Polymicrobial Bacteremia Research Articles

Resistance Genes and Mortality in Carbapenem-resistant Klebsiella pneumoniae Bacteremias: Effects of the COVID-19 Pandemic

Emerging carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) (CRKP) bacteremias are presenting significant public health risks due to limited treatment options and increased mortality. K. pneumoniae isolates exhibit carbapenem resistance rates that vary from 25% to 50% throughout the European continent, including our country. To assess the characteristics of CRKP bacteremia, a condition that has recently demonstrated an increasing prevalence in our center. We sought to ascertain the resistance rates of isolated strains to antibiotics other than carbapenems, identify the responsible carbapenemase genes, evaluate the efficacy of antibiotics, determine mortality rates, explore clonality among strains, and investigate the influence of the COVID-19 pandemic on all these factors. Retrospective observational study. This study included patients aged 18 and older who had experienced meropenem-resistant K. pneumoniae bacteremia. Meropenem resistance was confirmed by employing the Kirby-Bauer disk diffusion method. Meropenem minimum inhibitory concentration (MIC) levels were determined using the gradient test, while colistin MIC levels were ascertained using the disk elution technique. Carbapenemase genes were evaluated via colony polymerase chain reaction (PCR), and clonality analysis was performed using the arbitrarily primed PCR technique. The study comprised 230 patients, with a mean age of 63.1 ± 15.9 years, of whom 58.7% were male. Oxacillinase-48 (OXA-48) was detected in 74.8% of the patients, New Delhi metallo-beta-lactamase (NDM) in 12.6%, OXA-48 + NDM in 7.8%, and KPC in 4.8%. The 14-day and 30-day mortality rates were 57% and 69.6%, respectively. Multivariate analysis of the 30-day mortality revealed several crucial factors, including bacteremia development in the intensive care unit, the occurrence of bacteremia during the COVID-19 pandemic, polymicrobial bacteremia, the use of indwelling intravenous catheters, a platelet count of ≤ 140,000/μl, procalcitonin levels of ≥ 6 μg/l, and a Charlson comorbidity score ≥ 3. Notably, the OXA-48 and KPC genes were upregulated significantly during the COVID-19 pandemic, while the NDM gene groups were downregulated. Additionally, both 14-day and 30-day mortality rates increased significantly. In this study, the most prevalent carbapenemase gene was OXA-48; however, there has been a recent increase in KPC genes. No dominant epidemic strain was identified through clonality analysis. The clustering rate was 68% before the pandemic, increasing to 85.7% during the pandemic. The significance of infection control measures is underscored by the rise in both clustering and mortality rates during the COVID-19 pandemic.

Clinical and microbiological characteristics of anaerobic bacteremia during 1994–2019: A Danish population-based cohort study

ObjectivesBacteremia with anaerobic bacteria is generally a marker of severe prognosis. However, population-based data is lacking. Our aim was to describe the epidemiology and the 30-day mortality rate of anaerobic bacteremia in a Danish population-based setting. MethodsIn this population-based cohort study, all first-time episodes of anaerobic bacteremia from the North Denmark Bacteremia Research Database during 1994–2019 were identified. Information on comorbidities, discharge diagnoses, and mortality was retrieved. 30-day mortality rates were calculated and a multivariate logistic regression analysis to identify risk factors for death was performed. Results1750 episodes with anaerobic bacteremia were identified, corresponding to an incidence rate of 12.5 per 100,000 inhabitants (increasing from 11.2 in 1994–2014 to 17.7 in 2015–2019). Of these episodes, a third were polymicrobial, and the majority (70 %) of patients had one or more comorbid conditions. Abdominal infection was the source of bacteremia in 61 % of patients, while it was unknown for 15 %. The most frequently isolated genera were Bacteroides (45 %), Clostridium (20 %) and Fusobacterium (6 %). The overall crude 30-day mortality rate was 27 %, but rates were even higher for patients of high age, with liver disease, and solid tumors. The odds ratio (OR) for 30-day mortality was 1.32 for Clostridium species, and 1.27 for polymicrobial bacteremia with aerobic bacteria. ConclusionsThe incidence rate of anaerobic bacteremia increased, and the 30-day mortality rate remained high during the study period. Multiple factors influence 30-day mortality rates, including high age, liver disease, solid tumor, polymicrobial bacteremia, and bacteremia with Clostridium species.

