Polymicrobial Bloodstream Infections Research Articles

Diagnostic and therapeutic yield of imaging studies in polymicrobial and monomicrobial Gram-negative bloodstream infections – a retrospective cohort study

Purpose: Appropriate antimicrobial therapy and surgical drainage, improve survival in patients with Gram negative bloodstream infections (BSI). Data about the yield of imaging studies in polymicrobial BSI is sparse. The aim of the study was to assess the need for imaging studies and surgical drainage among patients with polymicrobial compared to monomicrobial BSI. Results: In a retrospective cohort study of adult patients with Gram negative BSI, 135 patients with monomicrobial BSI were compared to 82 with polymicrobial BSI. Imaging studies were performed in 56.3% of patients with monomicrobial BSI and in 50% of polymicrobial BSI (p=0.4), surgical drainage was performed in 20.1% of patients with monomicrobial BSI and 27.2% of polymicrobial BSI (p=0.25). Surgical drainage was performed in 26.2% of patients who survived vs. 11.8% of patients who died (p=0.035). Conclusions: There is no difference in the diagnostic approach to monomicrobial and polymicrobial Gram-negative BSI. Surgical drainage is associated with decreased mortality.

Strong Homology Between Colonizing and Bloodstream Carbapenem-Resistant Acinetobacter Spp.: Implications for Empiric Antibiotic Therapy in Hematological Patients.

This study aimed to assess the impact of colonization status on the outcomes of Acinetobacter spp. bloodstream infection (BSI) and investigate the homology and within-host evolution between colonizing and bloodstream carbapenem-resistant Acinetobacter spp. (CRA) to inform antibiotic therapeutic decisions. We analyzed clinical outcomes of 46 hematological patients with Acinetobacter spp. BSI and performed whole-genome sequencing on the remaining CRA isolates. Among the patients, 39.1% (n=18) had prior Acinetobacter spp. colonization. Colonized patients had higher rates of polymicrobial BSI (50.0% vs 21.4%, P=0.044) and CRA BSI (72.2% vs 17.9%, P<0.001), resulting in elevated inflammatory markers and increased 30-day mortality. Each of the eight pairs of the remaining respiratory colonizing and bloodstream CRA strains belonged to the same genomospecies. Each pair exhibited definitive agreement in at least 21 of the 22 most representative antibiotic susceptibility tests. The minimum spanning tree based on multilocus sequence typing (MLST) and phylogenetic trees based on MLST and single nucleotide polymorphism (SNP) all indicated that each pair shared the same minimum branch. Very few non-synonymous SNPs in genic regions were identified during the transition from respiratory colonization to bloodstream infection, with minimal changes in virulence genes. Homology analysis suggested that CRA BSI originated from colonizing isolates in the respiratory tract. Strict infection control measures are needed to manage Acinetobacter spp. colonisation in hematological patients. Appropriate empirical therapy can be administered for suspected CRA BSI based on the antimicrobial minimum inhibitory concentration of CRA colonising the respiratory tract.

Epidemiological patterns of candidaemia: A comprehensive analysis over a decade.

The prevalence of fungal bloodstream infections (BSI), especially candidaemia, has been increasing globally during the last decades. Fungal diagnosis is still challenging due to the slow growth of fungal microorganisms and need for special expertise. Fungal polymicrobial infections further complicate the diagnosis and extend the time required. Epidemiological data are vital to generate effective empirical treatment strategies. The overall aim of this project is to describe the epidemiology of monomicrobial candidaemia and polymicrobial BSI, both with mixed fungaemia and with mixed Candida/bacterial BSIs. We conducted a single-centre retrospective epidemiological study that encompasses 950,161 blood cultures during the years 2010 to 2020. The epidemiology of monomicrobial and polymicrobial candidaemia episodes were investigated from the electronic records. We found that 1334 candidaemia episodes were identified belonging to 1144 individual patients during 2010 to 2020. Candida albicans was the most prevalent species detected in candidaemia patients, representing 57.7% of these episodes. Nakaseomyces (Candida) glabrata and Candida parapsilosis complex showed an increasing trend compared to previous studies, whereas Candida albicans demonstrated a decrease. 19.8% of these episodes were polymicrobial and 17% presented with mixed Candida/bacterial BSIs while 2.8% were mixed fungaemia. C. albicans and N. glabrata were the most common combination (51.4%) in mixed fungaemia episodes. Enterococcus and Lactobacillus spp. were the most common bacteria isolated in mixed Candida/bacterial BSIs. Polymicrobial growth with candidaemia is common, mostly being mixed Candida/bacterial BSIs. C. albicans was detected in more than half of all the candidaemia patients however showed a decreasing trend in time, whereas an increase is noteworthy in C. parapsilosis complex and N. glabrata.

Polymicrobial bloodstream infections a risk factor for mortality in neonates at the national hospital, Tanzania: A case-control study.

