243. Analysis of Risk Factors Associated with Adverse Outcomes Following Calcium Sulfate Bead Use in Periprosthetic Joint Infections

Abstract Background Calcium sulfate (CS) beads are increasingly utilized in orthopedic surgeries as a delivery vehicle to administer local antimicrobials intraoperatively. Hypercalcemia, AKI, and elevated serum antimicrobial levels have been reported as potential complications, especially with higher bead volumes. We analyzed the risk factors associated with adverse outcomes among patients with PJIs who received intraoperative CS beads loaded with tobramycin and vancomycin. Methods We conducted a retrospective review of adult patients with PJIs who received CS beads from October 2019 to October 2020. Primary outcomes included the incidence of AKI (defined using RIFLE criteria) and hypercalcemia (≥ 11 mg/dL). Logistic regression with forward entry selection of independent variables based on a liberal probability significance of α < 0.25 was used to model the relationships between our variables. Independent variables with clinical relevance that did not meet the conditional selection were also included in the model. Results A total of 171 adult patients were included for the analysis. Postoperative AKI occurred in 42 patients (24.6%) who received a mean bead volume of 32 cc. Hypercalcemia occurred in 16 patients (9.4%) who had a mean bead volume of 40 cc. In a univariate analysis, the odds of having AKI and hypercalcemia increased significantly per 10 cc of bead volume with ORs of 1.39 (95%CI, 1.06, 1.82) and 1.65 (95%CI, 1.20, 2.29), respectively. In a multivariate analysis, significant predictors of AKI included: increased bead volume (aOR 1.52; 95%CI, 1.10-2.10), female sex (aOR 2.77; 95%CI, 1.00-7.71), CHF (aOR 3.48; 95%CI, 1.08-11.28), and CAD (aOR 3.90; 95%CI, 1.25-12.18). In the adjusted model, serum tobramycin levels increased (OR 2.67; 95%CI, 1.83-3.90), calcium levels increased with a mean of 0.2 mg/dL (95%CI, 0.12, 0.28), and GFR decreased with a mean of 5.6% (95%CI, 2.8, 8.7) per 10 cc bead volume. In a subset analysis, individuals more likely to experience AKI were patients aged 65 and older (OR 1.9; P=0.039) and had CAD (OR 15.26; P=0.028). Conclusion Higher volume of CS beads loaded with vancomycin and tobramycin is associated with adverse outcomes. Older patients with heart disease may be at higher risk for adverse outcomes. Disclosures All Authors: No reported disclosures


Rising Incidence of Finegoldia magna among Prosthetic Joint Infections
Background. Finegoldia magna is an anaerobic, Gram-positive coccus infrequently associated with osteoarticular infections. Since the adoption of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF), F. magna has been increasingly reported as a cause of osteoarticular infections. Our objective was to determine the incidence of F. magna prosthetic joint infections (PJIs) within our institution.
Methods. We conducted a retrospective longitudinal survey from 1 January 2016 -31 December 2020 at an academic tertiary care referral center. We constructed two Poisson count models to assess the incidence of Finegoldia magna PJIs: one consisting of a clinical microbiology database of synovial fluid and surgical tissue cultures and one using a PJI registry. Time served as the covariate of interest. We used number of cultures as an offset term in the clinical microbiology model, and number of PJI cases as the offset term in the prosthetic joint registry model -reflecting the relevant denominator for each dataset. The microbiology database was limited to synovial fluid aspirates and surgical tissue cultures to minimize risk of confounding by contaminants.

Figure 1
Incidence of Finegoldia magna Over Time Conclusion. Adoption of MALDI-TOF has expanded the clinical microbiology laboratory's capacity for rapid speciation, sometimes revealing previously unseen epidemiologic trends. While we saw no significant change in overall incidence of F. magna among synovial and surgical tissue cultures, we did detect a significant increase specifically among PJI cases. F. magna warrants attention as an emerging pathogen among PJI.
Disclosures. Background. Calcium sulfate (CS) beads are increasingly utilized in orthopedic surgeries as a delivery vehicle to administer local antimicrobials intraoperatively. Hypercalcemia, AKI, and elevated serum antimicrobial levels have been reported as potential complications, especially with higher bead volumes. We analyzed the risk factors associated with adverse outcomes among patients with PJIs who received intraoperative CS beads loaded with tobramycin and vancomycin.

