Enterococcus faecalis™ ATCC™ 33186™ can be used to assess Mueller-Hinton medium suitability for sulfonamide and trimethoprim testing.
Mueller-Hinton agar or broth medium containing excessive amounts of thymidine or thymine can reverse the inhibitory effect of sulfonamides and trimethoprim, which may result in smaller and less distinct disc diffusion zones and false-resistance reports.
With broth microdilution MIC testing, suitability of Mueller-Hinton broth for sulfonamide & trimethoprim tests can be evaluated by reviewing ease of reading the results: the end points should be clear at 80% or greater reduction in growth compared to the control.
The loop can be streaked directly onto appropriate media.
Alternatively, it may be dissolved in a liquid medium, Culti-Loops Aerobic Set Rehydration Fluid, Part No. R4631000.
Culti-Loops are individually sealed in a foil pouch and packaged five loops per package.