Authors:
Alexander Harper, Henry Kwon, Loay Kabbani, Milosh Djuric, Sana Soman

Body of Abstract:
Open and endovascular stent graft treatment for thoracic aortopathy has increased in the past decade. Thoracic endovascular aortic repair (TEVAR) has become a treatment modality for patients who may not have tolerated an open procedure and has increased in the past decade. A rare but devastating complication from grafts is infection of graft material.  Principals in treating this disease has been gleamed from infections of abdominal aortic aneurysm repairs or aortoiliac occlusive disease.

At a single institution tertiary referral center from January 2015 to November 2024, all patients treated for their initial event of an infection or inflammatory reaction due to vascular graft or implants were evaluated. Devices or grafts that were not endovascular stent grafts or grafts used for open repair of thoracic or abdominal aorta were excluded. The sample size and incidence of disease precluded any meaningful statistical comparisons.

In total, 41 patients were treated for an infection of an aortic graft: 2 for grafts in the ascending aorta and arch, one for a TEVAR graft, 1 for thoracoabdominal grafts, 16 patients for abdominal aortic grafts, and 15 with aortoiliac grafts.  The incidence of graft infection is low but those who did  have a graft infection, the mortality rate for grafts placed in the arch, TEVAR, and thoracoabdominal grafts were 100%. Grafts placed distal to the diaphragm mortality rates were 25% for abdominal aortic grafts and 6.7% for aortoiliac graft infections.

Infections of thoracic grafts were from gram positive species including staphylococcus aureus, methicillin resistant staphylococcus aureus (MRSA), and streptococcus pneumoniae. Inciting incidents included dental procedures, septic arthritis, and a fistula between the bronchus and aorta. Two patients underwent replacement of the grafts while two had no viable surgical options for replacing the infected graft. Mortalities associated with abdominal aortic graft infections had cultures that were positive for staphylococcus aureus, candida, enteric micro-organisms, and one expired prior to cultures were obtained. Those who survived underwent surgery for replacement of their graft with cultures often consistent with enteric organisms.  Aortoiliac grafts infections had a wide variety of organisms. Those who survived were often sent home on a 6-week course of antibiotics and required transfer to a subacute skilled nursing facility.

Although rare, infections of graft material of the thoracic aorta carry significant mortality with little opportunity for operative intervention in comparison to those with abdominal aortic graft infections and distal graft infections. Medical and surgical management is limited, and significant care should be taken in prevention of infections of these grafts.

Authors:
Anahita Jalilvand, Bradley Butsch, Courtney Collins, George Abboud, Jonathan Wisler, Patrick Quinn, Shachi Srivatsa

Body of Abstract:
Background: Management of necrotizing soft tissue infections (NSTI) consists of emergent surgical debridement and broad-spectrum antibiotic treatment. Methicillin-resistant staphylococcus aureus (MRSA) is one of the few resistant organisms frequently covered empirically. In this study, we aim to better assess the prevalence, outcomes, and predictors associated with MRSA-positive NSTIs.

Methods: A retrospective analysis of institutional data for patients diagnosed with NSTIs was identified (n = 634; 2011-2023). Outcomes of interest included mortality, length of stay, intensive care requirements, acute kidney injury (AKI), discharge destination, and 30-day readmission. Outcomes were examined based on whether the patient’s wound culture grew MRSA or not. Characteristics collected for each patient included demographics, comorbidities, micro-organisms, and index hospitalization data. Significant predictors of MRSA infection were identified using logistic regression.

Results: Of 634 patients, 77 (12.3%) grew MRSA-positive wound cultures, and 557 (89.2%) did not. The MRSA-positive cohort had higher incidences of liver disease (19.5% vs. 7.5%, p=0.001) and intravenous drug use (24.7% vs. 8.6%, p<0.001). Bacteremia was more prevalent in the MRSA-positive cohort (29.9% vs 15.6%, p = 0.003). MRSA-positive infections were more likely in upper limbs (19.7%), lower limbs (16.3%), and head/neck NSTIs (15.8%) and least likely in groin NSTIs (5.2%, p < 0.001). Groin infection was an independent negative predictor of having MRSA-positive cultures (odds ratio 0.35, 95% CI 0.17-0.71, p = 0.004). There was no difference between cohorts in in-hospital mortality, 90-day mortality, length of stay, amputation, debridement number, acute kidney injury, or discharge disposition. There was a higher rate of 30-day hospital readmission (32.5% vs 21.4%, p = 0.042) in the MRSA-positive cohort. Conclusion: Patients with MRSA-positive wound cultures were more likely to have bacteremia and had higher rates of 30-day readmission. Groin NSTIs were significantly less likely to grow MRSA than other NSTI locations.

