EMBARGOED UNTIL: Tuesday, September 10, 12:00 PM MDT
(Session 13, Paper D-121)
Hosp. de Bicetre, Le Kremlin Bicetre, -null-, France
Septicemia is a severe infection corresponding of the presence of pathogenic bacteria in the bloodstream of infected patients. Since the success of the treatment relies on the prompt administration of the appropriate antimicrobial agents, it is of utmost importance to rapidly detect the presence of multidrug resistance bacteria directly on blood cultures. Enterobacterial isolates (e.g Escherichia coli) are often the source of septicemia. Noticeably, multidrug-resistant enterobacterial strains producing clavulanic-acid inhibited extended-spectrum b-lactamases (ESBLs) are increasingly reported worldwide and therefore increasingly involved in septicemia. As ESBL-producing enterobacterial strain are often resistant to the empirical antibiotic treatments used to treat septicemia, a delay of 24h to 48h was commonly observed before the administration of the appropriate antimicrobial agents. This delay is mostly due to the time need for the accurate detection of those ESBL-producing bacteria (usually, 24h to 48h after the positivity of the blood culture). In this prospective study, we demonstrated that the use of the ESBL NDP test directly from positive blood culture could rapidly detect the presence of ESBL-producing bacteria. Thus, the delay between the positivity of the blood culture and the detection of a multidrug resistant bacteria might be drastically decrease from 48h to 30 min. Accordingly, the antibiotic treatment might be promptly adapted to treat infected patients.
The ESBL NDP test, a rapid chromogenic test based on detection of cefotaxime hydrolysis, has been used prospectively to detect ESBL-producing Enterobacteriaceae directly from blood cultures. From November 2012 to May 2013, a total of 96 blood cultures positive for Gram negatives were tested with the ESBL NDP test. Results of the ESBL NDP test, obtained in less than 30 min, were compared to those obtained with the double disk diffusion technique. All ESBL-producing isolates were then characterized at the molecular level. Identification of the Gram-negative bacteria was also performed directly on positive blood cultures using MALDI-TOF technology, and confirmed by a biochemical identification.
Eighteen blood cultures infected with ESBL-producing Enterobacteriaceae were detected, whereas 78 infected by non-ESBL-producing isolates gave negative results with the ESBL NDP test. Results of the ESBL NDP test correlate at 100% with those of the double disk-diffusion method, with the main advantage that they were obtained in less than 30 min directly from the clinical sample versus an additive 24h time of incubation for the double disk-diffusion method.
Using the ESBL NDP test, identification of an ESBL producer responsible for a bacteremia can be reduced from 24-48 hours to 30 min with 100% sensibility, 100% specificity, 100% negative predictive value and 100% positive predictive value. Since the successful treatment of septicemia relies on prompt administration of the appropriate antimicrobial agents, use of the ESBL NDP test directly from positive blood cultures may significantly improve the outcome of infected patients.