A Rapid Method for Identification and Antibiotic Susceptibility Testing of Bacteria from Pediatric Blood Culture

The prompt and accurate diagnosis of bloodstream infections are crucial. However, the routine conventional method of identification and antibiotic susceptibility testing (AST) of bacteria from the positive blood culture typically takes several days. We aimed to develop a rapid method for bacterial identification and AST in bloodstream infections, with the goal of accelerating diagnosis and enabling earlier treatment.

Our rapid method based on the biochemistry of identification and the microdilution broth method of AST for bacteria isolated from pediatric positive blood culture bottles is highly efficient and time-saving. In this study, we included 80 positive blood culture samples from pediatric patients. The samples were processed by centrifugation with the gel tube and then divided into Gram-positive and Gram-negative groups. Identification and AST were performed using an automated culture antibiogram device based on biochemical methods and microdilution broth method. For routine processing, media inoculated with positive blood culture were kept in the incubator for about 20 hours. The discrepancies in identification and AST were compared between the rapid and routine methods.

The results showed that 30 bacterial strains were categorized as Gram-positive and 50 as Gram-negative. The results showed a high level of agreement in identification, with 77 out of 80 samples (96.25%) showing concordant results between the rapid method and routine method. A total of 1,194 AST assays were performed. The rapid method demonstrated an essential agreement of 96.82% and a categorical agreement of 97.82%. Minor errors ratio, major errors ratio, and very major errors ratio were 1.17%, 0.84%, and 0.17%, respectively.

The rapid method holds potential for efficient and reliable identification and AST of bacteria from positive pediatric blood culture bottles.