Multivariate analysis showed that age, hypotension, and higher procalcitonin concentrations independently predicted the presence of bacteremia. Procalcitonin had better discriminative power than CRP, as reflected by area under the ROC curve analysis (0.746 [95% CI, 0.667-0.826] vs. 0.602 [95% CI, 0.509-0.694], p = 0.02). At a cut-off value of 1.63 μg/L, procalcitonin predicted bacteremia with a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 61.9, 81.0, 81.3, 61.4 and 70.1%, respectively., Conclusion: Procalcitonin concentration could be used as a reliable marker to predict bacteremia in patients with APN in the ED.

Antimicrobial susceptibility data for all microorganisms isolated from blood culture were collected from 13 institutions in Korea from June to September 2011. Data were compared with our previous studies performed during 2006-2007 and 2008. The prevalence of MRSA in 2011 has rebounded to 63.7% after a slight decrease in 2008. Vancomycin-resistant Enterococcus faecium declined to 24.1%. The resistance rates of Acinetobacter baumannii to imipenem and meropenem increased from 25.4% and 28.8% to 55.4% and 37.5%, respectively. Ciprofloxacin resistance of Escherichia coli has increased from 23.9% to 30.8%. The resistance rate of Klebsiella pneumoniae to ciprofloxacin has increased from 17.7% to 26.5%. Extended spectrum beta-lactamase-producing E. coli and K. pneumoniae have also seen increased levels of resistance, from 8.6% to 18.4% and 13.6% to 28.5%, respectively. An overall increase in antimicrobial resistance among gram-negative pathogens has been observed. Continued surveillance and intervention to slow the propagation of resistance are necessary., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: Although extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli has emerged as a significant pathogen, there is little information regarding treatment outcomes in community-onset bacteremia due to ESBL E. coli. The purpose of this study was to evaluate treatment outcomes of community-onset bacteremia caused by ESBL-producing E. coli and the factors associated with mortality., Methods: A retrospective cohort study was performed, including 92 adult patients with community-onset bacteremia caused by ESBL-producing E. coli., Results: The 30-day mortality rate was 10.9% (10/92). Independent risk factors for mortality were underlying liver disease and severity of illness (e.g., high Pitt bacteremia score, the presence of severe sepsis or septic shock; p < 0.05). Mortality in patients receiving inappropriate initial antimicrobial therapy was not significantly higher than mortality in those receiving appropriate empirical antimicrobial therapy (10.9 vs 10.7%; p = 0.975), if antimicrobial therapy was adjusted appropriately according to susceptibility results. Carbapenems, piperacillin/tazobactam, fluoroquinolones, and amikacin were the most effective antibiotics for community-onset bacteremia caused by ESBL-producing E. coli, although susceptibility profiles confirmed that alternatives to carbapenems are limited. Of 68 isolates in which the ESBLs and their molecular relationships were studied, all isolates produced ESBLs from the CTX-M family (CTX-M-14, 30 isolates; CTX-M-15, 22; and other CTX-M, 16)., Conclusions: In patients with community-onset bacteremia caused by ESBL-producing E. coli, severe sepsis and underlying liver disease were significantly associated with mortality, and a delay in appropriate antimicrobial therapy was not associated with a higher mortality if therapy was adjusted appropriately according to the susceptibility results.

Although extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) has emerged as a significant community-acquired pathogen, there is little epidemiological information regarding community-onset bacteremia due to ESBL-EC. A retrospective observational study from 2006 through 2011 was performed to evaluate the epidemiology of community-onset bacteremia caused by ESBL-EC. In a six-year period, the proportion of ESBL-EC responsible for causing community-onset bacteremia had increased significantly, from 3.6% in 2006 to 14.3%, in 2011. Of the 97 clinically evaluable cases with ESBL-EC bacteremia, 32 (33.0%) were further classified as healthcare-associated infections. The most common site of infection was urinary tract infection (n=35, 36.1%), followed by biliary tract infections (n=29, 29.9%). Of the 103 ESBL-EC isolates, 43 (41.7%) produced CTX-M-14 and 36 (35.0%) produced CTX-M-15. In the multilocus sequence typing (MLST) analysis of 76 isolates with CTX-M-14 or -15 type ESBLs, the most prevalent sequence type (ST) was ST131 (n=15, 19.7%), followed by ST405 (n=12, 15.8%) and ST648 (n=8, 10.5%). No significant differences in clinical features were found in the ST131 group versus the other group. These findings suggest that epidemic ESBL-EC clones such as CTX-M-14 or -15 type ESBLs and ST131 have disseminated in community-onset infections, even in bloodstream infections, which are the most serious type of infection.

