Microorganism Distributions and Antimicrobial Susceptibility in Community-Onset Bacteremia: A 6-Year Longitudinal Multicenter Cohort in Southern Taiwan.

Background: Prompt administration of appropriate antimicrobials has been correlated with improved prognoses in patients with bacteremia. Because the Clinical and Laboratory Standards Institute (CLSI) has numerously revised the interpretive criteria of susceptibility to numerous antimicrobials, the updated susceptibility is useful for empirical administration. Methods: In the multicenter retrospective cohort study consisting of adults with community-onset bacteremia in the emergency department (ED) during the period between January 2010 and December 2015, causative microorganisms were identified by the Vitek 2 system and prospectively collected. Antimicrobial susceptibility were respectively tested by the disk diffusion method for aerobes and the agar dilution method for anaerobes, in accordance with the contemporary CLSI criteria. Clinical information was retrospectively retrieved by reviewing the medical records. Results: Of the total 3,194 patients and 3,583 causative microorganisms, the leading source of bacteremia was the urinary tract infection (1,034 patients, 32.4%), and Escherichia coli accounted for the majority (1,332 isolates, 37.2%) of the total microorganisms. Overall, the lowest (58.2%) and highest (93.5%) susceptibility to cefazolin and piperacillin/tazobactam were, respectively, observed. In the leading five sources of bacteremia, in terms of the urinary tract infections, pneumonia, intraabdominal infections, skin and soft-tissue infections, and biliary tract infections, cefazolin or cefuroxime was only active against 49.3%-62.3% or 63.2%-74.1% of causative microorganisms, respectively. Notably, E. coli , Klebsiella species, and Proteus mirabilis (EKP) with the production of extended-spectrum beta-lactamases (ESBLs) accounted for 7.4% (142 isolates) of 1,908 EKP and 4.0% of all 3,583 microorganisms; and methicillin-resistant Staphylococcus aureus (MRSA) accounted for 37.7% (158 isolates) of S . aureus and 4.4% of all causative isolates. Conclusions: For adults with community-onset bacteremia, a low incidence (approximate 4%) of ESBL-producing EKP and MRSA among all causative microorganisms, but low susceptibility to cefazolin and cefuroxime were recognized. To achieve favorable prognoses by prompt administration of appropriate antimicrobials in EDs, our findings might offer useful information for the antimicrobial stewardship program.

Is Early Oral Antimicrobial Switch Useful for Less Critically Ill Adults with Community-Onset Bacteraemia in Emergency Departments?

To compare prognoses and adverse events between bacteraemic patients in the emergency department (ED) who received an early antimicrobial IV-to-PO switch and those treated with late or no IV-to-PO switch, an 8-year multicentre cohort consisting of adults with community-onset bacteraemia was conducted. The clinical characteristics and outcomes were compared in matched cohorts by the closest propensity score calculated based on the independent determinants of 30-day mortality identified by the multivariate regression model. Of the 6664 hospitalised patients who received no or late IV-to-PO switch, 2410 were appropriately matched with 482 patients treated with early IV-to-PO switch and discharged from the ED. There were no significant differences between the two matched groups in their baseline characteristics, including the patient demographics, severity and types of comorbidities, severity and sources of bacteraemia, and the 15- and 30-day mortality rates. Notably, in addition to the shorter lengths of intravenous antimicrobial administration and hospital stay, less phlebitis and lower antimicrobial costs were observed in patients who received an early IV-to-PO switch. Similarity was observed in the clinical failure rates between the two groups. Furthermore, the inappropriate administration of empirical antibiotics and inadequate source control were identified as the only independent determinants of the post-switch 30-day crude mortality in patients who received an early IV-to-PO switch. In conclusion, for less critically ill adults with community-onset bacteraemia who received appropriate empirical antimicrobial therapy and adequate source control, an early IV-to-PO switch might be safe and cost-effective after a short course of intravenous antimicrobial therapy.

The Hypotension Period after Initiation of Appropriate Antimicrobial Administration Is Crucial for Survival of Bacteremia Patients Initially Experiencing Severe Sepsis and Septic Shock.

