Citations

Abstract Background Phage therapy has emerged as a generally safe approach, as demonstrated in preclinical and clinical studies. However, data on efficacy, including optimal dosing frequency, remain limited. MRSE is a leading cause of foreign body-associated osteomyelitis and a potential target for phage therapy. Here, the activity of phage K alone and in combination with vancomycin (VAN), administered once (QD) or three times (TID) daily, against biofilms formed by two orthopedic infection-associated MRSE isolates on orthopedic screws was evaluated.Fig 1.in vitro multi-dose assay of methicillin-resistant S. epidermidis biofilm-coated cortical bone screws.IDRL, Infectious Diseases Research Laboratory; DMEM, Dulbecco's Modified Eagle Medium; PBS, phosphate-buffered saline; CFU, colony-forming units. Created in https://BioRender.comFig 2.Quantities of biofilm on screws after 24 hours of treatment.*Log10 CFU/cm² of biofilm on screws before treatments. Biofilm burden of the MRSE isolates prior to treatment ranged from 5.7 to 6.3 log10 CFU/cm². A Kruskal-Wallis test was performed to evaluate the statistical significance of biofilm reduction between treatment groups. The minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm bactericidal concentration (MBBC) of vancomycin for both IDRL-9410 and IDRL-9403 were 2, 2, and >128 µg/mL, respectively. Methods MRSE IDRL-9410 and IDRL-9403 biofilms were formed on titanium cortical bone screws (D 1.5 mm, L 4 mm, surface area 0.33 cm²) in 0.2 mL of tryptic soy broth containing 10⁶ CFU/mL (Fig 1); testing was performed in triplicate on two separate days. After 24 hours, screws were rinsed with PBS and randomly assigned to: Dulbecco’s Modified Eagle Medium (DMEM); vancomycin (VAN, 20 μg/mL) in DMEM; phage K (10⁹ PFU/mL) in DMEM; or VAN and phage K in DMEM. Every 8 hours, screws from the TID groups were transferred to new plates containing fresh treatment, with QD groups left in the original material. 24 hours post-treatment, screws were quantitatively cultured. Bactericidal activity was defined as ≥ 3 log₁₀ CFU/cm² reduction compared to the DMEM group, and synergy as ≥ 2 log₁₀ CFU/cm² reduction in the combination group compared to VAN or phage alone. Results After 24 hours, bactericidal activity was observed for QD and TID VAN-phage K groups against IDRL-9410 (p < 0.05 and p < 0.01, respectively) and IDRL-9403 (both p < 0.01). Synergy was observed in the VAN-phage K QD group, with a 2.2 log₁₀ CFU/cm² reduction for IDRL-9410 compared to VAN alone (Fig 2). 3.0 and 5.3 log₁₀ CFU/cm² reductions were observed in the VAN TID groups for IDRL-9410 and IDRL-9403, respectively, compared to the DMEM group (both p < 0.01). There was no statistically significant difference in biofilm reduction between the QD and TID groups for phage K alone or VAN-phage K for either strain. Conclusion Combination treatment with phage K and VAN, administered QD or TID, showed greater biofilm reduction compared to phage K alone. Increasing phage dosing frequency did not enhance biofilm reduction under the conditions studied. Disclosures Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection: a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection|MicuRx Pharmaceuticals and bioMérieux: Grant/Research Support|PhAST, Day Zero Diagnostics, DEEPULL DIAGNOSTICS, S.L., Nostics, HealthTrackRx, bioMérieux and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course: Honoraria

Abstract Background Staphylococcus aureus is a challenging pathogen which causes a multiplicity of human diseases around the globe, acquired in the community and healthcare settings alike. Treatment of S. aureus infection can be challenging and is further compromised by antimicrobial resistance. Understanding of its pathogenesis, transmission pathways and the dynamics of its genome evolution and associated adaptations is incomplete. One strategy to assess genome evolution is to assess codon bias. Historically, studies have focused on the consequences of coding changes; assessing silent mutations in the form of synonymous codon usage bias represents a novel approach to studying genetic adaptation.Figure 1.Principal component analysis (PCA) (A) and