Bacteremia In Adult Patients Research Articles

Epidemiology of Bacteremia in Patients with Hematological Malignancies and Hematopoietic Stem Cell Transplantation and the Impact of Antibiotic Resistance on Mortality: Data from a Multicenter Study in Argentina

The epidemiology of bacteremia and the antibiotic resistance profile (ARP) of Gram-negative bacilli (GNB) in hematological malignancies (HM) and hematopoietic stem cell transplant (HSCT) patients may differ according to geographic region. In addition, multidrug-resistant organisms (MDROs) may impact mortality. This is a prospective, observational, and multicenter study. The first episodes of bacteremia in adult patients with HM or HSCT were included. The risk factors for 30-day mortality were identified. One thousand two hundred and seventy-seven episodes were included (HM: 920; HSCT: 357). GNB were isolated in 60.3% of episodes, with Enterobacterales (46.9%) and P. aeruginosa (8.5%) being the most frequent. Gram-positive cocci were isolated in 41.9% of episodes, with coagulase-negative staphylococci (19.8%) and S. aureus (10.4%) being the most frequent. MDROs were isolated in 40.2% (24.4% GNB). The ARP of GNB in patients with HM vs. HSCT was cefepime: 36.8% vs. 45.7% (p = 0.026); piperacillin–tazobactam: 31.05% vs. 45.2% (p < 0.0001); carbapenems: 18.9% vs. 27.3% (p = 0.012); and aminoglycosides: 9.3% vs. 15.4% (p = 0.017), respectively. Overall mortality between patients with HM and HSCT was 17.5% vs. 17.6% (p = 0.951), respectively. The risk factors for mortality were relapsed and refractory underlying disease, corticosteroids use, respiratory source, septic shock, and GNB resistant to meropenem, while 7-day clinical response was a protective factor for survival. Bacteremia was frequently caused by GNB, with a large proportion of MDROs and a high level of antibiotic resistance, especially in patients with HSCT. Carbapenem-resistant GNB bacteremia was associated with a significant increase in mortality.

Diagnostic Potential of Serum Interleukin-6 in Predicting Bacteremia in Adult Patients with Sepsis: A Prospective Observational Study.

This study aimed to assess the potential of serum interleukin-6 (IL-6) as a diagnostic marker in predicting bacteremia and to determine its association with severity and outcome among sepsis patients. A prospective observational study was conducted, comprising a cohort of 118 patients admitted to the ICU with suspected sepsis from January 2019 to April 2020. Among the 108 patients analyzed, 60 (55.6%) were bacteremic and 48 (44.4%) were nonbacteremic. Of 60 patients with bacteremia, 13 (21.6%) had sepsis and 47 (78.3%) had septic shock. In predicting bacteremia, the area under the curve (AUC) for IL-6 was 0.512 [95% CI, 0.400-0.623]. The AUC for IL-6 in differentiating sepsis from septic shock was 0.724 [95% CI, 0.625-0.823]. The sensitivity and specificity for predicting bacteremia for IL-6 were 66% and 67%, respectively (p < 0.001). Multivariate analysis revealed that C-reactive protein (CRP) (p = 0.04) and APACHE II score (p = 0.025) were significant predictors of bacteremia, whereas lactate (p = 0.04), and APACHE II score (p < 0.001) were significant predictors of sepsis severity. Patients with elevated levels of procalcitonin PCT (p = 0.024), APACHE II (p = 0.003), and SOFA (p = 0.002) scores had significantly higher mortality rates. C-reactive protein and APACHE II score, lactate and APACHE II score, and PCT, SOFA, and APACHE II scores performed better in predicting bacteremia, sepsis severity, and clinical outcome, respectively compared with IL-6. Reddy PRV, Cherukuri M, Eshwara VK, Kudru CU, Prabhu RVK. Diagnostic Potential of Serum Interleukin-6 in Predicting Bacteremia in Adult Patients with Sepsis: A Prospective Observational Study. Indian J Crit Care Med 2024;28(7):637-644.

Clinical Utility of Follow-Up Blood Cultures Among Adult Cancer Patients with Gram-Negative Bacilli Bacteremia