Bacteremia is linked to substantial morbidity and medical costs. However, the association between the timing of achieving hemodynamic stability and clinical outcomes remains undetermined. Of the multicenter cohort consisted of 888 adults with community-onset bacteremia initially complicated with severe sepsis and septic shock in the emergency department (ED), a positive linear-by-linear association (γ = 0.839, p < 0.001) of the time-to-appropriate antibiotic (TtAa) and the hypotension period after appropriate antimicrobial therapy (AAT) was exhibited, and a positive trend of the hypotension period after AAT administration in the 15-day (γ = 0.957, p = 0.003) or 30-day crude (γ = 0.975, p = 0.001) mortality rate was evidenced. Moreover, for every hour delay of the TtAa, 30-day survival dropped an average of 0.8% (adjusted odds ratio [AOR], 1.008; p < 0.001); and each additional hour of the hypotension period following AAT initiation notably resulted in with an average 1.1% increase (AOR, 1.011; p < 0.001) in the 30-day crude mortality rate, after adjusting all independent determinants of 30-day mortality recognized by the multivariate regression model. Conclusively, for bacteremia patients initially experiencing severe sepsis and septic shock, prompt AAT administration might shorten the hypotension period to achieve favourable prognoses.

Antimicrobial escalation is not beneficial for Gram-negative bacteremia in adults who remained critically ill after appropriate empirical therapy.

To study whether antimicrobial escalation is beneficial for the outcome of bacteremia patients receiving appropriate but less responsive antimicrobials as empirical therapy, adults with community-onset Gram-negative bacteremia and remained the critical illness after appropriate empirical therapy with third-generation cephalosporins were retrospective enrolled. Clinical outcomes included incidental nosocomial infections, breakthrough bacteremia, and in-hospital crude mortality were compared between patients receiving escalation and non-escalation therapy, after propensity-score (PS) matching at a ratio of 1:3 using independent predictors of 30-day mortality recognized by the multivariate regression model. Initially, the higher proportion of fatal comorbidities (McCabe classification) and 30-day mortality rates was exhibited in the escalation group (51 patients), compared to the non-escalation group (de-escalation, 81; non-switch, 95). After appropriate PS-matching, similar proportions of clinical variables between the escalation (45 patients) and no-escalation (135) groups, in terms of patient demographics, bacteremia severity at onset, severity and types of comorbidities, and bacteremia sources, were observed. Consequently, poorer clinical outcomes, such as the higher rate of incidental nosocomial infections and in-hospital crude mortality as well as the longer length of intravenous antimicrobial administration and hospitalization, were statistically evidenced in the escalation group, compared to the non-escalation group. Conclusively, for patients exhibiting poor responses to appropriate empirical therapy, antimicrobial escalation did not significantly result in improved outcomes; otherwise, clinicians should pay more attention to the strategy of supportive care or adequate control of septic complication.

A Simple Scoring Algorithm That Predicts Abscesses in Adults with Community-Onset Klebsiella pneumoniae Bacteremia: Hypermucoviscosity Matters.

INTRODUCTION: Klebsiella pneumoniae is a pathogen commonly found in community-onset bacteremia. It causes an invasive syndrome that is frequently presented by metastatic infections and abscesses elsewhere and that is necessary for surgical or drainage intervention. To achieve a scoring algorithm to identify patients with community-onset K. pneumoniae bacteremia (CoKPB) who are at risk for abscess occurrences, a retrospective cohort study consisting of adults with CoKPB was conducted. METHODS: A 6-year cohort study consisting of adults having community-onset monomicrobial K. pneumoniae bacteremia was conducted. In addition to clinical variables collected from medical records, the hypermucoviscosity (HMV)-related gene (rmpA and magA) and an HMV phenotype were integrated into the proposed scoring algorithm. RESULTS: Of the 258 eligible adults, only 79 (30.6%) had abscesses related to bacteremia. Besides the presence of magA (ie, capsular serotype K1) and the HMV-phenotype, five clinical predictors were significantly associated with abscesses in a multivariate analysis: male gender, comorbidities with diabetes mellitus or neurological disorders, recent chemotherapy, and high c-reactive protein levels. Together, these predictors were used to calculate the CoKPB abscess score. Based on the scoring algorithm, a cut-off value of +2 yielded the high sensitivity (93.7%) and the acceptable specificity (50.8%); the area under the ROC curve was 0.83. CONCLUSION: A simple scoring algorithm that has substantial sensitivity and satisfactory specificity was proposed and the importance of the HMV phenotype or capsular K1 serotype was emphasized. The proposed predictive model needs external validation, but this scoring algorithm might be convenient and useful for clinicians.