Authors:
Amy McDonald, Chris Guidry, Jonathan Wisler, Joseph Cuschieri, Justin Dvorak, Laura Kreiner, Nimitt Patel, Rondi Gelbard, Todd Costantini

Body of Abstract:
Background: Blood transfusion is a cornerstone of trauma resuscitation. While early transfusion is associated with improved survival, blood transfusion is also associated with increased risk of infection, likely due to immunomodulatory mediators in blood products. Whole blood use is becoming increasingly common in trauma resuscitation, with a growing body of literature showing improved survival in patients that receive whole blood. However, less is known about the impact of whole blood on other outcomes, including infection. The aim of this study is to evaluate the association between whole blood and infection in trauma patients undergoing hemorrhage control laparotomy.

Methods: The American College of Surgeons Trauma Quality Improvement (TQIP) registry was queried for adult trauma patients between the years 2020 – 2022. Patients were included if they underwent early laparotomy for hemorrhage control, were undergoing resuscitation with PRBCs, and survived at least 30 days, or were discharged alive. Patient demographics, arrival vital signs, Injury Severity Score (ISS), units of packed red blood cells (PRBC), Fresh Frozen Plasma (FFP), Platelets (Plt), and Whole Blood (WB) transfused, length of stay, and surgical site infection (SSI) were collected. Primary outcome was the association between receipt of WB with SSI (defined in TQIP as a Deep SSI, Organ/Space SSI, or superficial SSI). For the primary outcome, receipt of WB was a binary variable (received or did not receive). Secondary outcome was the association between the total number of units of WB received and SSI. Subgroup analysis of patients who underwent a Massive Transfusion (MT) was also performed. Logistic regression was used to evaluate the association between WB and infection, with multivariate regression used to control for potential confounders, including age, race, ISS, shock index, and transfusion requirement.

Results: 19,144 patients were included in the study. Patients who received WB in the first 4 hours of arrival had higher odds for SSI on multivariate analysis compared to patients who did not (OR 1.27, 95% CI 1.11 – 1.46, p < 0.01). Increase risk of infection with WB was also seen in a dose dependent manner, with each additional unit of WB conferring a 6% increase in odds of infection (OR 1.06, 95% CI 1.03 – 1.09, p < 0.01). On subgroup analysis of patients who underwent MT, the association between receiving WB with and infection persisted on multivariate analysis (OR 1.31, 95% CI 1.11 – 1.55, p < 0.01) (Table). This was also seen in a dose-dependent manner for patients undergoing MT (OR 1.07, 95% CI 1.02 – 1.12, p < 0.01). Conclusions: Trauma patients undergoing hemorrhage control laparotomy who receive WB had increased odds of SSI compared to patients who did not. This was also seen in a dose-dependent manner, with increased SSI odds with each unit of WB. As WB use becomes more common, further research is needed to evaluate outcomes beyond survival.

Authors:
Anna Willingham, Jason McKee, Lena Perger, Noah Lucero, Rachel Sidebottom

Body of Abstract:
Authors: A.Willingham1, N. Lucero1, R. Sidebottom1, L.Perger2, J. McKee2
1University of New Mexico, School of Medicine, Albuquerque, NM, USA
2University of New Mexico, Department Of Surgery, Albuquerque, NM, USA

Background: Pediatric patients with suspected appendicitis often undergo abdominal ultrasound as the initial diagnostic modality. However, in pediatric surgery centers without access to high-quality, dedicated ultra-sonographers, the appendix is frequently not visualized, leading to non-diagnostic results. This poses a clinical challenge for pediatric surgery and emergency department providers in determining who should undergo additional diagnostic imaging, such as abdominal MRI. To address this issue, we evaluated 5 years of pediatric patients at the University of New Mexico Hospital who underwent abdominal MRI following non-diagnostic ultrasounds to identify predictive factors of MRI-confirmed appendicitis.