Polymicrobial bloodstream infections (BSI) are difficult to treat since empiric antibiotics treatment are frequently less effective against multiple pathogens. The study aimed to compare outcomes in patients with polymicrobial and monomicrobial BSIs. The study was a retrospective case-control design conducted at Muhimbili National Hospital for data processed between July 2021 and June 2022. Cases were patients with polymicrobial BSI, and controls had monomicrobial BSI. Each case was matched to three controls by age, admitting ward, and duration of admission. Logistic regression was performed to determine independent risk factors for in-hospital and 30-day mortality. Fifty patients with polymicrobial BSI and 150 with monomicrobial BSI were compared: the two arms had no significant differences in sex and comorbidities. The most frequent bacteria in polymicrobial BSI were Klebsiella pneumoniae 17% (17/100) and Enterobacter species 15% (15/100). In monomicrobial BSI, S. aureus 17.33% (26/150), Klebsiella pneumoniae 16.67% (25/150), and Acinetobacter species 15% (15/150) were more prevalent. Overall, isolates were frequently resistant to multiple antibiotics tested, and 52% (130/250) were multidrug resistance. The 30-day and in-hospital mortality were 33.5% (67/200) and 36% (72/200), respectively. On multivariable analysis, polymicrobial BSIs were independent risk factors for both in-hospital mortality (aOR 2.37, 95%CI 1.20-4.69, p = 0.01) and 30-day mortality (aOR 2.05, 95%CI 1.03-4.08), p = 0.04). In sub-analyses involving only neonates, polymicrobial BSI was an independent risk factor for both 30-day mortality (aOR 3.13, 95%CI 1.07-9.10, p = 0.04) and in-hospital mortality (aOR 5.08, 95%CI 1.60-16.14, p = 0.006). Overall, the median length of hospital stay post-BSIs was numerically longer in patients with polymicrobial BSIs. Overall, polymicrobial BSI was a significant risk for mortality. Patients with polymicrobial BSI stay longer at the hospital than those with monomicrobial BSI. These findings call for clinicians to be more aggressive in managing polymicrobial BSI.

Polymicrobial bloodstream infections per se do not increase mortality compared to monomicrobial bloodstream infections in sepsis patients: a Korean nationwide sepsis cohort study

BackgroundThere is limited information about the outcomes of polymicrobial bloodstream infections in patients with sepsis. We aimed to investigate outcomes of polymicrobial bloodstream infections compared to monomicrobial bloodstream infections.MethodsThis study used data from the Korean Sepsis Alliance Registry, a nationwide database of prospective observational sepsis cohort. Adult sepsis patients with bloodstream infections from September 2019 to December 2021 at 20 tertiary or university-affiliated hospitals in South Korea were analyzed.ResultsAmong the 3,823 patients with bloodstream infections, 429 of them (11.2%) had polymicrobial bloodstream infections. The crude hospital mortality of patients with sepsis with polymicrobial bloodstream infection and monomicrobial bloodstream infection was 35.7% and 30.1%, respectively (p = 0.021). However, polymicrobial bloodstream infections were not associated with hospital mortality in the proportional hazard analysis (HR 1.15 [0.97–1.36], p = 0.11). The inappropriate use of antibiotics was associated with increased mortality (HR 1.37 [1.19–1.57], p < 0.001), and source control was associated with decreased mortality (HR 0.51 [0.42–0.62], p < 0.001).ConclusionsPolymicrobial bloodstream infections per se were not associated with hospital mortality in patients with sepsis as compared to monomicrobial bloodstream infections. The appropriate use of antibiotics and source control were associated with decreased mortality in bloodstream infections regardless of the number of microbial pathogens.

Clinical Disease and Outcomes of Group B Streptococcus Bloodstream Infections at a Teaching Hospital in Saudi Arabia From 2015 to 2022.

Background Invasive disease due to group B Streptococcus (GBS) infection in adult males and nonpregnant females can cause various diseases, such as primary bacteremia, endocarditis, skin and soft tissue infection (SSTI), and meningitis. Especially in older people, invasive GBS infection has a high case fatality rate. In Saudi Arabia, little is known about the clinical signs and symptoms of GBS bacteremia and the associated risk factors and mortality rate. Methodology We performed a retrospective study at King Abdulaziz University Hospital in Jeddah, Saudi Arabia, a large tertiary hospital, to investigate clinical disease, potential risk factors, susceptibility patterns, and mortality related to GBS in adult males and nonpregnant females diagnosed with GBS bacteremia. All patients ≥14 years of age with GBS-positive blood cultures from January 1, 2015, until December 31, 2022, were included. Patient data such as age, sex, comorbidities, hospital ward, length of hospital stay, monomicrobial versus polymicrobial bloodstream infection, antimicrobials used for treatment, complications, whether an infectious disease specialist had seen them, and outcomes were extracted from the electronic health records. Results A total of 50 patients with GBS bacteremia met the inclusion criteria. The mean age of these patients was 57.0 years (SD = 16.0), and 27 (54%) were female. The 90-day mortality was 11 (22%). In total, 34 (68%) patients had a monomicrobial infection, and among those with polymicrobial infection, methicillin-resistant Staphylococcus aureus was the most common co-infection (56%, n = 9/16). The most common source of infection was SSTI and wound infection in 24 (48%) patients. Most patients had one or more comorbidities; the mean Charlson comorbidity index was 3.8 (SD = 2.4). The most prevalent comorbidity was diabetes mellitus in 35 (70%) patients. Of all variables analyzed, only age was significantly associated with mortality (p = 0.016), and age had a predictive value for mortality (p = 0.035). Conclusions In Saudi Arabia, as in other countries, GBS is an important pathogen, especially in older people, that should be considered when encountering a patient with bacteremia. In addition, in patients over 65 years old, GBS bacteremia carries a high risk for mortality.

