Can We Predict Surgically Complex Diverticulitis in Elective Cases?

BACKGROUND: Diverticulitis is separated into complicated and uncomplicated, based on the patient's presentation at the time of his or her initial attack of acute diverticulitis. OBJECTIVE: The aim of this study was to identify risk factors for persistent complex diverticulitis, defined as an abscess, fistula, or stricture, at the time of elective surgery, and to characterize outcomes in this patient population. DESIGN: This was a retrospective review of 2010 to 2016 in the American College of Surgeons National Surgical Quality Improvement Project database. SETTINGS: Individuals diagnosed with diverticulitis who underwent elective surgery were included. PATIENTS: A total of 1502 patients underwent elective surgery for diverticulitis, of which 559 (37%) patients had a surgical indication of persistent complex diverticulitis. INTERVENTIONS: We performed logistic regression analysis to identify risk factors for complex diverticulitis and evaluated a new prediction model. MAIN OUTCOME MEASURES: The predictive factors of persistent complex diverticulitis for elective colon resection were measured. RESULTS: The patients with complex diverticulitis were older (p < 0.001), had worse functional status (p < 0.001), more comorbidities (diabetes mellitus and hypertension), and a higher Charlson Comorbidity Index (2.7 vs 1.6, p < 0.001). They were more likely to have a history of tobacco or alcohol use (p < 0.001) and to be malnourished. Interestingly, patients found to have persistent complex diverticulitis did not have more episodes than patients with uncomplicated cases did (p = 0.67). Surgical time was longer in complex diverticulitis, and the patients were more likely to require diverting stomas and concurrent resections of adjacent structures. The area under the curve from the test set was (0.75; 95% CI, 0.72-0.78), sensitivity and specificity were 0.890 (95% CI, 0.870-0.891) and 0.450 (95% CI, 0.410-0.490). LIMITATIONS: The study was limited by its retrospective review and observational bias. CONCLUSIONS: Patients undergoing elective surgery for complex diverticulitis did not have more episodes. Instead, complex diverticulitis may be a reflection of a complicated patient, suggesting that complicated patients should have a different algorithm of care at the time of their initial presentation with diverticulitis to prevent the development of complex disease. See Video Abstract at http://links.lww.com/DCR/B183. ¿PODEMOS PREDECIR DIVERTICULITIS QUIRÚRGICAMENTE COMPLEJA EN CASOS ELECTIVOS?: La diverticulitis se divide en complicada y sin complicaciones, según la presentación del paciente en el momento de su ataque inicial de diverticulitis aguda.El objetivo de este estudio fue identificar los factores de riesgo para la diverticulitis compleja persistente, definida como un absceso, fístula o estenosis, en el momento de la cirugía electiva, y caracterizar los resultados en esta población de pacientes.Esta fue una revisión retrospectiva del 2010-2016 en la base de datos del Proyecto de Mejora de la Calidad Quirúrgica Nacional del Colegio Estadounidense de Cirujanos.Se incluyeron individuos diagnosticados con diverticulitis que se sometieron a cirugía electiva.1502 pacientes fueron sometidos a cirugía electiva por diverticulitis, de los cuales 559 (37%) pacientes tenían una indicación quirúrgica de diverticulitis compleja persistente.Realizamos un análisis de regresión logística para identificar los factores de riesgo de diverticulitis compleja y evaluamos un nuevo modelo de predicción.Se midieron los factores predictivos de diverticulitis compleja persistente para la resección de colon electiva.Los pacientes con diverticulitis compleja eran mayores (p <0,001), tenían un peor estado funcional (p <0,001), más comorbilidades (diabetes e hipertensión) y un índice de comorbilidad de Charlson más alto (2,7 frente a 1,6, p <0,001). Tenían más probabilidades de tener antecedentes de consumo de tabaco o alcohol (p <0.001) y estar desnutridos. Curiosamente, los pacientes con diverticulitis compleja persistente no tuvieron más episodios que los pacientes sin complicaciones (p = 0,67). El tiempo quirúrgico fue más largo en la diverticulitis compleja y era más probable que requirieran estomas para desvio y resecciones concurrentes de estructuras adyacentes. El área bajo la curva de prueba fue (0.75, intervalo de confianza del 95% 0.72-0.78), la sensibilidad y la especificidad fueron 0.890 (intervalo de confianza del 95%; 0.870-0.891) y 0.450 (intervalo de confianza del 95%; 0.410-0.490), respectivamente.El estudio estuvo limitado por su revisión retrospectiva y sesgo observacional.Los pacientes sometidos a cirugía electiva por diverticulitis compleja no tuvieron más episodios. En cambio, la diverticulitis compleja puede ser un reflejo de un paciente complicado, lo que sugiere que los pacientes complicados deben tener un algoritmo de atención diferente al momento de su presentación inicial con diverticulitis para prevenir el desarrollo de una enfermedad compleja. Consulte Video Resumen en http://links.lww.com/DCR/B183. (Traducción-Dr. Yesenia Rojas-Kahlil).

