247. The Predictive Value of Methicillin-Resistant Staphylococcus aureus Surveillance Swabs in Septic Arthritis

Abstract 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 sensitivity, specificity, positive predictive value and negative predictive value for MRSA surveillance swabs. Results One hundred seventy-two patients met inclusion criteria. Thirty patients had positive MRSA surveillance swabs. The prevalence of MRSA in joint cultures was 11.04%. The positive predictive value of MRSA surveillance swabs was 42.3% and the negative predictive value was 93.5% in all participants. The MRSA surveillance swab had a negative predictive value of 100% in participants with no risk factors for MRSA colonization. Conclusion The negative predictive value of MRSA surveillance swabs used independently is insufficient to confidently rule out MRSA as the causative pathogen in septic arthritis. When used in combination with MRSA risk factors, the absence of MRSA risk factors may help clinicians rule out MRSA as a causative pathogen. Disclosures All Authors: No reported disclosures

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.
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. All Authors: No reported disclosures S232 • OFID 2021:8 (Suppl 1) • Abstracts sensitivity, specificity, positive predictive value and negative predictive value for MRSA surveillance swabs. Results. One hundred seventy-two patients met inclusion criteria. Thirty patients had positive MRSA surveillance swabs. The prevalence of MRSA in joint cultures was 11.04%. The positive predictive value of MRSA surveillance swabs was 42.3% and the negative predictive value was 93.5% in all participants. The MRSA surveillance swab had a negative predictive value of 100% in participants with no risk factors for MRSA colonization.
Conclusion. The negative predictive value of MRSA surveillance swabs used independently is insufficient to confidently rule out MRSA as the causative pathogen in septic arthritis. When used in combination with MRSA risk factors, the absence of MRSA risk factors may help clinicians rule out MRSA as a causative pathogen.
Disclosures. Background. IDSA has published guidelines for the diagnosis and management of prosthetic joint infection (PJI). However, we have observed significant variability in the interpretation and application of these guidelines with respect to the management of those with PJI following debridement and implant retention (DAIR). It is not clear if variations in antimicrobial management are affecting clinical outcomes.
Methods. We performed a retrospective review at an academic hospital in rural New Hampshire. We included all adult patients from 1/1/2017 to 12/31/2018 with PJI of hip or knee who underwent DAIR. The demographic data, microbiology data, antibiotics treatment and duration were collected. The primary endpoint was overall re-infection rate within 2 years of surgery. Secondary endpoint was re-infection rate stratified by organism and antimicrobial type and duration.
Results. A total of 26 patients were included in our study. 65% involved knee joint. 50% had late-onset infection ( >12 months). The top organisms were Streptococcus spp. (34%), CoNS (26 %) and MSSA (18 %). 15% were associated with bacteremia. Ceftriaxone was the most common antibiotic used (54 %). 38 % of patients received Rifampin PO along with IV antibiotics. All patients received PO antibiotic(s) after completing the course of IV therapy, and 7 patients were also on concomitant rifampin PO. The duration of PO antibiotic therapy was varied. 30% of patients received PO antibiotics for 6 months post IV treatment. Life-long suppression therapy were noted in 9 patients. Treatment failure within 2 years occurred in 8 patients (31%). Among those, 75% had Staphylococcal infection. All patients required hardware removal except one patient who required amputation. 2 patients developed recurrent PJI after completing 6 months and one year of PO suppression therapy, one patient had a recurrent infection while on life-long suppression. Staphylococcal infection was significantly associated with treatment failure.
Conclusion. Treatment of PJI with DAIR is challenging. Despite long-term IV therapy followed by oral antibiotics, there was a high rate of treatment failure (31% in our study) particularly with Staphylococcal infection. There was no association of variation of treatments and outcomes in our small cohort.

Session: P-12. Bone and Joint
Background. Herein we aimed to evaluate osteomyelitis cases in our setting. Methods. We evaluated the hospital records of patients with osteomyelitis between January 2013 and December 2020 retrospectively. Osteomyelitis was confirmed by direct radiography or magnetic resonance imaging or pathology. Demographic features, risk factors, clinical/laboratory findings, treatment response and mortality rates were evaluated. Clinical response was defined as (resolution of clinical signs including fever and purulent discharge and other symptoms) and/or negative culture at the end of antimicrobial therapy.
Results. Patients were 33 female, aged 29-85 years (mean 59±12.6). Fourty nine of the patients were diabetic foot infection, 30 were spondylodiscitis, eight were primary, seven were post-traumatic, and five were post-surgical osteomyelitis. Overall 62 patients had diabetes mellitus and 16 patients had chronic renal failure. Peripheral arterial disease, neuropathy, diabetic retinopathy and venous insufficiency rate in the DM subgroup is shown in table. Fever was present in 24.2% of the cohort. İncreasing of CRP was in 95,9%, erythrocyte sedimentation rate in 83,9%, and leukocytosis in 37.3%. The radiological findings of osteomyelitis were detected via magnetic resonance imaging in 73 patients. Etiology in biopsy cultures were elucidated in 59.5% and the most common pathogen was S. aureus (30%) Table1. The most common empirical treatment regimens were tigecycline in 27 patients, ampicillin/sulbactam in 19 patients and ceftriaxone+teicoplanin in 12 cases. Duration of treatment was 36,2±17.3 days (range 6-104 days). Overall, clinical response was obtained in 91.9%. Fifty patients were performed surgical procedure + antibacterial treatment, clinical response was 96% (p:0.091). Surgical debridement could be performed in 22 patients, clinical response was obtained in all (p:0.193). Thirteen patients developed recurrence within one year. Sixty-seven patients received oral consecutive treatment after discharge. In hospital mortality rate was 2/99 (2,02%).

Conclusion.
Despite surgical debridement and/or developed antimicrobial treatment, approximately 1/5 of osteomyelitis cases required further treatment Further interventions seem to be needed to reach better outcomes.
Disclosures. Background. Approximately 10% of the population is labeled as penicillin (PCN) allergic, while only 1% of these individuals have a true IgE mediated allergy. This label influences the prescription of the most appropriate antibiotic and ultimately leads to antimicrobial resistance, hospital readmission, increased length of hospital stays, use of critical care beds, and greater healthcare costs. Post-surgical complications in patients undergoing total knee arthroplasty (TKA) or total hip arthroplasty (THA) are also increased when patients receive an alternative antibiotic due to PCN allergy.
Methods. A retrospective chart review identified patients who underwent a TKA or THA during the 2018-2020 calendar years at the Washington DC VA Medical Center. Multiple operations at different times on the same patient were regarded as separate events. The primary outcome was patients who were evaluable for penicillin allergy de-labeling and the secondary outcome was perioperative antibiotic choice.
Results. Patients in both groups were predominantly male, Black, and over the age of 60. Of a total of 317 procedures performed, we identified 28 procedures in which patients carried a PCN allergy label (PAL) and received a β-lactam alternative antibiotic for surgical prophylaxis. No patients in the PAL group received cefazolin for prophylaxis, compared to 87% of the non-PAL group who were appropriately given cefazolin. In the group carrying the PAL, 62% of patients received vancomycin and 29% of patients received clindamycin for pre-operative prophylaxis. Only one of these patients had a formal allergy consult note, but the PCN allergy was not addressed during that visit. Fewer patients (4%) required ICU admission during their hospitalization in the non-PAL group versus 10% of patients in the PAL group.