bluuebunny/crossref_metadata_2025 huggingface dataset:
178. Assessment of an IOTA (Intravenous to Oral Transition of Antimicrobial Therapy) in Gram Negative Bacteremias at a Community Teaching Hospital
Authors: Wilson Victoria , Gardner Sara R , Cady Beth
Published: November 2023

Background

Retrospective studies suggest that IV to oral therapy for gram-negative bacteremia has similar outcomes to IV regimens. The benefits of transitioning patients from IV to oral antibiotic therapy are well-recognized. The purpose of this study was to assess the percentage of patients (with a gram-negative bacteremia from a urinary source) who were transitioned from IV to oral antibiotics based on a pre-determined checklist.

Methods

This retrospective cohort study was performed at a 400-bed hospital from January 1, 2019 to May 31, 2022 . The primary objective was to assess the percentage of patients with a gram negative bacteremia (from a urinary source) who were eligible and switched from IV to oral antibiotics. Patients were included in the study if they were > 18 years old, had a positive blood culture for E. coli or K. pneumoniae (with > 1 susceptible oral antibiotic), had a monomicrobial infection from a urinary source, signs of clinical improvement, could tolerate oral medication, and had at least 24 hours of IV therapy.

Results

Sixty patients out of 200 (30%) with a gram negative bacteremia met the above eligibility criteria to be switched from IV to oral therapy. Sixty three percent (38/60) were switched to oral antibiotics for the completion of therapy. A majority of patients (95%) had E. coli bacteremia. Of the eligible patients, 70% (42/60) had received an ID consultation. Of those, 62% (26/42) were switched. Among the 18 eligible patients who did not receive an ID consult, 67% were switched to PO. Reasons for not switching (as determined from the EHR) for the 22 eligible patients include: 3 patients had pathogens resistant to fluoroquinolones, 8 had contraindications (unclear), 3 had concomitant infections, 7 had reasons unknown, and 1 patient denied oral antibiotics.

Conclusion

Most patients (63%) who met inclusion criteria derived by previous studies were switched from IV to oral antibiotics in the presence of monomicrobial E. coli or Klebsiella pneumoniae bacteremia from a urinary source with clinical improvement. There is an opportunity to educate providers to transition more patients from IV to oral antibiotics with a gram negative bacteremia.

Disclosures

All Authors: No reported disclosures
179. From Epidemiology of Community-onset Bloodstream Infections to the Development of Empirical Antimicrobial Treatment-decision Algorithm in a Region with High Burden of Antimicrobial Resistance
Authors: Chotiprasitsakul Darunee , Trirattanapikul Akeatit , Namsiripongpun Warunyu , Chaihongsa Narong , Santanirand Pitak
Published: November 2023

Background

More antimicrobial-resistant (AMR) infections have emerged in community settings. Our objectives were to study the epidemiology of community-onset bloodstream infections (BSIs), identify risk factors for AMR-BSI and factors associated with mortality, and develop the empirical antimicrobial treatment-decision algorithm.

Methods

A retrospective cohort study was conducted at a tertiary-care hospital. All positive blood cultures from adult patients at the emergency room and outpatient clinics were identified from 1 Aug 2021-15 Apr 2022. AMR was defined as the resistance of organisms to an antimicrobial to which they were at first sensitive. Risk factors associated with AMR-BSI and factors associated with 30-day mortality were determined. The independent risk factors for AMR-BSI were placed into steps to create an empirical treatment-decision algorithm. C-statistics were calculated. The internal validation cohort was evaluated.

Results

A total of 1,151 positive blood cultures were identified. There were 450 initial episodes of bacterial BSI, and 114 BSIs (25%) were AMR-BSI. Nonsusceptibility to ceftriaxone was detected in 40.9% of 195 E. coli isolates and 16.4% among 67 K. pneumoniae isolates. A treatment-decision algorithm was developed based on the independent risk factors for AMR-BSI: the presence of multidrug-resistant organisms (MDROs) within 90 days (aOR 3.63; 95% CI 1.95-6.75; P< 0.001), prior antimicrobial exposure within 90 days (aOR 1.94; 95% CI 1.08-3.50; P=0.03), and urinary source (aOR 1.79; 95% CI 1.06-3.01; P=0.03). The positive and negative predictive values were 53.3% (95% CI 45.4-61.1%) and 83.2% (95% CI 80.4-85.6%), respectively. The C-statistic was 0.73. Factors significantly associated with 30-day all-cause mortality were Pitt bacteremia score (aHR 1.39; 95% CI 1.20–1.62; P< 0.001), solid malignancy (aHR 2.61; 95% CI 1.30–5.24; P=0.01), and urinary source (aHR 0.30; 95% CI 0.11–0.79; P=0.02).

Univariable analysis and multivariable analysis of risk factors for antimicrobial resistance

Proposed empirical antimicrobial treatment algorithm for patients with suspected community-onset bloodstream infections

Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and C-statistics of the algorithm in predicting antimicrobial resistant infection

Conclusion

One-fourth of community-onset BSI were antimicrobial-resistant, and almost one-third of Enterobacteriaceae were nonsusceptible to ceftriaxone. Treatment-decision algorithm based on the presence of MDROs within 90 days, prior antimicrobial use within 90 days, and the urinary source may reduce overly broad antimicrobial treatment.