Prospective Creation and Validation of the PREVENTT (Prediction and Enaction of Prevention Treatments Trigger) Scale for Surgical Site Infections (SSIs) in Patients With Diverticulitis.

OBJECTIVE: Create and validate diverticulitis surgical site infection prediction scale. BACKGROUND: Surgical site infections cause significant morbidity after colorectal surgery. An infection prediction scale could target infection prevention bundles to high-risk patients. METHODS: Prospectively collected National Surgical Quality Improvement Program and electronic medical record data obtained on diverticulitis colectomy patients across a Healthcare Network-wide Colorectal Surgery Collaborative (5 hospitals). Patients with and without surgical site infections were compared. Predictive variables were identified using logistic regression model; model estimates obtained through 1000 bootstrap replications for scale validation. RESULTS: A total of 1737 colectomies were performed (2010-2016): mean age 59.9 years (SD 12.7), 56.4% female; 93.4% Caucasian; smokers 16.3%, diabetics 7.7%, steroid use 6.0%. Two hundred thirty-one (13.3%) were presented to operating room emergently and 138 (7.9%) with abscess at time of disease admission. Two hundred ninety-six patients underwent Hartman procedures, and 113 (6.5%) received diverted primary anastomosis. Average length of stay was 6.9 days (standard deviation 7.01), 30-day mortality was 1.5%, anastomotic leak rate was 3.1%. Twenty-one percent of patients (n = 366) developed a surgical site infection. Several predictors for infection were identified: obesity (body mass index >30), advanced age (>70 years), diabetes mellitus, preoperative abscess, open surgery, emergent operations, and prolonged operations (>3 h). Creation of protected anastomosis in emergent settings was associated with increased infection rates. Presence of more than 5 risk factors was associated with infection rates of 45.8% (c = 0.69). CONCLUSIONS: Patients with diverticulitis have high surgical site infection rates due to nonmodifiable risk factors. Our Prediction and Enaction of Prevention Treatments Trigger scale can risk stratify patients for targeting surgical site infection prevention bundles and outcomes risk adjustments.

Predictors of Prolonged Opioid Use Following Colectomy.

