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Septum sonication of removed ports for diagnosis of related bloodstream infections

Abstract number: R2398

Alonso M., Martinez A., Serrera A., Ramos A., Bilbao J.I., Etulain M.J., Leiva J., del Pozo J.L.

Objectives: Venous access ports are used in patients receiving long parenteral treatments. Diagnostics specific for port-related infections have not been enough developed. In these infections microorganisms are typically present forming biofilms. The aim of this study was to analyse the role of septum vortexing-sonication technique to diagnose port-related bloodstream infections (PRBI).

Methods: All the devices removed in our hospital during a 27-month period (august 2005 to October 2007) were prospectively studied. We compared the septum sonicate-fluid culture with the port internal lumen swabbing and the culture after sonication of the catheter tip. We considered a confirmed port infection when the same microorganism was isolated from blood cultures and in any port culture [for coagulase-negative staphylococci (CNS), cultures were considered positive if there were at least 1000 cfu/ml in any of the sonication techniques, or 15 cfu for the chamber swabbing. For other microorganisms any count was considered significative].

Results: 240 ports were removed from 240 patients. Ports were removed due to end of use in 187 (77.9%) cases, because of suspected PRBI in 29 (12.1%), because of mechanical complications in 19 (7.9%) and because of local infectious complications in 5 (2.1%). Finally, 27 patients met criteria for PRBI. Most of these patients (92%) were receiving antimicrobial therapy when port was removed. The most common isolated microorganisms were: Gram-negative bacilli (30.4%), CNS (21.7%), yeasts (21.7%) and Staphylococcus aureus (17.5%). Sensitivity of septum sonication (78.6%) was better than that of chamber swabbing (67.9%) (p > 0.05), and than that of catheter tip culture (51.8%) (p < 0.05). The specificity of the septum sonicate-fluid culture, chamber swabbing culture, and catheter tip culture were 97.1%, 95.7% and 93.7%, respectively. Positive and negative predictive values for the septum sonicate-fluid culture were 66.7% and 97.1%, respectively. The ROC curve analysis showed that the best threshold for the septum sonicate-fluid culture was 110 cfu/ml (S:78%, E:93%) for any isolated microorganism.

Conclusions: According to data from the present study, the septum sonicate-fluid culture was the most sensitive method for the microbiologic diagnostic of PRBI. The high negative predictive value of this technique permits to exclude port as origin of the bloodstream infection if culture is negative.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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