Disclosures

All Authors: No reported disclosures
182. Piperacillin/tazobactam (P/T) versus meropenem (Mero) for treatment of extended-spectrum beta-lactamase (ESBL)-producing E.coli and K. pneumoniae bloodstream infections (BSIs)
Authors: Cox Alexandra L , Beardsley James R , Williamson John C , Stone Tyler J , DeWitt Michael E , Palavecino Elizabeth , Luther Vera , Taylor Alex D
Published: November 2023

Background

A recent study of Mero vs. P/T for the treatment of BSIs caused by ceftriaxone-resistant Enterobacterales, including ESBL-producing organisms, revealed discouraging outcomes for patients (pts) receiving P/T. The purpose of this study is to evaluate clinical outcomes in pts treated with P/T versus Mero for BSIs caused by ESBL-producing E. coli or K. pneumoniae.

Methods

This is a single health-system, retrospective, observational study. Adult inpatients with blood cultures positive for ESBL-producing E. coli or K. pneumoniae during 2016-2020 were identified by a report from an automated broth microdilution system. Pts with an isolate susceptible to both P/T and Mero who received either P/T or Mero within 24 hours of culture collection and for a duration of least 48 hours were included. Pts who had neutropenia, expired or transitioned to comfort care within 48 hours of study drug initiation, did not have source control by day 5, had a polymicrobial infection, or had a concurrent infection caused by another gram-negative organism were excluded. Pts were screened for eligibility and then randomly selected until a target of 25 pts meeting study criteria in the Mero and the P/T groups were included. The primary outcome was all-cause mortality at 30 days. Secondary outcomes included length of hospital stay, clinical and microbiological resolution by day 5, and time to clinical and microbiological resolution.

Results

Forty-nine pts met study criteria and were included after one pt was excluded from P/T group due to a polymicrobial infection. Overall, the median age was 67 [53, 76], 29 (59%) pts were female, and 21 (43%) pts were admitted to an ICU at culture draw or within 24 hours. Forty-three of the 49 (88%) infections were caused by E.coli, and 38 (78%) infections originated from a urinary source. Results of the analysis are shown in table 1 and figures A-C.Table 1.Primary and Secondary OutcomesFigure:Boxplot A. Length of Stay, B. Time to Clinical Resolution, C. Time to Microbiological Resolution

Conclusion

In this real-world study of pts with ESBL-producing BSIs that were predominantly from a urinary source, pts treated with P/T and Mero had similar outcomes. These results demonstrate the need for additional randomized, controlled trials, in a variety of settings to further assess outcomes in this pt population.

Disclosures

Tyler J. Stone, PharmD, ViiV Healthcare: Employee
184. Implications of Enterococcus faecalis penicillin susceptibility in patients with bacteremia
Authors: Hedvat Jason , Gitman Melissa R , Nwoye Angella , Chen Li , Martin Colleen , Wang Mandie , Vasa Chirag , Cusumano Jaclyn A
Published: November 2023

Background

Enterococcus faecalis isolates with an elevated penicillin minimum inhibitory concentration (MIC) ≥ 4 mg/L have decreased in vitro ampicillin plus ceftriaxone bactericidal and synergistic activity, despite ampicillin susceptibility. This phenotype’s implication on patient outcomes and prevalence in the US is unknown due to limited penicillin susceptibility reporting.

Methods

This was a retrospective cohort study of adult patients with E. faecalis bacteremia between August 20, 2018 and May 13, 2021 from the Mount Sinai Health System in New York City. Patients were excluded if they were discharged or deceased within 48 hours of index blood culture, did not receive active definitive therapy, or the blood culture was determined to be contamination. The primary outcome was differences in 30-day and 90-day mortality based on the penicillin MIC and the secondary outcome was microbiological relapse. Multivariable logistic regression was used to identify risk factors for 90-day mortality. Corresponding blood isolates were tested for penicillin susceptibility by broth microdilution in accordance with CLSI.

Results

A total of 124 patients were included, with 27% having an elevated penicillin MIC ≥ 4 mg/L. Differences in baseline characteristics (Table 1) as well as source of infection and treatments received (Table 2) were similar between groups. Endocarditis infected 18.5% of patients and was less common in cases with an elevated penicillin MIC. Thirty-day and 90-day mortality, and microbiological relapse were higher in cases with an elevated penicillin MIC (14.4% vs. 20.6%, p=0.58; 20% vs. 26.5%, p=0.59; and 4.4% vs. 8.8%, p=0.39, respectively). Pitt bacteremia score and prior ceftriaxone usage had a higher odds of 90-day mortality (OR 1.2 [95% CI 1.03-1.4], p=0.02; OR 2.8 [95% CI 1.02-7.9], p=0.04, respectively), whereas definitive treatment with an aminopenicillin compared to piperacillin/tazobactam was protective of 90-day mortality (OR 0.21 [95% CI 0.05-0.93], p=0.04).

Conclusion

E. faecalis with an elevated penicillin MIC ≥ 4 mg/L is present in over a quarter of patients across New York City. Larger studies are warranted to determine the impact on patient outcomes. E. faecalis bacteremia treatment with piperacillin/tazobactam may be associated higher mortality.

Disclosures

Jaclyn A. Cusumano, PharmD, BCIDP, Shionogi: Advisor/Consultant
185. Pseudomonas aeruginosa (PA) Bacteremia and Patient Outcome during COVID-19 Pandemic
Authors: Vivekanandan Renuga , Witherspoon Kelsey , Destache Christopher J
Published: November 2023

Background

Pseudomonas aeruginosa (PA) bloodstream infection is associated with poor clinical outcomes. The purpose of this study was to evaluate treatment efficacy and patient outcomes from different antimicrobials used for treating PA bacteremia during 2020-2022.

Methods

This was a retrospective review of 2020-2022 hospitalized patients with PA bacteremias at our health system. Hospitalized patients from January 2020 - July 2022 with culture-positive PA were identified. Data collected included demographics, hospitalization and drug treatment length, SARS-CoV-2 infection, and need for vasopressors. Antibiotics used to treat PA, including dose, interval, and MIC data were evaluated. Finally, admission APACHE II score and hospital mortality were collected. Data were analyzed by SPSS. Data are presented as mean ± SD or percentage. Apriori significance was p ≤ 0.05.