sPLS-DA (B) separate S. aureus from complex mates.sPLS-DA component 1 relies on a hypothetical protein, identified here by its NCTC 8325 genomic coordinates, as important for separating S. aureus from complex mates (C). Methods Here, the codon bias of 2,872 genes was queried against all publicly available complete S. aureus plasmids and genomes. Using public BioSample data, genomes were sorted by disease state (e.g., bacteremia, pulmonary infection) and geographical collection site. Results Isolates from Nairobi, Kenya were most different from other isolates, suggesting that geographical isolation may shape codon bias signature. In addition, codon bias of two MSCRAMM proteins implicated in human disease - SdrC and FnBPB - varied between isolation sources, suggesting a role for codon bias in S. aureus genetic adaptation to selective pressures of infection. Additionally, codon bias out-performed coding and nucleic acid mutational metrics in separating members of the S. aureus complex, S. aureus, Staphylococcus argenteus, Staphylococcus schweitzeri, and Staphylococcus roterodami; Fig 1, sparse partial least squares analysis (sPLS-DA) mean AUC codon: 0.89762, nucleic acid: 0.82266, codon bias: 0.9996 (relying on hypothetical protein NC_007795.1:516850-517419). Conclusion This analysis suggests that codon bias in S. aureus is a source of genetic adaptation that can be used to separate strains by geographical isolation source, and separate S. aureus sensu stricto from other S. aureus complex members. Disclosures Nicholas Bedard, MD, Stryker: Advisor/Consultant Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection: a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection|MicuRx Pharmaceuticals and bioMérieux: Grant/Research Support|PhAST, Day Zero Diagnostics, DEEPULL DIAGNOSTICS, S.L., Nostics, HealthTrackRx, bioMérieux and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course: Honoraria

Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAb) is a multi-drug resistant, opportunistic pathogen. Colistin is one of a few remaining treatment options, but resistance exists globally. Methods Between 2017 and 2019, 551 CRAb isolates were collected through the international Study Network of Acinetobacter as a Carbapenem-Resistant Pathogen (SNAP). Demographics, clinical characteristics, mortality, and a desirability of outcome ranking (DOOR) measure combining lack of clinical response, unsuccessful discharge, renal failure, and C. difficile infection, were recorded for each patient. A central laboratory measured colistin minimum inhibitory concentrations (MICs), and each isolate was classified as colistin-intermediate (MIC ≤2µg/mL) or resistant (MIC ≥4µg/mL). All isolates were sequenced on the Illumina platform, and the genomes were used to construct a phylogenetic tree and assess for variants within known colistin resistance-related genes. Results 18% of the 551 isolates were colistin-resistant. Compared to patients with colistin-intermediate isolates, patients with resistant strains were more likely to have been admitted from a healthcare facility, but otherwise had similar demographics and Charlson comorbidity indices. Focusing on patients with bloodstream or respiratory infections (n=217) uncovered increased 30-day mortality in patients with monomicrobial, colistin-resistant infections (11/19, p=0.008) when compared to monomicrobial-intermediate (41/102), polymicrobial-resistant (4/20) and polymicrobial-intermediate infections (18/76). Comparative genomics indicated that the majority of isolates belonged to clonal complex 2 (CC2), and that colistin resistance concentrated in certain genetic lineages. Variant analysis uncovered nonsynonymous mutations near and within the histidine kinase domain of pmrB, part of the PmrAB two-component system that regulates lipopolysaccharide modifications which can alter colistin susceptibility. Conclusion In this global cohort, patients with monomicrobial, colistin-resistant CRAb infections had increased mortality. New treatment options are needed for multidrug-resistant CRAb, and this study provides further evidence that pmrB may serve as a worthwhile drug development target. Disclosures Madison