Definitive Cefazolin Therapy for Stabilized Adults with Community-Onset Escherichia coli, Klebsiella Species, and Proteus mirabilis Bacteremia: MIC Matters.

BACKGROUND: Cefazolin is in vitro active against wild isolates of Escherichia coli, Klebsiella species, and Proteus mirabilis (EKP), but clinical evidence supporting the contemporary susceptibility breakpoint issued by the Clinical and Laboratory Standards Institute (CLSI) are limited. METHODS: Between 2010 and 2015, adults with monomicrobial community-onset EKP bacteremia with definitive cefazolin treatment (DCT) at two hospitals were analyzed. Cefazolin minimum inhibitory concentrations (MICs) were correlated with clinical outcomes, including primary (treatment failure of DCT) and secondary (30-day mortality after bacteremia onset, recurrent bacteremia, and mortality within 90 days after the end of DCT) outcomes. RESULTS: Overall, 466 bacteremic episodes, including 340 (76.2%) episodes due to E. coli, 90 (20.2%) Klebsiella species, and 16 (3.6%) P. mirabilis isolates, were analyzed. The mean age of these patients was 67.8 years and female-predominated (68.4%). A crude 15- and 30-day mortality rate was 0.7% and 2.2%, respectively, and 11.2% experienced treatment failure of DCT. A significant linear-by-linear association of cefazolin MICs, with the rate of treatment failure, 30-day crude mortality, recurrent bacteremia or 90-day mortality after the DCT was present (all γ = 1.00, p = 0.01). After adjustment, the significant impact of cefazolin MIC breakpoint on treatment failure and 30-day crude mortality was most evident in 2 mg/L (>2 mg/L vs. ≤2 mg/L; adjusted hazard ratio, 3.69 and 4.79; p < 0.001 and 0.02, respectively). CONCLUSION: For stabilized patients with community-onset EKP bacteremia after appropriate empirical antimicrobial therapy, cefazolin might be recommended as a definitive therapy for cefazolin-susceptible EKP bacteremia, based on the contemporary CLSI breakpoint.

Differential impacts of inappropriate empirical therapy on ED patients with Staphylococcus aureus and streptococci bacteremia.

BACKGROUND: Staphylococcus aureus (S. aureus) and streptococci are leading Gram-positive pathogens causing community-onset bacteremia. The comparisons of initial presentations and impacts of inappropriate empirical antimicrobial therapy (EAT) on clinical outcomes between the two pathogens are lacking. METHODS: In a 6-year cohort study, adult patients with community-onset monomicrobial S. aureus or streptococci bacteremia in the emergency department (ED) were studied. Clinical variables were collected retrospectively from medical records; the primary outcome was 4-week mortality after ED arrival. The Cox regression model was studied for effects of inappropriate EAT on 4-week mortality, after adjustment of independent predictors of 4-week mortality recognized by the multivariate regression model. RESULTS: A difference of clinical manifestations between S. aureus (291 patients) and streptococci (223) bacteremia was exhibited, in terms of bacteremia sources and comorbidity types, but bacteremia and comorbidity severity at ED arrival were similar. Furthermore, a longer period of the time-to-defervescence and hospitalization as well as more frequencies of septic metastasis were disclosed in S. aureus bacteremia, compared to streptococcal bacteremia. Of note, a significant impact (adjusted odds ratio [ORa], 2.23; 95% confidence interval [CI], 1.25-3.96) of inappropriate EAT on 4-week mortality was evidenced in S. aureus bacteremia, but not in streptococcal bacteremia (ORa, 2.88; 95% CI, 0.85-9.86). CONCLUSIONS: For adults having community-onset monomicrobial bacteremia, the similarity of bacteremia and comorbidity severity at ED arrivals were observed between causative microorganisms of S. aureus and streptococci, but a crucial impact of inappropriate EAT on short-term mortality was only observed in S. aureus.

Differential effects of inappropriate empirical antibiotic therapy in adults with community-onset gram-positive and gram-negative aerobe bacteremia.

