bluuebunny/crossref_metadata_2025_split huggingface dataset:
P-1526. In vitro Activity of Ceftobiprole Against Prominent Methicillin-resistant Staphylococcus aureus Clonal Groups Collected Through the SENTRY Antimicrobial Surveillance Program
Authors: Mendes Rodrigo E , Kimbrough Hank , Maher Joshua , Smart Jennifer , Jones Mark E , Castanheira Mariana , Sader Helio S 
Published: January 2025

Abstract

Background
Ceftobiprole (BPR), an advanced generation cephalosporin, was recently (April 2024) approved by the US FDA for treating Staphylococcus aureus bacteremia (SAB), community-acquired bacterial pneumonia (CABP), and acute bacterial skin and skin structure infections (ABSSSI). This study examined the activity of BPR and the comparator agent ceftaroline (CPT) against a contemporary (2018-2019) collection of methicillin-resistant S. aureus (MRSA) isolates from major pandemic lineages.
Genomic features and susceptibility profile of MRSA isolates stratified by clonal group and subgroups.

Methods
150 MRSA collected from 38 hospitals in 18 countries were susceptibility (S) tested against BPR and CPT using CLSI broth microdilution methods; FDA breakpoints were applied. Total genomic DNA was extracted and sequenced. Assembled genomes were used to determine multi-locus sequence type (ST), clonal complex (CC), spa (not shown) and SCCmec types; results of typing methods were used to assign clonal group (CG).

Results
Twenty-four CGs, including subdivisions, were identified; 3 isolates could not be assigned a CG. Prominent CGs were USA300 (n=53, 35.3%), UK-EMRSA-15 (n=33, 22.0%), USA100 (n=28, 18.7%), and USA800 (n=15, 10.0%); rare CGs (≤ 3 isolates; n=21) totaled 14.0% (TABLE). Against all MRSA, 97.3% were BPR-S and 85.3% were CPT-S. BPR was more active than CPT across CGs and subdivisons: USA300, 100.0% BPR-S/94.3% CPT-S; UK-EMRSA-15, 93.9% BPR-S/69.7% CPT-S; USA100, 96.4% BPR-S/75.0% CPT-S; USA800, 100.0% BPR-S/CPT-S. Against rare or unknown CGs, 95.2% were BPR-S and 90.5% were CPT-S. Four (2.7%) and 22 (14.7%) isolates were BPR- and CPT-NS, respectively; all BPR-NS isolates were CPT-NS whereas 81.8% of CPT-NS isolates were BPR-S. No CG feature united BPR-NS isolates (n=2 UK-EMRSA-15, CC22/ST22/SCCmec-IV(2B); USA100-Swiss, CC5/ST105/SCCmec-II(2A); Hungarian-Brazilian; CC8/ST239/SCCmec-III(3A)), whereas 19/22 (86.4%) CPT-NS isolates were from subgroups of UK-EMRSA-15, USA100, or Hungarian-Brazilian CGs.

Conclusion
This study reports the potent activity of BPR against a global collection of MRSA from prominent pandemic lineages. The low frequency of BPR-NS isolates, particularly among highly represented CGs including UK-EMRSA and USA100, and its activity against CPT-NS isolates, support the use of BPR in the treatment of MRSA-associated SAB, ABSSSI, and CABP.

Disclosures
Rodrigo E. Mendes, PhD, GSK: Grant/Research Support Jennifer Smart, PhD, Basilea Pharmaceutica International Ltd: Employee|Basilea Pharmaceutica International Ltd: Stocks/Bonds (Public Company) Mark E. Jones, PhD, Basilea Pharmaceutica International Ltd: Employee|Basilea Pharmaceutica International Ltd: Stocks/Bonds (Public Company)
P-1565. Antimicrobial Resistance among Gram-negative Urinary Isolates from Kidney Transplant Recipients: Implications for Precision Antimicrobial Stewardship
Authors: London Abby , Farmakiotis Dimitrios , Vieira Kendra M , Rogers Ralph , Shi Yiyun 
Published: January 2025

Abstract

Background
Urinary tract infections (UTI) in kidney transplant recipients (KTR) can lead to chronic allograft dysfunction, progression to sepsis, graft loss, and death. With such morbidity and even mortality, it is important to determine if this population has similar antimicrobial resistance (AMR) patterns to those of the general patient population in the same community, to determine the need for dedicated antibiograms, formulate empiric protocols for treatment, and optimize antimicrobial stewardship (AMS) interventions.