Results

A total of 111 PA bacteremias occurred in 2020-2022, 65% of patients were male. Mean (± SD) age was 68 ± 13 years and weight were 88.2 ± 25 kg. Hospitalization length and duration of antibiotic therapy averaged 12 ± 13 days and 7.1 ± 5.9 days, respectively. Majority were treated with piperacillin-tazobactam (45%) or cefepime (44%). Median cefepime MIC was 2.0 (range 0.5-8). Thirty-seven (33%) PA-infected patients expired. Significantly more 7 of 17 (41%) cefepime patients died receiving 4G/d (1Gq6h) compared to 1 (9%) of 11 receiving 6G/d (2Gq8h), p< 0.001. Significant correlation between mortality and ICU status or mechanical ventilation (p< 0.001), respectively. No correlation between mortality and renal failure, SARS-CoV-2 co-infection, or vasopressor use. APACHE II score was significantly higher for expired patients (survived 13.9 ± 5.7 compared to 22 ± 8.3 in expired group, p< 0.001).

Conclusion

ICU status and mechanical ventilation significant reduced survival. Cefepime 4G/d resulted in significantly higher mortality.

Disclosures

Christopher J. Destache, Pharm. D., BioMerieux, Inc: Advisor/Consultant
186. The Role of Repeated Blood Cultures in Hematologic Malignancy Patients with Neutropenic Fever due to Gram-Negative Bacterial Bloodstream Infections
Authors: Dhanaraj Nitya , Foppiano Palacios Carlo
Published: November 2023

Background

Several observational studies and a recent meta-analysis suggest there is a mortality benefit associated with acquiring repeat blood cultures for gram-negative bacterial bloodstream infections (GNBSI). However, limited data are available among patients with febrile neutropenia. We sought to evaluate the utility of obtaining follow-up blood cultures (FUBC) in GNBSI among neutropenic hematological malignancy patients.

Methods

A retrospective chart review was conducted to identify all patients with a hematologic malignancy admitted with a diagnosis of neutropenic fever due to gram-negative rod bacteremia (GNRB) from 2018-2021 at a large urban academic medical center. We collected demographics, cancer diagnosis and treatment data, microbiology and antibiotic information, and death at discharge, 30 days, and 90 days. Descriptive statistics and chi-square tests were used.

Results

A total of 47 episodes of GNBSI among 43 patients were included. Mean age was 57 years, 61% were male, 49% were White, and 14% were Latino. Most patients had AML (47%), and most common chemotherapy regimen was R-CHOP (19%). 32% of GNRB were due to K. pneumoniae, in the setting of long-term central venous catheter (53%), and from a gastrointestinal source (49%). FUBC were collected among most patients (87%), but only two patients (5%) had positive FUBC. ESBL resistance profiles were uncommon (6%), and most were treated with beta-lactams (55%). Patients who died at discharge were less likely to have FUBC collected (p< 0.001). We also found an association between acquiring FUBC and mortality at 30 (p=0.01) and 90 days (p=0.02). However, there was no association between having a positive FUBC and mortality at discharge (p=0.47), 30 days (p=0.93), and 90 days (p=1.00).

Conclusion

Among patients with neutropenic fever found to have GNBSI, acquiring repeat blood cultures was associated with decreased mortality. Due to their immunocompromised status, patients with neutropenic fever and GNRB should have repeat blood cultures collected.

Disclosures

All Authors: No reported disclosures
199. Fast Detection of Ceftazidime-avibactam-resistant Enterobacterales with VITEK-MSTM Incorporating a Direct-on-target Microdroplet Growth Assay
Authors: haung Shenglei , qin Chengfeng , Pu Bingchun , Zhou Chunmei , ma Yan , Wang Beili , Pan Baishen , Hu Bijie , Guo Wei
Published: November 2023

Background

The direct-on-target microdroplet growth assay (DOT-MGA) was evaluated for its ability to rapidly detect ceftazidime-avibactam resistant Enterobacterales.

Methods

In this study, 47 non-duplicate CRE isolates were used to determine unequivocally the performance of ceftazidime-avibatam resistance detection of 7 organisms found in clinical isolates. The isolates were incubated for 3 to 6 h in the presence and absence of 8 µg/mL ceftazidime-avibatam in the broth applied as microdroplets directly on to the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) target spots. Following the incubation period, broth was separated from the microbes by pipette. MALDI-TOF MS was employed to evaluate the growth of isolates in each spot and to identify the microbes simultaneously. The micro-broth dilution method, recommended by EUCAST was used as a reference method. A PCR-based assay was carried out to evaluate the carbapenem resistance mechanisms by screening for the presence of various β-lactamase-encoding genes.

Results

It was found that a 3 h incubation time was insufficient for MS to identify isolates. At this time-point, the identification of valid results of the growth control was only 25.0%. Therefore, the study of 3 h incubation times was not continued. For ceftazidime-avibactam-resistant Enterobacter strains, 83.7% of growth controls were successfully detected after the 4 h-time-point of incubation when the sensitivity and specificity of drug resistance detection were both 100%. Following incubation for 5 h, the rate of growth controls, sensitivity and specificity were 98.0%, 100% and 100%. When the incubation was extended to 6 h, the rate of growth controls, sensitivity and specificity reached an ideal 100%.

Conclusion

The VITEK MS-based DOT-MGA is a fast, convenient and accurate in detecting Enterobacterales that is resistant to ceftazidime-avibatam within 5 to 6 h. The assay can also determine the resistance status of an isolate and the potential novel resistant mechanisms involved.