Background: Gram-negative bacilli (GNB) bacteremia is a common and potentially fatal infection with mortality rates estimated to be 14-34%, despite effective antimicrobial treatments. Follow-up blood cultures (FUBCs) are blood cultures that are repeated after an initial positive culture and are indicated in certain clinical scenarios, such as in candidemia or Staphylococcus aureus bacteremia to ensure clearance of the bloodstream infection. FUBCs are used in bacteremia to assess the appropriateness and duration of antimicrobial therapy. Currently, there are no guidelines in place regarding the use of FUBC for GNB bacteremia. Furthermore, the utility of FUBCs is not well-studied in adults living with cancer. The purpose of this study is to identify risk factors associated with persistent GNB bacteremia in adult patients with cancer. Methods: We conducted a single-center, retrospective study in patients aged ≥18 years, hospitalized during calendar year 2022, living with cancer, and with laboratory confirmed GNB bloodstream infection. FUBC was defined as a blood culture performed within 7 days of the initial positive blood culture. Patients were grouped as having the same organism on FUBC (+/same), FUBC with no growth (NG) (+/NG), and different organism on FUBC (+/Different). Patients with a different organism on FUBC were excluded from analysis. We gathered demographic information, suspected source of bacteremia, type of malignancy, identified organisms, presence of antimicrobial resistance, and comorbidities (eg. presence of central venous catheters, urinary catheters, end-stage renal disease). Categorical variables were compared using Chi-square or Fisher’s exact test. Continuous variables were compared using Wilcoxon rank sum tests. Logistic regression analysis was used to identify the independent predictors of persistent GNB bacteremia. Results: 356 unique patients with FUBC were identified after inclusion/exclusion criteria. 93/356 (26%) of patients had persistent GNB bacteremia (+/same). Multivariate analysis identified history of bacteremia within the preceding year (OR 2.95, 95% CI [1.6-5.6]) and Achromobacter spp. bacteremia (OR 10.03, 95% CI [1.59-63.23] as independent risk factors for persistence. Organisms with multidrug resistance such as extended-spectrum beta-lactamase (OR 2.47, 95% CI [1.21-5.07]) and carbapenem-resistant organisms (OR 3.35, 95% CI [1.04-10.81]) were also associated with persistent GNB bacteremia. Conclusions: This is the first study to specifically identify risk factors for persistent GNB bacteremia in patients living with cancer. FUBC may be useful in GNB bacteremia with less common organisms and/or if they exhibit multidrug resistance on susceptibility testing. The utility of FUBC should be further explored in patients with cancer with certain risk factors.

Factors and clinical prediction score for complication development after cellulitis diagnosis in adult patients.

Cellulitis is defined as a bacterial infection of the skin and subcutaneous tissue that can cause multiple complications, such as sepsis and necrotizing fasciitis. In extreme cases, it may lead to multiorgan failure and death. We sought to analyze the clinical factors that contribute to the development of complicated disease, including demographics, clinical presentation, initial vital signs, and laboratory studies. Our study is a retrospective cohort study carried out in a university-based tertiary care hospital in Bangkok, Thailand. Adult patients who presented with cellulitis from January 1, 2018, to December 31, 2022, were evaluated for eligibility and inclusion in this study. All related variables for both outcomes, bacteremia and necrotizing fasciitis, were gathered from electronic medical records and analyzed using multivariable logistic regression analysis. Of the 1,560 visits to this hospital, 47 cases reported at least one complication, with bacteremia noted in 27 visits (1.73%) and necrotizing fasciitis in 20 visits (1.27%). From the multivariable logistic regression analysis, six variables emerge as predictors of cellulitis complications. These are: Age ≥ 65 years, Body Mass Index ≥ 30kg/m2, diabetes mellitus, body temperature ≥ 38°C, systolic blood pressure ≤ 100 mmHg, and involvement of lower extremities. The predictive score was developed from these factors and was named the Ramathibodi Necrotizing Fasciitis/Bacteremia (RAMA-NFB) Prediction Score. Our predictive score has an accuracy of 82.93% (95% CI, 0.77-0.89). Patients in the high-risk group (RAMA NFB score > 6) have a likelihood ratio of 8.75 (95% CI, 4.41-18.12; p < 0.001) times to develop complications of cellulitis. In our study, the RAMA-NFB Prediction Score predicts complications of necrotizing fasciitis and bacteremia in adult patients who present with cellulitis. External validation of this predictive score is still needed for further practical application.

Diagnostic accuracy of procalcitonin for bacteremia in the emergency department: a systematic review

