Viroxy's microbiologist inserting inoculated cotton swab into neutralizer

Surface Monitoring with Swab Method

Surface monitoring using cotton swabs method is best to evaluate the effectiveness of hygiene procedures on uneven surfaces.

Viroxy conducts surface monitoring test using swab method according to ISO 18593:2018 standard. The method is most suitable to acquire samples from uneven surfaces. To comply with the standard and acquire reliable samples, we use sterile cotton swabs.

The Method

The cotton swab is dipped into 5 ml neutralizer or broth medium and rubbed against the selected test area. The swab is returned into the test tube containing neutralizer or broth medium. Approximately 1 ml of the medium is acquired and plated onto a petri dish.

Desired agar is added for the enumeration of microorganism. Agar is added with TSA to evaluate bacterial presence or SDA to evaluate the presence of yeast and mould.

In instances where a sample is collected right after disinfection, appropriate neutralizer can be added to the broth if disinfectant residue is suspected.

The medium can also be diluted if sample is expected to contain high amounts of microbial load. Incubate bacteria for 2 days at 37°C and yeast and mould for 3 days at 30°C.

The swab method is suitable for small areas and areas with cracks and crevices. Swabs can cover larger areas compared to contact plates. The downside of using this method is that microorganism might reduce or increase in the neutralizer or broth medium (depending on the media) if the time between sampling and plating is too long.

Sample Site Selection Criteria

When selecting sites to be sampled, it is important to ask the following questions:

Include sites that are known to harbor high-levels of microorganism.


Colony Findings

Findings are categorised according to this table.


Service Request Process

  1. To request for this service, submit your enquiry through the contact form and we will contact you. Alternatively, call us at +603 2630 8888 for a discussion.
  2. Please determine the size of the premises you wish to test before discussing with us. 
  3. List potential sites of contamination that may require testing such as door handle, playpen, table etc.
  4. Wait for an e-mail from us which will contain a submission form and quotation. Fill in your details if you agree and send the form back to us.
  5. Wait for a sample acquisition date from us.
  6. We will acquire samples from the premises on the set date and transport them to the lab immediately for plating. We do not recommend clients to acquire the samples themselves for this test.
  7. Wait for the result from us. It takes one week to gather the result and another week to generate test report and issue a certificate.

Contact us to discuss with one of our experts