Objective: This study was performed to identify risk factors for the development of bacteremic pneumonia and to evaluate the impact of bacteremia on the outcome of pneumococcal pneumonia., Methods: Using a database from a surveillance study of community-acquired pneumococcal pneumonia, we compared data of the bacteremic group with that of the non-bacteremic group., Results: Among 981 adult patients with pneumococcal pneumonia, 114 (11.6%) patients who had documented pneumococcal bacteremia were classified into the bacteremic group. In a multivariable analysis, use of immunosuppressant drugs, younger age (<65 years), and DM were independent risk factors associated with the development of bacteremic pneumonia among patients with pneumococcal pneumonia (all P < 0.05). The mortality rate was significantly higher in the bacteremic group than in the non-bacteremic group (28.6% vs. 8.5%; P < 0.001). The multivariable analysis revealed that concomitant bacteremia was one of the significant risk factors associated with mortality (OR, 2.57; 95% CI, 1.24-5.29), along with cerebrovascular disease and presentation with septic shock (all P < 0.05)., Conclusions: Bacteremia was a common finding in pneumococcal pneumonia and was associated with a higher mortality rate. Several clinical variables may be useful for predicting bacteremic pneumonia among patients with pneumococcal pneumonia., (Copyright © 2012. Published by Elsevier Ltd.)

The emergence of antimicrobial resistance threatens the successful treatment of pneumococcal infections. Here we report a case of bacteremic pneumonia caused by an extremely drug-resistant strain of Streptococcus pneumoniae, nonsusceptible to at least one agent in all classes but vancomycin and linezolid, posing an important new public health threat in our region.

Objectives: The aim of this study was to more precisely delineate the characteristics and outcomes of bloodstream infections in adult cancer patients., Methods: Using a database for nationwide surveillance of bacteremia, we analyzed data related to bacteremia in adult patients with cancer in order to evaluate clinical features and outcomes and to define predictive factors for mortality., Results: Of 1,246 patients, 896 (71.9%) had solid tumors, 328 (26.3%) had hematologic malignancies, and 22 (1.8%) had both. The following conditions were more common in the neutropenic group than in the non-neutropenic group: nosocomial acquisition, hematologic malignancy, corticosteroid use, immunosuppressant use, primary bacteremia, and pneumonia (all P < 0.05). The infections were caused by Gram-negative bacilli in 55.6% and by Gram-positive cocci in 32.7%. Gram-negative pathogens were more frequently isolated from neutropenic patients than from non-neutropenic patients (61.9% vs. 53.5%, P = 0.010), with a significant predominance of Escherichia coli and Klebsiella pneumoniae. Among 1,001 patients whose outcomes could be evaluated, the overall 30-day mortality rate was 24.1%, and multivariate analysis showed that Staphylococcus aureus bacteremia was a significant factor associated with mortality (odds ratio (OR), 1.80; 95% confidence interval (CI), 1.03-3.15), along with nosocomial acquisition, pneumonia, severe sepsis or septic shock, and higher Pitt bacteremia score (all P values <0.05)., Conclusion: This study represents the comprehensive assessment of bloodstream infections in neutropenic versus non-neutropenic cancer patients. Given the pathogenic significance of S. aureus bacteremia in adult patients with cancer, additional strategies for the management of S. aureus bacteremia in cancer patients are needed to improve outcomes.

