Targeted Molecular Detection of Nosocomial Carbapenemase-Producing Gram-Negative Bacteria-On Near- and Distant-Patient Surfaces

Background: Here, we describe an integrative method to detect carbapenemase-producing Gram-negative bacteria (gn-Cp) on surfaces/fomites in the patient environment. We examined environmental samples from 28 patient rooms occupied with patients who were proven to be colonised with gn-Cp by rectal screening. Methods: We took samples after 24 h, 72 h and one week. For sampling, we divided the patient environment into four parts and took samples from near- and extended patient areas. To obtain a representative bacterial swab from a larger surface, such as the patient cabinet, we used Polywipes. Bacterial DNA was isolated. Carbapenemase was detected with specific qPCR primers. Results: With this culture- and molecular-based approach, we could control the effectiveness of cleaning and disinfection in everyday clinical practice. Therefore, we could track the spread of gn-Cp within the patient room. The number of positive detections fluctuated between 30.5% (mean value positive results after 72 h) and 35.2% (after 24 h and one week). Conclusion: The method used to detect multidrug-resistant bacteria in the environment of patients by using Polywipes(TM) is reliable and can therefore be used as an effective, new tool in hygiene and infection control.

Automated summary

The integrative method described in this study allows for the detection of carbapenemase-producing Gram-negative bacteria on surfaces and fomites in patient environments. By using Polywipes(TM) to sample surfaces and specific qPCR primers for detection, the spread of these bacteria within patient rooms can be effectively tracked.