Disclosures

All Authors: No reported disclosures
203. Evaluating the Impact of Extended-Infusion Beta-Lactam Therapy on Clinical Outcomes and the Subsequent Emergence of Resistance in Adults with Gram-Negative Bloodstream Infections
Authors: Karaba Sara M , Hyoung Lee Jae , Fiawoo Suiyini , Cosgrove Sara E , Tamma Pranita
Published: November 2023

Background

Data are conflicting regarding the impact of extended-infusion beta-lactam (EI-BL) therapy on patient outcomes. We investigated the impact of EI-BL therapy on clinical outcomes and subsequent emergence of resistance in adults with Gram-negative bloodstream infections (GN-BSI) admitted to 24 US hospitals in 2019.

Methods

Patients who received ≥ 3 days of EI-BL (i.e., ≥ 3-hour infusion) were compared to patients who received the same agents as ≤ 1-hour standard infusions (SI-BL). The EI-BL group underwent 3:1 nearest neighbor propensity score matching without replacement with the SI-BL group based on: Pitt bacteremia score ≥ 4, Charlson comorbidity index ≥ 5, severe immunocompromise, ICU status, source control, active empiric therapy, urinary source, and the 3 most common species. Multivariable regression was applied to the matched cohort to investigate mortality, recurrent infection with the same species, subsequent emergence of resistance (i.e., ≥ 4-fold increase in MIC of the β-lactam used to treat the index BSI), and treatment-related adverse events (AEs), all censored at day 90.

Results

There were 352 and 4,509 patients in the EI-BL and SI-BL groups, respectively. Excellent balance was achieved across all variables in the 3:1 matched cohort. The odds of mortality at day 90 were lower in the EI-BL vs SI-BL group (aOR=0.71, 95% CI 0.52-0.97, p=0.033). When stratified to evaluate the mortality benefit in those with and without severe illness or elevated MICs, a significant mortality benefit was only identified in patients with severe illness and/or elevated MICs. No differences were observed in recurrent infection. There was an increased odds of catheter complications (aOR=3.14, 95% 1.66-5.96, p< 0.001) and early antibiotic discontinuation because of AEs (aOR=3.66, 95% CI 1.68-7.95, p=0.001) in the EI-BL group. Emergence of resistance was similar in the EI-BL and SI-BL groups at 2.9% vs 7.2%, respectively (p=0.351).

Conclusion

The benefits of EI-BL therapy need to be balanced with associated AEs. EI-BL therapy should be prioritized in the severely ill or those infected with non-susceptible organisms. The subsequent emergence of resistance warrants investigation in a larger cohort.

Disclosures

Sara M. Karaba, MD, PhD, MHS, Entasis: Advisor/Consultant Sara E. Cosgrove, MD, MS, Debiopharm: Advisor/Consultant|Duke Clinical Research Institute: Advisor/Consultant
207. The increased frequency and clinical characteristics of Streptococcus agalactiae serotype VIII from blood isolates at two tertiary care hospital in South Korea over 14 years
Authors: Ji kim Min , Ji Sehyun , Lee Ahrang , Kim Sarah , Jung Lee Yoon , Sung Jeong Hae , un Shin Sung , Jin Kim Uh , Kang Seung-Ji , Park Kyung-Hwa , Jung Sook-In , Eun Kim Seong
Published: November 2023

Background

Invasive group B Streptococcus (GBS) infections are increasing among non-pregnant adults with underlying diseases. Previous studies have shown that the proportion of GBS serotype of pregnant women were differed from geographic regions. However, studies on the serotype of invasive GBS infection in non-pregnant adults are sparse. This study aimed to evaluate epidemiology and clinical characteristics of strains caused GBS bloodstream infection according to serotypes.

Methods

S. agalactiae blood isolates were collected between March 2007 and December 2021, and their clinical data were obtained from two tertiary hospital of South Korea. Species identification was performed using MALDI-TOF MS and serotyping test was performed using commercial latex particle agglutination kit. Antimicrobial susceptibility tests are conducted using automated equipment.

Results

A total of 130 patients with GBS bacteremia were identified and among them 125 isolates were serotypeable. The median age were 66 years and 46% were male. Serotype VIII was most dominant (31.5%) and Ib, III, Ia, V were as follows (20.8%, 13.8%, 12.3%, 11.5% retrospectively). The proportion of serotype VIII increased from 27.3% to 53.3% from 2015 to 2021. Most common source of GBS bloodstream infection were primary bacteremia (34.4%), followed by bone and joint infections (16.8%) and skin and soft tissue infections (13.6%). Cardiovascular disease (79.2%) was most frequently reported in GBS bacteremia patients, followed by malignancy (44.6%) and diabetes mellitus (40%). The 30-day mortality rate was 12.3% and there was no difference in 30-day mortality according to serotypes (log rank test P=0.39). In logistic regression analysis, high SOFA score was significantly associated with 30-day mortality (odd ratio 1.28, 95% C.I. 1.28-2.53, P< 0.01). All isolated GBS were susceptible to penicillin and resistances were identified against clindamycin, erythromycin and levofloxacin as 30%, 26.9%, 24.6% of the isolates, respectively.

Conclusion

We found the most common capsular serotype was VIII (31.5%) in Korea and the proportion of type VIII increasing over time. It is necessary to consider GBS vaccine in adults with underlying disease and its composition for serotype VIII according to epidemiologic characteristics.

Disclosures

All Authors: No reported disclosures
208. Clinical Characteristics and Risk Factors for Septic Shock in Patients with Pyometra: A Retrospective Multicenter Cohort Study
Authors: Jang Sukbin , Jeon Minji , Jun Mun Seok , Kim Si-Ho
Published: November 2023

Background

Pyometra is a disease of pus collection in the uterine cavity. The clinical characteristics and etiology of pyometra have not been well-described. In this study, we investigated the clinical characteristics, epidemiology, outcomes, and risk factors of septic shock in patients with pyometra.