Characteristics, Treatment, and Outcomes of Invasive Group A Streptococcal Infections

Background: Group A Streptococcus (GAS; Streptococcus pyogenes) is an important human pathogen that can cause life-threatening invasive disease, ranging from skin/soft tissue infections to infective endocarditis. In the fall of 2022, the Center for Disease Control & Prevention (CDC) issued an alert due to a global increase in invasive GAS infections, particularly among children and adults with co-morbidities. An increase in invasive disease was observed at our five-hospital healthcare system in Southeast Michigan. The objective of this study was to describe characteristics of patients with invasive GAS and characterize treatment and outcomes of disease. Methods: This was a retrospective cross-sectional study of patients from June 2013 to August 2023 with positive blood cultures for GAS. Patients were identified using a data query for positive blood cultures for GAS through Microsoft SQL Server. Patients with age < 1 8 years, polymicrobial bacteremia, incomplete data, or who were enrolled in hospice and/or died within 48-hours of admission were excluded. Collected variables included: demographics, infection characteristics (syndrome, duration of bacteremia), microbiological characteristics (antimicrobial susceptibility testing; AST), antimicrobial treatment (empiric and final, antitoxin therapy), and clinical outcomes (length of hospital stay [LOS], treatment-associated adverse events, 30-day mortality and infection-related readmission). Results: 250 patients were included (Table 1). More than half were male with median age of 57.5 years. Diabetes mellitus (38%) and chronic kidney disease (23%) were common comorbidities [Table 1]. Persons experiencing homelessness and persons who use injection drugs accounted for 9% and 13% of the cases, respectively. The most common infective syndrome accompanying bacteremia was cellulitis (57%). The majority of patients received vancomycin for empiric therapy (81%) and penicillin (38%) or cephalosporin (36%) for final regimen [Table 2]. A total of 79 GAS isolates (32%) were clindamycin resistant. Clindamycin was included in the empiric regimen of 20 (8%) patients, the final regimen in 44 (18%) of patients, and as antitoxin adjunct therapy in 135 (54%) of patients. A third (33%) of patients received no antitoxin. The average duration of antitoxin therapy was 3.6 days and antimicrobial therapy 19.9 days. The mean LOS was 11.4 days (Table 3). Thirty nine (16%) patients had treatment failure and 8 (3%) experienced C. difficile infection within 30 days of antimicrobial treatment. Thirty-day mortality was 11%; of these, 9% had in-hospital mortality. Conclusions: Invasive GAS infection confers significant morbidity and mortality, and ongoing research is needed to determine the best treatment regimens in the era of increasing clindamycin resistance.

A comprehensive, predictive mortality score for patients with bloodstream infections (PROBAC): a prospective, multicentre cohort study.

Bloodstream infections (BSI) are an important cause of mortality, although they show heterogeneity depending on patients and aetiological factors. Comprehensive and specific mortality scores for BSI are scarce. The objective of this study was to develop a mortality predictive score in BSI based on a multicentre prospective cohort. A prospective cohort including consecutive adults with bacteraemia recruited between October 2016 and March 2017 in 26 Spanish hospitals was randomly divided into a derivation cohort (DC) and a validation cohort (VC). The outcome was all-cause 30-day mortality. Predictors were assessed the day of blood culture growth. A logistic regression model and score were developed in the DC for mortality predictors; the model was applied to the VC. Overall, 4102 patients formed the DC and 2009 the VC. Mortality was 11.8% in the DC and 12.34% in the CV; the patients and aetiological features were similar for both cohorts. The mortality predictors selected in the final multivariate model in the DC were age, cancer, liver cirrhosis, fatal McCabe underlying condition, polymicrobial bacteraemia, high-risk aetiologies, high-risk source of infection, recent use of broad-spectrum antibiotics, stupor or coma, mean blood pressure <70 mmHg and PaO2/FiO2 ≤ 300 or equivalent. Mortality in the DC was <2% for ≤2 points, 6%-14% for 3-7 points, 26%-45% for 8-12 points and ≥60% for ≥13 points. The predictive score had areas under the receiving operating curves of 0.81 (95% CI 0.79-0.83) in the DC and 0.80 (0.78-0.83) in the VC. A 30 day mortality predictive score in BSI with good discrimination ability was developed and internally validated.

