2123. Rapid Phenotypic Detection of Gram-Negative Bacilli-Resistant to Oximinocephalosporins and Carbapenems in Positive Blood Cultures Using a Novel Protocol

Abstract

BackgroundEarly and adequate antibiotic treatment are the cornerstones to improve clinical outcomes in patients with Bloodstream infections (BSI). Delays in appropriate antimicrobial therapy have catastrophic consequences for patients with BSI. Microbiological characterization of multi-drug-resistant pathogens (MDRP) allow clinicians to provide appropriate treatments. Current available microbiologic techniques may take-up to 96 hours to identify causative pathogens and its resistant patterns. Therefore, there is an important need to develop rapid diagnostic strategies for MDRP. However, rapid detection techniques are costly and are not widely available. We tested a modified protocol designed to detect Gram-negative bacilli (GNB) resistant to oximinocephalosporins and carbapenems from positive blood cultures.MethodsThis is a prospective, cohort study of consecutive patients with bacteremia. We developed a modified protocol using HB&L® system to detect MDRP. We then attempted to determine accuracy, concordance and reduction of identification time of this novel method in a reference hospital. Descriptive statistics and logistical regressions were used.ResultsNinety-six patients with BSI were included in the study. A total of 161 positive blood cultures were analyzed. Escherichia coli (50%, 81/161) was the most frequently identified pathogen followed by Klebsiella pneumoniae (15%, 24/161) and Pseudomonas aeruginosa (8%, 13/161). 32% of isolations had usual resistance patters. However, in 29/161 (18%) of identified pathogens were producer of carbapenemasases and 21/161 (13%) of extended-spectrum β-lactamases. Concordance among our HB&L® modified protocol and traditional method was 99% (159/161). Finally, identification times were significantly shorter using our HB&L® modified protocol than traditional methods (Mean, hours [SD], 20.8 [6.22] vs. 62.8 [6.22], P < 0.001).ConclusionHere we provided novel evidence that using our HB&L® modified protocol is an effective strategy to reduce the time to MDRP detection/identification; with a great concordance rate when compared with the gold standard. Further studies are needed to confirm these findings and to determine whether this method may improve clinical outcomes.Disclosures All authors: No reported disclosures.