Inhibition Zones

Antimicrobial bioassays to determine the efficacy of antibiotics are conducted by public health laboratories and in the pharmaceutical, veterinary and medical device industries. One of the most widely used methods is to culture bacteria in the presence of the antibiotic, usually applied as an inpregnated disk, or in a well cut into the agar. The resultant zone of inhibition, i.e. the region around the disk or well where growth has been prevented, is then measured. Traditionally, this has been done by manual or electronic calipers, but today is achieved using image analysis.

Sorcerer being used to analyse inhibition zone areas

Sorcerer Image Analysis System

For inhibition zone analysis

Our most versatile system for inhibition zone bioassays is Sorcerer, combined with a purpose-built macro illumination stand. This stand can accomodate 90mm & 150mm Petri-dishes as well as large format 12" square culture trays. It has various illumination techniques enabling it to be used for opaque or transparent culture media.

Inhibition zones are measured by virtue of the difference in contrast between the bacterial lawn and that surrounding the disk or well where growth has been prevented. Special algoritms for hole-filling and edge-enhancement ensure accurate measurement of zone diameter or area. Zones can be analysed singly, at high magnification, or as multiple zones using programmable scanning measurement frames. Data can be sent directly to Microsoft Excel or Oracle databases for further processing.

The Sorcerer system is designed to conform to Good Laboratory Practice and is fully compliant with the FDA 21 CFR Part 11 Final rule on electronic records and electronic signature. Perceptive Instruments has attained ISO 9001:2008 approval for its Quality Management System from a UKAS and ANAB accredited certification body.

Sorcerer for inhibition zones

  • Automatic measurement of zone area and diameter
  • Single or multiple zone scanning
  • Interactive measurement of hazy or problematic zones
  • Data transfer to Excel & Oracle databases
  • Electronic signature and GLP compliance
  • Automatic hole-filling algorithm
  • Rapid, accurate, easy to use