Stellfox, MD, PhD, Cumberland Pharmaceuticals: Grant/Research Support Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection: a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection|MicuRx Pharmaceuticals and bioMérieux: Grant/Research Support|PhAST, Day Zero Diagnostics, DEEPULL DIAGNOSTICS, S.L., Nostics, HealthTrackRx, bioMérieux and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course: Honoraria David van Duin, MD, PhD, British Society for Antimicrobial Chemotherapy: Editor stipend|Merck: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Advisor/Consultant|Roche: Advisor/Consultant|Shionogi: Advisor/Consultant Yohei Doi, MD, PHD, GSK: Advisor/Consultant|Meiji Seika Pharma: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi: Honoraria

Abstract Background Phage therapy has gained increasing interest as an approach to treat antimicrobial- resistant bacterial infections. Standardized, reproducible PST methods are needed to rapidly identify active phages for potential clinical use. Here, PST of 24 clinical isolates of carbapenem-resistant K. pneumoniae (CR-Kp) to 6 K. pneumoniae phages (3 from KlebPhaCol and 3 from phage hunting) was assessed using a plaque assay (PA) and a liquid assay (LA), and results compared. Phage Susceptibility Testing: Agreement Between Plaque Assay and Liquid Assay Methods For the PA, 2µL of 10−1-10−8 phage dilutions were spotted on bacterial laws of CR-Kp (double agar overlay), and plaques scored upon overnight incubation at 37°C [0 (no activity), 1+ (lysis from without), 2+ (concentration-dependent lysis), 3+ (clear plaques, small or medium size), 4+ (clear plaques of large size); scores ≥ 2+ were considered susceptible]. Testing was performed on 3 different days. If ≥ 2 replicates scored ≥ 2+, the result was classified as susceptible. For the LA, phages and bacteria were combined (MOI=10) in 96-well plates [phage-bacteria combinations (3 replicates), phage controls (106 PFU/mL), bacterial controls (BC, 105 CFU/mL), media sterility controls] and plates incubated at 37°C for 24h, with OD600 measured every 15 min. Hold time (HT) — delay in achieving inflection at the beginning of exponential growth phase — was calculated for phage-treated compared to BC wells. Testing was performed on 2 different days. Mean HT was computed for each phage-bacteria combination and results assessed as susceptible or not using cutoff HTs of 4h and 8h. Results Using a LA HT cutoff of 4h, there was complete agreement with results of the PA for 3 phages, and 96, 79 and 67% overall agreement for 3 other phages (Table). Using a LA HT cutoff of 8h, there was complete negative agreement for 4 phages, but lower overall agreement between the LA and PA (58-96%). Increased classification as susceptible by PA compared to LA was the main source of disagreement when using a LA HT cutoff of 8h. Conclusion Here, two PST assays were compared, and greater agreement was found when using a 4h compared to an 8h HT LA cutoff. These results represent a step forward in the standardization of PST methods, bearing in mind that correlation of results with pre-clinical and clinical outcomes is needed. Disclosures Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection: a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection|MicuRx Pharmaceuticals and bioMérieux: Grant/Research Support|PhAST, Day Zero Diagnostics, DEEPULL DIAGNOSTICS, S.L., Nostics, HealthTrackRx, bioMérieux and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course: Honoraria

Abstract Background Staphylococci are the most frequent microorganisms in periprosthetic joint infection (PJI) and treatment remains challenging. Phage is being considered as a potential treatment. Here, the in vitro activity of phages SaMD07FSphi1or SaNSI1469phi1, alone and in combination with vancomycin against staphylococcal biofilms was evaluated. Figure 1 In vitro activity of phage SaMD07FSphi1 against S. aureus and S. epidermidis biofilms Figure 2 In vitro activity of phage SaNSI1469phi1 against S. aureus and S. epidermidis biofilms Methods Biofilms were grown at 37°C on 4 cm stainless steel K-wires in tryptic soy broth (TSB) with 106 cfu/ml of S. epidermidis or S. aureus (8 PJI isolates with