Spiral Plating is a U.S Official Method (Journal of the AOAC, 60 1977, Methods) recognized by the Association of Official Analytical Chemists (AOAC). Thanks to the spiral method, a known volume of sample is inoculated, from the center to the periphery of the plate. This pattern implies a decrease in the concentration of the sample while the process takes place.

The Spiral Plater is a two-in-one method: diluter and plater at the same time. IUL’s spiral plater, Eddy Jet 2W, enables the user to reduce the cost per test, hands-on time, and consumable use during bacterial enumeration while he increases a microbiology lab’s productivity.

This cutting-edge spiral plater automates, standardizes, and streamlines plate inoculations with its patented cross-contamination free technology. Microsyringes confer the system unique, unmatched advantages that make it a bestseller.


A brief history of the spiral method

In 1973, Dr. J.Ed Campbell introduced the spiral inoculation method with the market introduction of the Model A Spiral Plater (Spiral Systems, Cincinnati, OH, U.S) which the sample was inoculated describing an Archimedes spiral pattern. This spiral draws a curve in which the radius is directly proportional to the angle (r= a0).

The pattern made by the spiral method is achieved through the increasing of the angle and the radius, and the reduction of the sample flow from the center to the outside of the dish. Furthermore, the volume of sample deposed per unit area of plate decreases across the spiral ending up in a dilution effect, up to one-thousand-fold dilution range.


The spiral plate method provides the same results as the traditional methods?

In 1973, Gilchrist et al. compared the spiral plate method to the pour plate procedure with the use of pure and mixed cultures. The results obtained by the spiral plate method did not demonstrate differences in variance which limits were within the limits of error for traditional quantitative methods.

In 1977, Jarvis et al. compared the Spiral plate method with the pour plate, the surface spread plate, and the drop count, using four types of food and different operators from entry-level to experienced microbiologists. The results showed no statistically significant differences between the methods neither between the types of foods used nor the operators. Even the variations that could be found with different operators were lower with the use of the spiral plater.

The spiral plate method, in many cases, can replace advantageously any of the other methods for the quantitative estimation of viable microorganisms in foods. Jarvis et al. that carrying out 100 colony counts by the spiral plate method required only 31% of the labor necessary for the drop count method.


 Advantages of spiral plating

  • Reduces the number of serial dilutions needed for microbiological testing. 3 dilutions in 1 plate!
  • Reduces the number of Petri dishes needed. Reducing the number of dilutions, fewer Petri dishes are required.
  • The growth rate of the same species is the same, resulting in colonies of about the same size.
  • The Spiral distribution enables a reduction of the counting procedure. In most cases, the count is only needed to be performed on one portion of the agar.
  • Different diameters of Petri dishes can be used: 90, 100, or 150 mm.

Advantages of Eddy Jet

The IUL’s Spiral plater boosts the advantages of the spiral plating method increasing the performance and the security of the procedure.

  1. Intuitive interface without setup times

2. Electron Beam micro syringe sterilization which makes cleaning cycles unnecessary, saving large amounts of time

3. Stepper Microcontroller motors can regulate the instrument’s high precision micros syringe liquid dispensing
4. Different final volumes in different distribution patterns depending on the program. Precise distribution patterns such as proportional, logarithmic, or linear
5. Avoids cross-contamination

More than 25 spiral distributions with Eddy Jet

Eddy Jet can perform more than 25 spiral distributions. Each type corresponds to a different pattern in liquid samples spreading across the spiral and makes suitable a rapid plating even for the most concentrated samples.


Standard Exponential Mode

Causes exponentially decreasing amounts of sample to be deposited for bacterial enumeration by spiral plating method and for single colony isolation.

Slow Exponential Mode

Used when plating organic compounds such as ethanol, or when using wet plates – prevents spirals from being splashed by centrifugal force. 

Proportional Mode

Useful for amplifying the response of bacterial populations to anti-microbial agents or mutagents over the narrow range of their gradient.

Uniform Mode

Causes the sample to be deposited at a constant rate over the entire spiral path.

Lawn Mode

Useful for test requiring precise and even distribution of substances or microbes across a plate such as disk diffusion tests.

Eddy Jet 2W, more productivity for microbiology labs

Eddy Jet 2W is mostly used by food, cosmetic and pharmaceutical labs, but any microbiology lab can largely benefit from its use. Eddy Jet 2W reduces cost per test, hands on time, and consumable use during bacterial enumeration while increasing a microbiology lab’s productivity.