Clostridium Cadaveris Bacteremia in an Immunocompromised Host

Clostridial bacteremia is an exceedingly rare clinical entity that can cause significant morbidity and mortality. Immunocompromised patients with insult to the gastrointestinal mucosa are especially prone to the development of clostridial sepsis based on limited existing literature. Here we report a case of a 65-year-old male nursing home resident with incompletely treated colorectal adenocarcinoma who was admitted for sepsis. He was found to have polymicrobial bacteremia with Escherichia coli and Clostridium cadaveris. He was successfully treated with intravenous piperacillin/tazobactam followed by an oral regimen of amoxicillin/clavulanic acid.

Characterization of Prescribing Practices for Uncomplicated Streptococcal and Enterococcal Bacteremias: The NARRATE Study.

Bloodstream infections (BSIs) rank among the top causes of death in North America. Despite the prevalence of these infections, there remain significant practice variations in the prescribing of antibiotics. To investigate current prescribing practices for management of uncomplicated streptococcal and enterococcal BSIs. A retrospective cohort study was conducted using charts for patients admitted to an acute care centre in British Columbia between November 16, 2019, and October 20, 2020. Adult patients (≥ 18 years of age) with a diagnosis of uncomplicated streptococcal or enterococcal BSI were included. Patients were excluded if they had polymicrobial bacteremia or deep-seated infection or had been admitted for no more than 48 hours. The primary outcomes were duration of antibiotic therapy (IV and oral) and time to appropriate oral therapy for treatment of BSI. The secondary outcomes were observed rates of re-initiation of antibiotics and readmission with recurrent BSI. Descriptive statistics were calculated and regression analysis was performed for the primary and secondary outcomes. A total of 96 patients met the inclusion criteria. The median total duration of therapy for uncomplicated streptococcal and enterococcal BSI was about 2 weeks. Streptococcus pneumoniae BSIs were associated with a significantly shorter duration of IV therapy and were more likely to be associated with transition to oral antibiotics. No recurrent BSIs were observed in patients for whom therapy was transitioned to oral antibiotics. Further study is warranted to explore shorter duration of antibiotic therapy and transition to oral therapy as treatment approaches for uncomplicated streptococcal and enterococcal BSI. Other outcomes of interest for future research include determining the optimal time for transition to oral therapy.

Polymicrobial Bacteremia Due to SARS-CoV-2–Related Superior Mesenteric Vein Thrombosis

Polymicrobial Bacteremia Due to SARS-CoV-2–Related Superior Mesenteric Vein Thrombosis

193. Standard of Care versus Alternative Beta-lactams for Treatment of Infections due to Serratia marcescens

Abstract Background The threat of inducible resistance and treatment failure positioned cefepime and carbapenems as the standard of care (SOC) treatment agents for infections due to AmpC-producing Enterobacterales regardless of antimicrobial susceptibility testing results. Recently published Infectious Diseases Society of America Guidance (IDSA) classifies the overall risk of clinically relevant AmpC expression for Serratia marcescens as low (&amp;lt; 5%). We aimed to compare the clinical outcomes of patients treated with a SOC antibiotic (carbapenem or cefepime) to those treated with an alternative beta-lactam agent for S. marcescens bloodstream infection (BSI). Methods This multisite, retrospective study included patients from five hospitals in the Atlanta-Metropolitan area with S. marcescens BSIs between January 1, 2018 and December 31, 2022. Patients were included if they received at least 72 hours of therapy with a beta-lactam antibiotic whose in vitro susceptibility was confirmed. Patients with polymicrobial bacteremia, those receiving combination therapy for &amp;gt; 72 hours, or those with a diagnosis of endovascular infection were excluded. We used a desirability of outcome ranking (DOOR) analysis to determine the probability of having a more desirable outcome receiving SOC antibiotics compared to receiving an alternative beta-lactam agent. The DOOR analysis includes counting undesirable events (Figure 1) and was performed using an online calculator (https://methods.bsc.gwu.edu).Figure 1:Primary endpoint - Desirability of outcome ranking. Abbreviations: AKI = acute kidney injury; CDI = Clostridioides difficile infection; EMR = electronic medical record; SCr = serum creatinine Results Of the 175 S. marcescens blood cultures reviewed, 66 patients met criteria for study inclusion, 43 in the SOC group and 23 in the alternative group. Baseline characteristics were comparable in both groups (Figure 2). The DOOR distribution between treatment groups was similar (Figure 3) and there was no significant difference in the probability of a more desirable outcome for patients who received an alternative beta-lactam compared to SOC (54.2% [95% CI, 40.3 - 67.5%]; Figure 4).Figure 2:Baseline patient characteristics. Abbreviations: BMT = bone marrow transplant within previous 12 months; Corticosteroid = ≥15 mg prednisolone daily equivalents; HIV = human immunodeficiency virus; ICU = intensive care unit; IQR = interquartile range; NS = non-significant; SOC = standard of care; SOT = any history of solid organ transplantFigure 3:Desirability of Outcome Ranking Distribution Summary Desirability of outcome ranking distribution for the standard of care and alternative beta-lactam treatment groups; SOC = standard of careFigure 4:Desirability of Outcome Ranking Probability Summary Forest plot of desirability of outcome ranking probabilities by overall treatment group and individual ranking components; CI = confidence interval, DOOR = desirability of outcome ranking, SOC = standard of care Conclusion The overall outcome of patients receiving alternative beta-lactam antibiotics was similar to those receiving SOC antibiotics in this study. These results support use of alternative beta-lactams for treatment of susceptible S. marcescens BSIs as recommended by IDSA guidance. Disclosures Joseph Torrisi, PharmD, BCIDP, Clinical Care Operations: Honoraria Ahmed Babiker, MBBS, Roche: Advisor/Consultant