Increasing multidrug resistance (MDR) among extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae (ESBL-EK) is of a great concern, because the therapeutic options are severely limited. Thus, we performed a case-control study to evaluate risk factors for MDR among nosocomial bacteremia caused by ESBL-EK. All adult patients with ESBL-EK bacteremia from January 2009 through December 2010 were identified at our institution. MDR was defined as ESBL-EK that demonstrated in vitro resistance to trimethoprim-sulfamethoxazole (TMP-SMX), fluoroquinolone (FQ), and gentamicin. Case patients were those with an MDR ESBL-EK isolate, and control patients were those with a non-MDR ESBL-EK isolate. Among a total of 123 ESBL-EK isolates (74 [60.2%] E. coli and 49 [39.8%] K. pneumoniae) causing nosocomial bacteremia, 33 (26.8%) cases were due to MDR ESBL-EK. In a univariate analysis, the factors significantly associated with acquisition of MDR ESBL-EK were neutropenia, immunosuppressant use, urinary tract infection, and prior use of antibiotics, especially FQ (all p<0.05). A multivariable analysis showed that a prior receipt of FQ (odds ratio [OR]=2.93; 95% confidence interval [CI]=1.07-8.01; p=0.036), percutaneous tube insertion (OR=4.04; 95% CI=1.56-10.75; p=0.005), and neutropenia (OR=4.22; 95% CI=1.56-11.45; p=0.005) were independent risk factors for MDR among ESBL-EK bacteremia in hospitalized patients. The CTX-M-15 enzyme was predominant in both the MDR ESBL-EK and non-MDR ESBL-EK groups (55% [11/20] vs. 55.6% [15/27]). Our data suggest that strategies designed to reduce MDR in ESBL-EK bacteremia should focus on limiting the use of FQ and minimizing invasive procedures such as tube insertion.

The identification of clinical characteristics that could identify patients at high risk for Pseudomonas aeruginosa or Acinetobacter baumannii bacteremia would aid clinicians in the appropriate management of these life-threatening conditions, especially in patients admitted to the emergency department (ED) with community-onset infections. To determine clinical risk factors for P. aeruginosa or A. baumannii bacteremia in patients with community-onset gram-negative bacteremia (GNB), a post hoc analysis of a nationwide bacteremia surveillance database including patients with microbiologically documented GNB was performed. Ninety-six patients with P. aeruginosa or A. baumannii bacteremia were compared with 1230 patients with Escherichia coli or Klebsiella pneumoniae bacteremia. A solid tumor or hematologic malignancy was more likely to be associated with P. aeruginosa or A. baumannii bacteremia, whereas concurrent neurologic disease was less frequently seen. In regards to the site of infection, pneumonia was more common in P. aeruginosa or A. baumannii bacteremia, whereas a urinary tract infection was less frequently seen. Factors associated with P. aeruginosa or A. baumannii bacteremia in multivariate analysis included pneumonia (odds ratio [OR], 3.60; 95% confidence interval [CI], 1.86-6.99), hematologic malignancy (OR, 2.71; 95% CI, 1.26-5.84), male sex (OR, 2.17; 95% CI, 1.31-3.58), solid tumor (OR, 1.89; 95% CI, 1.15-3.12), and health-care-associated infection (OR, 1.88; 95% CI, 1.48-2.41). Our data suggest that an initial empirical antimicrobial coverage of P. aeruginosa or A. baumannii bacteremia should be seriously considered in patients with pneumonia, a hematologic malignancy, solid tumor, or health-care-associated infection, when GNB is suspected, even in community-onset infections., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Failure of vancomycin in the treatment of meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia has been reported despite full susceptibility of the organism to vancomycin. A retrospective observational cohort study including 137 patients with MRSA bacteraemia was performed at two centres in South Korea during 2009-2010. A total of 137 patients with MRSA bacteraemia receiving vancomycin therapy were enrolled during the study period. Isolates from 13 (9.5%) of the 137 patients had minimum inhibitory concentrations (MICs) ≥1 μg/mL. The 30-day cumulative survival was 53.8% for patients infected with isolates having a MIC≥1 μg/mL and 79.8% for patients infected with isolates having a MIC<1 μg/mL (log-rank test, P=0.026). Vancomycin MIC≥1 μg/mL [hazard ratio (HR)=7.0, 95% confidence interval (CI) 2.2-22.1; P=0.001], nosocomial acquisition of bacteraemia (HR=5.4, 95% CI 1.4-20.1; P=0.013), rapidly fatal underlying diseases (HR=20.5, 95% CI 3.9-106.4; P<0.001), presentation with septic shock (HR=8.4, 95% CI 3.0-23.3; P<0.001), presence of complicated infections (HR=5.6, 95% CI 2.0-15.8; P=0.001) and persistent MRSA bacteraemia for ≥3 days (HR=4.2, 95% CI 1.4-12.7; P=0.012) were independent predictors of 30-day mortality in patients with MRSA bacteraemia. In patients with high Pitt bacteraemia scores (Pitt score ≥2), the delay in initiation of vancomycin therapy was significantly different between non-survivors and survivors (2.4 days vs. 1.1 days; P=0.012). Vancomycin MIC≥1 μg/mL had a significant impact on mortality of patients with MRSA bacteraemia. These findings support early consideration of alternative anti-MRSA agents in patients with MRSA bacteraemia who have high vancomycin MICs as well as prompt initiation of anti-MRSA treatment in patients with MRSA bacteraemia, especially those with high Pitt scores., (Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)

