Researchers at the University of Alabama, USA, are using automated colony counter as part of an improved opsonophagocytic killing assay to save time when evaluating novel pneumococcal vaccines
Synbiosis, a manufacturer of automated colony counters, reports that scientists in the University of Alabama at Birmingham (UAB), USA, a centre of excellence for microbiology, are using the Protocol system to save time with evaluating new pneumococcal vaccines.
Researchers in the Department of Pathology at UAB are using the Protocol as part of an improved opsonophagocytic killing assay (OPKA).
The system automatically counts surviving antibiotic-resistant pneumococci on Todd-Hewitt agar plates with yeast extract and an agar overlay containing antibiotics and 2,3,5-triphenyl tetrazolium chloride (TCC).
The pneumococci plated out are those that survived the opsonising effect of antibodies induced with different pneumococcal vaccines.
Moon Nahm, director of clinical immunology at UAB said: "We found colony counting for the OPKA was tedious and time consuming so we evaluated various counters to speed up the process. "However, the low contrast between the medium and colonies meant it was difficult to distinguish between the two. "Therefore, we added TCC to the plates to colour the colonies red.
"On re-evaluation of the systems we found the Protocol had many subtle features, including excellent data transfer, but for us it was the enhanced contrast that led us to purchase.
"Using the Protocol we can instantly count thousands of colonies, even ones of less than 0.2mm diameter, with ease.
"This allows us to routinely plate bacteria from 24 reaction wells onto a single square petri dish, thus reducing the number of plates to a manageable amount and ensuring colony counting is no longer the rate limiting step in our OPKA work," continued Professor Nahm.
Simon Johns, international product manager for Synbiosis, added: "We are delighted the Protocol is being used to help evaluate new pneumococcal vaccines, for which there is currently a huge demand.
The research being performed at UAB shows the Protocol can rapidly count even low contrast colonies, making it important technology which could become a crucial part of many bactericidal assays."