2238. Effect of Cefazolin Breakpoint Update in Susceptibility Reports on Antimicrobial Use

Abstract Background The Clinical Laboratory Standards Institute updated the breakpoints for cefazolin in the treatment of E. coli, Klebsiella, and Proteus (EKP) infections in 2011 to reflect doses used in clinical practice and achievable therapeutic concentrations in different body sites (urine vs. non-urine). The UTMB clinical microbiology laboratory adopted this update in January 2022 with the introduction of MicroScan™ technology. Our objective was to evaluate the effect of the cefazolin breakpoint update on antimicrobial use in EKP bloodstream infections. Methods This was a retrospective, multicenter, pre-post, study conducted at four UTMB hospitals. Pre-intervention data was collected from January 2021 to December 2021 and post-intervention data was collected from February 2022 to March 2023. Patients ≥ 18 years old were included if they were admitted to a UTMB hospital and received antibiotics for EKP bacteremia. Texas Department of Criminal Justice patients, those with beta-lactam anaphylaxis, polymicrobial bacteremia, immunocompromised patients, and Klebsiella aerogenes isolates were excluded. The primary outcome was cefazolin days of therapy (DOTs) for EKP bacteremia. Extended-spectrum beta-lactamase (ESBL)-producing isolates and Clostridioides difficile (C. difficile) infection six months after the index admission, and in-hospital and 28-day mortality were also assessed. Results There were 50 and 48 patients included in the pre- and post-intervention periods, respectively. Most patients were female (59%) with a mean age of 67.8 years (standard deviation [SD] 14.9). The most isolated gram-negative pathogen was Klebsiella pneumonia (81%) followed by Proteus mirabilis (13%) from urinary sources of infection (59%). There was no significant difference in median cefazolin DOTs before (0 days; interquartile range [IQR] 0,0) and after (0 days; IQR 0,0) the breakpoint update (p=0.35). There was no difference in ESBL-producing pathogens (2 vs. 3, p=0.67), C. difficile infection (1 vs. 2, p=0.61), in-hospital (3 vs. 7, p=0.20), or 28-day mortality (0 vs. 0, p=1) between the pre- and post-breakpoint update groups. Conclusion Updating the breakpoint to a lower value for EKP isolates in the blood did not have an effect on cefazolin use. Disclosures All Authors: No reported disclosures

144. Impact of Rapid Identification and Resistance Gene Detection using an Algorithm-Based Approach in Gram-Negative Bacteremia