BACKGROUND: The United States is in the middle of an opioid epidemic. Gastrointestinal surgery has been ranked in the top 3 surgical subspecialties for highest opioid prescribing. OBJECTIVE: The goal of this study is to determine the rate of and risk factors for prolonged opioid use following colectomy. DESIGN: This study utilized data (2015-2017) from the American College of Surgeons National Surgical Quality Improvement Program from 5 institutions. SETTINGS: This study was conducted at 2 academic and 3 community hospitals. PATIENTS: Included were 1243 patients who underwent colectomy. MAIN OUTCOME MEASURES: The primary outcome was rate of prolonged opioid use defined as a new opioid prescription 90 to 180 days postoperatively. RESULTS: A total of 132 (10.6%) patients were prolonged opioid users. In univariate analysis, patients who were prolonged opioid users were significantly more likely to have had more than one opioid prescription in the prior year, to have a higher ASA classification, to undergo an open procedure, to have an ostomy created, and to be discharged with a high quantity of opioids (all p < 0.05). Prolonged opioid users were significantly more likely to have a complication (p = 0.007) or readmission (p = 0.003) within 30 days of the index procedure. In multivariable analysis, prior opioid use (OR, 2.6; 95% CI, 1.6-4.2; p < 0.001), ostomy creation (OR, 2.1; 95% CI,1.2-3.7; p = 0.01), higher quantity of opioid prescription at discharge (OR, 1.9; 95% CI,1.1-3.3; p = 0.03), higher ASA classification (OR, 1.7; 95% CI, 1.1-2.6; p = 0.02), and hospital readmission (OR, 2.0; 95% CI, 1.2-3.4; p = 0.01) were independent predictors of prolonged opioid use. LIMITATIONS: This study is a retrospective review, and all variables related to prolonged opioid use are not collected in the data. CONCLUSIONS: A significant proportion of patients undergoing colectomy become prolonged opioid users. We have identified risk factors for prolonged postoperative opioid use, which may allow for improved patient education and targets for intervention preoperatively, as well as implementation of programs for monitoring and cessation of opioid use in the postoperative period. See Video Abstract at http://links.lww.com/DCR/A973. PREDICTORES DEL USO PROLONGADO DE OPIOIDES DESPUÉS DE LA COLECTOMÍA: Los Estados Unidos se encuentran en medio de una epidemia de opioides. La cirugía gastrointestinal ha sido clasificada entre las tres subespecialidades quirúrgicas principales para la prescripción más alta de opioides. OBJETIVO: El objetivo de este estudio es determinar la tasa y los factores de riesgo para el uso prolongado de opioides después de la colectomía. DISEÑO:: Este estudio utilizó datos (2015-2017) del Programa Nacional de Mejoramiento de la Calidad Quirúrgica del Colegio Americano de Cirujanos de cinco instituciones. MARCO: Dos hospitales académicos y tres comunitarios. PACIENTES: 1,243 pacientes sometidos a una colectomía. MEDIDAS DE RESULTADO PRINCIPALES: El resultado primario fue la tasa de uso prolongado de opioides, definida como una nueva receta de opioides entre 90 y 180 días después de la operación. RESULTADOS: Un total de 132 (10.6%) pacientes fueron usuarios de opioides por tiempo prolongado. En el análisis univariado, los pacientes que eran usuarios prolongados de opioides tenían una probabilidad significativamente mayor de haber tenido más de una receta de opioides en el año anterior, tenían una clasificación más alta de la Asociación Americana de Anestesiólogos, se sometieron a un procedimiento abierto, se les creó una ostomía y se les dio de alta con una cantidad grande de opioides (todos p < 0.05). Los usuarios de opioides prolongados fueron significativamente más propensos a tener una complicación (p = 0.007) o readmisión (p = 0.003) dentro de los 30 días del procedimiento índice. En el análisis multivariado, el uso previo de opioides (OR, 2.6; IC 95%, 1.6-4.2; p < 0.001), creación de ostomía (OR, 2.1; IC 95%, 1.2-3.7; p = 0.01), mayor cantidad de prescripción de opioides al dar de alta (OR, 1.9; IC 95%, 1.1-3.3; p = 0.03), clasificación más alta de la Asociación Americana de Anestesiólogos (OR, 1.7; IC 95%, 1.1-2.6; p = 0.02) y reingreso hospitalario (OR, 2.0; IC del 95%, 1.2-3.4, p = 0.01) fueron predictores independientes del uso prolongado de opioides. LIMITACIONES: Este estudio es una revisión retrospectiva y todos los variables relacionadas con el uso prolongado de opioides no se colectaron en los datos. CONCLUSIONES: Una proporción significativa de pacientes con colectomía se convierten en usuarios prolongados de opioides. Hemos identificado factores de riesgo para el uso prolongado de opioides postoperatorios, que pueden permitir una mejor educación del paciente y objetivos para la intervención preoperatoria, así como la implementación de programas para la supervisión y cese del uso de opioides en el período postoperatorio. Vea el Video de Resumen en http://links.lww.com/DCR/A973.

Truth in Reporting: How Data Capture Methods Obfuscate Actual Surgical Site Infection Rates within a Health Care Network System.

