New test method makes staphylococci detection quicker and easier

By Rory Harrington

- Last updated on GMT

A new diagnostic test method will make the identification and enumeration of coagulase-positive staphylococci (CPS) in foods both simpler and significantly quicker, said Oxoid.

The UK-based company said its Brilliance Staph 24 Agar analysis allows the isolation and calculation of CPS levels within 24 hours – cutting result waiting times in half. Traditional media – such as Baird-Parker Egg Yolk Tellurite Agar – take at least 48 hours to produce a result, Oxoid industrial product manage Dr. Alastair Thomas told

The test also provides greater specificity in results as it prevents the growth of non- target organisms. This reduces the need for confirmation testing. The company said customer demand for faster testing with heightened specificity had been instrumental in developing the new product.

“After speaking to the industry we found that the low specificity of some traditional testing media was an issue,”​ said Thomas. “If specificity is low, it is necessary to carry out more confirmation testing – which can be both time consuming and costly. Our new test is more precise, which can save both time and money for food processors.”

Staphylococci are found in a broad range of foods, including meat, dairy, bakery and ready-to-eat products. EU regulations on acceptable limits of staphylococci in cheese, milk powder and shellfish are in place - with levels exceeding 1x105​CFU/g considered as dangerous.

Food producers therefore need to demonstrate that their products contain levels lower than this concentration, said the company, which is part of Thermo Fisher Scientific. Foods that require extensive handling, preparation or are kept at slightly elevated temperatures after manufacture are commonly implicated in staphylococcal food poisoning.

Early warning

The quicker turnaround time for results is also important even if pathogen concentrations in a sample are below EU regulatory levels, said Thomas, as it could indicate that there are handling issue in a particular plant or process

“The detection of lower levels of CPS, or other pathogens, can be an indication that the food process is not optimal,”​ he added. “Time is clearly an important factor in this and means that, should there be an issue, preventative actions can be implemented sooner.”

The system is also simpler to interpret as CPS growth is shown by the presence of dark blue colonies on a clear agar background. – allowing rapid and easy identification, said Oxoid.

The Oxoid Brilliance Staph 24 Agar method has been validated and approved by MicroVal according to the ISO 16140 standard against the reference method ISO 6888:1999-Horizontal method for the enumeration of coagulase-positive staphylococci (Staphylococcus aureus and other species) - Part 1: Technique using Baird-Parker Agar medium for meat, dairy, seafood, bakery products and composite food.

Related topics: Processing & Packaging