Methods
We captured positive urine cultures between 1/1/09 and 11/4/19 in KTR at Brown-University affiliated hospitals. We compared resistance rates to preferred oral antibiotics for the management of UTI and for ceftriaxone (CTX, marker of extended-spectrum beta-lactamase production) to those reported in our institutional antibiogram. The study was approved by the Lifespan Institutional Review Board.

Results
We studied 236 isolates from 294 KTR. 122 (42%) were females; 57 (19%) were Black. Median age at transplant was 55 (range: 10-82) years old. The most common causes of end-stage renal disease included hypertension (n=93, 32%) and diabetes (n=55, 19%). Of 187 Gram-negative organisms isolated, the most common were E. coli (n=112), K. pneumoniae (n=59), K. oxytoca (n=10), and E. cloacae (n=6). Compared to our general population, those isolates were more frequently resistant to ciprofloxacin (29% vs. 16%), nitrofurantoin (NTF, 29% vs. 16%), trimethoprim/sulfamethoxazole (TMS 65% vs. 19%) and CTX (12% vs. 7%) (Table, P&lt; 0.05).

Conclusion
KTR are at high risk for the development of AMR, not only to TMPS, which they receive as Pneumocystis jirovecii prophylaxis, but other antibiotic classes as well. KTR-specific institutional antibiograms and targeted AMS interventions, such as provider education against treatment of asymptomatic bacteriuria in KTR, could help improve clinical outcomes and mitigate AMR.

Disclosures
Dimitrios Farmakiotis, M.D., Astra Zeneca: Grant/Research Support|Viracor: Advisor/Consultant|Viracor: Honoraria
P-1575. Trends in antibiotic resistance in community-acquired urinary tract infections among children - a retrospective descriptive nation-wide study
Authors: Yeshurun Michal Stein , Stein Michal , Ben David Shirley Shapiro 
Published: January 2025

Abstract

Background
Urinary tract infection (UTI) is one of the most common bacterial infections in children. Early antibiotic treatment may prevent complications. Empirical treatment requires up-to-date knowledge of the local epidemiology. This study aims to describe trends in resistance rates in community-acquired UTI`s between 2017-2022, assess whether current recommendations for empirical treatment are valid and identify risk factors for resistance.

Methods
Data was collected retrospectively from the computerized system of Maccabi Health Services for all children under 18 years-old diagnosed with a UTI in 2017 and 2022 and analyzed using chi-square test and regression models.

Results
A total of 240,122 urinary samples were included in the study. The most common isolated pathogen was Escherichia coli (78%); there was a slight but significant increase in extended-spectrum beta-lactamases (ESBL) incidence for all Gram-negative Enterobacteriaceae from 6% in 2017 to 8% in 2022, (P-value 0.001). Higher incidence (12%) was detected among Klebsiella isolates compared to E. coli (8%). Aminoglycosides resistance rates increased from 5% to 6% (P-value 0.001). The most impressive increase was in resistance to Fluoroquinolones from 7% to 23% (P-value 0.001).
Female gender, younger age, previous antibiotic treatment and urinary tract abnormalities were associated with an increased resistance rate.

Conclusion
The increased resistance rate observed for most pathogens and antibiotics was statistically significant, nevertheless, due to small absolute changes, the recommendations for empirical antibiotic treatment in Israel are still valid. Fluoroquinolones, which are not recommended as empirical treatment, should be avoided due to high levels of resistance.

Disclosures
Shirley Shapiro Ben David, MD, GSK: Lecturer|Pfizer: Grant/Research Support|Pfizer: Lecturer
P-1586. Urine Culture Reflex Implemented to Reduce Inappropriate Testing
Authors: Orner Erika , Zimilover Adam , Cheng Sammy , Cowman Kelsie , Thwe Phyu , Szymczak Wendy , Gendlina Inessa 
Published: January 2025

Abstract

Background
Improper ordering of urine cultures and patient care based solely on positive culture in the absence of urinalysis suggestive of infection can lead to overtreatment of asymptomatic bacteriuria, increased healthcare costs, and increased risk of antimicrobial-related adverse events like C. difficile infection and increased antimicrobial resistance.
Table 1
Results of specimens collected Oct 24-Nov 4, 2022 pre-implementation