phage activity against planktonically-grown bacteria). After 24 h, 3 K-wires were quantitatively cultured to define pre-treatment bacterial loads, with the remaining assigned to one of four treatment groups: TSB, phage (4 x 106 plaque forming units/ml), vancomycin (16 µg/ml) or phage/vancomycin. K-wires were incubated for 6 or 24 h at 37°C, rinsed, sonicated, and quantitatively cultured. Testing was performed in triplicate and on 3 separate days and mean log10 cfu/K-wire reduction factors (LRFs) versus TSB calculated. Results Phage SaMD07FSphi1 (Figure 1) plus vancomycin showed LRFs of 2.8 (p, 0.0003) and 2.3 (p, 0.0177) log10 cfu/K-wire at 24 h for S. aureus IDRL-6121 and S. aureus IDRL-8454, respectively, whereas phage alone showed was 3.1 (p, 0.0003) and 3.0 (p, 0.0003), respectively. All treatments were ≤1.0 log10 cfu/K-wire 24 h LRFs for S. aureus IDRL-6175, S. epidermidis IDRL-5966 and S. epidermidis IDRL-6108.This phage plus vancomycin showed LRFs of 0.6 log10 cfu/K-wire at 6 h for S. epidermidis IDRL-5966 and S. aureus IDRL-6175, with bacterial regrowth at 24 h. Phage SaNSI1469phi1 (Figure 2) plus vancomycin showed 24 h LRFs of 2.0 (p, 0.02) and 3.2 (p, 0.003) log10 cfu/K-wire for S. epidermidis IDRL-6955 and S. aureus IDRL-7299, respectively, whereas phage alone was 0.2 (p, 0.17) and 0.5 (p, 0.03) log10 cfu/K-wire, respectively. All treatments showed ≤1.0 log10 cfu/K-wire 24-hour LRFs log10 cfu/K-wire for S. epidermidis IDRL-10273. This phage alone showed 6 h LRFs of 1.0 and 1.3 for S. epidermidis IDRL-6955 and S. aureus IDRL-7299, with bacterial regrowth at 24 h. Conclusion Phages SaMD07FSphi1 and SaNSI1469phi1 alone and with vancomycin showed activity against staphylococcal biofilms formed by 4 isolates. Increased activity was observed at 6 h in some cases, with bacterial regrowth at 24 h. Disclosures Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection: a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication, a patent on PET imaging of bacterial infection|MicuRx Pharmaceuticals and bioMérieux: Grant/Research Support|PhAST, Day Zero Diagnostics, DEEPULL DIAGNOSTICS, S.L., Nostics, HealthTrackRx, bioMérieux and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course: Honoraria

Abstract Purpose: Mutant IDH1 (mIDH1) defines a therapeutically targetable subtype of intrahepatic cholangiocarcinoma (ICC), with the mIDH1 inhibitor ivosidenib approved for advanced disease. A subset of patients experiences prolonged disease stabilization; however, the molecular basis for eventual progression remains poorly defined. Experimental Design: We performed molecular profiling of matched baseline and postprogression circulating tumor DNA (ctDNA) samples from patients with mIDH1 ICC enrolled in the ClarIDHy phase III trial. Functional studies were conducted to characterize candidate resistance mechanisms. Results: Longitudinal ctDNA analysis of 18 patients treated with ivosidenib for >6 months revealed emergent genomic alterations in multiple cases. Acquired mutations in mitogen-activated protein kinase (MAPK) pathway genes (KRAS, NRAS, MAP2K1, NF1) were identified in five cases, with instances of concurrent alterations and/or high variant allele fractions (VAF). Additional candidate resistance events included a secondary IDH1 mutation and a hotspot IDH2 mutation, detected at low VAF in the same patient. Functional studies showed that these IDH mutations conferred sustained 2-hydroxyglutarate production and ivosidenib resistance, whereas MAPK activation blunted gene expression induced by ivosidenib plus IFNγ, a key therapeutic output of mIDH1 inhibition. In parallel, baseline ctDNA profiling of 81 patients revealed that ARID1A mutations and elevated mIDH1 VAF were associated with reduced clinical benefit. Conclusions: MAPK pathway alterations represent a recurrent mechanism of resistance to mIDH1 inhibition in ICC, whereas emergent IDH1/IDH2 mutations appear infrequent. Functional data suggest that MAPK-mediated resistance may involve impaired IFN signaling. These results support MAPK-directed combination strategies and highlight the utility of ctDNA profiling to identify predictive and resistance biomarkers in mIDH1-driven ICC.