Dissecting bloodstream infections in febrile neutropenic patients with hematological malignancies, a decade-long single center retrospective observational study (2009–2019)

BackgroundThe use of ill-suited antibiotics is a significant risk factor behind the increase in the mortality, morbidity, and economic burden for patients who are under treatment for hematological malignancy (HM) and bloodstream infections (BSI). Such unfitting treatment choices intensify the evolution of resistant variants which is a public health concern due to possible healthcare-associated infection spread to the general population. Hence, this study aims to evaluate antibiograms of patients with BSI and risk factors associated with septicemia. MethodsA total of 1166 febrile neutropenia episodes (FNE) among 513 patients with HM from the National Center for Cancer Care and Research (NCCCR), Qatar, during 2009–2019 were used for this study. The socio-demographic, clinical, microbial, and anti-microbial data retrieved from the patient’s health records were used. ResultsWe analyzed the sensitivity of gram-negative and gram-positive bacilli reported in HM-FN-BSI patients. Out of the total 512 microorganisms isolated, 416 (81%) were gram-negative bacteria (GNB), 76 (15%) were gram-positive bacteria (GPB) and 20 (4%) were fungi. Furthermore, in 416 GNB, 298 (71.6%) were Enterobacteriaceae sp. among which 121 (41%) were ESBL (Extended Spectrum Beta-Lactamase) resistant to Cephalosporine third generation and Piperacillin-Tazobactam, 54 (18%) were Carbapenem-resistant or multidrug-resistant organism (MDRO). It's noteworthy that the predominant infectious agents in our hospital include E. coli, Klebsiella species, and P. aeruginosa. Throughout the study period, the mortality rate due to BSI was 23%. Risk factors that show a significant correlation with death are age, disease status, mono or polymicrobial BSI and septic shock. ConclusionDecision pertaining to the usage of antimicrobials for HM-FN-BSI patients is a critical task that relies on the latest pattern of prevalence, treatment resistance, and clinical outcomes. Analysis of the antibiogram of HM-FN-BSI patients in Qatar calls for a reconsideration of currently followed empirical antibiotic therapy towards better infection control and antimicrobial stewardship.

Microbiology and Clinical Outcome of Bloodstream Infections in Patients After Hematopoietic Stem Cell Transplantation.

Patients after hematopoietic stem cell transplantation (HSCT) are often followed by bloodstream infections (BSIs). BSI is an important cause of non-relapse mortality (NRM) in HSCT patients. We conducted a retrospective cohort study of patients (aged >14 years) who underwent HSCT at our hospital from 2017 to 2021. Population characteristics, BSI microbiology, resistance to common antibiotics, and 30-day all-cause mortality were analyzed. Of 3054 patients, 169 (5.5%) had BSIs after HSCT. Male, not in complete remission at transplantation and longer duration of neutropenia were risk factors for the development of BSI after HSCT. These BSIs were Gram-negative bacterial (n=123, 69.49%), Gram-positive bacterial (n=27, 15.25%), fungal (n=11, 6.36%), and polymicrobial (n=16, 9.25%). Among the Gram-negative bacteria, the proportions of isolates resistant to ceftazidime, cefepime, and piperacillin-tazobactam were similar (72.93%, 74.80%, and 77.42%, respectively). The overall drug resistance rates of amikacin and imipenem were 16.13% and 43.90%, respectively. Staphylococcus isolates were methicillin-resistant. In Enterococcus isolates, the penicillin resistance rate was 84.62%. Eleven isolates of Candida tropicalis were resistant to fluconazole and were sensitive to amphotericin B and flucytosine. The 30-day all-cause mortality rate of the 169 patients with BSIs was 8.88%. The 30-day all-cause mortality of patients with Gram-negative bacterial BSIs was 7.32%, 25.00% for polymicrobial BSIs, and 36.36% for fungal BSIs. The 30-day all-cause mortality of patients with fungal BSIs was significantly higher than that of patients with Gram-negative (P=0.0023) and Gram-positive bacteria (P=0.0023). Fungal BSI and non-Hodgkin's lymphoma (NHL) were associated with higher 30-day mortality. Our study reveals the microbiological characteristics and 30-day all-cause mortality in patients with bloodstream infections after HSCT. Our data provides strong support for empirical antimicrobial therapy and infection prevention strategies for patients with BSIs after HSCT.