Obtaining blood cultures (HC) is performed in 15% of the patients treated with suspicion of infection in the Hospital Emergency Services (ED) with a variable diagnostic yield (2-20%). The 30-day mortality of patients with bacteremia is two or three times higher than the rest with the same process. Procalcitonin (PCT) is a biomarker that has been used as a tool to help predict bacteremia in HEDs. The main objective of this systematic review is to investigate the diagnostic accuracy of PCT in predicting true bacteraemia in adult patients treated with clinical suspicion of infection in the ED, as well as to identify a specific PCT value as the most relevant from the clinical decision diagnostic point of view that can be recommended for decision making. A systematic review was performed following the PRISMA guidelines in the PubMed, Web of Science, EMBASE, Lilacs, Cochrane, Epistemonikos, Tripdatabase and ClinicalTrials.gov databases from January 2010 to May 31, 2023 without language restrictions and using a combination of MESH terms: "Bacteremia/ Bacteraemia/ Blood Stream Infection", "Procalcitonin", "Emergencies/ Emergency/ Emergency Department" and "Adults". Observational cohort studies and partially an systematic review were included. No meta-analysis techniques were performed, but the results were compared narratively. A total of 1,372 articles were identified, of which 20 that met the inclusion criteria were finally analyzed. The included studies represent a total of 18,120 processed HC with 2,877 bacteraemias (15.88%). Ten studies were rated as high, 9 moderate and 1 low quality. The AUC-COR of all the studies ranges from 0.68 (95% CI: 0.59-0.77) to 0.98 (95% CI: 0.97-0.99). The PCT value >0.5 ng/ml is the most widely used and proposed in up to ten of the works included in this systematic review, whose estimated mean yield is an AUC-COR of 0.833. If only the results of the 6 high-quality studies using a cut-off point (PC) >0.5 ng/mL PCT are taken into account, the estimated mean AUC-COR result is 0.89 with Se of 77.6% and It is 78%. PCT has a considerable diagnostic accuracy of bacteraemia in patients treated in EDs for different infectious processes. The CP>0.5 ng/ml has been positioned as the most suitable for predicting the existence of bacteraemia and can be used to reasonably rule it out.

Early diagnosis of candidemia with explainable machine learning on automatically extracted laboratory and microbiological data: results of the AUTO-CAND project

Background Candidemia is associated with a heavy burden of morbidity and mortality in hospitalized patients. The availability of blood culture results could require up to 48–72 h after blood draw; thus, early treatment decisions are made in the absence of a definite diagnosis. Methods In this retrospective study, we assessed the performance of different supervised machine learning algorithms for the early differential diagnosis of candidemia and bacteremia in adult patients on a large dataset automatically extracted within the AUTO-CAND project. Results Overall, 12,483 episodes of candidemia (1275; 10%) or bacteremia (11,208; 90%) were included in the analysis. A random forest classifier achieved the best diagnostic performance for candidemia, with sensitivity 0.98 and specificity 0.65 on the training set (true skill statistic [TSS] = 0.63) and sensitivity 0.74 and specificity 0.57 on the test set (TSS = 0.31). Then, the random classifier was trained in the subgroup of patients with available serum β-D-glucan (BDG) and procalcitonin (PCT) values by exploiting the feature ranking learned in the entire dataset. Although no statistically significant differences were observed from the performance measures obtained by employing BDG and PCT alone, the performance measures of the classifier that included the features selected in the entire dataset, plus BDG and PCT, were the highest in most cases. Conclusions Random forest classifiers trained on large datasets of automatically extracted data have the potential to improve current diagnostic algorithms for candidemia. However, further development through implementation of automatically extracted clinical features may be necessary to achieve crucial improvements.

Blood culture positivity in patients with acute appendicitis: A propensity score-matched prospective cohort study.

The prevalence of bacteremia in acute appendicitis is unknown. We aimed to assess prevalence and predictive factors of bacteremia in adult patients with appendicitis. In this prospective propensity score-matched cohort study, patients were recruited as part of one single-center prospective observational study assessing appendicitis microbiology in concurrence with two randomized controlled trials on non-operative treatment of uncomplicated acute appendicitis. All patients evaluated for enrollment in these three trials between April 2017 and December 2018 with both a confirmed diagnosis of appendicitis and available blood culture on admission were included in this study. Potential predictive factors of bacteremia (age, sex, body mass index (BMI), body temperature, C-reactive protein (CRP), leukocyte count, comorbidities, symptom duration, and appendicitis severity) were assessed. Prevalence of bacteremia was determined by all available blood cultures followed by propensity score matching using sex, age, BMI, CRP, leukocyte count, and body temperature of the patients without available blood culture. Out of the 815 patients with appendicitis, 271 patients had available blood culture and the prevalence of bacteremia was 12% (n = 33). Based on propensity score estimation, the prevalence of bacteremia in the whole prospective appendicitis cohort was 11.1%. Bacteremia was significantly more frequent in complicated acute appendicitis (15%; 29/189) compared with uncomplicated acute appendicitis (5%; 4/82) (p = 0.015). Male sex (p = 0.024) and higher body temperature (p = 0.0044) were associated with bacteremia. Estimated prevalence of bacteremia in patients with acute appendicitis was 11.1%. Complicated appendicitis, male sex, and higher body temperature were associated with bacteremia in acute appendicitis.

Comparing the Outcomes of Ceftaroline plus Vancomycin or Daptomycin Combination Therapy versus Vancomycin or Daptomycin Monotherapy in Adults with Methicillin-Resistant Staphylococcus aureus Bacteremia-A Meta-Analysis.

