Efficiency of four sampling methods used to detect two common nosocomial pathogens on textiles

Detecting microorganisms on textiles is useful for many purposes, for example to determine the bioburden before laundering, assess the reduction in bacterial counts in connection with various laundry processes, or trace transfer routes in infection control investigations. Therefore a validated, reproducible and rational method is needed. For sampling microorganisms on textile surfaces the most commonly used method is the contact plate method using RODAC plates, first described by Hall and Hartnett followed by the swab sampling technique. Both methods can only capture microorganisms on the surface of the textiles while microorganisms that have penetrated into the deeper structure of the material will not be detected. In our research the contact plate method and the swabbing technique were compared with two wash-off methods. For the first wash-off method the destructive elution method was used, where microorganisms were eluted from the fabrics by shaking the fabrics for a certain time in an elution medium. For the fourth sampling method a nondestructive method that included a compact test device called Morapex® was used, which is based on forced desorption by pressing the microorganisms through the fabric without destroying the fabric. In our research, two types of microorganisms were included (Klebsiella pneumoniae and Staphylococcus aureus) that cause common nosocomial infections. The aim of this study was to compare the efficiency of the four sampling methods for detecting microorganisms on textiles and to determine the lowest concentration, which can still be detected. The percentage of microorganisms that were detected by both elution methods was substantially higher than by sampling of fabrics with the contact plate method or swabbing. It can be concluded that a nondestructive method using a modified Morapex® device can be applied for quick determination of the hygienic condition of textiles.