Diagnostic performance and clinical impact of blood metagenomic next-generation sequencing in ICU patients suspected monomicrobial and polymicrobial bloodstream infections.

Early and effective application of antimicrobial medication has been evidenced to improve outcomes of patients with bloodstream infection (BSI). However, conventional microbiological tests (CMTs) have a number of limitations that hamper a rapid diagnosis. We retrospectively collected 162 cases suspected BSI from intensive care unit with blood metagenomics next-generation sequencing (mNGS) results, to comparatively evaluate the diagnostic performance and the clinical impact on antibiotics usage of mNGS. Results showed that compared with blood culture, mNGS detected a greater number of pathogens, especially for Aspergillus spp, and yielded a significantly higher positive rate. With the final clinical diagnosis as the standard, the sensitivity of mNGS (excluding viruses) was 58.06%, significantly higher than that of blood culture (34.68%, P<0.001). Combing blood mNGS and culture results, the sensitivity improved to 72.58%. Forty-six patients had infected by mixed pathogens, among which Klebsiella pneumoniae and Acinetobacter baumannii contributed most. Compared to monomicrobial, cases with polymicrobial BSI exhibited dramatically higher level of SOFA, AST, hospitalized mortality and 90-day mortality (P<0.05). A total of 101 patients underwent antibiotics adjustment, among which 85 were adjusted according to microbiological results, including 45 cases based on the mNGS results (40 cases escalation and 5 cases de-escalation) and 32 cases on blood culture. Collectively, for patients suspected BSI in critical condition, mNGS results can provide valuable diagnostic information and contribute to the optimizing of antibiotic treatment. Combining conventional tests with mNGS may significantly improve the detection rate for pathogens and optimize antibiotic treatment in critically ill patients with BSI.

Microbiological Analysis and Mortality Risk Factors in Patients with Polymicrobial Bloodstream Infections.

To study the etiological characteristics and risk factors affecting the prognosis of patients with polymicrobial bloodstream infections. Overall, 141 patients with polymicrobial bloodstream infections in Henan Provincial People's Hospital during 2021 were included. Laboratory test indexes, department of admission, sex, age, intensive care unit (ICU) admission, surgical history, and central venous catheter placement were collected. Patients were divided into surviving and deceased groups based on outcomes at discharge. Mortality risk factors were identified by univariate and multivariable analyses. Seventy-two of 141 patients survived. Patients were mainly from the ICU and the Departments of Hepatobiliary Surgery and Hematology. Overall, 312 microbial strains were detected: 119 gram-positive, 152 gram-negative, and 13 anaerobic bacteria and 28 fungi. Among the gram-positive bacteria, coagulase-negative staphylococci were most frequent (44/119, 37%), followed by enterococci (35/119, 29.4%). Among coagulase-negative staphylococci, methicillin-resistant coagulase-negative staphylococci incidence was 75% (33/44). Among gram-negative bacteria, Klebsiella pneumoniae was most common (45/152, 29.6%), followed by Escherichia coli (25/152, 16.4%) and Pseudomonas aeruginosa (13/152, 8.6%). Among K. pneumoniae, the incidence of carbapenem-resistant (CR) K. pneumoniae was 45.7% (21/45). On univariate analysis, mortality risk factors included increased white blood cells and C-reactive protein, decreased total protein and albumin, CR strains, ICU admission, central venous catheter, multiple organ failure, sepsis, shock, pulmonary diseases, respiratory failure, central nervous system diseases, cardiovascular diseases, hypoproteinemia, and electrolyte disturbances (P < 0.05). Multivariable analysis showed that ICU admission, shock, electrolyte disorders, and central nervous system diseases were independent mortality risk factors. The survival curve shows that the survival rate of patients with polymicrobial CR bloodstream infections was lower than that of patients with polymicrobial non-CR bloodstream infections (P=0.029). Patients with polymicrobial bloodstream infections are typically critically ill and harbor multidrug-resistant bacteria. Thus, to minimize mortality rate in critically ill patients, changes in infectious flora should be monitored, antibiotics selected reasonably, and invasive procedures reduced.

Staphylococcus aureus bloodstream infection in a Chinese tertiary-care hospital: A single-center retrospective study.

Staphylococcus aureus bloodstream infection in a Chinese tertiary-care hospital: A single-center retrospective study.