Introduction: Combination therapy with daptomycin plus ceftaroline to treat methicillin-resistant Staphylococcus aureus bacteremia has been reported to reduce methicillin-resistant Staphylococcus aureus bacteremia-related mortality. The purpose of the current meta-analysis was to compare the clinical outcome of methicillin-resistant Staphylococcus aureus bacteremia in patients treated with daptomycin or vancomycin plus ceftaroline combination therapy versus daptomycin or vancomycin monotherapy. Methods: Studies were included if they directly compared the efficacy of daptomycin or vancomycin plus ceftaroline combination therapy with that of daptomycin or vancomycin monotherapy in the treatment of methicillin-resistant Staphylococcus aureus bacteremia in adult patients. Results: One randomized controlled trial and five retrospective studies were included in the meta-analysis. The combination therapy group had an in-hospital mortality, duration of bacteremia, and adverse event rate similar to those patients who had monotherapy. There was less bacteremia recurrence in the combination group. Initial combination therapy with ceftaroline for the treatment of methicillin-resistant Staphylococcus aureus bacteremia showed a trend of reducing the risk of in-hospital mortality in the current meta-analysis. Conclusions: Randomized controlled trials are needed to further study the role of initial combination therapy with daptomycin or vancomycin plus ceftaroline in the treatment of methicillin-resistant Staphylococcus aureus bacteremia.

Clinical impact of time-to-positivity of blood cultures on mortality in patients with Pseudomonas aeruginosa bacteremia

To investigate the impact of the time-to-positivity of blood cultures (TTP) on 30-day mortality in patients with Pseudomonas aeruginosa bacteremia. All nonduplicated episodes of P. aeruginosa monomicrobial bacteremia in adult patients from January 2013 to February 2020 were analysed. Epidemiological and clinical data were collected. TTP of blood cultures for P. aeruginosa isolates was automatically recorded. Multivariate analysis identified factors predicting 30-day overall mortality. A total of 328 patients were identified. The median TTP for P. aeruginosa isolates was 15 h (interquartile range [IQR] 12-18 h). All multidrug-resistant and extensively drug-resistant (MDR/XDR) episodes were positive within the first 36 h. The 30-day mortality rate was 32.3%. The best cut-off value of the TTP for predicting mortality was 16 h (area under the receiver operating characteristic curve 0.62, 95% confidence interval [CI] 0.56-0.67, P=0.001). The 30-day mortality rate was significantly higher in the TTP ≤16 h group (41.0% vs. 19.5%, P < 0.001). In a multivariate analysis, severe neutropenia (adjusted odds ratio [aOR] 2.67, 95% CI 1.4-5.09, P=0.002), septic shock (aOR 3.21, 95% CI 1.57-5.89, P < 0.001), respiratory source (aOR 4.37, 95% CI 2.24-8.52, P < 0.001), nosocomial acquisition (aOR 1.99, 95% CI 1.06-3.71, P=0.030), TTP ≤16 h (aOR 2.27, 95% CI 2.12-4.25, P=0.010), and MDR/XDR phenotype (aOR 2.54, 95% CI 1.38-4.67, P=0.002) were independently associated with 30-day mortality. A short TTP (≤16 h) was independently associated with increased 30-day mortality. After local validation, this routinely available microbiological parameter might be useful for guiding empirical antipseudomonal therapies and supporting the close monitoring of patients with P. aeruginosa bacteremia.

Bacteremia in Adults Admitted from the Emergency Department with Laboratory-Confirmed Respiratory Syncytial Virus.

Collecting blood cultures from patients admitted from the emergency department (ED) with acute respiratory infection (ARI) is common, but the rate of secondary bacteremia in adult patients admitted from the ED with ARI associated with respiratory syncytial virus (RSV) is unknown. Indiscriminate collection of blood cultures can be associated with contaminated blood cultures and increased inappropriate antimicrobial use and health care costs. This study sought to determine the rate and etiology of secondary bacteremia, factors associated with secondary bacteremia, and factors associated with collecting blood cultures in the ED, in adults hospitalized with RSV. We performed a retrospective substudy using data from a prospective study of adults admitted with RSV infections during two respiratory seasons (October 2017 to April 2018 and October 2018 to April 2019). Blood cultures were collected at the discretion of ED providers. We compared demographic and clinical characteristics among those with and without secondary bacteremia and among those with and without blood cultures collected using multivariate logistic regression models. Of the 365 hospitalized RSV-positive patients (mean age 68.8 years), 269 (73.7%) had blood cultures collected in the ED and 18 (6.7%) patients had secondary bacteremia, most commonly from a nonrespiratory source (n=13). Patients with asthma and chronic obstructive pulmonary disease were significantly less likely to have secondary bacteremia. Patients who were immunocompromised, met systemic inflammatory response syndrome criteria, or had pneumonia described on chest x-ray reports were more likely to have blood cultures collected. Overall, 6.7% of adults hospitalized with RSV infections had secondary bacteremia, more commonly from nonrespiratory sources.

