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Background Costosternal cartilages and the costal margin, collectively termed costal cartilage, are hyaline cartilage connecting ribs to the sternum and to adjacent ribs, respectively. Presence of intact costal cartilage is essential for elasticity of the chest wall. Anecdotally, costal cartilage injuries are underdiagnosed on trauma CT scan in patients with rib fractures. Our aim was to determine a baseline frequency of acute costal cartilage injury among patients presenting with rib fractures. Methods We performed a retrospective cohort study of injured adult patients admitted to Level I/II trauma centers with rib fractures from January 2020 to July 2024. CT images obtained at admission were manually reviewed by chest wall surgeons for presence of costal cartilage injury. Concordance with the original radiology report was obtained. Multivariable regression was used to analyze factors associated with costal cartilage injury and missed cartilage fractures. Results 1441 patients were identified; 197 (14%) had a costal cartilage fracture. A plurality of injuries included falls (n=667, 46%). Median ISS (Injury Severity Score) was 13 (IQR: 9 to 21), median Abbreviated Injury Scale thorax score was 3 (IQR: 3 to 3), and median number of fractured ribs was 3 (IQR: 3 to 7). 294 (21%) patients had radiographic flail segments, and 136 (9%) had sternal fractures. 172 (87%) patients had a costal cartilage fracture missed on initial trauma chest CT. On multivariable analysis, ISS (adjusted OR (aOR) 1.02 (95% CI 1.01 to 1.04), radiographic flail segment (aOR 1.6 (95% CI 1.10 to 2.31)) and presence of sternal fracture (aOR 1.85 (95% CI 1.19 to 2.89)) were associated with costal cartilage fractures. Only the total number of rib fractures was associated with a missed costal cartilage fracture on univariate analysis (OR 1.17 (95% CI 1.01 to 1.36)). Conclusions Costal cartilage injuries are common and frequently are not identified during interpretation of the initial trauma CT. A higher index of suspicion is warranted for costal cartilage fractures among patients with greater injury burden, radiographic flail segment, and sternal fractures. Level of evidence Level III.

The prevalence of carbapenem-resistant Klebsiella pneumoniae (CR Kp ) infections in nosocomial settings remains a public health challenge. High-risk clones such as clonal group 258 (CG258) are particularly concerning due to their association with bla KPC carriage, which can severely complicate antimicrobial treatments.

Abstract Background Carbapenem-resistant Enterobacterales (CRE) and specifically Klebsiella pneumoniae (CRKp) are a global threat. CRE rapidly spreading in a healthcare network may infect a distinct patient cohort or have higher virulence. We determined the impact of cluster assignment of CRKp on transmission dynamics and clinical outcomes. Methods CRACKLE-2 is a multi-site, prospective, observational cohort study of hospitalized patients with a clinical CRE culture from any anatomic site. We analyzed 351 patients enrolled 4/30/2016–8/31/2017 in 42 US hospitals with clonal group 258 CRKp. Static clusters were set as ≤ 21 core single nucleotide polymorphisms (SNPs), identified by Snippy, and sharing a recent common ancestor, using a maximum likelihood phylogeny (RAxML v8.2.4). Dynamic clusters were set as > 80% probability of being within 3 transmissions by the R program transcluster (λ = 4, β = 1.6). Clinical outcome was assessed by desirability of outcome ranking with best outcome as alive without events and worst outcome as death. Events were no clinical response, unsuccessful discharge, and adverse events. We compared patients in and out of clusters. For patients in clusters, we also compared intra- vs inter-hospital clusters. Results In total, there were 49 static (median: 5, IQR: 2, 8) and 45 dynamic clusters (median: 5, IQR: 2, 20). For static clusters, 176 patients (50%) were in clusters with 82 (47%) patients in intra-hospital clusters. A higher proportion of patients in clusters, vs not in clusters, had a CRKp culture > 3 days from admission (P = 0.037). More patients in inter-hospital, vs intra-hospital, clusters had diabetes (P = 0.02). For dynamic clusters, 179 patients (51%) were in clusters with 69 (39%) patients in intra-hospital clusters. A lower proportion of patients in clusters, vs not in clusters, had CRKp isolated from urine (P = 0.04). More patients in inter-hospital, vs intra-hospital, clusters had a CRKp culture 3 days from admission (P = 0.04). Clinical outcomes were the same for patients in clusters vs not in clusters for static and dynamic clusters. Conclusion This analysis shows that clinical outcomes are independent of clustering assignment. Static clustering better represented nosocomial spread, based on a higher proportion of patients in clusters having a later CRKp culture. Disclosures Gregory Weston, MD MSCR, Allergan (Grant/Research Support) W. Charles Huskins, MD, MSc, ADMA Biologics (Consultant)Pfizer, Inc (Consultant) Jason C. Gallagher, PharmD, Allergan (Consultant)Astellas (Consultant)Merck (Consultant)Nabriva (Consultant)Qpex (Consultant)scPharmaceuticals (Consultant)Shionogi (Consultant)Spero (Consultant)Tetraphase (Consultant) Robert A. Bonomo, MD, Entasis, Merck, Venatorx (Research Grant or Support) Cesar A. Arias, MD, MSc, PhD, FIDSA, Entasis Therapeutics (Scientific Research Study Investigator)MeMed (Scientific Research Study Investigator)Merck (Grant/Research Support) David van Duin, MD, PhD, Achaogen (Advisor or Review Panel member)Allergan (Advisor or Review Panel member)Astellas (Advisor or Review Panel member)MedImmune (Advisor or Review Panel member)Merck (Advisor or Review Panel member)NeuMedicine (Advisor or Review Panel member)Qpex (Advisor or Review Panel member)Roche (Advisor or Review Panel member)Sanofi-Pasteur (Advisor or Review Panel member)Shionogi (Advisor or Review Panel member)T2 Biosystems (Advisor or Review Panel member)Tetraphase (Advisor or Review Panel member)