Bacteremia is associated with high morbidity and mortality, which contribute substantially to health care costs. A beneficial influence of appropriate empirical antimicrobial therapy (EAT) on patient outcome is evidenced; However, the evidence highlighting a comparison of clinical manifestations and of the effects of inappropriate EAT between Gram-positive and Gram-negative bacteremia is insufficient. In a retrospective 6-year cohort study, the total 2053 adults (Gram-positive, 566; Gram-negative 1487) presenting with community-onset monomicrobial aerobes bacteremia were recruited. Inappropriate EAT was defined as the first dose of an appropriate antimicrobial agent not being administered within the first 24 h after blood cultures were drawn. Although the bacteremia severity (a Pitt bacteremia score) at onset, comorbidity severity (the McCabe-Johnson classification), and 28-day mortality rate were similar in the two groups. Furthermore, after adjustment of independent predictors of 28-day mortality respectively recognized by the multivariate regression model in Gram-negative and Gram-positive groups, the Kaplan-Meier curve and Cox regression analysis revealed a significant difference (adjust odds ratio [AOR], 2.68; P < 0.001) between appropriate and inappropriate EAT in the Gram-negative group, but not in the Gram-positive group (AOR, 1.54; P = 0.06). Conclusively, patients with Gram-positive and Gram-negative bacteremia exhibited the similar presentation in bacteremia severity, but a greater impact of inappropriate EAT on survival of patients with Gram-negative aerobe bacteremia was evidenced.

Validation of MEDS score in predicting short-term mortality of adults with community-onset bacteremia.

BACKGROUND: The Mortality in Emergency Department Sepsis (MEDS) score can be used to stratify ED patients with suspected infections according to mortality risk. However, it has yet to be externally validated for patients having bloodstream infections. METHODS: We retrospectively computed clinical information for the MEDS score, Pitt bacteremia score (PBS), Charlson comorbidity index (CCI), and McCabe-Jackson comorbid classification (MJCC) for adults with community-onset bacteremia. The MEDS score was validated by the comparisons with the following scoring systems: the PBS, CCI, MJCC, PBS plus MJCC, and PBS plus CCI. We evaluated goodness-of-fit statistics and c-statistics as measures of model calibration and discrimination, respectively. RESULTS: Of 2328 adults, a good calibration for 28-day crude mortality was obtained only in the MEDS score and PBS plus MJCC; a higher c-statistic (0.870, P < 0.001) were achieved by the MEDS score, compared to the PBS, CCI MJCC, PBS plus MJCC, and PBS plus CCI. A high c-statistic was observed in two combinative scoring system: the PBS plus CCI (0.855, P < 0.001) and PBS plus MJCC (0.843, P < 0.001). According to the Kaplan-Meier curves, 28-day crude mortality significantly differed between patients with scores equal to or higher than selected cutoff values and those with scores lower than selected cutoff values: 10 in the MEDS score and 5 in the PBS plus MJCC, respectively. CONCLUSION: The MEDS score is an excellent predictor of short-term outcomes in patients with community-onset bacteremia because it provides estimates with higher calibration and discrimination than those of the other scoring systems.

Beneficial effects of early empirical administration of appropriate antimicrobials on survival and defervescence in adults with community-onset bacteremia.

BACKGROUND: Bloodstream infections are associated with high morbidity and mortality, both of which contribute substantially to healthcare costs. The effects of early administration of appropriate antimicrobials on the prognosis and timing of defervescence of bacteremic patients remain under debate. METHODS: In a 6-year retrospective, multicenter cohort, adults with community-onset bacteremia at the emergency departments (EDs) were analyzed. The period from ED arrival to appropriate antimicrobial administration and that from appropriate antimicrobial administration to defervescence was regarded as the time-to-appropriate antibiotic (TtAa) and time-to-defervescence (TtD), respectively. The primary study outcome was 30-day mortality after ED arrival. The effects of TtAa on 30-day mortality and delayed defervescence were examined after adjustment for independent predictors of mortality, which were recognized by a multivariate regression analysis. RESULTS: Of the total 3194 patients, a TtAa-related trend in the 30-day crude (γ = 0.919, P = 0.01) and sepsis-related (γ = 0.909, P = 0.01) mortality rate was evidenced. Each hour of TtAa delay was associated with an average increase in the 30-day crude mortality rate of 0.3% (adjusted odds ratio [AOR], 1.003; P < 0.001) in the entire cohort and 0.4% (AOR, 1.004; P < 0.001) in critically ill patients, respectively, after adjustment of independent predictors of 30-day crude mortality. Of 2469 febrile patients, a TtAa-related trend in the TtD (γ = 0.965, P = 0.002) was exhibited. Each hour of TtAa delay was associated with an average 0.7% increase (AOR, 1.007; P < 0.001) in delayed defervescence (TtD of ≥ 7 days) after adjustment of independent determinants of delayed defervescence. Notably, the adverse impact of the inappropriateness of empirical antimicrobial therapy (TtAa > 24 h) on the TtD was noted, regardless of bacteremia severity, bacteremia sources, or causative microorganisms. CONCLUSIONS: The delay in the TtAa was associated with an increasing risk of delayed defervescence and 30-day mortality for adults with community-onset bacteremia, especially for critically ill patients. Thus, for severe bacteremia episodes, early administration of appropriate empirical antimicrobials should be recommended.