In Vitro Cytotoxicity and Clinical Correlates of MRSA Bacteremia.

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections are associated with significant morbidity and mortality. MRSA secretes a number of virulence factors and pore-forming toxins that enable tissue invasion. Prior studies have found associations between decreased toxin production and poor outcomes in invasive MRSA infection, particularly in pneumonia. In this retrospective observational cohort study of MRSA bacteremia in adult patients from 2007 to 2015, we examined whether cytotoxicity was associated with 30-day mortality. Isolates were obtained from 776 patients and screened for cytotoxicity in a human HL-60 cell model, antimicrobial susceptibility, and spa type, and clinical data were abstracted from charts. We did not find an association between low cytotoxic activity and 30-day mortality in univariate logistic regression analyses. There was a difference in distribution of the genotypes across cytotoxicity phenotypes, with spa-CC008 accounting for a larger proportion of isolates in the high cytotoxicity group. Isolates with a skin and soft tissue primary infective site had a higher median cytotoxicity. There was no association between cytotoxicity and host factors such as age or comorbidity burden. The isolates in our study came from heterogeneous primary sites of infection and were predominantly from spa-CC002 and spa-CC008 lineages, so it is possible that findings in prior studies reflect a different distribution in genotypes and clinical syndromes. Overall, in this large study of cytotoxicity of MRSA bloodstream isolates, we did not find the low cytotoxicity phenotype to be predictive of poor outcomes in MRSA bacteremia.

A bacteraemia risk prediction model: development and validation in an emergency medicine population.

Design a risk model to predict bacteraemia in patients attended in emergency departments (ED) for an episode of infection. This was a national, prospective, multicentre, observational cohort study of blood cultures (BC) collected from adult patients (≥ 18years) attended in 71 Spanish EDs from October 1 2019 to March 31, 2020. Variables with a p value < 0.05 were introduced in the univariate analysis together with those of clinical significance. The final selection of variables for the scoring scale was made by logistic regression with selection by introduction. The results obtained were internally validated by dividing the sample in a derivation and a validation cohort. A total of 4,439 infectious episodes were included. Of these, 899 (20.25%) were considered as true bacteraemia. A predictive model for bacteraemia was defined with seven variables according to the Bacteraemia Prediction Model of the INFURG-SEMES group (MPB-INFURG-SEMES). The model achieved an area under the curve-receiver operating curve of 0.924 (CI 95%:0.914-0.934) in the derivation cohort, and 0.926 (CI 95%: 0.910-0.942) in the validation cohort. Patients were then split into ten risk categories, and had the following rates of risk: 0.2%(0 points), 0.4%(1 point), 0.9%(2 points), 1.8%(3 points), 4.7%(4 points), 19.1% (5 points), 39.1% (6 points), 56.8% (7 points), 71.1% (8 points), 82.7% (9 points) and 90.1% (10 points). Findings were similar in the validation cohort. The cut-off point of five points provided the best precision with a sensitivity of 95.94%, specificity of 76.28%, positive predictive value of 53.63% and negative predictive value of 98.50%. The MPB-INFURG-SEMES model may be useful for the stratification of risk of bacteraemia in adult patients with infection in EDs, together with clinical judgement and other variables independent of the process and the patient.

Relevance of anaerobic bacteremia in adult patients: A never-ending story?

Obligate anaerobic bacteria are considered important constituents of the microbiota of humans; in addition, they are also important etiological agents in some focal or invasive infections and bacteremia with a high level of mortality. Conflicting data have accumulated over the last decades regarding the extent in which these pathogens play an intrinsic role in bloodstream infections. Clinical characteristics of anaerobic bloodstream infections do not differ from bacteremia caused by other pathogens, but due to their longer generation time and rigorous growth requirements, it usually takes longer to establish the etiological diagnosis. The introduction of matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) has represented a technological revolution in microbiological diagnostics, which has allowed for the fast, accurate and reliable identification of anaerobic bacteria at a low sample cost. The purpose of this review article is to summarize the currently available literature data on the prevalence of anaerobic bacteremia in adults for physicians and clinical microbiologists and to shed some light on the complexity of this topic nowadays.

