Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2017

Evaluation of a novel fastidious culture medium (KS agar) for recovery of organisms from positive blood cultures (#216)

Michael Findlay 1 , James Ho 1 , Peter Huntington 1 , Archie Darbar 1
  1. Pathology North, Royal North Shore Hospital, St Leonards, NSW, Australia

Background: The isolation and identification of bacterial pathogens from blood cultures is one of the most important services provided by diagnostic microbiology laboratories.  We evaluated a novel culture medium (KS Agar) in use at our laboratory for performance of isolating organisms from blood cultures compared to conventional culture media (Horse Blood Agar and Chocolate Agar). Methods:  Positive blood cultures over a two month period in our laboratory were cultured onto KS Agar and incubated aerobically and anaerobically. This was compared to a conventional protocol of culture onto horse blood agar and chocolate agar. We also compared the performance of KS Agar to blood agar and chocolate agar using selected reference strain isolates.  Results: 145 isolates from patient specimens were included in this comparison. All organisms that were recoverable on conventional media were also recoverable on KS Agar. One isolate (Fusobacterium nucleatum) was recoverable only on KS Agar. Twelve isolates demonstrated larger colony size and ten isolates demonstrated better semi-quantitative growth on KS Agar compared to conventional media at 24hrs of incubation. Conclusion: KS Agar demonstrated at least equivalent and in some cases superior performance to blood and chocolate agar for the isolation of pathogens from blood cultures. The decreased number of plates required and better growth demonstrated for some fastidious organisms has proven useful in improving laboratory workflow and allowing earlier identification and susceptibility testing on isolates.