Kathryn L. McGillen MD, Presenter: Nothing to Disclose

Ruvandhi Nathavitharana MD, Abstract Co-Author: Nothing to Disclose

Alexander Brook PhD, Abstract Co-Author: Spouse, Research Grant, Guerbet SA

Maryellen Ruth Morris Sun MD, Abstract Co-Author: Investigator, Bracco Group Investigator, Glaxo SmithKline plc

Bettina Siewert MD, Abstract Co-Author: Nothing to Disclose

Vassilios D. Raptopoulos MD, Abstract Co-Author: Nothing to Disclose

Robert A. Kane MD, Abstract Co-Author: Nothing to Disclose

Robert G. Sheiman MD, Abstract Co-Author: Nothing to Disclose

Olga Rachel Brook MD, Abstract Co-Author: Research Grant, Guerbet SA

To evaluate the clinical impact of pre-drainage antibiotics on culture yield from samples obtained during CT-guided drainage.

This retrospective, HIPAA-compliant, IRB-approved study evaluated 300 consecutive patients that underwent CT-guided aspiration or drainage for suspected infection (11/2011-9/2013) at a single institution. Patient imaging and clinical characteristics were evaluated by an abdominal imaging fellow and culture results and patient management were evaluated by an infectious diseases fellow.

Sixteen patients were excluded because they either received no pre-procedure antibiotics or samples for culture were not obtained. 284 patients constituted the final study cohort, with average age of 55±16 yrs and M:F ratio of 54:46. Leukocytosis was present in 165/284(58%) and fever in 65/284(23%). The average collection size was 8.5±4.2cm, gas was present in 141/284(50%) of collections, average amount drained was 108±209mL, and purulent material was obtained in 174/284(62%). 85% (242/284) of collections received drains and the remainder were aspirated. Cultures were positive in 209/284(74%) with change in management in 186/284(65%). The change in management included change of antibiotics in 72/186(39%), narrowing the regimen in 97/186(52%) and cessation of antibiotics in 17/186 (9%). Multidrug resistant bacteria were cultured in 53/284 (19%). The following factors were found to be statistically significant predictors of positive cultures (p<.05): leukocytosis (sens 62%, spec 53%), gas (sens 59%, spec 77%), purulent material (sens 76%, spec 76%), and presence of polymorphonuclear cells in the specimen. Patients with positive cultures had shorter median time difference between antibiotic initiation and drainage than patients with negative cultures (1.0 vs. 3.7 days, p<.001).

CT-guided drainage has a high yield of positive cultures despite pre-drainage antibiotic therapy and the resulting culture information has a positive impact on patient management change. Leukocytosis, gas, polymorphonuclear cells and purulent material in the specimen are significant predictors of positive culture. Also, a shorter interval between starting antibiotics and the procedure results in more positive cultures.

Pretreatment with antibiotics should not preclude specimen collection at the time of CT-guided drainage, as it has high potential to change clinical management.

McGillen, K, Nathavitharana, R, Brook, A, Sun, M, Siewert, B, Raptopoulos, V, Kane, R, Sheiman, R, Brook, O, Change in Management as a Result of Culture Obtained during CT-Guided Drainage in Patients Who Receive Pre-Drainage Antibiotics.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14011362.html