Abstract Background Time to appropriate antimicrobial therapy is the most important predictor of survival among patients with sepsis due to Gram-negative bacteria (GNB). Infections due to multidrug-resistant (MDR) pathogens often result in inappropriate empiric treatment (tx). The GenMark ePlex identifies organisms and resistance markers within 1.5 hours from blood culture positivity compared to 48-72 hours by conventional methods. Methods We are conducting a single-center study to assess outcomes before and after ePlex implementation. The pre-intervention period included patients with GN bacteremia from January to June 2021. Patients were excluded if they received comfort-only care within 48 hours, had polymicrobial GN bacteremia, or were infected by an organism not on the ePlex panel. Primary outcome is time to in-vitro active therapy from blood culture collection. Results 208 patients were identified during the pre-intervention period; 154 met inclusion criteria. Median age was 64 years, 49% were male, and 28% were immunocompromised. Median (IQR) Charlson Comorbidity index and Pitt Bacteremia scores were 6 (4-8) and 2 (1-8), respectively (Table 1). 16% of patients were infected by MDR GNB and 21% received inactive empiric tx. Overall median (IQR) time to in-vitro active tx was 3.9 (1–19) hours, but was 39.5 (13.6-71.9) hours among those who received inactive empiric tx. Median (IQR) time to first antibiotic modification was 2.7 (1.0-3.4) days. 38% of patients were transitioned to oral antibiotics at a median (IQR) of 4.2 (3.1-6.1) days. The median (IQR) duration of tx was 15 (10-17) days; 4.5% of patients were treated with ≤ 7 days. Median (IQR) length of hospitalization was 15.5 (7-36) days. 7.8% were re-admitted within 30 days (Table 2). In-hospital and 30-day mortality rates were numerically higher among patients who received inactive empiric therapy (27% and 21%, respectively) when compared to patients who received active empiric therapy (16.5% and 12%, respectively) (Figure 1). Results Table 1: Patient demographics, underlying conditions and infection and treatment characteristics in the pre-intervention group Results Table 2 Results Figure 1 Conclusion Our pre-intervention data highlight opportunities to improve the management of GN bacteremia. Implementation of ePlex is likely to decrease the proportion of patients treated with inactive therapy, shorten time to optimal tx and reduce lengths of stay. Disclosures Ryan K. Shields, PharmD, MS, Allergan: Advisor/Consultant|Cidara: Advisor/Consultant|Entasis: Advisor/Consultant|GSK: Advisor/Consultant|Melinta: Advisor/Consultant|Melinta: Grant/Research Support|Menarini: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Advisor/Consultant|Roche: Grant/Research Support|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support|Utility: Advisor/Consultant|Venatorx: Advisor/Consultant|Venatorx: Grant/Research Support

1858. Examining the Racial Differences in Polymicrobial Bacteremia Infections in an Area of Varying Social Vulnerability

Abstract Background Polymicrobial bacteremia (PMB) is associated with heightened disease severity and an increased burden of comorbidities has been identified as a key risk factor. Of interest, racially and ethnically minoritized (REM) individuals that reside in areas of high vulnerability have been shown to be more likely than their non-racially and ethnically minoritized (n-REM) counterparts to be diagnosed with chronic comorbidities. Nonetheless, there is a cessation of data that examines the confluence of these factors on PMB infection outcomes. This study aims to describe the racial differences in the outcomes of patients diagnosed with PMB in an area of varying social vulnerability. Methods This is an IRB-approved, retrospective cohort study of adult patients hospitalized at Loma Linda University Medical Center between January 2018 and April 2021. Positive polymicrobial blood culture samples were identified with the use of Microscan Bacterial Identification Panel. Demographics (including race/ethnicity), comorbid conditions, sepsis incidence, and infection source were collected through chart review. The Centers for Disease Control and Prevention (CDC) SVI scoring tool was used to determine the social vulnerability index (SVI). A P value of ≤ 0.05 was defined as statistically significant. Results A total of 70 patients REM (60%, 42/70) and non-REM (40%, 28/70) among PMB gram-negative (GN) and gram-positive (GP) cultures collected from hospitalized adult patients were included. Hispanic/Latino was the most prominent REM group (59.5%) and overall, REM patients were more likely to be classified as “highly vulnerable” when compared to non-REM patients (47.6% vs 42.9%). Also, REM patients were younger (61.5 years vs. 65.1 years) and were more likely to have underlying comorbidities (diabetes mellitus (47.6% vs 21.4%; p=0.026 and moderate to severe chronic kidney disease (28.8% vs 14.3%; p= 0.329). Additionally, REM patients were more likely to develop sepsis and severe sepsis (45.2% vs. 25.0%; p= 0.13 and 40.6% vs 35.7%, p=0.804), respectively, though there was no difference in mortality. Conclusion Ultimately, further research is needed to understand the confluence of race/ethnicity and social vulnerability factors on PMB clinical outcomes. Disclosures Jacinda C. Abdul-Mutakabbir, PharmD, MPH, Entasis: Advisor/Consultant|Entasis: Honoraria|Shionogi: Advisor/Consultant|Shionogi: Honoraria