1826. Comparative Use of Vancomycin versus Ampicillin for Blood Stream Infections Caused by Ampicillin-susceptible Enterococcus faecalis

Abstract Background Available studies assessing the efficacy of beta-lactam antibiotics compared to vancomycin (VAN) in the treatment of Enterococcal blood stream infections (BSI) have varying results and have not assessed the impact of rapid diagnostic testing. We aimed to compare clinical outcomes of ampicillin (AMP) vs. VAN for E. faecalis BSI treatment. Methods A multisite, retrospective evaluation of adults with E. faecalis BSI between 2017 to 2021 was performed. Patients who received at least four days of AMP or VAN as definitive therapy were analyzed; only initial episodes were included. All positive blood cultures underwent multiplex polymerase chain reaction blood culture identification (BCID). Patients with polymicrobial BSI were excluded, or if they received ≥ 50% concomitant use of AMP and VAN. The primary outcome was 30-day all-cause mortality. Secondary objectives included 90-day all-cause mortality, hospital length of stay, incidence of treatment failure, persistent BSI, change from initial definitive therapy, and adverse drug reactions (ADRs). Other microbiology endpoints included time to active treatment, BCID, beta-lactam coverage, definitive therapy, and culture clearance. A sample size of 208 patients was estimated to provide a 15% mortality difference with 80% power. Results In total, 123 patients with E. faecalis BSI were analyzed (AMP, n = 92; VAN, n = 31). Baseline characteristics were similar among both groups except gender and baseline penicillin allergy (p &amp;lt; 0.001) (Table 1). All-cause 30-day mortality was not significantly different between patients treated with AMP and VAN (10.8% vs. 22.6%, p = 0.130). No difference was found in secondary objectives except time to definitive therapy was longer for the AMP treatment arm (56.7 hours vs. 15.8 hours, p &amp;lt; 0.001) (Table 2). The incidence of ADRs were similar between the two groups (Table 3). Conclusion No difference in mortality was observed in the treatment with AMP or VAN for patients with E. faecalis BSI, but the study was not sufficiently powered. Despite the use of rapid BCID testing, earlier initiation of AMP was not observed. AMP or VAN may be reasonable options for treatment of E. faecalis BSI, but further research is warranted. Disclosures All Authors: No reported disclosures.

167. Clinical Impact of Rapid Multiplex Polymerase Chain Reaction-Based Diagnostic Testing for Hospitalized Patients with Bloodstream Infections (BSIs) in a National Cohort of Veterans Affairs Patients

Abstract Background Polymerase chain reaction (PCR)-based diagnostic testing for BSIs, such as the BioFire FilmArray® Blood Culture Identification (BCID) Panel, has the potential to shorten time to appropriate therapy and duration of overly broad-spectrum antibiotics. The clinical benefit of PCR-based diagnostic technologies for BSIs has been demonstrated but data supporting their utility in larger multi-center settings are limited. This study sought to evaluate outcomes associated with the implementation of the BioFire BCID in the US Veterans Affairs (VA) system. Table Methods A retrospective multi-center pre-post quasi-experimental study was performed among patients admitted to any VA hospital that adopted BioFire BCID Panel for ≥ 1 year. Patients with ≥ 1 BSI due to bacteria on the BioFire BCID Panel (19 bacterial targets) were included. Exclusion criteria were polymicrobial BSI or death within 48 hours of BSI. Patients were categorized into two groups: i) BSI in the 1-year prior to implementation (pre-BCID) and ii) 1-year post implementation (post-BCID). Post-BCID period commenced 2 months after first BCID-BSI. Outcomes included early de-escalation, defined as a reduction in antimicrobial spectrum score within 48 hours of index BSI, time to appropriate therapy, 30-day mortality, and 90-day CDI incidence. Results A total of 4099 patients across 33 VA facilities met study criteria (n=2088 pre-BCID; n=2011 post- BCID). Groups were similar at baseline (Table). BioFire BCID implementation was associated with an improvement in early de-escalation (38.3% in post-BCID vs 34.8% in pre-BCID, p=0.02) and reduction in median (IQR) time to appropriate therapy (8 [4-19] hours in post-BCID vs 9 [3-19] hours in pre-BCID, P&amp;lt; 0.01). There was no significant difference in 30-day mortality (11.1% in post-BCID vs 12.4% in pre-BCID, p=0.2) or CDI (4.6% in post-BCID vs 4.8% in pre-BCID, p=0.8) between BCID groups. Conclusion In this large VA cohort study, implementation of the BioFire BCID panel was associated with a significant improvement in early antimicrobial de-escalation and time to appropriate therapy. These data suggest this rapid diagnostic technology aids in optimization of antimicrobial use in hospitalized VA patients with BSIs. Disclosures Nicholas Britt, PharmD, MS, Gilead Sciences: Advisor/Consultant|Gilead Sciences: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support|Shionogi: Grant/Research Support Karim Khader, PhD, BioFire Diagnostics: Grant/Research Support Tristan T. Timbrook, PharmD, bioMerieux: Employee of bioMerieux Thomas Lodise, Jr., Pharm.D., PhD, BioFire Diagnostics: Grant/Research Support|cidara: Advisor/Consultant|cidara: Honoraria|Entasis: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support|Paratek: Advisor/Consultant|Shionogi: Advisor/Consultant|Spero: Advisor/Consultant|Venatrox: Advisor/Consultant.

