title: Utilizing BD MAX™ Enteric Bacterial Panel to Detect Stool Pathogens from Rectal Swabs.
abstract: BACKGROUND
  The BD MAX™ Enteric Bacterial Panel (BDM-EBP) is designed and FDA-cleared to detectSalmonella, Shigella, Campylobacter,and Shiga toxin genesstx1/2from stool samples. However, rectal swabs, which are not FDA-cleared for clinical testing with the BDM-EBP, are common specimens received from pediatric patients for enteric pathogen testing. The purpose of this study was to evaluate the ability of the BDM-EBP to detect stool pathogens from rectal swabs.
  
  
  METHODS
  Routine cultures, Shiga toxin testing, and molecular testing with BDM-EBP were performed on 272 sequential rectal swabs collected from August 2015 to December 2015. Discrepant test results were resolved using Verigene® Enteric Pathogens Nucleic Acid Test (EP). 36 challenge samples (13Salmonellaspp., 3Shigellaspp., 10Campylobacterspp., and 10 Shiga toxin positiveEscherichia coli) were tested using reference strains (American Type Culture Collection) and previous patient isolates diluted to103-104cfu/ml in saline then added to Sample Buffer Tube (SBT) with negative stool matrix delivered via a swab. Limit of detection testing was performed by serial 10 fold dilutions in saline then added to SBT with negative stool matrix provided via a swab.
  
  
  RESULTS
  A total of 272 rectal swab specimens were evaluated and 89 were positive by culture and/or MAX EBP. All discrepant results were BDM-EBP positive and culture negative. 21 of 31 (68%) of the apparent false positive BDM-EBP discrepant results resolved as positive with Nanosphere's Verigene® EP. After resolution of the discordant results, the Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) are as follows for each target:Salmonella(n= 4) 100%, PPA and 100%, NPA;Shigella(n= 79) 100%, PPA and 95.3%, NPA;Campylobacter(n= 4) 100%, PPA and 99.6%, NPA; and Shiga toxin producing organisms (n= 2) 100%, PPA and 100%, NPA. 8.8% of the patient samples did not initially yield a result on the BDM-System. Upon repeat, half of the problematic samples resolved, and 4.4% of the total specimen tested did not yield a result. All organisms in the challenge samples were detected. Limits of detection for BDM-EBP testing of rectal swabs were as follows (in cfu/ml in SBT):Salmonella-1.44 × 102;Shigella-5.10 × 100;Campylobacter-1.51 × 101; and Shiga Toxin-1.13 ×103.
  
  
  CONCLUSIONS
  Rectal swabs are acceptable samples for detectingSalmonella,Shigella,Campylobacter, and Shiga toxin using BDM-EBP.
authors.affiliation: Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229 USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: DeBurger
authors.affiliation: Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229 USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hanna
authors.affiliation: Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229 USA.
authors.forename: Eleanor A
authors.initials: EA
authors.lastname: Powell
authors.affiliation: Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229 USA.
authors.forename: Cindi
authors.initials: C
authors.lastname: Ventrola
authors.affiliation: Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229 USA.
authors.forename: Joel E
authors.initials: JE
authors.lastname: Mortensen
keywords: BDM-; Bacterial stool pathogens; Diarrhea; Rectal swabs