Methods.
We conducted a retrospective review of adult patients with PJIs who received CS beads from October 2019 to October 2020. Primary outcomes included the incidence of AKI (defined using RIFLE criteria) and hypercalcemia (≥ 11 mg/dL). Logistic regression with forward entry selection of independent variables based on a liberal probability significance of α < 0.25 was used to model the relationships between our variables. Independent variables with clinical relevance that did not meet the conditional selection were also included in the model.
Conclusion. Higher volume of CS beads loaded with vancomycin and tobramycin is associated with adverse outcomes. Older patients with heart disease may be at higher risk for adverse outcomes.
Disclosures. All Authors: No reported disclosures

Risk Factors Associated with Complications/Sequelae in Pediatric Patients with Osteomyelitis
Nancy Evelyn Aguilar Gómez 1 ; Aaron Espinosa Atri, n/a 1 ; Rafael Oscar Santamaría Vásquez, n/a 1 ; Alejandra Aquino Andrade, n/a 1 ; Isabel Medina Vera, n/a 1 ; Oscar Daniel Isunza Alonso, n/a 1 ; Leonor Patricia Saltigeral Simental, n/a 1 ; 1 Instituto Nacional de Pediatría, Mexico, Distrito Federal, Mexico Session: P-12. Bone and Joint Background. Osteoarticular infections are serious invasive pathologies in the pediatric population. They have high morbidity, especially if antimicrobial treatment is inadequate and late. Based on pediatric series patients with osteomyelitis require prolonged antibiotic schemes, long stay and high hospital costs, multiple surgical procedures and develop short and long-term sequelae.
Methods. A retrospective, observational, longitudinal and analytical study was conducted in patients under 17 years of age diagnosed with osteomyelitis at the National Institute of Pediatrics from January 2009 to January 2019. Demographic information, clinical presentation, microbiological, treatment and six-month follow-up were recorded.
Conclusion. Osteomyelitis is still a health problem in our country. The diagnosis of osteomyelitis may be challenging as lack of suspicion often leads to delayed diagnosis. Knowledge of the risk factors for complications in pediatric patients could be useful to give early and proper antibiotic and surgical treatment. It is a priority to have a multidisciplinary team for the diagnosis and treatment of osteoarticular infections. Methods. This was a single center, retrospective study of adult patients with an open fracture who received antibiotic prophylaxis and were admitted for at least 24 hours between March 2011 and October 2020. Patients were excluded if open fracture was due to gun-shot wound, had a history of renal replacement therapy, MDRO, or C. difficile infection, were an outside hospital transfer, received antibiotics for another indication, or had a delayed presentation. The primary outcome was to identify risk factors for infection and secondary outcomes to identify risk factors for AKI, MDRO, C. difficile infection, and to evaluate guideline adherence. Patient demographics including injury details and management, microbiologic cultures, and antibiotic information were collected. Data were analyzed by univariate analysis, as appropriate, and logistic regression.

Risk Factors Associated with Open Fracture Complications Following Antibiotic Prophylaxis
Results. A total of 401 patients met study criteria; median age 46 years, 62% male, and 77% white. Fracture classifications were similar: 30% type I, 39% type II, and 30% type III. Infection occurred in 18% of patients, AKI in 18%, MDRO in 3%, and no patients developed C. difficile. Of those with culture-positive infection, 51% grew gram-positive organisms. In bivariate analysis, fracture classification (p=0.023), medical fracture management (p=0.034), and antibiotic choice (p=0.004) were associated with infection. The only independent risk factor associated with AKI was receiving a nephrotoxic medication (p=0.012). Eighty-one percent received guideline adherent antibiotics and of those that received too narrow antibiotics, 36% developed an infection (p=0.004).
Conclusion. Appropriate fracture classification and antibiotic choice is crucial to reduce infection following open fracture. Reducing concomitant exposure to nephrotoxic agents may reduce the risk of AKI.
Disclosures. Background. Osteoarticular tuberculosis (TB) represents 1% to 3% of all TB cases, among which spondylodiscitis is the most common presentation of the disease. Non-axial TB is less frequent. We aimed to study the clinical, therapeutic and evolutionary features of non-axial osteoarticular TB.
Methods. We conducted a retrospective study including all patients hospitalized in the infectious diseases department for non-axial osteoarticular TB between 1999 and 2019.
Conclusion. Non-axial osteoarticular TB was not a rare disease. Multiple sites might be involved which facilitate the diagnosis confirmation. Prolonged antitubercular therapy might be required.
Disclosures. Background. Septic arthritis is a destructive form of acute arthritis secondary to infection. With an annual incidence of 2 to 5 cases per 100 000 individuals, it is associated with significant morbidity and mortality. Prompt source control and antimicrobial therapy remain the mainstays of management. Epidemiology, microbiology studies, and local resistance patterns are important in guiding therapeutic decisions. Staphylococcal and streptococcal species are the most common pathogens with Methicillin-resistant Staphylococcus aureus (MRSA) becoming an increasingly important pathogen. The increasing incidence of MRSA provides clinicians with the challenge of deciding which patients require empiric coverage for MRSA. MRSA nasal screening has been shown to have a high negative predictive value in pneumonia, bloodstream infections, and nosocomial infections in critically ill patients. However, little is known about the diagnostic utility of MRSA surveillance swabs for predicting MRSA infections in septic arthritis.
Methods. A retrospective cohort study was performed in 3 tertiary hospitals from September 1, 2010 to December 31, 2020. All adult patients with confirmed septic arthritis of the ankle, wrist, knee, or hip and an MRSA surveillance swab performed within 72 hours of admission were included in the study. These data were used to calculate the