Abstract Background Frontotemporal dementia (FTD) is a neurodegenerative disorder marked by early impairments in executive function and altered prefrontal neural circuitry. These traits are also observed in Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD), suggesting the possibility of shared mechanisms and a role for developmental neurocognitive factors in the onset of FTD. High‐penetrance mutations in GRN, C9orf72, and MAPT increase FTD risk and are suspected to influence neurodevelopment. This study hypothesizes that pre‐symptomatic carriers of these mutations exhibit cognitive and behavioral traits that overlap with those observed in ADD/ADHD. Method This cross‐sectional study analyzed participants from the ARTFL‐LEFFTDS Longitudinal FTLD (ALLFTD) Study. Inclusion criteria restricted the sample to mutation carriers with pathogenic variants in GRN, C9orf72, or MAPT while excluding individuals with prior psychiatric diagnoses (e.g., bipolar disorder, major depressive disorder) and those taking antipsychotic or anxiolytic medications to avoid potential confounding effects on test validity and interpretation. The final sample included N = 338 participants, categorized as pre‐symptomatic mutation carriers ( N = 227) or asymptomatic noncarriers ( N = 111). To assess potential overlaps with ADD/ADHD traits, a targeted subset of measures reflecting executive function, working memory, attention, social behavior, and hyperactivity were extracted from validated cognitive and neuropsychiatric assessments. Mutation carriers were further classified as either converters ( N = 20) who progressed to symptomatic FTD (CDR ≥ 1) or non‐converters ( N = 95) who remained asymptomatic. Only pre‐conversion scores were analyzed for converters. Group comparisons were conducted using general linear models adjusted for age and sex. Result Pre‐symptomatic mutation carriers showed significantly lower verbal fluency ( p = 0.004) and a trend toward reduced working memory ( p = 0.05) compared to noncarriers. Converters exhibited poorer overall cognitive performance ( p <0.0001), verbal fluency ( p = 0.001), and memory and attention ( p = 0.04) compared to non‐converters. Converters demonstrated higher Neuropsychiatric Inventory scores ( p = 0.0001), particularly in hyperactivity ( p = 0.003), reflecting greater behavioral disturbances. Conclusion Baseline impairments in cognitive function, memory, and neuropsychiatric profiles distinguish converters from non‐converters, highlighting overlaps between ADD/ADHD traits and prodromal FTD. These findings suggest shared neurobiological mechanisms and underscore the need for mutation‐specific studies to further explore the neurodevelopmental factors driving FTD progression.