1825. Comparative Effectiveness of Ampicillin versus Vancomycin or Daptomycin for the Treatment of Ampicillin-Susceptible Enterococcus spp. Bloodstream Infections

Abstract Background Treatment options against Enterococcus spp., a common nosocomial pathogen, are limited due to intrinsic resistance to multiple antibiotics. Ampicillin is considered drug of choice if susceptible, but data comparing outcomes between ampicillin, daptomycin, and vancomycin for ampicillin-sensitive Enterococcus spp. bacteremia are limited. Methods This was a single-center retrospective cohort study of adults with confirmed ampicillin-sensitive Enterococcus spp. bloodstream infection (BSI) who received definitive treatment with intravenous ampicillin, daptomycin, or vancomycin from January 2013 to December 2021. Polymicrobial BSI were excluded. Definitive treatment was defined as the active antibiotic used for more than 50% of the total treatment duration following availability of susceptibility results. The primary outcome was 28-day all-cause hospital mortality; secondary outcomes were 90-day readmission due to microbiological recurrence and all-cause hospital mortality. Multivariate Cox regression analysis was performed to identify independent risk factors for 28-day hospital mortality. Results A total of 199 patients (ampicillin, n = 141; daptomycin, n = 17; vancomycin, n = 41) were evaluated. Overall in-hospital all-cause mortality was 15.1% (n = 30). Twenty-eight-day hospital mortality was numerically lower with ampicillin and daptomycin compared to vancomycin (9.2%, 11.8%, and 22%, respectively; p = 0.088). Ninety-day readmission due to microbiological recurrence (4.3%, 5.9%, and 7.3%; p = 0.722) and all-cause hospital mortality (12.8%, 17.6%, and 22%; p = 0.335) were not significantly different between treatment groups. Independent risk factors for 28-day hospital mortality included age (hazard ratio [HR] 1.05, 95% confidence interval [CI] 1.02 to 1.09; p = 0.003), E. faecium BSI (HR 3.94, 95% CI 1.39 to 11.1; p = 0.010), and definitive treatment with vancomycin (HR 2.54, 95% CI 1.04 to 6.21; p = 0.040). Conclusion Vancomycin used as definitive therapy for ampicillin-sensitive Enterococcus spp. bacteremia was found to be an independent risk factor for 28-day mortality. Further studies evaluating the role of daptomycin in this setting are warranted. Disclosures All Authors: No reported disclosures.

1815. Assessment of Therapy Duration for Non-Staphylococcal Gram-Positive Bloodstream Infections

Abstract Background The optimal duration of antimicrobial therapy for non-staphylococcal Gram-positive (GP) bloodstream infections (BSIs) remains unknown. The purpose of this study was to evaluate clinical outcomes in patients with short (6-10 days) vs. long (11-21 days) duration of therapy (DOT) for non-staphylococcal GP BSIs. Methods Adult patients with BSI due to Streptococcus or Enterococcus spp. admitted to a community health system from January 2016 to December 2021 were included in this retrospective chart review. Patients were excluded for polymicrobial BSI, positive culture deemed contamination, infectious source requiring prolonged treatment, DOT &amp;lt; 6 or &amp;gt; 21 days, or transfer, hospice, or death prior to therapy completion. The primary endpoint was 90-day all-cause mortality. Descriptive statistics, chi-square or Fisher’s exact test, and the student t-test were used for data analysis. Results Of 3,544 patients identified, 384 were screened and 86 included. There were 71 patients in the long DOT group and 15 patients in the short DOT group. All included patients were on active therapy for the entire DOT. Baseline characteristics were similar except patients in the long DOT group were more likely to have an infectious diseases consultation and a non-pulmonary source of infection (Table 1). All-cause mortality at 90 days was similar between short vs. long DOT groups (0% vs. 3%, p=0.51) (Table 2). The secondary endpoints of 30-day all-cause mortality, 30-day and 90-day BSI recurrence due to the same organism, 30-day readmission, and hospital length of stay were not statistically different between groups (Table 2). The most common pathogen identified in the short DOT group was Streptococcus pneumoniae (n=8), and the most common identified pathogens identified in the long DOT group was Streptococcus agalactiae (n=22), Enterococcus faecalis (n=14), and S. pneumoniae (n=13) (Table 3). Conclusion In this retrospective review of non-staphylococcal GP BSIs, there was no statistical difference in clinical outcomes between the short and long DOT arms. Additional research is needed to identify the optimal duration of antimicrobial therapy for non-staphylococcal GP BSIs. Disclosures All Authors: No reported disclosures.