Methods

The study population was selected from adult patients (≥ 18 years old) diagnosed with the International Classification of Diseases 10th code for inflammatory disease of the uterus (N71) in four academic hospitals between 2010 and 2021. Only patients with definitive pus collection in the uterus confirmed by imaging tests were included. Intra-or post-partum infection and surgical site infection were excluded. The primary endpoint was all-cause 28-day mortality, and the secondary endpoint was a 1-year recurrence. Clinical characteristics and outcomes were compared among patients with or without septic shock.

Results

Among 406 patients diagnosed with the N71 code, 193 patients were classified as pyometra. 28-day all-cause mortality was 5.0%, and the 1-year recurrence rate was 6.1%. The median patient age was 74.5 years. The most common symptom was abdominal pain (48.7%) and vaginal discharge (48.2%). The most common pathogens isolated from culture were Escherichia coli (39.9%), Streptococcus spp.(16.6%), and Klebsiella pneumoniae(16.0%) and isolated from polymerase chain reaction (PCR) were Mycoplasma spp., and Ureaplasma spp. Patients with septic shock were older and have a shorter interval between symptom onset (or discovery) and diagnosis. These patients had larger pyometra diameters, more frequent uterine perforation, more dementia, and were more frequently referred from long-term care facilities. The 28-survival rate was lower in patients with septic shock (72.8%) than without septic shock (98.7%, P < 0.001)

Conclusion

Our study suggested pyometra is a unique gynecological infectious syndrome in post-menopausal women. The most common pathogen was similar to pathogens causing urinary tract infections. Risk factors with septic shock suggested that decreased cognitive functions could delay early diagnosis of pyometra, and lead to more septic shock and higher mortality.

Disclosures

All Authors: No reported disclosures
209. Validation of a New Risk Stratification System-Based Management for Methicillin-Resistant Staphylococcus aureus Bacteremia: Analysis of a Multicenter Prospective Study
Authors: Kim Taeeun , Lee Sang-Rok , Yeon Park Seong , Mi Moon Song , Jung Jiwon , Jae Kim Min , Sung Heungsup , Kim Mi-Na , Kim Sung-Han , Choi Sang-Ho , Lee Sang-Oh , Soo Kim Yang , Hee Song Eun , Pil Chong Yong
Published: November 2023

Background

Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteremia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the various manifestation of SAB. In the light of this, Koujizer et al. proposed a new risk stratification system for metastatic infection in SAB, which involves a stepwise approach to diagnosis and treatment. We tested this risk stratification system in methicillin-resistant SAB (MRSAB) patients.

Methods

We retrospectively analyzed data of a 3-year multicenter, prospective cohort of hospitalized patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes, as well as microbiologic features.

Results

The demographic and baseline characteristics of patients are shown in Table 1. The most frequent source of MRSAB was central venous catheter-related infection (25.5%), followed by unknown origin (15.3%) and pneumonia (11.1%). Echocardiography was performed in 248 cases (65.3%). Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection (Figure 1). No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 17.7% in the high-risk groups (P=0.03) (Figure 2A). After an in-depth diagnostic work-up, patients were finally diagnosed as ‘without metastatic infection (6.3%)’, ‘with metastatic infection (15.8%)’, and ‘uncertain metastatic infection (77.9%)’. 30-day mortality increased markedly as the severity of diagnosis shifted from ‘without metastatic infection’ to ‘uncertain’ and ‘with metastatic infection’ (P=0.07) (Figure 2B). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteremia score ≥4, and persistent bacteremia.

Figure 1.

Flowchart of risk stratification and final diagnosis

Figure 2.

Outcomes of metastatic infection and 30-day mortality. A, metastatic infection according to the risk stratification, B, 30-day mortality according to the final diagnosis

Conclusion

The new risk stratification system provides good discrimination in predicting metastatic complications, making it a reliable tool for guiding work-up and management of MRSAB. However, minimizing the number of ‘uncertain metastatic infection’ cases remains an area for improvement.

Disclosures

All Authors: No reported disclosures
211. Disease burden of bacteremia with extended-spectrum beta-lactamase-producing or carbapenem-resistant Enterobacteriaceae in Korea
Authors: Mi Lee Chan , Lee Shinwon , Beom Park Wan , Gyun Choe Pyoeng , Kim Chung-Jong , Kim Bongyoung , Mi Moon Song , Gyung Kwak Yee , Kim Yeon-Sook , Keun Kim Young , Jin Sohn Yu , Park Kyung-Hwa , Eun Kim Seong , Suk Kim Eu , Bin Kim Hong , Ahn Jeonghoon , Song Kyoung-Ho
Published: November 2023

Background

Despite the importance of multidrug-resistant organisms (MDRO) bacteremia, especially extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) or carbapenem-resistant Enterobacteriaceae (CRE), the disease burden of those has not been investigated in detail. Thus, we tried to evaluate the clinical outcomes and estimate the socioeconomic burden of those MDROs bacteremia at a nationwide level in the Republic of Korea.

Methods

We retrospectively searched for all cases of ESBL-E or CRE bacteremia, as well as matched control patients, in ten hospitals representing regions across the country over a six-month period. Patients with ESBL-E or CRE bacteremia were classified as the R group, while matched controls with antibiotic-susceptible bacteremia or those without infection were classified as the S and N groups, respectively. Patients’ clinical data, including demographic data, underlying medical conditions, and microbiologic data were collected. We estimated economic burden by considering medical expenses, loss of productivity, and total costs.