Bacteraemia caused by non-faecalis and non-faecium Enterococcus species—a retrospective study of incidence, focus of infection, and prognosis

Background/aimEnterococcus faecalis and Enterococcus faecium cause human infections including bacteraemia and infective endocarditis (IE). Only few studies describing non-faecalis and non-faecium Enterococcus (NFE) infections have been conducted. We aimed to describe the incidence, prognosis, and focus of infection of bacteraemia with NFE.MethodsThis retrospective population-based study included all episodes of patients having a blood culture with growth of NFE between 2012 and 2019 in Region Skåne, Sweden. Information was collected from medical records. Episodes of bacteraemia caused by NFE were compared to episodes of bacteraemia caused by E. faecalis and E. faecium.ResultsDuring the study period, 136 episodes with NFE bacteraemia were identified corresponding to an incidence of NFE bacteraemia of 16 cases per 1,000,000 person-years among adults. Enterococcus casseliflavus (n=45), Enterococcus gallinarum (n=34), and Enterococcus avium (n=29) were the most common species. The most common foci of infection were biliary tract infections (n=17) followed by gastrointestinal infections (n=7). Urinary tract infections were not commonly caused by NFE (n=1), and no episodes of IE were caused by NFE. Polymicrobial bacteraemia was more common with NFE (73%) than with E. faecalis (35%) and E. faecium (42%). Community acquired infections were more common in bacteraemia with NFE compared to E. faecium. 30- and 90-day survival rates were 76% and 68%, respectively, and recurrent NFE bacteraemia was seen after 3% of the episodes.ConclusionBacteraemia caused by NFE is rare and is often polymicrobial. Biliary tract focus is common in NFE bacteraemia whereas IE and urinary tract focus are uncommon.

Impact of Gram-Negative Rod Bacteremia Rapid Diagnostic Testing and Real-Time Clinical Pharmacist Intervention

Background: The optimal method for implementing rapid diagnostic testing (RDT) into clinical practice has not been determined for gram-negative rod (GNR) bacteremia. At our institution, RDT was implemented in conjunction with real-time notification of results to decentralized clinical pharmacists. Objective: To determine the impact of RDT result notification plus real-time clinical pharmacist review on the management of GNR bacteremia. Methods: This retrospective, matched cohort study included patients with a positive blood culture for a GNR on the BIOFIRE® Blood Culture Identification 2 panel from September 2020 to August 2021 (historical) and October 2021 to September 2022 (interventional). Exclusion criteria were polymicrobial bacteremia, discrepant RDT results from traditional culture, 24-hour mortality, and comfort care or not admitted at the time of RDT result. Patients were matched based on age, pathogen, and resistance. The primary endpoint was time from Gram stain to appropriate antibiotic therapy. Results: This study consisted of 240 patients (n = 120 historical, n = 120 interventional). Escherichia coli was isolated in 71% of patients with extended-spectrum beta-lactamase-producing organisms isolated in 8%. There was no difference in median time to appropriate therapy (0 vs 0 hours, P = 0.28). There was a statistically significant decrease in time to first organism-directed change in therapy (40 vs 11 hours; P < 0.01). Length of stay, days of anti-pseudomonal therapy, and inpatient mortality did not differ between groups. Conclusion: Implementation of RDT plus real-time clinical pharmacist review did not significantly decrease time to appropriate therapy in patients with GNR bacteremia but significantly reduced time to organism-directed antibiotic changes.

Blood culture identification (BCID) performance in polymicrobial bacteremia

The rapid multiplex PCR (rmPCR)-based FilmArray® blood culture identification (BCID) assay reduces time from positive blood culture to organism identification. Polymicrobial bacteremia (PMB) is a known area of reduced diagnostic fidelity for BCID and remains incompletely characterized. All cases of clinically confirmed PMB at a large academic single center from a 23-month period were evaluated in a retrospective cohort analysis. A total of 207 samples were identified and studied. Overall, 49.3% (N = 102) of polymicrobial cultures were incompletely identified by FilmArray® result. There were no significant between-group differences in comorbidity status, length of stay, mortality, or source between patients with PMB who had complete versus incomplete BCID identification. Our results suggest that rmPCR-based assays frequently miss organisms in PMB and should be interpreted accordingly.