Bloodstream infections in Injecting drug users: A 15 year prospective single-centre study

• IDUs accounted for nearly 8% of all community acquired bloodstream infections. • S . aureus and S. pyogenes were the most common pathogens. • The commonest foci of infection were skin/soft tissue and septic thrombophlebitis. • Infective endocarditis was relatively uncommon but was associated with mortality. • Septic thrombophlebitis caused more septic pulmonary emboli than endocarditis. To describe the microbiological and clinical characteristics of bloodstream infections (BSIs) in Injecting Drug Users (IDUs). All episodes of community-acquired BSI in IDUs were reviewed. Demographic, clinical and microbiological data were analysed. Detailed analyses were performed for septic thrombophlebitis and infective endocarditis (IE). Historical analysis of microbiological characteristics of BSIs from 1970 to 2018 was performed. There were 406 episodes of BSI in IDUs accounting for 7.8 % of community-acquired BSIs from 2004 to 2018. Patients were male in 77.3 % of episodes. Median age was 38.1 years. Positive HIV status was confirmed in 14 % of episodes. The commonest infecting species were Staphylococcus aureus (45.8 %) and Streptococcus pyogenes (11.8 %). Polymicrobial BSIs accounted for 20.2 % of infections; other streptococci (12.8 %), gram-negative bacilli (4.9 %) and anaerobes (2.7 %) accounted for most of the remainder. The commonest foci of infection were skin and soft tissue (26.4 %), septic thrombophlebitis (20.4 %), bone and joint (17.5 %) and IE (11.8 %). Overall inpatient mortality was 5.9 %. IE and necrotizing fasciitis were associated with increased risk of death. IDUs accounted for a significant proportion of community-acquired BSIs. Skin and soft tissue infection and septic thrombophlebitis were the commonest foci of infection. IE is rare, but mortality is high.

Pathogen load and species monitored by droplet digital PCR in patients with bloodstream infections: A prospective case series study

Background and objectives:Bloodstream infection (BSI) is a life-threatening condition in critically ill patients, but pathogen quantification techniques during treatment are laborious. This study aimed to explore the impact of monitoring pathogen DNA load changes and polymicrobial infection in blood by droplet digital polymerase chain reaction (ddPCR) on the prognosis of patients with BSIs.MethodsThis prospective case series study was conducted in the general intensive care unit of the Zhejiang Provincial People’s Hospital and included patients with BSIs from May 2020 to January 2021. Pathogens DNA load and presence of polymicrobial BSIs were dynamically monitored by ddPCR.ResultsSixteen patients with BSIs proven by blood culture were recruited (87.5% men; mean age, 69.3 ± 13.7 years). All pathogens identified by blood culture were Gram-negative bacteria, among which seven were multidrug-resistant strains. The 28-day mortality rate was 62.5%. Compared to the 28-day survivors, the non-survivors were older (P = 0.04), had higher pathogen DNA load on the second (day 3–4) and third (day 6–7) ddPCR assay (P < 0.01 in both cases). In addition, the changes of pathogen DNA load in the 28-day survivors had a downward trend in the first three ddPCR assay, whereas stable load or an upward trend was observed in the 28-day non-survivors. Moreover, the number of pathogen species in patients with BSIs in the 28-day survivors decreased during the period of effective antibiotic treatment.ConclusionThe changes of pathogen DNA load and species monitored in blood by ddPCR may be used to determine antibiotic efficacy and make a more accurate prognostic assessment in patients with BSIs.

P215 Investigation of an outbreak of neonatal Candida emia in the NICU of a 300 -bedded hospital in North India

Poster session 2, September 22, 2022, 12:30 PM - 1:30 PMObjectivesNeonatal Candidaemia causes significant morbidity and mortality in very low birth weight neonates. We report the occurrence of an outbreak of neonatal Candidaemia due to Candida krusei in the neonatal intensive care unit (NICU) of a 300-bedded hospital in North India.MethodsA total of 96 blood cultures from 80 neonates admitted in the NICU from October 2020 to April 2021 were received and processed manually in the Microbiology lab. A total of 5 among the 47 yeast isolates were sent to a teaching hospital for identification and antifungal susceptibility testing by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF). Clinical parameters (very low birth weight, gestational age, birth asphyxia, broad-spectrum antimicrobial therapy, intra-uterine growth restriction, and total parenteral nutrition), lab parameters (CRP, platelet count), and patient outcome were evaluated. A total of 26 environmental samples and hand swabs from six health care workers were collected to trace the source of the outbreak. The samples were inoculated on 5% sheep blood agar and MacConkey agar. Regular rounds of the NICU and training sessions were conducted by the infection control team to intensify the infection control measures.ResultsBlood culture results: In all, 57 neonates (71.25%; 57/80) admitted to the NICU had positive blood cultures. A total of 47 blood cultures yielded non-albicans Candida spp. (82.45%; 47/57). The other microorganisms isolated from blood cultures were Pseudomonas aeruginosa (4), MRSA (3), Klebsiella pneumoniae (4) and Acinetobacter baumanni (1). Polymicrobial bloodstream infections were detected in two neonates. All the yeast isolates subjected to MALDI-TOF were identified as Candida krusei and had similar MICs of 0.25, 4, 16, 1, 0.25 and 16 μg/ml for voriconazole, itraconazole, posaconazole, caspofungin, micafungin and fluconazole respectively.Culture results of environmental sampling: Yeast could not be isolated from any environmental sample and hand swabs of health care workers. However, MRSA was isolated from the hands of one health care worker.Observation during the infection control rounds:Sterile gauze pieces soaked in iodine and kept in plastic bottles were being used for skin antisepsis before collecting samples or before introducing an IV cannula.The nursing staff did not wear sterile gloves while collecting blood samples or introducing IV cannula in case of NICU patients.It was observed that the used bottles of IV fluids (eg. Ringer lactate, normal saline) were not capped and kept at room temperature.Intensive infection control measures and training sessions were effective in controlling the outbreak.ConclusionWe report the occurrence of a massive outbreak of neonatal Candidaemia in the NICU of our hospital with a positivity rate of 58.75% (47/80). Identification of yeast and determination of antifungal susceptibility is important for prompt treatment. Though the source of the outbreak could not be traced but intensifying infection control practices could control the outbreak. This study emphasizes the value of educating healthcare workers and regular monitoring of disinfection practices to prevent health-care-associated infections.