We compared the 16S rRNA gene sequencing results analyzed with the GenBank, EzTaxon, and BIBI databases for blood culture specimens for which identifications were incomplete, conflicting, or unidentifiable using conventional methods. Analyses performed using GenBank combined with EzTaxon (kappa = 0.79) were more discriminative than those using other databases alone or in combination with a second database.

Objectives: This study was performed to evaluate clinical features of community-onset Enterobacter bacteremia and determine the risk factors for Enterobacter bacteremia among patients admitted to the emergency department., Methods: A post hoc analysis of a nationwide surveillance database of bacteremia was performed. A total of 53 patients with community-onset Enterobacter bacteremia were compared with 882 patients with Escherichia coli bacteremia., Results: As for the underlying disease, solid tumor was more likely common in Enterobacter bacteremia than in E. coli bacteremia (39.6% [21/53] vs 19.7% [174/882], P < .001). Neutropenia, indwelling urinary catheter, and tube insertion were significantly more common in Enterobacter bacteremia than in E. coli bacteremia (all Ps < .05). As for the site of infection, lung and abdomen were more likely common in Enterobacter bacteremia than in E. coli bacteremia, whereas urinary tract was less likely frequent in Enterobacter bacteremia than in E. coli bacteremia (all Ps < .05). In the multivariate analysis, pneumonia, tube insertion, solid tumor, and health care-associated infection were found to be significantly associated with Enterobacter bacteremia (all Ps < .05)., Conclusions: Enterobacter species were important pathogens among community-onset gram-negative bacteremia, in association with health care-associated infections. Pneumonia, tube insertion, solid tumor, and health care-associated infections were found to be significantly associated with Enterobacter bacteremia., (Copyright © 2012 Elsevier Inc. All rights reserved.)