Abstract Background Agitation is a clinically significant symptom contributing to behavioral and psychological symptoms of dementia (BPSD) but is poorly understood across the different syndromes related to Frontotemporal Lobar Degeneration (FTLD). This study investigates sex differences in agitation across FTLD‐related syndromes and its relationship to various neuropsychiatric symptoms (NPS). Method We analyzed data from 1,654 participants (916 males, 738 females; average ages 65.8 and 65.9, respectively) from the National Alzheimer's Coordinating Center (NACC) and ARTFL‐LEFFTDS Longitudinal Frontotemporal Lobar Degeneration (ALLFTD) study with a FTLD‐related syndrome: behavioral variant FTD (bvFTD), Primary Progressive Aphasia (non‐fluent variant (nfvPPA), semantic variant (svPPA)), Corticobasal syndrome (CBS) and Progressive Supranuclear Palsy (PSP). Participants’ symptoms were assessed using the Neuropsychiatric Inventory (NPI). Prevalence ratios and odds ratios were computed to assess the likelihood of NPS comorbidities when agitation was present in males and females. Principal Component Analysis (PCA) was performed to identify NPS associated with agitation and how they varied by sex. Result Males were more likely to experience anxiety (bvFTD: p <0.001, CBS: p <0.01, PSP: p <0.0001), apathy (nfvPPA: p <0.01, PSP: p <0.01), depression (bvFTD: p <0.0001, PSP<0.01), disinhibition (nfvPPA: p <0.0001), PSP: p <0.001), and motor symptoms (bvFTD: p <0.01, CBS: p <0.01) when agitation was present. In contrast, females had a higher likelihood of experiencing disinhibition in svPPA ( p <0.001). These findings suggest that agitation is associated with a wider range of NPS in males than in females. Agitation and NPS are especially prominent in males with PSP. Conclusion This study reveals significant sex differences in NPS in FTLD‐related syndromes when agitation is present. Males and especially PSP, are more likely to experience a broader range of NPS in association with agitation. These findings underscore the need for further investigation into the underlying mechanisms driving these sex differences, particularly focusing on the neurobiological impact of agitation, the recognition of symptoms in the presence of greater behavioral disturbances, and potential variations from informant reports. Understanding these factors will provide valuable insights into the role of agitation in the presentation of NPS across FTLD‐related syndromes. Ultimately, addressing these gaps will enhance our ability to effectively treat and manage agitation in both male and female patients with FTLD‐related syndromes.

Abstract Background Staging disease severity in dementia research requires input from an informant. The Clinical Dementia Rating Sum of Boxes (CDR) is the most used instrument for staging in Alzheimer's Disease (AD); but has been expanded to stage patients with frontotemporal lobar degeneration (FTLD) with the CDR PLUS NACC‐FTLD. An informant effect on the CDR has been reported in AD. The aim of this study is to evaluate whether informant characteristics influence the CDR PLUS NACC‐FTLD in a large cohort of participants with frontotemporal dementia (FTD). Method We included participants with a FTLD‐related syndrome from the ALLFTD study. We included participants with a CDR PLUS NACC‐FTLD higher than 0, information on the Montreal Cognitive Assessment (MoCA) scores, and the Neuropsychiatric Inventory Questionnaire (NPI‐Q). We performed a conditional growth model using multilevel linear regression analysis. We performed an exploratory stratified analysis by patient sex. Result We included 1411 participants, totalling 2063 visits. The patient's age at the initial visit was 64.7±9.4 years and 44.0% were females. Females were 69.2% of the informants, and the relationship was 79.1% spouse or partner, 10.6% children, 4.1% were siblings and 6.2% other. The CDR PLUS NACC‐FTLD scores were affected by informant characteristics. The CDR PLUS NACC‐FTLD scores were 0.41 (CI 95%:0.08 to 0.75) higher with female informants. The frequency of visits was associated with a CDR PLUS NACC‐FTLD score 0.86 higher (CI 95%:0.17 to 0.56) when visiting at least once a week, 1.46 higher (CI 95%:0.46 to 2.47) when visiting daily, and 0.83 higher (CI 95%:0.06 to 1.60) when living with the patient compared with visiting less than once a week. As expected, CDR‐FLTD scores increased with lower MoCA and higher NPI‐Q scores. In the stratified analysis by sex, we found that female informant was associated with higher CDR PLUS NACC‐FTLD scores only when patients were male. Conclusion We found that the CDR PLUS NACC‐FTLD is influenced by informant sex and frequency of visits in patients with FTLD‐related syndromes. These results are similar to those observed in AD patients and underscore the need to recognize that informant characteristics may impact dementia severity scales.