Timing of follow-up blood cultures for community-onset bacteremia.

Bacteremia is associated with high morbidity and mortality, but the utility and optimal timing of follow-up blood cultures (FUBCs) remain undefined. To assess the optimal timing of FUBCs related to appropriate antibiotic therapy (AAT), adults with community-onset bacteremia and FUBCs after bacteremia onset were retrospectively studied during the 6-year period in two hospitals. Based on the time gap between the initiation of AAT and FUBC sampling, 1,247 eligible patients were categorized as FUBCs prior to AAT (65 patients, 5.2%), 0-3 days (202, 16.2%), 3.1-6 days (470, 37.7%), 6.1-9 days (299, 24.0%), and ≥9 days (211, 16.9%) after AAT. The prognostic impact of the growth of the same bacteria in FUBCs on 30-day mortality was evidenced only in patients with FUBCs at 3.1-6 days after AAT (adjusted odds ratio [AOR], 3.75; P < 0.001), not in those with FUBCs prior to AAT (AOR, 2.86; P = 0.25), 0-3 days (AOR, 0.39; P = 0.08), 6.1-9 days (AOR, 2.19; P = 0.32), and ≥9 days (AOR, 0.41; P = 0.41) of AAT, after adjusting independent factors of 30-day mortality recognized by the multivariable regression in each category. Conclusively, persistent bacteremia in FUBCs added prognostic significance in the management of adults with community-onset bacteremia after 3.1-6 days of AAT.

Clinical Benefit of Empiric High-Dose Levofloxacin Therapy for Adults With Community-onset Enterobacteriaceae Bacteremia.

PURPOSE: Levofloxacin is commonly prescribed to treat varied community-acquired gram-negative infections; knowledge of the therapeutic efficacies of high-dose (HD) administration is helpful to improve patient care. METHODS: In this 6-year cohort, adults with community-onset Enterobacteriaceae bacteremia were retrospectively studied in 2 hospitals. To overcome the confounding factors in the dosage choice of empiric administration, patients receiving empiric intravenous HD (750 mg/d) therapy were matched with those receiving the conventional dose (CD; 500 mg/d) by using individual propensity scores, calculated by the independent predictors of 30-day crude mortality. FINDINGS: Initially, more patients with critical illness (Pitt bacteremia score [PBS] ≥4) at bacteremia onset and comorbid malignancies and the higher 15- and 30-day mortality rate were recorded in 136 patients receiving HD therapy, compared to 103 receiving CD therapy. After appropriate matching, differences in patient demographic and clinical characteristics between the HD (n = 103) and CD (n = 103) groups were nonsignificant. Consequently, crude mortality rates at 3, 15, or 30 days after onset of bacteremia did not differ. However, the period of time to defervescence, total intravenous antimicrobial administration, and hospital stay was shorter in the HD group than in the CD group. Similarly, regardless if patients had more critical illness (PBS ≥2) or stabilized illness (PBS <2), the advantage of empiric HD therapy on defervescence remained significant. Within 60 days after discontinuation of intravenous levofloxacin therapy, the proportion of recurrent bacteremia, posttreatment overall infections, and posttreatment crude mortality was similar between the HD and CD groups. IMPLICATIONS: For adults with community-onset Enterobacteriaceae bacteremia, empiric administration of HD levofloxacin was as effective as CD levofloxacin in reducing mortality and, notably, led to more rapid defervescence compared with CD administration.

Short versus long duration antimicrobial treatment for community-onset bacteraemia: A propensity score matching study.