This study was performed to evaluate the impact of extended-spectrum β-lactamase (ESBL)-producing bacteremia on outcome in patients with hematologic malignancy. We collected and analyzed data on 156 hematologic malignancy patients with Escherichia coli or Klebsiella pneumoniae bacteremia from the database of nationwide surveillance studies for bacteremia. Thirty-seven of the 156 patients (23.7%) harbored ESBL-producing bacteremia. No significant differences in underlying diseases were found in either group. The multivariate analysis showed that significant factors associated with ESBL-producing bacteremia were ICU care (OR = 7.03, 95% CI = 1.79-27.6) and nosocomial acquisition (OR = 5.66, 95% CI = 1.60-20.23). There was an association between prior receipt of cephalosporins and ESBL-producing bacteremia, although this association was not statistically significant (OR = 2.27, 95% CI = 0.99-5.23). The overall 30-day mortality rate of the study population was 20.4% (29/142), and the 30-day mortality rate for the ESBL group was significantly higher than that for the non-ESBL group (44.8% vs. 14.2%, P < 0.001). Multivariate analysis showed that ESBL-producing bacteremia was the most important risk factor associated with 30-day mortality (OR, 5.64; 95% CI, 1.91-16.67), along with ICU care (OR = 4.35, 95% CI = 1.16-16.26) and higher Pitt bacteremia score (per 1-point increment) (OR = 1.50, 95% CI = 1.18-1.92). In conclusion, ESBL-producing bacteremia was the most important risk factor associated with 30-day mortality in patients with hematologic malignancy, along with ICU care and higher Pitt bacteremia score. Our data suggest that determining the optimal empiric antimicrobial therapy in patients with hematologic malignancy is now becoming a challenge for clinicians in the era of multidrug-resistant Gram-negative bacilli.

Objective: The purpose of this study was to evaluate clinical features and outcomes of bacteremia in patients with liver cirrhosis (LC) and determine whether underlying LC is an independent risk factor for mortality in a population of patients with different underlying diseases., Methods: From the database of nationwide surveillance studies for bacteremia, data regarding bacteremia in patients with LC were analyzed and compared with those in patients with other diseases., Results: A total of 195 patients with LC were compared with 1659 patients with other underlying diseases. As for the site of infection, intraabdominal infection was more frequent in the LC group (P < 0.001), while pneumonia, urinary tract bacteremia, and primary bacteremia were more prevalent in the other diseases group (all P < 0.05). Patients with LC were more likely to have Klebsiella pneumoniae bacteremia (20.1% vs. 14.3%, P = 0.018), but less likely to have coagulase-negative staphylococcal bacteremia (5.1% vs. 10.4%, P = 0.028). The 30-day mortality rate was significantly higher in the LC group compared to the other disease group (27.2% [53/195] vs. 20.3% [336/1659], P = 0.025). Multivariate analysis revealed underlying LC as a significant predictor for mortality (OR, 2.11; 95% CI, 1.43-3.13; P < 0.001), along with old age, nosocomial acquisition, pneumonia, severe sepsis, and a higher Pitt bacteremia score., Conclusions: The mortality rate of patients with LC was significantly higher than that of patients with other diseases when they developed bacteremia. Underlying LC was found to be one of the independent risk factors for mortality in patients with bacteremia., (Copyright © 2011 The British Infection Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: Bacteremia is an important clinical condition in febrile neutropenia that can cause clinical failure of antimicrobial therapy. The purpose of this study was to investigate the clinical factors predictive of bacteremia in low-risk febrile neutropenia at initial patient evaluation., Methods: We performed a retrospective cohort study in a university hospital in Seoul, Korea, between May 1995 and May 2007. Patients who met the criteria of low-risk febrile neutropenia at the time of visit to emergency department after anti-cancer chemotherapy were included in the analysis., Results: During the study period, 102 episodes of bacteremia were documented among the 993 episodes of low-risk febrile neutropenia. Single gram-negative bacteremia was most frequent. In multivariate regression analysis, initial body temperature ≥39°C, initial hypotension, presence of clinical sites of infection, presence of central venous catheter, initial absolute neutrophil count <50/mm(3), and the CRP ≥10 mg/dL were statistically significant predictors for bacteremia. A scoring system using these variables was derived and the likelihood of bacteremia was well correlated with the score points with AUC under ROC curve of 0.785. Patients with low score points had low rate of bacteremia, thus, would be candidates for outpatient-based or oral antibiotic therapy., Conclusions: We identified major clinical factors that can predict bacteremia in low-risk febrile neutropenia.

