Germ indicators

Colony-forming indicators for the microbiological monitoring of surfaces

Microbial indicators are used to quickly assess microbial contamination without the need for a full laboratory setup. In the field of diagnostics, this category addresses the need to test surfaces, semi-solid materials, or liquids for microbial contamination directly on-site—for example, as part of hygiene monitoring in medical practices, hospitals, or food processing facilities.

Currently, the product line includes a specialized product specifically designed for the combined determination of total bacterial count as well as yeast and mold counts.

Features and Benefits of Microbial Indicators

Microbial indicators, such as the Schülke mikrocount® duo currently available in the product line, are designed for direct use without the need for complex laboratory equipment.

Typical features:

• Combined determination of total microbial count as well as yeast and mold
• Can be used on surfaces, semi-solid materials, and in liquids with just one product
• No preparation time required before use
• No expensive laboratory equipment required
• Results are available within 24 to 72 hours, according to the product specifications
• Inactivates any residual disinfectants present, according to product specifications

These characteristics apply to the product currently available in our product line and have been verified based on the actual product specifications.

For which applications is the microbial indicator suitable?

The Schülke mikrocount® duo microbial indicator is suitable for testing surfaces as part of hygiene monitoring, such as after surface disinfection. According to the product specifications, it enables the combined determination of total microbial count as well as yeast and mold counts using a single product.

Since, according to the product specifications, the same microbial indicator can also be used for semi-solid materials and liquids, a single product covers multiple sample types, eliminating the need for a separate test system for each sample type.

Those who regularly test several different sample types in a single step will benefit from this combined application; on the other hand, those who wish to specifically detect individual groups of microorganisms will find specialized culture media in the “Culture Media” category.

What should you look for when purchasing microbial indicators?

The most important factor is the type of sample to be tested: For surfaces, semi-solid materials, or liquids, a combined microbial indicator such as the Schülke mikrocount® duo is suitable, eliminating the need to purchase a separate test system for each sample type.

The available laboratory equipment also plays a role: Since, according to the product specifications, the microbial indicator does not require expensive laboratory equipment, it can be used even where a complete microbiological laboratory infrastructure is not available.

The turnaround time until results are available is also important: With 24 to 72 hours required until a readable result is obtained, the test should be planned accordingly in advance, for example as part of routine hygiene inspections. Within the field of diagnostics, it is also worth considering supplementary testing methods if additional parameters need to be assessed in addition to bacterial count determination.

Combined microbial indicator or traditional culture medium—which method is right?

A combined microbial indicator such as the Schülke mikrocount® duo covers multiple detection targets with a single product: total microbial count as well as yeasts and molds. This reduces the number of different test systems required when the focus is on obtaining a general overview of microbial contamination.

Conventional culture media, on the other hand, are usually designed to detect individual, precisely defined groups of microorganisms, such as specific bacterial or fungal species. They are therefore particularly suitable when the goal is to specifically detect a particular pathogen or a specific group of microorganisms, rather than to obtain a general overview.

Which method is more appropriate depends on the specific question at hand: The microbial indicator is ideal for a quick, combined assessment following cleaning or disinfection, while specialized culture media provide more meaningful results when specifically searching for individual microorganism species. Neither method completely replaces the other—they complement each other within the context of laboratory diagnostics.

Application and Notes on Germ Indicators

According to the product instructions, the microbial indicator is applied directly to the surface being tested, the semi-solid material, or the liquid, without the need for any separate preparation time.

After application, an incubation period of 24 to 72 hours must be observed before the result can be read. For a reliable evaluation, the manufacturer’s instructions regarding storage, application, and reading should be strictly followed.

If results are abnormal or unclear, it is recommended to consult a specialist rather than drawing broader conclusions based solely on the bacterial indicator. Further information can be found in the accompanying data sheets, as specified in the product description.

Compatible Accessories for Bacterial Indicators

• Culture media
• Laboratory Diagnostics
• Surface disinfection

Culture media complement the microbial indicator when specific groups of microorganisms need to be cultured and detected. Laboratory diagnostics provides a broader framework for in-depth analysis when additional data must be collected beyond simple microbial count determination. Surface disinfection completes the cycle, as the microbial indicator can be used to verify whether a disinfection procedure has achieved the desired effect. Together with the rest of the diagnostic product line, this enables the implementation of a comprehensive hygiene and control process.