Methods
A reflex urinalysis-to-urine culture was implemented with a threshold of urine culture performed only when 5+ WBC/HPF are seen in urinalysis. Pre-implementation (10/24/22–11/4/22) data from inpatients with concurrent urinalysis and urine culture was analyzed to determine how results would be impacted if urinalysis was utilized as criteria to perform urine culture. Post-implementation (10/24/23–11/4/23) data was also analyzed.
Table 2
Results of specimens collected Oct 24-Nov 4, 2023 post-implementation

Results
Pre-implementation, 1428 urine cultures were done on average per week. During the pre-implementation period, 1695/2273 patients had UA done on the same day as culture. 1376/1695 cultures were negative, 264/1695 cultures were positive, and 55/1695 cultures were contaminated ( ≥3 organisms). Using 5+ WBC/HPF as culture criteria, 1228/1695 (72%) specimens would not have qualified for culture and only 5.8% of cultures would have been falsely negative. Post-implementation, there were 863 urine cultures/week on average. 1125/1513 reflex specimen did not qualify for culture. 375/1513 had 5+ WBC/HPF and qualified for culture but only 140/377 were culture positive. 791/1155 standalone cultures had UA done on the same day. Only 227/791 would have qualified for culture.
Figure 1
Number of urine cultures performed weekly from June to November 2023. Implementation of reflex testing was done Oct 24, 2023

Conclusion
As predicted, using WBCs as criteria to perform urine culture has significantly reduced our urine culture volume. 14% of cultures are still being done without corresponding UA indicating test utilization could further improve. Future studies will analyze the impact reflex testing has on clinical diagnosis and treatment.

Disclosures
Wendy Szymczak, PhD, Quidel: Advisor/Consultant
P-1593. Experience with a Rapid Diagnostic Blood Culture Identification Panel in Patients with Neutropenic Fever
Authors: Patel Dhruv , Mansoor Armaghan-E Rehman 
Published: January 2025

Abstract

Background
Rapid identification of organisms in bloodstream infections can expedite selection of appropriate antimicrobials. This can significantly impact patient care, especially in immunocompromised hosts. Our retrospective study evaluates a single-center experience with a rapid diagnostic blood culture panel (BCID) in patients with neutropenic fever.

Methods
Between January 2020 and October 2023, all adult patients with neutropenic fever for whom blood cultures were obtained were reviewed. As standard protocol, a reflex BCID was performed with the FilmArray© panel for all blood cultures with microbial growth. We evaluated concordance between cultures and BCID data, and clinical implication of discrepant results. Patient demographics, cause of neutropenia, and 90-day mortality was documented.

Results
Of 6382 blood cultures in 1604 episodes for neutropenic fever, 253 unique blood cultures in 189 patients met criteria (Figure 1). Median age was 59 (SD±14.9) years, with 95 (50.3%) being female. A central venous catheter (CVC) was present in 75 patients (39.7%). The most common etiology for neutropenic fever was malignancy or chemotherapy in 124/189 (65.6%), followed by shock in 10/189 (5.3%).
BCID identified resistance genes in 86/253 (34.0%) of samples, with mecA (64, 25.3%) and CTX-M (11, 4.3%) most commonly reported. BCID and routine susceptibility testing showed similar results in 219/253 (86.6%) specimens (Table 1). Of the discordant results, 9/31 BCID results missed presence of an on-target multi-drug resistant organism (Table 2).
A change in therapy occurred based on BCID results from 143 (56.5%) of cultures in 94 (49.7%) of patients. There was no significant difference in 90-day mortality among patients where BCID led to an antibiotic change (37.2% vs 36.8%, p-value=0.96), and no difference in 90-day mortality among patients with discordant data (28.9% vs 37.5%, p-value=0.26).

Conclusion
In 239 episodes of neutropenic fever, BCID results correlated with routine results in 87% of blood cultures. BCID results resulted in quicker change to culture-appropriate antimicrobials in nearly half of the patients, however this was not associated with a mortality benefit.

Disclosures
All Authors: No reported disclosures
P-1614. Verigene's Impact on Time to Preferred Antibiotics in Gram Positive Bacteremia
Authors: Martinez-Palmer Meaghan , Robins Alison 
Published: January 2025

Abstract

Background
Utilization of rapid identification methods for positive blood cultures has been instrumental in the efforts of antimicrobial stewardship programs (ASPs). Studies have shown that the use of molecular testing techniques on positive blood cultures, which identify select bacteria and their genetic resistance, have enabled timelier initiation of targeted therapy.
Type of Bacteremia
Species of bacteremia identified in both the standard identification period and the identification by Verigene period