Longitudinal trajectory patterns of plasma albumin and C-reactive protein levels around diagnosis, relapse, bacteraemia, and death of acute myeloid leukaemia patients

BackgroundNo study has evaluated C-reactive protein (CRP) and plasma albumin (PA) levels longitudinally in patients with acute myeloid leukaemia (AML).MethodsWe studied defined events in 818 adult patients with AML in relation to 60,209 CRP and PA measures. We investigated correlations between CRP and PA levels and daily CRP and PA levels in relation to AML diagnosis, AML relapse, or bacteraemia (all ±30 days), and death (─30–0 days).ResultsOn the AML diagnosis date (D0), CRP levels increased with higher WHO performance score (PS), e.g. patients with PS 3/4 had 68.1 mg/L higher CRP compared to patients with PS 0, adjusted for relevant covariates. On D0, the PA level declined with increasing PS, e.g. PS 3/4 had 7.54 g/L lower adjusted PA compared to PS 0. CRP and PA levels were inversely correlated for the PA interval 25–55 g/L (R = − 0.51, p < 10–5), but not for ≤24 g/L (R = 0.01, p = 0.57). CRP increases and PA decreases were seen prior to bacteraemia and death, whereas no changes occurred up to AML diagnosis or relapse. CRP increases and PA decreases were also found frequently in individuals, unrelated to a pre-specified event.ConclusionsPA decrease is an important biomarker for imminent bacteraemia in adult patients with AML.

Risk Factors for Mortality among Patients with Pseudomonas aeruginosa Bloodstream Infections: What Is the Influence of XDR Phenotype on Outcomes?

This study aimed to assess the impact of extensively drug-resistant (XDR) phenotype on mortality in Pseudomonas aeruginosa bacteremia. A retrospective cohort study was performed in a tertiary hospital from January 2000 to December 2018. All consecutive prospectively recorded P. aeruginosa bacteremia in adult patients were assessed. In this study, 382 patients were included, of which 122 (31.9%) due to XDR P. aeruginosa. Independent factors associated with 14-day mortality were as follows: high-risk source of bacteremia (hazard ratio (HR) 3.07, 95% confidence interval (CI), 1.73–5.46), septic shock (HR 1.75, 95% CI, 1.12–2.75), and higher Pitt scores (one-point increments; HR 1.25, 95% CI, 1.12–1.38). Otherwise, the appropriateness of definitive antibiotic therapy was a protective factor (HR 0.39, 95% CI, 0.24–0.62). The same variables were also associated with 30-day mortality. XDR phenotype was not associated with 14- or 30-day mortality. In a subanalysis considering only high-risk source cases, combined antimicrobial therapy was independently associated with 14-day favorable outcome (HR 0.56, 95% CI, 0.33–0.93). In conclusion, XDR phenotype was not associated with poor prognosis in patients with P. aeruginosa bacteremia in our cohort. However, source of infection, clinical severity, and inappropriate definitive antibiotic therapy were risk factors for mortality. Combined antimicrobial therapy should be considered for high-risk sources.

562. Reducing MRSA Bacteremia in Adult Patients through MRSA Decolonization Bundle

BackgroundPatients colonized with methicillin-resistant Staphylococcus aureus (MRSA) are at an increased risk of developing a subsequent MRSA infection. Moreover, these individuals may serve as an endogenous reservoir to spread the bacteria to other patients. In an attempt to reduce MRSA bacteremia rates, a decolonization protocol was developed and implemented at a tertiary teaching hospital in Detroit, Michigan. In this study, we evaluate the intervention’s impact on community-onset (CO) and hospital onset (HO) MRSA bacteremia rates.MethodsInfection Control developed an MRSA decolonization bundle for adults that consisted of daily Chlorhexidine gluconate (CHG) bathing and twice-daily nasal swabs with 10% Povidone–iodine (PI) or Nozin for individuals with iodine allergies. Patients with known risk factors for developing an MRSA infection, such as patients residing in an intensive care unit and/or undergoing specified procedure, were prescribed the bundle for their length of stay (Figure 1). Countraindications for nasal decolonization included inhalation injuries, CSF leaks, ENT surgeries, and transphenoidal surgeries. A retrospective chart review of high-risk patients was conducted to determine compliance with the elements of the MRSA decolonization bundle. Rates of CO and HO MRSA bacteremia per 1,000 patient-days were graphed against compliance with bundle elements (2 nasal swabs and 1 CHG bath per day). To quantify the correlation, a linear regression model and the Pearson coefficient was used.ResultsApproximately 2,000 and 1,000 opportunities for nasal decolonization and CHG bathing, respectively, were identified between September 2018 and March 2019. The data suggest a strong correlation between compliance with MRSA decolonization elements and rate of HO MRSA bacteremia (R2 = 0.785) and a moderate association between nasal decolonization and rate of CO bacteremia (R2 = 0.322) (Figures 2 and 3).ConclusionThe MRSA decolonization bundle of CHG bathing and nasal swabs appears to be an effective strategy to decrease HO MRSA bacteremia rates with higher bundle compliance being associated with lower rates of infection. Disclosures All authors: No reported disclosures.