Objectives: This study was performed to identify risk factors in Pseudomonas aeruginosa bacteremia among Gram-negative bacterial infections in non-neutropenic patients with solid tumor., Methods: A case-control study was performed to identify clinical predictors for P. aeruginosa bacteremia among non-neutropenic patients with Gram-negative bacteremia. Each case of P. aeruginosa bacteremia was matched to one or two controls with Escherichia coli, Klebsiella, Enterobacter or Citrobacter species in non-neutropenic patients with solid tumor., Results: Seventy-eight patients with P. aeruginosa bacteremia were compared with 98 control patients who had other Gram-negative bacteremias. The most common types of cancer were biliary tract cancer (49/176, 27.8%) and hepatocellular carcinoma (38/176, 21.6%), followed by gastric and bladder cancer. Factors associated with development of P. aeruginosa bacteremia were the presence of lung cancer, percutaneous tubes, nosocomial exposure, an invasive procedure and previous antimicrobial therapy (all P < 0.05). Independent risk factors for P. aeruginosa bacteremia included the presence of lung cancer and previous antimicrobial therapy. In the subgroup analysis including 90 patients with community-onset bacteremia, the previous use of antimicrobial agents and presence of bladder cancer were independent factors significantly associated with P. aeruginosa bacteremia., Conclusions: Underlying lung cancer and previous antimicrobial treatment were significantly associated with P. aeruginosa bacteremia in non-neutropenic patients with solid tumor. P. aeruginosa should be considered as a probable cause of Gram-negative bacteremia in this patient group., (Copyright © 2011 The British Infection Association. Published by Elsevier Ltd. All rights reserved.)

Background/aims: The purpose of this study was to evaluate the value of initial C-reactive protein (CRP) as a predictor of clinical outcome and to investigate whether follow-up CRP measurement is useful for the prediction of the clinical outcome of bloodstream infections in patients with liver cirrhosis (LC), whose CRP production in response to infection may be attenuated., Methods: A retrospective, observational study including 202 LC patients with Escherichia coli or Klebsiella pneumoniae bacteremia was conducted to assess the usefulness of serial CRP measurements in predicting clinical outcome in LC patients. The CRP ratio was defined as the ratio of the follow-up CRP level to the initial CRP level., Results: The overall 30-day mortality rate of the study population was 23.8% (48/202). In the multivariate analysis, advanced age (≥ 70 years), healthcare-associated or nosocomial infections, model for end-stage liver disease (MELD) score of ≥ 30, and initial body temperature of < 37℃ were significant factors associated with mortality (all p < 0.05). No association between initial CRP level and mortality was found. In a further analysis including 87 evaluable cases who had repeated CRP measurements at day 4 and/or 5, a CRP ratio of ≥ 0.7 was found to be a significant factor associated with mortality (odds ratio, 19.12; 95% confidence interval, 1.32 to 276.86; p = 0.043) after adjusting for other confounding variables., Conclusions: Initial CRP level did not predict mortality of sepsis in LC patients. However, serial CRP measurements during the first week of antimicrobial therapy may be useful as a prognostic factor for mortality in LC patients.

Background/aims: We evaluated the clinical features of ciprofloxacin-resistant Proteus mirabilis bacteremia and risk factors for ciprofloxacin resistance., Methods: From October 2000 to July 2009, 37 patients with clinically significant P. mirabilis bacteremia were identified and data from patients with ciprofloxacin-resistant and ciprofloxacin-susceptible P. mirabilis bacteremia were compared., Results: The most common underlying diseases were neurologic disease (37.8%) and solid tumors (29.7%). The most common site of infection was the urinary tract (35.1%). Ten of the 37 patients (27.0%) were infected with ciprofloxacin-resistant isolates, and univariate analysis revealed a significant relationship between ciprofloxacin-resistant P. mirabilis bacteremia and neurologic disease, recent operation, L-tube insertion, percutaneous tube use, and extended-spectrum β-lactamase (ESBL) production (all p < 0.05). ESBL was detected in six of 10 (60%) ciprofloxacin-resistant isolates, while only three of 27 (11%) ciprofloxacin-susceptible isolates produced ESBL (p = 0.005). In a logistic regression analysis, ESBL production remained a significant factor associated with ciprofloxacin resistance, after adjusting for other variables., Conclusions: These data indicate a close association between ciprofloxacin resistance and ESBL-production in P. mirabilis bacteremia. This association is particularly troublesome because the therapeutic options for serious infections caused by ESBL-producing P. mirabilis are severely restricted.