Abstract Background Rapid blood culture diagnostics are of unclear benefit for patients with gram-negative bacilli (GNB) bloodstream infections (BSIs). We conducted a multicenter, randomized, controlled trial comparing outcomes of patients with GNB BSIs who had blood culture testing with standard-of-care (SOC) culture and antimicrobial susceptibility testing (AST) vs rapid organism identification (ID) and phenotypic AST using the Accelerate Pheno System (RAPID). Methods Patients with positive blood cultures with Gram stains showing GNB were randomized to SOC testing with antimicrobial stewardship (AS) review or RAPID with AS. The primary outcome was time to first antibiotic modification within 72 hours of randomization. Results Of 500 randomized patients, 448 were included (226 SOC, 222 RAPID). Mean (standard deviation) time to results was faster for RAPID than SOC for organism ID (2.7 [1.2] vs 11.7 [10.5] hours; P < .001) and AST (13.5 [56] vs 44.9 [12.1] hours; P < .001). Median (interquartile range [IQR]) time to first antibiotic modification was faster in the RAPID arm vs the SOC arm for overall antibiotics (8.6 [2.6–27.6] vs 14.9 [3.3–41.1] hours; P = .02) and gram-negative antibiotics (17.3 [4.9–72] vs 42.1 [10.1–72] hours; P < .001). Median (IQR) time to antibiotic escalation was faster in the RAPID arm vs the SOC arm for antimicrobial-resistant BSIs (18.4 [5.8–72] vs 61.7 [30.4–72] hours; P = .01). There were no differences between the arms in patient outcomes. Conclusions Rapid organism ID and phenotypic AST led to faster changes in antibiotic therapy for gram-negative BSIs. Clinical Trials Registration NCT03218397.

Abstract Background Rapid blood culture diagnostics increase cost and have unclear benefit for patients with Gram-negative bacilli (GNB) bloodstream infections (BSIs). We conducted a multicenter, prospective randomized controlled trial (RAPIDS-GN), comparing outcomes of patients with GNB BSI who had blood culture testing with standard of care (SOC) culture and antibiotic susceptibility testing (AST) vs. rapid organism identification (ID) and phenotypic AST using the Accelerate Pheno System (AXDX). Methods Subjects with blood culture Gram stain showing GNB were randomized to receive SOC testing with antimicrobial stewardship review (AS) or AXDX plus SOC testing with AS, at two academic medical centers between October 2017 and October 2018. SOC testing included rapid MALDI-TOF mass spectrometry ID and agar dilution or broth microdilution AST. In a modified intention to treat analysis, subjects were excluded if: Gram stain was erroneous, culture was positive during off-hours, blood culture in the prior week had GNB, they were deceased/on comfort care, or admitted to a nonparticipating hospital. The primary outcome was time to first antibiotic modification within 72 hours after randomization. Subjects without antibiotic modifications were assigned a time of 72 hours. No censoring was observed. T-tests and Wilcoxon rank-sum tests were used for statistical analyses. Results Of 500 randomized subjects, 448 were included (226 SOC, 222 AXDX). Groups did not differ in baseline characteristics (Table 1). Median (IQR) hours to first antibiotic modification was faster in the AXDX vs. SOC group [8.6 (2.6, 27.6) vs. 14.9 (3.3, 41.1)], P = 0.02 (Figure 1). Median (IQR) hours to first Gram-negative antibiotic modification (including escalation and de-escalation) was faster in the AXDX than SOC group [17.4 (4.9, 72) vs. 42.1 (10.1, 72)], P < 0.001 (Figure 2). Groups did not differ in clinical outcomes (Table 2). Mean (S.D.) time to results was faster for AXDX than SOC for organism ID [2.7 (1.2) h vs. 15.6 (20.3) h, P < 0.001] and AST [13 (55.7) h vs. 54.6 (45.5) h, P < 0.001]. Conclusion In the largest trial to evaluate the clinical impact of a blood culture diagnostic for GNB BSI, we found that rapid organism ID and phenotypic AST led to faster changes in antibiotic therapy for Gram-negative bacteremia. Disclosures Ritu Banerjee, MD, PhD, Accelerate Diagnostics: Grant/Research Support; BioFire: Research Grant; Biomerieux: Research Grant; Roche: Research Grant Robin Patel, MD, ASM and IDSA: Other Financial or Material Support, Travel reimbursement, editor’s stipends; CD Diagnostics, Merck, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics, ContraFect, TenNor Therapeutics Limited, Shionogi: Grant/Research Support; Curetis, Specific Technologies, NextGen Diagnostics, PathoQuest, Qvella: Consultant; NBME, Up-to-Date, the Infectious Diseases Board Review Course: Honorarium recipient, Other Financial or Material Support; Patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, and a patent on an anti-biofilm substance issued: Other Financial or Material Support, Patents.