Clinical characteristics and mortality rates of bacteremia caused by Streptococcus anginosus group: A retrospective study of 84 cases at a tertiary hospital in South Korea

The Streptococcus anginosus group (SAG) is a subgroup of viridans streptococci comprising three species: S. anginosus, S. constellatus, and S. intermedius. SAG usually resides in the oral cavity and colonizes the throat, and the gastrointestinal and genitourinary tracts. SAG can form abscesses in various parts of the body; however, the clinical features of SAG infection are not clear. Here, we reviewed the medical records of all SAG bacteremia patients aged over 18 years who were diagnosed between January 2010 and December 2021 at a tertiary university hospital. We then compared clinical characteristics, source of infection, need for surgical or interventional treatment, and 28-day mortality rates among each species of SAG. Differences in percentages between groups were compared using a proportion test, and differences between mean values were assessed using the Kruskal-Wallis test with post-hoc Bonferroni correction. In total, 84 cases of SAG bacteremia (40 S. anginosus cases, 31 S. constellatus cases, and 13 S. intermedius cases) were identified. The most common comorbidity was diabetes mellitus (n = 26, 31%), and the most common source was hepatobiliary infection (n = 30, 35.7%). Polymicrobial bacteremia was observed in 22.6% (19/84) of cases. Twenty-eight day mortality due to S. anginosus bacteremia was 12.5%; no deaths were reported in the S. constellatus and S. intermedius groups. However, the difference among the groups was not significant (p = 0.054). Hepatobiliary infection was the most common source of SAG bacteremia. In addition, S. anginosus bacteremia resulted in more severe disease and higher mortality rates than S. constellatus or S. intermedius bacteremia.

Clinical impact of the accelerate PhenoTest® BC system on patients with gram-negative bacteremia and high risk of antimicrobial resistance: a prospective before-after implementation study

BackgroundThe Accelerate PhenoTest® BC system (AXDX) is a novel assay for rapid bacterial identification and antimicrobial susceptibility (AST). We report an evaluation of its impact on treatment of patients with Gram-negative bacteremia (GNB) with a high risk of antimicrobial resistance (AMR).MethodsA prospective single-center evaluation before and after implementation of AXDX in addition to standard-of-care (SOC) microbiology and antimicrobial stewardship program (ASP). Patients with GNB reported during laboratory working hours and prespecified risk factors for AMR were included. The primary outcome was an ASP-oriented beneficial antimicrobial change, defined as either an escalation of an inappropriate empiric treatment or de-escalation of a broad-spectrum treatment of a susceptible organism. Main secondary outcomes were time to an appropriate treatment, antimicrobial treatment duration, length of stay (LOS) and mortality.ResultsIncluded were 46 and 57 patients in the pre- and post-intervention periods, respectively. The median time to an AST-oriented beneficial change was 29.2 h vs. 49.6 h, respectively (p < 0.0001). There were no significant differences in the time to appropriate treatment, LOS or mortality. Antimicrobial treatment duration was longer during the intervention period (10 vs. 8 days, p = 0.007). AXDX failed to correctly identify pathogens in all 6 cases of polymicrobial bacteremia. In two cases patient care was potentially compromised due to inappropriate de-escalation.ConclusionsAXDX implementation resulted in a 20.4-hour shorter time to an ASP-oriented beneficial antimicrobial change. This should be weighed against the higher costs, the lack of other proven clinical benefits and the potential harm from mis-identification of polymicrobial bacteremias.

Evaluation of interprovider consistency in interpretation of blood culture guidelines at an academic medical center