BACKGROUND: Two systems measure surgical site infection rates following colorectal surgeries: the American College of Surgeons National Surgical Quality Improvement Program and the Centers for Disease Control and Prevention National Healthcare Safety Network. The Centers for Medicare & Medicaid Services pay-for-performance initiatives use National Healthcare Safety Network data for hospital comparisons. OBJECTIVE: This study aimed to compare database concordance. DESIGN: This is a multi-institution cohort study of systemwide Colorectal Surgery Collaborative. The National Surgical Quality Improvement Program requires rigorous, standardized data capture techniques; National Healthcare Safety Network allows 5 data capture techniques. Standardized surgical site infection rates were compared between databases. The Cohen κ-coefficient was calculated. SETTING: This study was conducted at Boston-area hospitals. PATIENTS: National Healthcare Safety Network or National Surgical Quality Improvement Program patients undergoing colorectal surgery were included. MAIN OUTCOME MEASURES: Standardized surgical site infection rates were the primary outcomes of interest. RESULTS: Thirty-day surgical site infection rates of 3547 (National Surgical Quality Improvement Program) vs 5179 (National Healthcare Safety Network) colorectal procedures (2012-2014). Discrepancies appeared: National Surgical Quality Improvement Program database of hospital 1 (N = 1480 patients) routinely found surgical site infection rates of approximately 10%, routinely deemed rate "exemplary" or "as expected" (100%). National Healthcare Safety Network data from the same hospital and time period (N = 1881) revealed a similar overall surgical site infection rate (10%), but standardized rates were deemed "worse than national average" 80% of the time. Overall, hospitals using less rigorous capture methods had improved surgical site infection rates for National Healthcare Safety Network compared with standardized National Surgical Quality Improvement Program reports. The correlation coefficient between standardized infection rates was 0.03 (p = 0.88). During 25 site-time period observations, National Surgical Quality Improvement Program and National Healthcare Safety Network data matched for 52% of observations (13/25). κ = 0.10 (95% CI, -0.1366 to 0.3402; p = 0.403), indicating poor agreement. LIMITATIONS: This study investigated hospitals located in the Northeastern United States only. CONCLUSIONS: Variation in Centers for Medicare & Medicaid Services-mandated National Healthcare Safety Network infection surveillance methodology leads to unreliable results, which is apparent when these results are compared with standardized data. High-quality data would improve care quality and compare outcomes among institutions.

Loss of red cell chemokine scavenging promotes transfusion-related lung inflammation.

Red cell transfusions are associated with the development of acute lung injury in the critically ill. Recent evidence suggests that storage induced alterations of the red blood cell (RBC) collectively termed the "storage lesion" may be linked with adverse biologic consequences. Using a 2-event model of systemic endotoxemia followed by a secondary challenge of RBC transfusion, we investigated whether purified RBC concentrates from syngeneic C57BL/6 mice altered inflammatory responses in murine lungs. Transfusion of RBCs stored for 10 days increased neutrophil counts, macrophage inflammatory protein-2 (MIP-2) and chemokine (KC) concentrations in the airspaces, and lung microvascular permeability compared with transfusion of less than 1-day-old RBCs. Because RBCs have been shown to scavenge inflammatory chemokines through the blood group Duffy antigen, we investigated the expression and function of Duffy during storage. In banked human RBCs, both Duffy expression and chemokine scavenging function were reduced with increasing duration of storage. Transfusion of Duffy knockout RBCs into Duffy wild-type endotoxemic mice increased airspace neutrophils, inflammatory cytokine concentrations, and lung microvascular permeability compared with transfusion of Duffy wild-type RBCs. Thus, reduction in erythrocyte chemokine scavenging is one functional consequence of the storage lesion by which RBC transfusion can augment existing lung inflammation.

A multi-center analysis of cumulative inpatient opioid use in colorectal surgery patients.

BACKGROUND: There are little data on risk factors for increased inpatient opioid use and its relationship with persistent opioid use after colorectal surgery. METHODS: We identified colorectal surgery patients across five collaborating institutions. Patient comorbidities, surgery data, and outcomes were captured in the American College of Surgeons National Surgical Quality Improvement Program. We recorded preoperative opioid exposure, inpatient opioid use, and persistent use 90-180 days after surgery. RESULTS: 1646 patients were analyzed. Patients receiving ≥250 MMEs (top quartile) were included in the high use group. On multivariable analysis, age <65, emergent surgery, inflammatory bowel disease, and postoperative complications, but not prior opioid exposure, were predictive of high opioid use. Patients in the top quartile of use had an increased risk of persistent opioid use (19.8% vs. 9.7%, p < 0.001), which persisted on multivariable analysis (OR 1.48; p = 0.037). CONCLUSIONS: We identified risk factors for high inpatient use that can be used to identify patients that may benefit from opioid sparing strategies. Furthermore, high postoperative inpatient use was associated with an increased risk of persistent opioid use.

The better colectomy project: association of evidence-based best-practice adherence rates to outcomes in colorectal surgery.