Background: Although several studies have evaluated the association of antimicrobial resistance and mortality in patients with Gram-negative bacteraemia, little is known regarding the impact of antimicrobial resistance on outcome in patients with intra-abdominal infections caused by Gram-negative bacilli (GNB). This study was performed to evaluate the impact of broad-spectrum cephalosporin resistance on outcome in patients with intra-abdominal infections caused by GNB., Methods: Data on 365 patients with bacteraemic intra-abdominal infections caused by GNB were obtained from the database of a nationwide surveillance for bacteraemia, and analyzed., Results: Seventy-one of the 365 patients (19.5%) harboured broad-spectrum cephalosporin-resistant infections. When compared with patients with susceptible infections, the group of patients with resistant infections had a lower treatment success rate at 7 days after the initiation of antimicrobial therapy (73.2% vs 85.0%, p = 0.023). However, the 30-day mortality rate for the resistant group was not significantly higher than for the susceptible group (16.9% vs 10.2%, p = 0.112). Multivariable analysis showed that severe sepsis was the most important risk factor associated with mortality (odds ratio 4.91, 95% confidence interval 2.26-10.63), along with underlying liver disease, nosocomial acquisition, underlying solid tumour, and higher Pitt bacteraemia score (all p < 0.05). Antimicrobial resistance and inappropriate initial antimicrobial therapy were not found to be associated with mortality., Conclusions: Our data suggest that antimicrobial resistance and inappropriate initial antimicrobial therapy may not be significant determinants for the prognosis in intra-abdominal infections caused by GNB, for which drainage or decompression procedures of intra-abdominal sources are often necessary.

Background: The aim of this study was to identify risk factors for development of severe sepsis or septic shock and to evaluate the clinical impact of severe sepsis on outcome in patients with gram-negative bacteremia (GNB)., Methods: From the database of a nationwide surveillance for bacteremia, patients with GNB were analyzed. Data of patients with severe sepsis or septic shock were compared with those of patient with sepsis., Results: Of 2286 patients with GNB, 506 (22.1%) fulfilled the criteria of severe sepsis or septic shock. Factors associated with severe sepsis or septic shock in the multivariate analysis included renal disease, indwelling urinary catheter, hematologic malignancy, and neutropenia. The 30-day mortality of patients with severe sepsis or septic shock was significantly higher than that of patients with sepsis (39.5% [172/435] vs. 7.4% [86/1170]; P < 0.001). Multivariable analysis revealed that solid tumor, liver disease, pulmonary disease, pneumonia, and pathogens other than Escherichia coli, which were risk factors of development of severe sepsis or septic shock, were also found to be strong predictors of mortality. Severe sepsis or septic shock was a significant factor associated with mortality (OR, 3.34; 95% CI, 2.35-4.74), after adjustment for other variables predicting poor prognosis., Conclusions: Severe sepsis or septic shock was a common finding in patients with GNB, predicting a higher mortality rate. Renal disease and indwelling urinary catheter were the most important risk factors significantly associated with severe sepsis or septic shock among patients with GNB., (Copyright © 2010 The British Infection Association. Published by Elsevier Ltd. All rights reserved.)

This study was performed to determine clinical predictors for enterococcal bacteraemia among hospitalized patients with suspected sepsis of abdominal origin. Among patients with bacteraemic intra-abdominal infections, 50 patients with enterococcal bacteraemia were compared with 618 patients with Gram-negative bacteraemia. Nosocomial acquisition and recent operation were found to be significantly associated with enterococcal bacteraemia, along with haematological malignancy, percutaneous trans-hepatic biliary drainage, and solid tumour (p < 0.05 for all).

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., (Copyright (c) 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)

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.