Methods
Data was collected via chart review over two separate 6-month periods (7/1/2021- 1/1/2022 and 7/1/2022-1/1/2023), with Verigene BCID having been implemented in June 2022. The primary endpoint was the time to preferred therapy for organisms reported in the Verigene gram-positive panel, including MSSA, MRSA, Enterococcus species (faecalis and faecium), VRE, and Streptococcus species. Demographic variables, the source of bacteremia when established (i.e., skin/soft tissue, urinary, etc), as well as interventions for source control were also collected.
Source of Bacteremia

Results
In this study, we analyzed a total of 168 cases of gram-positive bacteremia. Among these, 94 cases occurred between 7/1/2021-1/1/2022 with identification via the standard method, while 74 cases occurred between 7/1/2022-1/1/2023 with identification via Verigene BCID. The average age of patients at the onset of bacteremia was 68 years, with a predominance of males (94.6%). Common underlying comorbidities included diabetes (50%) and coronary artery disease (48.7%).
Regarding bacteremia etiology, 29.8% were caused by MSSA, 22.6% by MRSA, 32.7% by Streptococcus species, 11.3% by Enterococcus spp, and 6% by VRE. The most common primary source of bacteremia was identified as skin and soft tissue (34.5%).
The time to administration of preferred antibiotics, as defined by our ASP recommendations, showed improvement across all gram-positive bacteremia types, decreasing from a mean of 61.5 hours with standard identification methods to 36 hours with Verigene identification. Time to preferred therapy decreased from 81.4 hours to 39.8 hours for MSSA bacteremia, and from 61.9 hours to 39.5 hours for Strep bacteremia.
Time to Preferred Antibiotics
Time in hours to preferred antibiotics for all cases analyzed, Streptococcus species, and MSSA.

Conclusion
The implementation of rapid blood culture identification utilizing Verigene BCID technology lead to a significant improvement in time to preferred antibiotics in cases of gram positive bacteremia.

Disclosures
All Authors: No reported disclosures
P-1615. Inappropriate Urine Cultures: The Order Stops Here
Authors: Hale Molly , Christianson Angela , Casas Mary T , Cronin Jason , Pelz Robert K 
Published: January 2025

Abstract

Background
Our most frequently missed bundle element from catheter-associated urinary tract infection (CAUTI) case reviews was that the urine culture did not meet evidence-based criteria for testing. Possible harm to the patient from an inappropriate urine culture and subsequent treatment includes unnecessary antibiotics, diagnostic anchoring, Clostridioides difficile infection, and longer length of stay. Risks to the organization include artificially inflated infection rates, associated lower quality and safety scores, and reduced federal reimbursements.Figure 1:Catheter-Associated Urinary Tract Infection (CAUTI) Rate
CAUTI rate before (0.61 cases per 1,000 catheter days) and after (0.22 cases per 1,000 catheter days) diagnostic stewardship intervention in March 2022 (p=0.005).

Methods
In March 2022 an automated report was built in a third-party software system using data from the electronic health record to identify urine cultures ordered in a patient hospitalized for two or more days with an indwelling urinary catheter (IUC), or who had an IUC removed in the previous two days. When a qualifying culture was identified, laboratory personnel held results and contacted the Antimicrobial Stewardship (AMS) Pharmacist. The case was discussed at AMS rounds with an Infectious Disease provider and the decision made whether to release the results. In cases where the culture was not appropriate, the patient’s provider was notified that the result would not be finalized and released. The infection rate pre- and post-intervention was calculated, and statistical analysis conducted with the Student’s T-test.

Results
In the 11 months prior to implementation of the urine culture review protocol, the average CAUTI rate was 0.61 cases per 1,000 IUC days. In the 23 months since the intervention, the average CAUTI rate was 0.22 cases per 1,000 IUC days, a 63.9% reduction in the infection rate (p=0.005). 19% of orders reviewed were determined to be appropriate. The AMS team reports the volume of culture reviews is manageable. When notified that the culture results would not be released, ordering providers responded favorably to the decision and no objections or adverse patient outcomes have been observed.

Conclusion
Our non-traditional intervention of enlisting the expertise of the AMS team for a diagnostic stewardship review has been successful in preventing unnecessary treatments to patients and has saved the institution from reportable CAUTI cases that did not meet clinical indication for testing.