1053. Biofilm Production and Clinical Characteristics of S. maltophilia Causing Persistent or Relapsing Bacteremia

BackgroundThis study aimed to identify clinical or microbiological factors related to persistence or recurrence of Stenotrophomonas maltophilia bacteremia in adult patients.Methods S. maltophilia isolated from blood in two tertiary hospitals between 2011 and 2017 were investigated. Persistent bacteremia was defined as the consecutive blood culture positive for ≥5 days after initiation of appropriate antibiotics therapy. Relapse was defined as isolation of S. maltophilia from blood after completion of antibiotics treatment for the first episode of bacteremia. Biofilm formation was assessed in 96-well polystyrene plate with Trypticase Soy Broth using 0.5% crystal violet staining. The presence of smf-1 gene was detected by polymerase chain reaction.ResultsOf total 100 patients with S. maltophilia bacteremia, 10 of persistent, 8 of relapsing, and 46 of nonpersistent, nonrelapsing cases were investigated. The presence of indwelling urinary catheter (P = 0.011), nasogastric tube (P = 0.003), mechanical ventilator treatment (P = 0.001), and previous colonization of S. maltophilia (P = 0.016) were more frequently observed in patients with persistent bacteremia compared with nonpersistent, nonrelapsing bacteremia cases. In patients with relapsing bacteremia, hematologic malignancy (P = 0.022), neutropenia (P = 0.001), and concomitant isolation of S. maltophilia in clinical samples other than blood (P = 0.041) were more common than nonpersistent, nonrelapsing bacteremia patients. Catheter-related infection (37.0%) followed by pneumonia (28.3%) was the most common primary focus of nonpersistent, nonrelapsing bacteremia whereas pneumonia was the most frequent cause of bacteremia in both of persistent and relapsing cases (40.0% and 50.0%). Most of isolates (63 of 64) were susceptible to cotrimoxazole. The resistance to levofloxacin were comparable among isolates from persistent, relapsing and nonpersistent, nonrelapsing cases (10.0% vs. 12.5% vs. 15.2%, P = 0.988). Biofilm formation ability was not significantly different between three groups (optical density at 595, mean ± SD, 0.69 ± 0.34 vs. 0.78 ± 0.33 vs. 0.70 ± 0.33, P = 0.529). The smf-1 gene was found in all isolates.ConclusionMore careful treatment approaches to patients with risk factors for S.maltophilia treatment failure should be warranted.Disclosures All authors: No reported disclosures.

Diagnostic value of serum procalcitonin, lactate, and high-sensitivity C-reactive protein for predicting bacteremia in adult patients in the emergency department.

BackgroundFew studies compared the diagnostic value of procalcitonin with a combination of other tests including lactate and high-sensitivity C-reactive protein in the prediction of pathogenic bacteremia in emergency department adult patients.MethodsWe performed a retrospective study assessing the differences in performances of procalcitonin at a cutoff of 0.5 ng/mL, lactate at a cutoff of 19.8 mg/dL, high-sensitivity C-reactive protein at a cutoff of 0.8 mg/dL and their combinations for predicting bacteremia in emergency department adult patients. Sensitivity, specificity, overall accuracy, positive-test and negative-test likelihood, and diagnostic odds ratio with 95% confidence interval for each test combination were calculated for comparison. The receiver operating characteristic curve for every single test were compared using DeLong’s method. We also performed a sensitivity analysis in two expanded patient cohorts to assess the discriminative ability of procalcitonin or test combination.ResultsA total of 886 patients formed the initial patient cohort. The area under the receiver operating characteristic curve for discriminating positive blood culture was: procalcitonin = 0.72 (95% CI [0.69–0.75]) with a derived optimal cutoff at 3.9 ng/mL; lactate 0.69 (0.66–0.72) with an optimal cutoff at 17.9 mg/dL; high-sensitivity C-reactive protein 0.56 (0.53–0.59) with an optimal cutoff of 13 mg/dL; with pairwise comparisons showing statistically significant better performance of either procalcitonin or lactate outperforming high-sensitivity C-reactive protein. To predict positive blood cultures, the diagnostic odds ratio for procalcitonin was 3.64 (95% CI [2.46–5.51]), lactate 2.93 (2.09–4.14), and high-sensitivity C-reactive protein 0.91 (0.55–1.55; P = 0.79). About combined tests, the diagnostic odds ratio for procalcitonin and lactate increases were 3.98 (95% CI [2.81–5.63]) for positive blood culture prediction. Elevated procalcitonin level rendered a six-fold increased risk of positive gram-negative bacteremia with a diagnostic odds ratio of 6.44 (95% CI [3.65–12.15]), which showed no further improvement in any test combinations. In the sensitivity analysis, as a single test to predict unspecified, gram-negative and gram-positive bacteremia, procalcitonin performed even better in an expanded cohort of 2,234 adult patients in terms of the diagnostic odds ratio.DiscussionsFor adult emergency patients, procalcitonin has an acceptable discriminative ability for bacterial blood culture and a better discriminative ability for gram-negative bacteremia when compared with lactate and high-sensitivity C-reactive protein. High-sensitivity C-reactive protein at a cutoff of 0.8 mg/dL performed poorly for the prediction of positive bacterial culture.