OBJECTIVE: To evaluate whether adherence to evidence-based best practices in colorectal surgery predicts improved postoperative outcomes. SUMMARY AND BACKGROUND DATA: Over a quarter of a million colon and rectal resections are performed annually in the United States. The average postoperative complication rate for these procedures approaches 30%. METHODS: A panel of colorectal and general surgeons from 3 hospitals (1 academic medical center and 2 community hospitals) was assembled to ascertain a set of 37 evidence-based practices that they felt were the most pertinent to the evaluation and management of a patient undergoing a colorectal resection. Fifteen of these practices were classified as "key processes" for the prevention of complications. We then retrospectively reviewed medical records for 370 consecutive patients undergoing colorectal resection at these institutions. We evaluated the association of best-practice adherence to complications in the subset of patients with outcome data available through the American College of Surgeons National Surgical Quality Improvement Program. RESULTS: Nonadherence rates exceeded 40% for 11 practices (including 2 key processes: avoidance of unnecessary blood transfusions and timely removal of central venous catheters). Among 198 patients with American College of Surgeons National Surgical Quality Improvement Program outcomes data, 38 (19%) experienced complications, of which 31 (82%) involved postoperative infection. Nonadherence to key-processes significantly predicted the occurrence of a complication (P = 0.002). Each additional process missed increased the odds of a postoperative complication by 60% (odds ratio: 1.6; 95% confidence interval: 1.2­2.2). CONCLUSIONS: Failures of adherence with best practices in colorectal surgery is associated with an increased occurrence of complications. This study merits further research to confirm that improvement in compliance with perioperative best practices will reduce complication rates significantly.

Leveraging Quality Improvement Science to Reduce C. difficile Infections in a Community Hospital.

BACKGROUND: The most common infection acquired in US hospitals is Clostridium difficile, which can lead to protracted diarrhea, severe abdominal cramping, and infectious colitis and an attributable mortality of 6.5%. The mortality associated with C. difficile is of major clinical importance. The best strategy to prevent such infections is an open question. METHODS: A multiyear quality improvement initiative was performed in our community hospital to determine where hospitals should focus their resources to achieve sustainable reductions in hospital-acquired C. difficile infection (CDI). Quality improvement methodology was used to evaluate the impact of sequential interventions in environmental cleaning, infection prevention, and antibiotic stewardship over time. RESULTS: After four years, hospital-acquired CDI declined 55.5%, from 12.2 to 5.4 cases/10,000 patient-days (Poisson rate test, p = 0.002). High-risk antibiotic use declined 88.1%, from 63.7 to 7.6 days on treatment/1,000 patient-days (Student's t-test, p < 0.001). The highest-impact intervention was stewardship on diagnostics and high-risk antibiotics using home-grown decision support tools. CONCLUSION: Translating scientific evidence into clinical practice using quality improvement methods led to sustained reductions in C. difficile transmission and identified high-risk antibiotics and diagnostics as key leverage points.

Does electronic stewardship work?

Faced with national requirements to promote antimicrobial stewardship and reduce drug-resistant infections, community hospitals are challenged to make the best use of existing resources. Eighteen months after building antibiotic decision support into our electronic order platform, high-risk antibiotic use decreased by 83% (P < .001) at our community hospital. Hospital-acquired Clostridium difficile infections declined 24% (P = .07).

Can 360-Degree Reviews Help Surgeons? Evaluation of Multisource Feedback for Surgeons in a Multi-Institutional Quality Improvement Project.

BACKGROUND: Medical organizations have increased interest in identifying and improving behaviors that threaten team performance and patient safety. Three hundred and sixty degree evaluations of surgeons were performed at 8 academically affiliated hospitals with a common Code of Excellence. We evaluate participant perceptions and make recommendations for future use. STUDY DESIGN: Three hundred and eighty-five surgeons in a variety of specialties underwent 360-degree evaluations, with a median of 29 reviewers each (interquartile range 23 to 36). Beginning 6 months after evaluation, surgeons, department heads, and reviewers completed follow-up surveys evaluating accuracy of feedback, willingness to participate in repeat evaluations, and behavior change. RESULTS: Survey response rate was 31% for surgeons (118 of 385), 59% for department heads (10 of 17), and 36% for reviewers (1,042 of 2,928). Eighty-seven percent of surgeons (95% CI, 75%-94%) agreed that reviewers provided accurate feedback. Similarly, 80% of department heads believed the feedback accurately reflected performance of surgeons within their department. Sixty percent of surgeon respondents (95% CI, 49%-75%) reported making changes to their practice based on feedback received. Seventy percent of reviewers (95% CI, 69%-74%) believed the evaluation process was valuable, with 82% (95% CI, 79%-84%) willing to participate in future 360-degree reviews. Thirty-two percent of reviewers (95% CI, 29%-35%) reported perceiving behavior change in surgeons. CONCLUSIONS: Three hundred and sixty degree evaluations can provide a practical, systematic, and subjectively accurate assessment of surgeon performance without undue reviewer burden. The process was found to result in beneficial behavior change, according to surgeons and their coworkers.