Disclosures
All Authors: No reported disclosures
P-1658. Healthcare Provider Perspectives on Antibiotic Use in Immigrants and Refugees in the United States: A Qualitative Study
Authors: Croxton Rachel , Ladines-Lim Joseph , Schurz Timothy , Guetterman Timothy , Patel Payal K 
Published: January 2025

Abstract

Background
Antimicrobial resistance (AMR) is a global health threat with greater prevalence in refugee populations. Prior work demonstrated that compared to native-born Americans, immigrants/refugees from low- and middle-income countries have lower health literacy about AMR, increasing risk for inappropriate antibiotic use. Healthcare provider (HCP) perceptions of prescribing practices regarding immigrant/refugee populations in the United States (US) is lacking. We aimed to understand US HCP views on antibiotic prescribing practices and barriers that may lead to disparities affecting immigrants/refugees.

Methods
From September 1, 2023 through April 27, 2024, as a follow up to patient-centered work on antibiotic knowledge in the immigrant/refugee population, we conducted semi-structured qualitative interviews of 14 HCPs, both prescribers (e.g. physicians, advanced practice providers) and non-prescribers (e.g. nurses, medical assistants), from primary care clinics in SE Michigan that care for immigrants/refugees. We also collected participant demographic information. We generated a codebook through an iterative, inductive process using Dedoose software to code interviews and facilitate thematic analysis.

Results
Self-reported proportions of participants’ patient panels comprised of immigrants, refugees, and non-English speakers were 31.0%, 30.1%, and 48.2% , respectively. Most participants were prescribers and graduate-degree holders (Table 1). Eight major themes emerged: Clinical Decision-Making, Discussing Antimicrobial Consequences, Patient Life Challenges, Patient Medical Background, Antibiotic Use Differences, Patient Perspectives, Clinic Dynamics, and Patient-Provider Communication. There was consensus that distinctive challenges exist for appropriate antimicrobial prescribing among immigrant/refugee populations (Table 2).

Conclusion
Findings suggest that immigrant/refugee populations face multiple barriers to care. This population may benefit from an interdisciplinary outpatient team to navigate cultural differences and trauma-informed care. Our findings can inform ambulatory antibiotic stewardship interventions in immigrant/refugee populations.

Disclosures
All Authors: No reported disclosures
P-1660. Clinical Microbiology of Xylazine-Associated Wound Infections
Authors: Berg Deanna , Maguire Christina , Binkley Amanda , Torgersen Jessie , Hinton Matthew , Peiffer Derek , Huo Samantha , Foster Sean 
Published: January 2025

Abstract

Background
Over 90% of illicit opioids in Philadelphia contain xylazine, a potent centrally acting α-2 adrenergic agonist that can promote the development of skin and soft tissue wounds with a subsequent risk of infection. Optimal wound management, including the need for broad antimicrobial coverage, remains uncertain. This study sought to describe culture positivity and the clinical microbiology of xylazine-associated wounds to inform the optimal antimicrobial spectrum of activity.

Methods
We conducted a retrospective, single-center, cross-sectional study of adults with xylazine-associated wounds between April 1, 2022, and December 1, 2023. Patients were included if they received antimicrobials for suspected wound infection related to injection drug use, along with one of the following: (1) a positive urine xylazine test, (2) a positive urine fentanyl test with patient-reported xylazine use. For patients with multiple hospitalizations and/or wound cultures, the earliest encounter with the single most invasive method of wound culture acquisition was utilized. Microbiology results and causative pathogens are reported.

Results
Of the 685 patients with positive urine toxicology, 166 were included in the analysis, and 56% had positive cultures. Wound cultures were obtained in 81 (49%) patients; superficial bedside cultures were the only culture type obtained in 61% of patients, and operative cultures were collected in 39% of patients. Methicillin-resistant Staphylococcus aureus (MRSA) was the most common causative pathogen, and Pseudomonas aeruginosa was isolated in 9% of patients, most of whom had a bone or joint infection (88%). Nearly one in four patients were bacteremic (Table 1).

Conclusion
Over half of patients with suspected infected xylazine-associated wounds had clinical microbiology results to guide antimicrobial therapy. Gram-positive organisms were most frequently isolated, while gram-negative organisms were infrequently observed. These observations suggest that suspected infected xylazine-associated wounds should include empiric coverage of MRSA and β-hemolytic streptococci. Empiric anti-pseudomonal and/or anaerobic coverage may not be necessary for most patients being treated for skin and soft tissue infections.

Disclosures
Christina Maguire, PharmD, Viiv: Advisor/Consultant Amanda Binkley, PharmD, BCIDP, AAHIVP, Viiv: Advisor/Consultant