Risk Factors and Outcomes of Bloodstream Infections Among People With Human Immunodeficiency Virus: A Longitudinal Cohort Study From 2000 to 2017.

BackgroundBloodstream infections (BSIs) among people with human immunodeficiency virus (PWH) remain a poorly studied source of morbidity and mortality. We characterize the epidemiology, microbiology, and clinical outcomes including reinfection, hospitalization, and mortality rates of both community-acquired and hospital-acquired BSI in PWH.MethodsWe identified all BSI, between January 1, 2000 and December 31, 2017 in PWH in care at Southern Alberta Clinic, by linking data from laboratory and clinical databases. Crude incidence rates per 1000 person-years for BSI and death were calculated. Cox proportional hazards models estimated crude and adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) to conduct a risk factor analysis of BSI in PWH. Logistic regression models with generalized estimating equations estimated crude and adjusted odds ratios (aORs) to identify characteristics associated with 1-year mortality after BSI.ResultsAmong 2895 PWH, 396 BSI episodes occurred in 228 (8%) PWH. There were 278 (72%) Gram-positive and 109 (28%) Gram-negative BSI. People with human immunodeficiency virus with lower CD4 nadirs, higher Charlson comorbidity indices, and hepatitis C virus were at highest risk for BSI. Long-term all-cause mortality was greater in those experiencing BSI (HR, 5.25; 95% CI, 4.21–6.55). CD4 count <200 cells/mm3 measured closest to the time of BSI was associated with 1-year mortality after BSI (aOR, 3.88; 95% CI, 1.78–8.46). Repeat episodes (42%) and polymicrobial BSI (19%) were common.ConclusionsBloodstream infections continue to occur at an elevated rate among PWH with high reoccurrence rates and associated morbidity and mortality. To risk stratify and develop targeted interventions, we identified PWH at greatest risk for BSI. People with human immunodeficiency virus with low immunity at the time of BSI are at highest risk of poor outcomes.

Multidrug-Resistant Acinetobacter baumannii May Cause Patients to Develop Polymicrobial Bloodstream Infection.

Background The incidence of polymicrobial bloodstream infections is increasing, the clinical characteristics of polymicrobial Acinetobacter baumannii bloodstream infections (AB-BSI) are unclear, and there are no reports of polymicrobial AB-BSI in mainland China. Therefore, our objective was to identify the clinical characteristics, risk factors, and outcomes of polymicrobial AB-BSI versus monomicrobial AB-BSI. Methods A retrospective survey of all patients with AB-BSI from January 1, 2015, to December 31, 2019, and their clinical data were collected and analyzed by reviewing electronic medical records. All data were compared and analyzed between groups of monomicrobial and polymicrobial AB-BSI. Risk factors for polymicrobial AB-BSI were assessed using multivariable logistic regression analysis. Results A total of 204 patients were included, of which 39 (19.1%) were patients with polymicrobial AB-BSI. The main sources of the pathogenicity of polymicrobial Acinetobacter baumannii bloodstream infections were skin and soft tissue (38.5% vs. 16.4%, p=0.002). Resistance to piperacillin/tazobactam as an independent factor for polymicrobial AB-BSI was found in multivariate analysis. Patients with polymicrobial AB-BSI had longer hospital stays compared to those with monomicrobial AB-BSI. However, there was no significant difference in mortality between the two groups. Conclusions Polymicrobial AB-BSI accounted for a significant proportion among all AB-BSI, and it did not influence mortality but was related to slightly longer total hospital stays. Multidrug resistance was associated with the development of polymicrobial AB-BSI but does not directly lead to polymicrobial AB-BSI, whereas resistance to piperacillin/tazobactam was highly correlated with polymicrobial AB-BSI. Therefore, while treating A. baumannii bloodstream infections, clinicians cannot ignore the multidrug-resistant A. baumannii, especially piperacillin/tazobactam-resistant A. baumannii, which may predispose to the development of polymicrobial AB-BSI.