Why Our Different Methods Produce The Same Result
Roth Bioscience, LLC is built around a core of unique diagnostic microbiological methods that provide the confidence that each method produces virtually identical results. This versatility allows the user to choose their preferred approach with the confidence that the results among the methods will not vary if defined SOP (protocols) are followed.
For example, KwikCount® MF is a method that allows the development and counting of the target organisms in a very short incubation period (eg—8hrs vs the standard 24 hrs incubation) to achieve this short incubation period when fluorogenic compounds are incorporated. These may be exclusively fluorogenic (mugal) or duogenic® (such as 6-chloro, 3 methyl, indolyl, b-D- gal). If MUG is used, the results can be read from 7-24 hrs incubation or later. If a duogen is used, the fluorescent phase can be read at 7-10 hours, but the fluorogenic properties disperse and disappear (usually about 20-24 hrs) and are then replaced by a non-spreading chromogenic color that is evidenced by changing the color of the colony to a permanent color in ambient light (the duogenic® feature). The colony count remains identical to that of the fluorescent phase. This method may be used with a petri dish containing a sterile white absorbant pad to which a sterile liquid nutrient medium is added. (KwikCount MF) The test sample is filtered through a micropore filter and then (after lifting the dish lid) placed on the wet pad, the lid is replaced, and the inoculated dish is placed in an incubator. (see further instructions and comments later)
The 2-SIDED-R-CARD® is another innovative variation that allows the culture of two separate test samples while using a single “bottom” part. It therefore consists of one bottom part and two “top” parts. To use, lift the top part on one side and deposit the test sample (for example, E. coli) and drop the top part down on that sample, which will then spread and gel. When gelling is complete, turn the R-CARD® over and inoculate the unused #2 side with another sample (duplicate the first sample or use another completely different sample (such as Enterococcus faecalis). This saves using two “bottom” parts and takes less space to ship or incubate.
The R-CARD® KwikCount® is a newer, alternative method to the KwikCount® MF method described above that gives the same Accurate results, but does not involve the use of a petri dish. Instead of a petri dish, pad and separate liquid nutrient medium, they are replaced by a card consisting of two parts, (1) a waterproof, stiff bottom part, and (2) a transparent, thin “top” part that contains an adhesive on one of its sides. This adhesive holds a fine dry nutrient powder with the equivalent nutrients to those contained in the sterile liquid used in the KwikCount® MF medium. The test inoculum is applied by (1) Lifting the top piece and depositing 1 ml on the center of the bottom piece and dropping the top piece onto it, at which time it gels after spreading into a circle. Or (2) filtering the inoculum and removing the filter, lifting the top piece and depositing the filter ono the bottom piece and adding about 0.75 ml of sterile water, and then lowering the top piece which forms a gel, followed by incubation.
Advantages of Different Methods
By Jonathan N. Roth,--- Roth Bioscience June 28, 2023