Results

We identified a total of 795 patients, including 265 cases with ESBL-E or CRE bacteremia, and their matched controls after propensity-score matching. The mean total length of stay for ESBL-E and CRE matching in the R group were 7.8 days and 18.3 days longer compared to the S group, and 12.2 days and 14.5 days longer compared to the N group. The 90-day mortality rates for ESBL-E and CRE matching in the R, S, and N groups were 12.1%, 5.6%, 3.4%, and 24.0%, 12.0%, 0.0%, respectively. The total costs of the R, S, and N groups showed significant differences in both ESBL-E and CRE matching ($11,151 vs. $8,712 vs. $6,063, P = 0.004; $40,464 vs. $8,748 vs. $7,279, P = 0.024).

Conclusion

The mortality rates of ESBL-E or CRE bacteremia were found to be tremendously high. Furthermore, the economic burden imposed by ESBL-E or CRE bacteremia, compared to controls without infection, were approximately two and five times higher, respectively. These findings suggest that ESBL-E and CRE bacteremia impose a significant clinical and economic burden, and adequate efforts to control these resistant bacteremia might be necessary to reduce this burden.

This Study is sponsored by Pfizer Pharmaceuticals Korea Ltd.

Disclosures

All Authors: No reported disclosures
216. A Comparison of Multidrug-Resistant Gram-negative Bacteremia in Cancer and Non-Cancer Patients
Authors: Haris Khan Muhammad , Munshi Ruhul , Wangjam Tamna , Bhuiyan Mohammad Alfrad Nobel , Self Michelle , Alam Mohammad , Malek Alexandre E
Published: November 2023

Background

Multidrug-resistant gram-negative bacteremia (MDR-GNB) is a growing threat worldwide as it is associated with increased morbidity and mortality. We sought to describe the clinical features of MDR-GNB and outcomes in cancer and non-cancer Pts.

Methods

We performed a retrospective study of adult patients with MDR-GNB at the Ochsner LSU Health Shreveport between January 2018 and July 2022. We collected patients' demographics, medical comorbidities, cancer diagnosis, causative bacteria (MDROs), source of bacteremia, antibiotics therapy, and clinical outcomes.

Results

We identified 112 Pts with MDR-GNB. Pts were divided into 2 groups: cancer group (n=33, 29%) and non-cancer group (n=79, 71%). In the cancer group, the majority of Pts had solid tumors (n=20, 61%) vs liquid tumors (n=13, 39%). Mean age was 69 y in cancer compared to 57 y in the non-cancer group. Enterobacteriaceae were isolated in 28 cancer Pts (85%) including ESBL E. coli in 20 Pts (61%), Klebsiella s.p (CRE/ESBL) in 5 Pts (15%), and ESBL P. mirabilis in 3 Pts (9%). Pseudomonas aeruginosa CRO in 3 Pts (9%) and A. baumannii in 2 Pts (6%). In non-cancer Pts, Enterobacteriaceae were isolated in 65 Pts (82%) including ESBL E. coli in 40 Pts (51%), Klebsiella s.p (CRE/ESBL) in 18 Pts (23%) and ESBL P. mirabilis in 6 Pts (8%). P. aeruginosa CRO found in 6 Pts (8%) and A. baumannii in 8 Pts (10%). The sources of bacteremia in cancer group were UTI in 14 Pts (42.4%), osteoarticular infection (OAI) in 5 Pts (15%), pneumonia in 3 Pts (9%), CLABSI in 2 Pts (6%), endovascular in 1 Pt (3%) and unknown in 8 Pts (24%), whereas in non-cancer group, UTI was reported in 40 Pts (68%), pneumonia in 9 (27%), OAI in 1 (1.3%), endocarditis in 1 Pt (1.3%), and unknown in 20 Pts (25.3%). Mean duration of targeted antibiotics was 9 days in cancer vs 13.3 days in non-cancer group (p-value=0.4). Mean length of hospital stay was comparable, 34 d in cancer vs 31 d in non-cancer(p-value= 0.87). 9 Pts were admitted to ICU in cancer group (27%) vs 39 Pts (49%). Mortality rate was 39% in cancer (8 pts went to hospice) vs 16.4% in non-cancer.

Conclusion

Our data showed that the common source of MDR-GNB remains urinary tract infection in both groups and the bacterial epidemiology is comparable between the two groups. Further studies are warranted to assess the impact of resistant organisms on cancer Pts.

Disclosures

All Authors: No reported disclosures
217. Eosinophil count recovery as a predictor of bloodstream clearance in Staphylococcus aureus bacteremia
Authors: McHugh Jack W , Khodadadi Ryan B , Yetmar Zach , Halvorsen Andrew , Abu Saleh Omar M
Published: November 2023

Background

Eosinopenia has previously been studied as a predictor of bacteremia and sepsis, and has been identified as a marker of increased mortality in critically ill patients. To date, one study has examined changes in eosinophil count during bacterial infection, noting quicker normalization of eosinophil count versus traditional markers of inflammation, whereas no studies have examined eosinophil count recovery as a predictor of blood stream clearance.

Methods

We conducted a multicenter, retrospective cohort study of adult patients diagnosed with Staphylococcus aureus bacteremia (SAB) between January 2018 and December 2019 at Mayo Clinic campuses. Patients with eosinopenia on the date of the first positive blood culture were selected for further analysis. Eosinopenia was defined as an eosinophil count < 0.03 x10(9)/L. Eosinophil count recovery was defined as the first subsequent date where an eosinophil count ≥0.03 x10(9)/L was recorded. Clearance of SAB was defined as negative blood cultures at 48 hours on two consecutive days, and the date of clearance was defined as the date of first negative blood culture.