The efficacy and safety of short-course intravenous (i.v.) antimicrobial therapy for bloodstream infections is unknown. Therefore, a retrospective 8-year cohort study including 1431 hospitalised adults was conducted to compare the outcomes of patients receiving short-course (5-10 days) and long-course (11-16 days) i.v. antibiotic therapy for community-onset bacteraemia. Of 1010 patients who received short-course therapy, 726 were matched with 363 patients in the long-course group through propensity score matching at a ratio of 1:2 based on independent predictors of 30-day mortality identified in the multivariate regression model. Following appropriate matching, similarities between the two groups in the proportion of baseline characteristics (age, sex, major co-morbidities, co-morbidity severity, bacteraemia severity at onset and major bacteraemia sources) and 30-day crude mortality rate after bacteraemia onset were observed. Notably, clinical outcomes within 30 days after the end of i.v. therapy, in terms of proportions of post-treatment overall infections (2.2% vs. 6.1%; P = 0.001), infections caused by antimicrobial-resistant pathogens (ARPs) (1.7% vs. 4.4%; P = 0.007), and thereby post-treatment crude mortality (1.4% vs. 3.6%; P = 0.009), were lower in the short-course group. In conclusion, for adults with community-onset uncomplicated bacteraemia, short-course (5-10 days) i.v. antibiotic treatment did not result in an increased risk of mortality but instead decreased the odds of overall and ARP infections after the treatment course.

Etiology of community-onset monomicrobial bacteremic pneumonia and its clinical presentation and outcome: Klebsiella and Pseudomonas matters.

To describe the difference of the clinical features, bacteremia severity, and outcome of patient with community-onset bacteremic pneumonia between Pseudomonas, Klebsiella, and other causative microorganisms, the total 278 adults with community-onset monomicrobial bacteremic pneumonia were studied in a retrospective cohort. Klebsiella (61 patients, 21.9%) and Pseudomonas (22, 7.9%) species was the leading and the fifth common pathogen, respectively. More patients having initial presentation with critical illness (a Pitt bacteremia score ≥ 4) and a fatal comorbidity (McCabe classification) as well as a higher short- (30-day) or long-term (90-day) mortality rate was evidenced in patients infected with Klebsiella or Pseudomonas species, compared to other causative microorganisms. Compared to patients in the Klebsiella group, more frequencies of recent chemotherapy and an initial presentation of febrile neutropenia, and less proportions of diabetes mellitus were disclosed among those in the Pseudomonas group. Of importance, a significantly differential survival curve between Klebsiella or Pseudomonas species and other species during 30-day or 90-day period after bacteremia onset but a similarity of Pseudomonas and Klebsiella species was evidenced, using the Cox-regression after adjusting the independent predictors of 30-day mortality. Conclusively, of pathogens causing community-onset bacteremic pneumonia, Klebsiella and Pseudomonas species should be recognized as the highly virulent pathogens and resulted in poor short- and long-term prognoses.

Propensity score matched analysis comparing the clinical outcome of Klebsiella pneumoniae and Escherichia coli causing community-onset monomicrobial bacteremia.

Bacteremia is a life-threatening condition that is associated with substantial healthcare costs. Escherichia coli and Klebsiella pneumoniae are the leading causes of community-onset gram-negative bacteremia. However, a comprehensive comparison between these pathogens involved in bacteremia episodes has yet to be reported.In this retrospective cohort study, adults with community-onset monomicrobial bacteremia caused by E coli or K pneumoniae were recruited in the emergency department of a medical center during a 6-year period, and the clinical variables were collected retrospectively from medical records. The complicated abscess occurrence was determined through imaging studies, according to the opinion of an infectious disease consultant. According to the independent predictors of 28-day mortality identified through multivariate regression analyses, patients in the E coli group were propensity score matched (PSM) in a 1:1 ratio to those in the K pneumoniae group.A total of 274 and 823 adults with K pneumoniae and E coli bacteremia were included in the present study. The K pneumoniae group had more patients with fatal comorbidities (McCabe classification), critical illness (Pitt bacteremia score ≥ 4) at bacteremia onset, and initial syndrome (e.g., severe sepsis and septic shock) as well as a higher crude mortality rate than did the E coli group. After appropriate matching, no significant differences were observed in the critical illness at bacteremia onset, initial syndrome, major comorbidities, and comorbidity severity of the 2 groups (E coli, n = 242; K pneumoniae, n = 242). Furthermore, despite similar 14- and 28-day crude mortality rates between the 2 PSM groups, more frequent abscess occurrences and a longer length of hospitalization were observed in the K pneumoniae group than in the E coli group.Conclusively, numerous clinical features at initial presentations varied between the E coli and K pneumoniae groups. Despite conducting a PSM analysis to control the differences in the baseline characteristics, a longer length of hospitalization and more frequent abscess occurrences were observed in the K pneumoniae group than in the E coli group.