Clinical predictors of Stenotrophomonas maltophilia bacteremia in adult patients with hematologic malignancy.

Stenotrophomonas maltophilia (SM) has emerged as an important nosocomial pathogen with high morbidity and mortality. Because of its unique antimicrobial susceptibility pattern, appropriate antimicrobial therapy for SM bacteremia is still challenging, especially in immunocompromised patients. The present study was performed to assess clinical predictors of SM bacteremia in adult patients with hematologic malignancy. From 2006 through 2016, a case-control study was performed at a tertiary-care hospital. Case patients were defined as SM bacteremia in patients with hematologic malignancy. Date- and location-matched controls were selected from among patients with gram-negative bacteremia (GNB) other than SM. A total of 118 cases of SM bacteremia were identified and compared to 118 controls. While pneumonia was the most common source of SM bacteremia, centralline-associated infection was most common in the controls. The overall 30-day mortality rate of cases with SM bacteremia was significantly higher than that of the controls (61.0 and 32.2%, respectively; P < 0.001). A multivariable analysis showed that polymicrobial infection, previous SM isolation, the number of antibiotics previously used ≥ 3, and breakthrough bacteremia during carbapenem therapy were significantly associated with SM bacteremia (all P < 0.01). Previous use of trimethoprim/sulfamethoxazole (TMP/SMX) was negatively association with SM bacteremia (P = 0.002). Our data suggest that SM is becoming a significant pathogen in patients with hematologic malignancy. Several clinical predictors of SM bacteremia can be used for appropriate antimicrobial therapy in hematologic patients with suspected GNB.

Antimicrobial resistance patterns, clinical features, and risk factors for septic shock and death of nosocomial E coli bacteremia in adult patients with hematological disease: A monocenter retrospective study in China.

The aim of this retrospective analysis was to evaluate the antimicrobial resistance, clinical features, and risk factors for septic shock and death of nosocomial E coli bacteremia in adult patients in a single hematological center in China. A retrospective case-control study of 157 adult hematological patients with 168 episodes of E coli bacteremia was initiated from April 2012 to July 2015. Antimicrobial susceptibility as well as antimicrobial co-resistance rates were analyzed. Clinical features and outcomes were also studied. In addition, risk factors for septic shock and death were investigated. Among the 553 positive blood isolates during the study period, the prevalence of E coli was 33.3% and ESBL production strains represented 61.9% of those examined. In all the E coli strains isolated, 85.6% were multidrug-resistance (MDR), 2.4% were extensive drug resistance (XDR), and 6.0% were resistant to carbapenems. More MDR phenotype was noted in ESBL-EC strains (98.6% vs 62.8%, P<.001) and isolates from neutropenic patients (98.6% vs 62.8%, P < .001). In the antimicrobial susceptibility test, carbapenems and amikacin exhibited not only higher in vitro activity against E coli (94.0% and 92.0%, respectively), but lower co-resistance rates to other antibiotics. Carbapenem resistant strains retained full sensitivity to tigecycline and 60% to amikacin. Piperacillin/tazobatam was the third sensitive drug to both ESBL-EC (77.1%) and non-ESBL-EC (86.0%). In our series, 81.6% episodes received appropriate initial antibiotic treatment and no significant decrease in it was found in bacteremia due to ESBL E coli and patients with neutropenia, septic shock. Septic shock was noted in 15.5% patients and the overall 30-day mortality rate was 21.7%. Multivariate analysis revealed that induction chemotherapy (OR 2.126; 95% CI 1.624–11.332; P = .003) and polymicrobial infection (OR 3.628; 95% CI 1.065–21.219; P = .041) were risk factors for septic shock, whereas male (OR 2.223; 95% CI 1.132–12.022; P < .01) and septic shock (OR 52.359; 95% CI 19.951–292.690; P = .030) were risk factors for death.In the hematology department, ESBL-producing and MDR are widely prevalent in E coli bacteremia which is still a major life-threatening problem, especially for patients with septic shock. For empirical antimicrobial therapy, combination based on aminoglycoside, especially amikacin, will be helpful to increase the antimicrobial coverage against ESBL-EC while combining tigecycline with aminoglycoside should be considered for seriously carbapenem-resistant infectious patients.