Results

A total of 213 cases of SAB were identified where an eosinophil count was obtained on date of first positive blood culture. Of these cases, 132 (62.0%) had eosinopenia at time of diagnosis. Data related to count recovery was available for 90 patients, with associated characteristics for this cohort detailed in Table 1. S. aureus isolates were oxacillin susceptible in 91.1% (82/90) of cases. The median time to clearance of bacteremia was 2.7 days (IQR 1.8-4.7 days), and the median time to eosinophil count recovery was 2.0 days (IQR 2.0-3.0 days). Data related to timing of eosinophil count recovery are presented in Table 2. Resolution of eosinopenia occurred within 48 hours of bloodstream clearance in 79/90 (87.8%) of cases and preceded or occurred within 48 hours of blood culture clearance in 88/90 (97.8%) of cases.

Conclusion

Eosinopenia is a common finding at time of diagnosis of SAB, and recovery of eosinophil count is suggestive of imminent clearance of blood cultures.

Disclosures

All Authors: No reported disclosures
220. Effectiveness of Piperacillin/tazobactam Loading Dose for Extended Infusion Dosing Among Patients with Gram-negative Bacteremia (EZ-LD)
Authors: Patel Savan , Mohayya Sana , Yassin Arsheena , Aboujaoude Emily , Dao Judy , Bhatt Pinki , Kaye Keith S , Abdul Azim Ahmed , Narayanan Navaneeth
Published: November 2023

Background

The rationale for a loading dose (LD) prior to administering extended infusion piperacillin/tazobactam (PTZ) is theoretical and based on pharmacokinetic/pharmacodynamic (PK/PD) principles and simulations. The clinical data to support the use of a LD for extended infusion are limited.

Methods

This is a single-center, retrospective cohort study evaluating adult patients with gram-negative bacteremia who received extended infusion PTZ for at least 48 hours between 2015 and 2022. In December 2019, the study institution developed a policy that automatically ordered a PTZ LD whenever PTZ therapy was prescribed. The study compared patients who received the loading dose to those who did not. Electronic medical records were queried for patient demographic and clinical data. The primary endpoint was 30-day mortality. Key secondary endpoints included clinical cure, time to clinical cure, 14-day mortality, in-hospital mortality, time to mortality, and microbiologic cure. Clinical cure was defined by antibiotic discontinuation or narrowing of antibiotics in the setting of patient survival. Descriptive and inferential statistics were used for all data analyses. Logistic regression modeling was performed to control for confounding.

Results

A total of 102 patients were included in the analysis, with 51 patients in the LD group and 51 patients in the no LD group. Baseline characteristics were similar in both treatment groups with the exception of ICU admission which was higher in the LD group (41% vs. 24%; P = 0.57). The 30-day mortality was 12% (6/51) in the LD group compared to 6% (3/51) in the no LD group (P = 0.49). There were no significant differences in 14-day mortality, in-hospital mortality, clinical cure, and microbiologic cure. After adjusting for potential confounders, there were no significant associations between LD and 30-day mortality (OR, 1.69; 95% CI, 0.36 to 7.96).

Conclusion

We observed no significant association between LD for extended infusion PTZ and clinical outcomes. Larger cohorts with adequately powered sample sizes are needed to validate these findings. Future investigations should evaluate the impact of a LD for extended infusion PTZ on safety and PK/PD outcomes.

Disclosures

Pinki Bhatt, MD, Sanofi: Grant/Research Support Keith S. Kaye, MD, MPH, Abbvie: Advisor/Consultant|Abbvie: Honoraria|Entasis: Advisor/Consultant|Entasis: Honoraria|GSK: Advisor/Consultant|GSK: Honoraria|Merck: Advisor/Consultant|Merck: Honoraria|Shionogi: Advisor/Consultant|Shionogi: Honoraria|VenatoRx: Advisor/Consultant|VenatoRx: Honoraria Navaneeth Narayanan, PharmD, MPH, BCIDP, Astellas: Honoraria|Beckman Coulter: Honoraria|Merck: Grant/Research Support|Shionogi: Grant/Research Support
222. Oral Step-Down Therapy for Uncomplicated Enterococcus Bacteremia
Authors: Ni Jessica , Decano Arnold , Zacharioudakis ioannis , Mazo Dana , Dubrovskaya Yanina , Siegfried Justin , Marsh Kassandra
Published: November 2023

Background

The mainstay of therapy for uncomplicated Enterococcal bloodstream infections (BSI) is intravenous (IV) antibiotics which have higher bioavailability than oral (PO) options. This study evaluated clinical outcomes and the safety of early step-down to oral antibiotics in uncomplicated Enterococcus bacteremia.

Methods

This was a retrospective study of adult patients admitted from January 2013 to October 2022 with an initial bacteremia episode and positive blood culture for Enterococcus species who completed treatment with PO or IV antimicrobial therapy. The primary endpoint was clinical cure, defined as no evidence of transition back to IV therapy after starting PO therapy or no need for escalation of definitive IV therapy due to new fever, leukocytosis, or hemodynamic instability. Safety endpoints were C. difficile or adverse drug events leading to discontinuation or change in therapy.