Methods: A total of 411 pediatric patients who underwent abdominal MRI following non-diagnostic abdominal ultrasounds were identified. A comprehensive chart review of each patient was performed to collect data on patient age, year evaluated, maximum temperature reported, symptom duration, white blood cell count (WBC), and C-reactive protein (CRP) levels. Radiologic findings, including specification descriptions from ultrasound, CT, and MRI studies, were also recorded. Data analysis involved calculating relative risk ratios, sensitivity, and specificity for each variable to determine its contribution to predicting a positive MRI result.

Results: Of the 411 patients included in the study, 9 (2.1%) had positive MRI findings consistent with appendicitis. All patients with appendicitis met at least one diagnostic criterion, such as elevated WBC or CRP. Among these patients, 8 out of 9 had elevated WBC counts (>11.0) and elevated CRP levels (>0.5), while 4 out of 9 had a temperature >38°C. The sensitivity and specificity for WBC were 0.89 and 0.63, respectively, while CRP had a sensitivity of 0.89 and specificity of 0.51. In contrast, temperature >38°C demonstrated a lower sensitivity of 0.44 but a higher specificity of 0.81. These findings highlight the diagnostic value of combining clinical and laboratory parameters to identify appendicitis.

Conclusion: Abdominal MRI following a non-diagnostic abdominal ultrasound for appendicitis demonstrated a high true negative rate, with elevated WBC and CRP levels serving as highly sensitive predictors. Given the high healthcare utilization cost of obtaining an abdominal MRI, particularly in a lower resource hospital setting, a higher threshold for obtaining an abdominal MRI should be adopted for pediatric patients.

Authors:
Cuthbert Simpkins, Gelilla Daniel, Gelilla Daniel, Vidit Minda, William Gutheil

Body of Abstract:
Introduction: With the rise of multidrug resistant organisms, sepsis has become increasingly difficult to treat. The discovery of a treatment that is not solely reliant on standard antibiotics is vital. We decided on an approach that optimized macrophage activity. Studies have shown that the ketone, beta-hydroxybutyrate, suppresses differentiation of pro-inflammatory M1 macrophages and augments anti-inflammatory M2 macrophage lineages. Our previous studies demonstrated that lipid nanoparticles (VBI-1) reduce the expression of M1 macrophage genes. Hence, we tested the efficacy of ketones [Ethyl Acetoacetate (EAA), Beta-Hydroxybutyrate (BHB), and Ethyl Hydroxybutyrate (EHB)] and VBI-1 on the survival of rats subjected to lethal intra-abdominal infection.

Methods: We utilized a cecal ligation and laceration (CLL) model to induce lethal sepsis in adult male and female Sprague-Dawley rats. The cecum was ligated below the ileocecal junction with silk suture; then, a 0.5 cm laceration was made in the distal cecum. The cecum was then returned to the peritoneal cavity and the laparotomy was closed. The control rats received a intraperitoneal (IP) injection of isotonic aqueous solution in a volume equal to 8% of the rat’s body weight. The treatment group received an IP injection of the same solution with 125 mM of the ketones (EAA, BHB, EHB), VBI-1, or a combination of VBI-1 and ketones. The injection was delivered thirty minutes or five hours after the procedure. No source control, antibiotics, or intravascular fluids were given. Survival of rats beyond 24 hours was considered a success. Rats were observed for a maximum of thirty days. Statistical analysis was carried out using a one-way ANOVA and LSD post-hoc test.

Results: All control rats died within 24 hours of the CLL. Within thirty minutes post-CLL, there was no statistical significance between rats that received EAA and control (p=0.072). 60% survival was noted with BHB (p=0.009). Survival of 80% was shown with EHB (p=0.001). We further assessed the efficacy of EHB by performing the injection five hours post-CLL with a survival rate of 67% (p = 0.004). 40% survival was noted with VBI-1 alone (p=0.029). We then injected a combination of VBI-1 and EHB thirty minutes post-CLL which showed a survival of 100% of rats (p <0.0001). We further analyzed the combination at five hours post-CLL with a survival of 50% (p=0.015). To better understand the mechanism, we performed an in vitro study to evaluate the minimum inhibitory concentrations of EHB and BHB against E. coli and MRSA. The EHB exhibited the greatest level of bacterial suppression, most effectively against E. coli. Conclusion: EHB is a ketone with minimal research on its role in the mitigation of sepsis. It exhibits an improvement on survival with and without VBI-1 in a lethal model of sepsis without reliance on standard antibiotics. Continued research is being conducted to further understand its mechanism of action in macrophage activity.