Phosphatidylserine targets single-walled carbon nanotubes to professional phagocytes in vitro and in vivo.

Broad applications of single-walled carbon nanotubes (SWCNT) dictate the necessity to better understand their health effects. Poor recognition of non-functionalized SWCNT by phagocytes is prohibitive towards controlling their biological action. We report that SWCNT coating with a phospholipid "eat-me" signal, phosphatidylserine (PS), makes them recognizable in vitro by different phagocytic cells - murine RAW264.7 macrophages, primary monocyte-derived human macrophages, dendritic cells, and rat brain microglia. Macrophage uptake of PS-coated nanotubes was suppressed by the PS-binding protein, Annexin V, and endocytosis inhibitors, and changed the pattern of pro- and anti-inflammatory cytokine secretion. Loading of PS-coated SWCNT with pro-apoptotic cargo (cytochrome c) allowed for the targeted killing of RAW264.7 macrophages. In vivo aspiration of PS-coated SWCNT stimulated their uptake by lung alveolar macrophages in mice. Thus, PS-coating can be utilized for targeted delivery of SWCNT with specified cargoes into professional phagocytes, hence for therapeutic regulation of specific populations of immune-competent cells.

Comparison of acute structural and histopathological changes of the porcine ciliary processes after endoscopic cyclophotocoagulation and transscleral cyclophotocoagulation.

BACKGROUND: The objective of this study is to investigate the acute histological effects of transscleral cyclophotocoagulation and endoscopic cyclophotocoagulation on the ciliary body and other structures of porcine eyes compared with untreated controls. METHODS: Transscleral cyclophotocoagulation and endoscopic cyclophotocoagulation were performed on porcine eyes. Detailed histological evaluations were performed with light and scanning electron microscopy of treated eyes and compared with untreated controls. RESULTS: Histological changes were observed with both light and scanning electron microscopy for all treated tissues. Tissue treated with transscleral cyclophotocoagulation showed pronounced tissue disruption of the ciliary body muscle and stroma, ciliary processes, and both pigmented and non-pigmented ciliary epithelium. Endoscopic cyclophotocoagulation-treated tissue exhibited pronounced contraction of the cilliary processes with disruption of the ciliary body epithelium, with less architectural disorginization and sparing of the ciliary body muscle. The sclera was not affected by either laser treatment. CONCLUSION: The endoscopic cyclophotocoagulation treatment caused less damage to the ciliary body compared with the transscleral cyclophotocoagulation when evaluated by light and scanning electron microscopy. Compared with transscleral cyclophotocoagulation, endoscopic cyclophotocoagulation appears to be a more selective form of cyclophotocoagulation resulting in less tissue disruption while achieving the goal of destroying ciliary body epithelium.

Association of gag multimers with filamentous actin during equine infectious anemia virus assembly.

A role for the actin cytoskeleton in retrovirus assembly has long been speculated. However, specific mechanisms by which actin facilitates the assembly process remain elusive. We previously demonstrated differential effects of experimentally modified actin dynamics on virion production of equine infectious anemia virus (EIAV), a lentivirus related to HIV-1, suggesting an involvement of actin dynamics in retrovirus production. In the current study, we used bimolecular fluorescence complementation (BiFC) to reveal intimate (<15 nm) and specific associations between EIAV Gag and actin, but not tubulin. Specific interaction between Gag and filamentous actin was also demonstrated by co-immunoprecipitation experiments combined with the actin severing protein gelsolin to solubilize F-actin. Deletion of capsid (CA) or nucleocapsid (NC) genes reduced Gag association with F-actin by 40% and 95%, respectively. Interestingly, GCN4, a leucine zipper motif, could substitute for the NC domain in mediating F-actin association. Furthermore, deficiency of the DeltaNC Gag in F-actin interaction was restored upon co-expression of Gag constructs containing both CA and NC or the GCN4, suggesting a requirement for Gag polyprotein multimerization prior to F-actin association. The observed Gag-F-actin association appeared to correlate with viral budding, as enhanced budding of the DeltaNC mutant was evident upon restoration of F-actin association. Intracellular association of Gag complexes with F-actin was also detected by immunoscanning electron microscopy of Triton-extracted EIAV-infected cells. Together, these data suggest that Gag multimers induced by CA and NC domains interact with F-actin and that this association is important for efficient virion production.