Results

A total of 110 patients were included in the analysis, and 49% received oral step-down therapy (n=54). The most commonly used PO agents were linezolid (59%) and amoxicillin (22%). The severity of illness of the IV and PO groups was assessed by Pitt bacteremia score [1.7 (interquartile range, 0-2.8) vs. 1.3 (IQR, 0-2.0)], Charleston Comorbidity Index [6 (IQR, 4.0-8.0) vs. 5 (IQR, 3.8-6.0)] and ICU admission (35.2% vs. 13.0%; P=0.008). The most commonly identified sources of infection were gastrointestinal (23%) and urinary (23%). No statistical differences were seen between the IV and PO groups in clinical cure (91.1% vs. 98.1%; P=0.111), microbiological cure (98.2% vs. 100%; P=0.509), mortality (1.9% vs. 8.9%; P=0.111), or infectious readmissions at 30-day (5.6% vs. 12.5%; P=0.163) and 90-day (14.8% vs. 19.6%; P=0.384). HLOS was 12.5 days in the IV group and 8.5 days in the PO group (P=0.038). No differences were seen in safety outcomes. The majority of patients in both the IV and PO groups were followed by ID consult (76.8% vs. 81.5%; P=0.356) and Antimicrobial Stewardship (75.0% vs. 77.8%; P=0.453).

Conclusion

Our results suggest that oral antibiotic step-down therapy in uncomplicated Enterococcal BSIs may be a safe alternative to IV therapy in a carefully selected patient population. Larger studies are required to confirm these results.

Disclosures

All Authors: No reported disclosures
223. Clinical Characteristics and Outcomes of Acinetobacter baumannii XDR and Pseudomonas aeruginosa XDR in a Tertiary Referral Medical Center in Mexico
Authors: Ojeda Yuren Alicia Sarahi , Murillo López Maricarmen , Gómez Abrajan Mariana , Salinas Arteaga Gustavo , Rodríguez González José Carlos , González De León María Fernanda Osorno , Domínguez Valdez Sandra Ivet , Ruiz Araceli Acosta , Gónzalez Cardel Ana Maria , Montiel López Luis , Lopez Luis Bruno Ali
Published: November 2023

Background

Highly resistant gram-negative bacteria such as Acinetobacter baumannii (AB) Complex and Pseudomonas aeruginosa (PA) have developed into Extremely Drug-Resistant organisms (XDR). This study aims to identify the clinical characteristics and outcomes of bacteremia caused by non-fermenting bacilli (Acinetobacter baumanni and Pseudomonas Aeruginosa) XDR in a Mexican population of a tertiary medical center in Mexico.

Methods

From January 2019 to December 2021, the results of positive bloodstream cultures for AB XDR and PA XDR were collected from the microbiology laboratory. The electronic records of these patients were obtained, and the variables associated with their clinical characteristics and outcomes were extracted for their analytical description.

Results

A total sample of 49 patients was gathered, from which 26 were men (53%) and 23 (46%) were women, with an average age of 55 years. 71% of patients were admitted to the critical care units. The average Charlson Index was 3.01. 12% had an immunosuppressive condition, 24% had presented a previous hospitalization last year, and 38% had received a previous antibiotic regimen. The length of stay from the AB group had an average of 29 days compared with 46 days in the PA group. The persistence of bacteremia with AB was an average of 11 days versus 22 days with PA. Only 16% of these patients were treated with colistin. The Pitt Index at the time of the first positive culture had an average of 7.56 points in the AB XDR group with 73% mortality, compared to a PA XDR Pitt Index score of 2.4 points and a 42% mortality.

Conclusion

The infections of these pathogens were more prevalent in patients greater than 50 years of age with similar distribution between sexes. Hospitalization in critical care units and immunosuppressive conditions were frequent characteristics of the patients. However, despite the diagnosis of XDR by blood cultures, few patients received colistimethate or another antibiotic with corroborated susceptibility, probably contributing to their complications. Finally, an increase in the length of stay after a positive blood culture is observed in the outcomes, being lower in AB XDR baumannii infections but with higher mortality than PA XDR infections.

Disclosures

Luis Montiel López, Medical Doctor, Merck: Speaker|Novartis: Speaker
228. Increased Incidence of Invasive Haemophilus influenzae Infections in Adults in Central Massachusetts
Authors: Qadri Qadija H , Ellison Richard T , Ward Doyle V , Yoon Jungwon
Published: November 2023

Background

Since the advent of the Haemophilus influenzae B vaccine, the incidence of infections due to this pathogen has substantially decreased, although occasional cases of severe infections due to other serotypes are observed. Routine surveillance at an academic medical center in central Massachusetts identified an apparent increase in the incidence of community-acquired bacteremic H. influenzae infections in adult patients and further investigation was undertaken.

Methods

A retrospective review was performed of all patients with positive blood or cerebrospinal fluid cultures for H. influenzae hospitalized at UMass Memorial Medical Center between January 1, 2008 and March 31, 2023. Available blood culture isolates of H. influenzae from recent bacteremic cases underwent whole genome sequencing (WGS).

Results

There was a notable increase in the quarterly incidence of H. influenzae cases seen in the last quarter of 2022 (3 cases) and first quarter of 2023 (8 cases) as compared to the period from 2008 through the third quarter of 2022 (0.7 cases) [figure 1]. The 11 cases involved 2 children and 9 adults with the median age of adults 66 years. All cases were bacteremic with 8 associated with pneumonia and 1 with pharyngitis, with 2 other infections. Underlying conditions included emphysema, cancer, diabetes, Crohn's disease and others; 2 patients died. There was no apparent geographic clustering. Three isolates were available for WGS with two being in serotype F clade (HiF) and one a non-typeable clade. The two HiF isolates had 1210 SNV differences suggesting the same genomic clade, but not related by recent transmission.

Conclusion

A notable increase in invasive H. influenzae infections has been seen in our institution. The majority of the most recent cases have been in adults, and about 72% of the 11 cases were in association with pneumonia. Of the case fatalities, one was taking an IL-1 inhibitor, and another with cancer. Potential etiologies could be the emergence of a new and more invasive H. influenzae strain, as well as changes in either the host immunity to this pathogen or the upper respiratory tract microbiome in relation to the recent COVID pandemic and the effect of social isolation and increased use of face masks.

Disclosures

All Authors: No reported disclosures