Sterile individually wrapped swabs containing transport medium are used aseptically to collect bacteria from solid surfaces by gently and firmly rubbing against a specific area of approximately 5x5cm. After which the swab is placed back into the transport medium, labelled for identification, and immediately placed in a temperature-controlled fridge (2-8°C) with analysis commencing within 2 hours to preserve viability.
Once at our laboratory, any bacteria is dispersed by vortexing the swab and is then pipetted and spread aseptically onto plate count agar (PCA) and Sabouraud dextrose agar (SAB) for total viable counts (TVC) of bacterial species and fungi respectively.
The PCA plates are then inverted and incubated at 35°C for 48 hours; the colonies are initially counted at 24 hours and again at 48 hours for the final read to account for any slow-growing bacteria. However, the SAB plates are incubated at 30°C for 21 days and the plate reading is performed at 14 days and 21 days.
Airborne microorganisms are often found in occupied rooms or grafted onto skin cells, with very few present on their own. In settle plate sampling, microbe-bearing particles descend into Petri-dishes via gravity at a rate of approximately 1cm/s. The number of microbes deposited onto an agar surface throughout exposure is ascertained by incubation and counting the number of microbial colonies.
Sabouraud dextrose agar (SAB) and nutrient agar are used as suitable growth media for fungi and bacteria respectively. The SAB plates are inverted and incubated at 30°C for 21 days, however, a preliminary reading is performed during the incubation period on day 14. After recording the results, the plates are incubated, and the final reading is performed on day 21. The TSA settle plates are inverted and placed in a 35°C incubator for 48hours. A preliminary reading is taken after 24hours of incubation and the final reading is taken after 48 hours.
After the sample examination, we will provide a comprehensive and confidential report describing our findings along with any other relevant information allowing the client to make informed decisions on any steps that may need to be taken. BioLabTests offers consultancy and expert advice that can help to demonstrate good hygiene and cleaning practices in your environment.
If environmental testing would be of interest to you or you would like to explore other microbiological testing, please do not hesitate to get in touch with a member of our team at +0333 254 9486. Alternatively, you can contact us via our form for a quote or more information regarding our environmental testing capabilities.