Background: Blood cultures are a fundamental tool in the diagnosis of infections, but they can lead to clinical confusion and waste resources when they yield false results. To optimize blood-culture orders at our institution, we developed an evidence-based clinical guideline (Fig. 1) to be used by frontline providers on nonneutropenic hospitalized adult inpatients. We retrospectively reviewed charts of patients with positive blood cultures to evaluate whether frontline providers and infectious diseases (ID) attending physicians were able to consistently interpret the guidelines to determine whether blood cultures were drawn appropriately. Methods: In total, 95 nonneutropenic adults with an initial positive blood culture collected while on an inpatient unit were identified through a query of the electronic medical record from January 2021 through June 2022. Patients with polymicrobial bacteremia and bacteremia due to Enterococcus, Streptococcus, and gram-positive rods were excluded. Moreover, 4 medical resident physicians reviewed all patients and 2 ID attending physicians reviewed one-quarter of cases; all were blinded to the culture results. Blood cultures were determined to be either appropriately or inappropriately performed based on our institution’s guideline. The free-marginal multirater κ statistics with 95% CIs were calculated to evaluate interrater agreement. Results: Baseline patient demographics are shown in Table 1. Immune compromise without neutropenia was noted in 21 of 95 patients. Most patients were at high risk for bacteremia (72%) per our institutional guideline, most of whom were septic (67.7%). Low risk for bacteremia was found in only 12.3% of reviews. Medical resident physicians, ID attending physicians, and all reviewers combined agreed on whether blood cultures were drawn appropriately or inappropriately (84.2%, 92%, and 86.4% agreement rates, respectively). The free-marginal κ statistic was highest for ID attending physicians (0.84; 95% CI, 0.62–0.78), followed by attending physicians and resident physicians combined (0.73; 95% CI, 0.56–0.90), and resident physicians alone (0.68; 95% CI, 0.58–0.78). In the 21 patients with immune compromise, the agreement rates on blood culture appropriateness remained high among all reviewers, resident physicians, and ID attending physicians were 86.6%, 90.5%, and 95%, respectively. Conclusions: In our retrospective study of nonneutropenic hospitalized adult inpatients, frontline providers and ID attending physicians interpreted blood-culture guidelines consistently, largely agreeing on which patients had cultures drawn appropriately. Agreement among ID attending physicians was excellent and remained substantial among medical resident physicians. Guidelines on the appropriate use of blood cultures are vital to limiting unnecessarily collected cultures, which can lead to extended length of stay and increase cost across hospital systems. Further analyses on the clinical impact of this guideline are ongoing.Disclosures: None

Polymicrobial bacteremia in a heart transplant recipient: More than what meets the eye

Each month, the American Journal of Transplantation will feature Images in Transplantation, a journal-based CME activity, chosen to educate participants on the current developments in the science and imaging of transplantation. Participants can earn 1 AMA PRA Category 1 Credit per article at their own pace.

Lesson from the COVID-19 pandemic lockdown: A major change of hospital-diagnosed bacteremia epidemiology

ObjectivesWhen the COVID-19 pandemic reached France early in 2020, the enforced nationwide lockdown deeply altered lifestyle as well as hospital processes and modalities of care. The aim of the study was to evaluate the impact during the lockdown of the first epidemic wave on the epidemiology of bacteremia in one French University Hospital. Patients and MethodsRetrospective cohort study including adult patients with positive blood culture between 23rd March to 24th May 2020. The clinical-microbiological characteristics were compared with those of the period from 25th March to 26th May 2019. The data were adjusted to the number of hospitalizations (h). ResultsIn 2020, 189 bacteremia were diagnosed from 1939 vials (9658 hospitalizations, 10911 emergency room consultations) compared to 143 from 1976 vials (14797 hospitalizations, 16493 emergency room consultations) recorded in 2019. The incidence of bacteremia increased up to 19.7 per 1000h in 2020 vs 9.7 in 2019 (p < 0.001). The main differences (2020 vs 2019) were: Staphylococcus aureus bacteremia (2.4 vs 1.0/1000h, p = 0.012), polymicrobial bacteremia (2.2 vs 0.9/1000h p = 0.013) and Gram-negative bacteremia (8.9 vs 4.3/1000h, p < 0.01). Conversely, Streptococcus pneumoniae incidence decreased (0 vs 0.47/1000h, p = 0.047). The standardized incidence ratio calculation confirmed these results. ConclusionThe lockdown and the impact of the first wave of the Covid-19 pandemic on the health system resulted in increased hospital-diagnosed bacteremia and decreased pneumococcal bacteremia. Disruption and overload of ICUs, lockdown with preventive control measures, and decrease in human-to-human interaction may have been the main reasons.

Case Series of Granulicatella Bacteremia: A Single-centered, Five-year Retrospective Study.

Granulicatella species are rare, nutritionally variant streptococci that cause infective endocarditis. Their clinical and microbiological characteristics remain unknown. We reviewed five years of Granulicatella cases in our hospital database (Jan 2017-Jun 2022), finding 6 Granulicatella adiacens cases and 1 Granulicatella elegans case. Clinical backgrounds and bacteremia sources were diverse; 3 cases developed polymicrobial bacteremia. Antimicrobial testing showed non-susceptibility to penicillin G in 4 of 7 cases (57.1%), and high susceptibility to carbapenems and vancomycin in all cases. Determining optimal antibiotic therapy for Granulicatella infections is vital in this era of antimicrobial resistance.