Pediatric multicenter evaluation of the Verigene gram-negative blood culture test for rapid detection of inpatient bacteremia involving gram-negative organisms, extended-spectrum beta-lactamases, and carbapenemases.

We evaluated the investigational use only (IUO) version of the rapid Verigene Gram-negative blood culture test (BC-GN), a microarray that detects 9 genus/species targets (Acinetobacter spp., Citrobacter spp., Enterobacter spp., Escherichia coli/Shigella spp., Klebsiella oxytoca, Klebsiella pneumoniae, Proteus spp., Pseudomonas aeruginosa, and Serratia marcescens) and 6 antimicrobial resistance determinants (blaCTX-M, blaKPC, blaNDM, blaVIM, blaIMP, and blaOXA) directly from positive blood cultures. BC-GN was performed on positive BacT/Alert Pediatric FAN and Bactec Peds Plus blood cultures with Gram-negative organisms at two tertiary pediatric centers. Vitek MS (bioMérieux, Durham, NC) was used to assign gold standard organism identification. The Check MDR CT-102 microarray (Check Points B.V., Wageningen, Netherlands) was used as an alternative method for detecting resistance determinants. In total, 104 organisms were isolated from 97 clinical blood cultures. BC-GN correctly detected 26/26 cultures with Acinetobacter spp., P. aeruginosa, and S. marcescens, 5/6 with Citrobacter spp., 13/14 with Enterobacter spp., 23/24 with E. coli, 2/3 with K. oxytoca, 16/17 with K. pneumoniae, and 0/1 with Proteus spp. BC-GN appropriately reported negative BC-GN results in 8/13 blood cultures that grew organisms that were not represented on the microarray but failed to detect targets in 3/5 cultures that grew multiple Gram-negative organisms. BC-GN detected 5/5 and 1/1 clinical blood cultures with blaCTX-M and blaVIM. All 6 results were corroborated by Check MDR CT-102 microarray testing. The Verigene BC-GN test has the potential to expedite therapeutic decision making in pediatric patients with Gram-negative bacteremia. Sensitivity was satisfactory but may be suboptimal in mixed Gram-negative blood cultures.

Superior sensitivity and decreased time to detection with the Bactec Peds Plus/F system compared to the BacT/Alert Pediatric FAN blood culture system.

Here, we compare the sensitivities and times to detection (TTD) of BacT/Alert Pediatric FAN (PF) and Bactec Peds Plus blood culture bottles. Test bottles were inoculated with 2 ml of banked whole blood, 1-ml aliquots of antibiotic suspension, and organisms diluted to simulate a bacteremia level of 10 to 100 CFU/ml. The control bottles were inoculated with 3 ml of banked blood and organism suspensions only. The organism-drug combinations were Staphylococcus epidermidis and vancomycin, methicillin-resistant Staphylococcus aureus and vancomycin, Streptococcus pneumoniae, vancomycin, and ceftriaxone, Streptococcus agalactiae, ampicillin, and cefotaxime, Escherichia coli, cefotaxime, and cefepime, Pseudomonas aeruginosa, piperacillin-tazobactam, cefepime, and gentamicin, Neisseria meningitidis and ceftriaxone, and Haemophilus influenzae and ceftriaxone. The control and test bottle combinations were tested in duplicate. The bottles were incubated for 5 days; 32 control and 104 test bottles were incubated. Overall, the bacterial recovery rates for the PF and Peds Plus bottles were 37% and 62%, 94% and 100% in the controls, 19% and 50% in the test bottles, and 33% and 92% in the bottles with vancomycin, respectively. No bacteria were recovered from the bottles with S. pneumoniae, S. agalactiae, E. coli, N. meningitidis, or H. influenzae in combination with cefotaxime or ceftriaxone. The Peds Plus system detected P. aeruginosa in bottles with cefepime and piperacillin-tazobactam, but the PF system recovered bacteria only in bottles with trough levels of piperacillin-tazobactam. The mean TTD were shorter in the Peds Plus system controls (14.2 versus 18.0 h; P = 0.001) and the test bottles (14.3 versus 17.8 h; P = 0.008) than in the PF bottles. Overall, we demonstrated superior sensitivity, TTD, and antibiotic neutralization in the Bactec Peds Plus system compared to those in the Pediatric FAN system.

Rapid detection of Gram-positive organisms by use of the Verigene Gram-positive blood culture nucleic acid test and the BacT/Alert Pediatric FAN system in a multicenter pediatric evaluation.

Assays that expedite the reporting of organism identification and antibiotic susceptibility status in positive blood cultures can fast track interventions that improve clinical outcomes. We evaluated the Verigene Gram-positive blood culture nucleic acid test (BC-GP) in two pediatric hospitals. Positive BacT/Alert Pediatric FAN blood cultures with Gram-positive organisms were tested using the BC-GP in tandem with routine laboratory procedures. To test organisms underrepresented in the clinical blood culture evaluation, blood culture bottles were spiked with diluted organism suspensions at concentrations of 10 to 100 CFU per milliliter. A total of 249 Gram-positive bacterial isolates were recovered from 242 blood cultures. The BC-GP detected Staphylococcus aureus, methicillin-susceptible S. aureus, and methicillin-resistant S. aureus with sensitivities of 100%, 99%, and 100% and specificities of 100%, 100%, and 99.5%, respectively. The BC-GP detected Staphylococcus epidermidis, methicillin-susceptible S. epidermidis, and methicillin-resistant S. epidermidis with sensitivities of 95%, 80%, and 96%, respectively, and 100% specificity. The BC-GP correctly identified 14/15 cases of Enterococcus faecalis and Enterococcus faecium bacteremia and 9 cases of Streptococcus pneumoniae. It misidentified 5/15 clinical blood cultures with Streptococcus mitis/Streptococcus oralis and 1/3 blood cultures spiked with Streptococcus anginosus group as S. pneumoniae. The BC-GP detected a case of Streptococcus pyogenes bacteremia but failed to detect 2/3 clinical blood cultures with Streptococcus agalactiae. BC-GP's rapid accurate detection of Staphylococcus spp., E. faecium, and E. faecalis and its ability to ascertain mecA, vanA, and vanB status may expedite clinical decisions pertaining to optimal antibiotic use. False-positive S. pneumoniae results may warrant reporting of only "Streptococcus spp." when this organism is reported by the BC-GP.