Microbial contamination of environmental surfaces can be evaluated more accurately using microbiological methods. Swab cultures are commonly used because they are easy to perform and can be used to sample irregular surfaces and hands [12]. Moistened sterile swabs were applied to the sample surfaces and inoculated onto agar, often with enrichment broth. Specific pathogens can be identified during an outbreak using the information obtained about the pathogens from swab cultures.

Replicate Organism Detection and Counting (RODAC) contact plates are small Petri plates filled with agar that can acquire samples by direct application on the surface. These are easy to use and standardized for quantitative measurement (colony forming units/cm2). However, high costs, limited sampling, and reduced sensitivity are disadvantages of the RODAC contact plate [12].

Agar slide cultures are used to sample flat and hard surfaces, often in conjunction with aerobic colony counts (ACC). The limitations of the ACC method include lack of accepted criteria for defining a surface as “clean,” cost of processing, delay in results, and small sample area per swab or slide [13]. Microbiological methods are very useful for providing precleaning levels of microbial contamination for each object or surface, but their sensitivity depends on many factors, such as the type of surface being sampled, specific pathogens, and user technique. Therefore, quality control assessments are essential and should be supervised by certified environmental microbiology laboratories.

Environmental cultures are highly sensitive and specific in providing a direct indication of the presence of specific pathogens. Culture methods are useful for identifying sources of outbreaks and environmental reservoirs. The disadvantages of culture methods are that they are not suitable for routine use, are expensive, and lack a defined threshold for determining the level or status of cleanliness. It also requires prolonged time to obtain results (> 48 h) and access to laboratory resources and trained personnel for interpreting results.

The assessment and feedback of cleaning performance are important for environmental infection control [13]. Visual inspection is a simple and basic monitoring modality that assesses the adequacy of routine cleaning and disinfection practices. Another advantage is that it allows immediate and direct feedback from individual staff. However, it is subjective, based on individual determinations, and does not assess or correlate with the bioburden.

UV-visible surface markers display the contamination of high-touch surfaces before room cleaning and disinfection to determine adequate removal [13]. A fluorescent tracer marks predetermined items and surfaces before cleaning. After cleaning, a trained observer uses UV light to determine if any tracing agent has remained. The advantages of this method are that it is rapid, inexpensive, easy to use, and objective. It requires minimal training and provides immediate feedback on performance. However, it does not assess or correlate with bioburden and labor intensiveness, as surfaces should be marked before cleaning and checked after cleaning has been completed. Additionally, some difficulties have been documented in the removal of markers from porous or rough surfaces.

Adenosine triphosphate assay detects microbial and biological materials [13]. The objects are tested before and after cleaning to determine the effectiveness of the cleaning procedure using a predetermined threshold. This method can provide immediate feedback, requires minimal training, and the results are objective. However, this method is expensive, less sensitive, less specific, and lacks a standardized threshold or benchmark for determining the cleanliness level or status. Other disadvantages include constantly changing technology and interference from bleach, microfibers, and stainless steel.