Microbiological contamination of ear, nose and throat (ENT) units

Aim: In ENT (Ear, Nose and Throat) treatment units, medical devices for examination are commonly stored on open trays. The aim of this study is to investigate whether open storage is a relevant cause for microbiological contamination of ENT instruments during a working day. Methods: Qualitative and quantitative tests, such as imprints and swabs, were performed on the instruments and the surfaces of the treatment units in an ENT outpatient clinic at the beginning and at the end of consultation hours. The microbiological analysis of the samples focused on potential pathogens, e.g., Staphylococcus aureus or Pseudomonas aeruginosa, bacteria of skin and oral microbiota, as well as the number of colony forming units (CFU). The samples were collected at three distinct ENT treatment units over five working days. Results: The samples taken at the beginning of consultation hours showed a low number of CFU and no pathogens. Overall, 5% of the instruments were contaminated with bacteria of skin microbiota. At the end of a working day, this rate increased significantly to 17.5% (p<0.01). At the beginning of the working day, the mean number on the instrument trays was 4 CFU/25 cm², which increased to 34 CFU/25 cm² at the end of the working day. In some cases of the imprints taken at the end of the working day showed that a bacterial lawn had formed. In two cases, the pathogens Ralstonia picketii and Enterobacter cloacae were detected; in another case Bacillus spp. was identified. The contamination of ENT instruments and the ENT treatment unit increased significantly (p<0.01) over the duration of consultation hours. Conclusion: The results show that the current hygiene requirements for storage und reprocessing are not sufficient to conform to the mandatory guidelines of the German Commission on Hospital Hygiene and Infection Prevention. Although we could not find a pressing risk for the patients, we also cannot exclude it in the long term. Thus, new concepts are needed.