Semiautomated detection of Pseudomonas aeruginosa from diverse water samples using highly selective Z-broth and a redox potential monitor

Abstract

AbstractPseudomonas aeruginosa is a facultative bacterial pathogen with increasing public health risk potential. Contaminated water in hospital environments is a growing cause of multidrug-resistent P. aeruginosa nosocomial infections that are life-threatening and are costly to treat. P. aeruginosa is common in natural water bodies, but it is not unusual in drinking water and has been detected in bottled water, also. Suppliers in Europe must eliminate live forms of the bacterium in drinking water to meet human consumption requirements. Laboratory testing for the presence of viable P. aeruginosa is mostly done manually using culture media but conductance/impedimetry measurements for detection are also available. In order to improve expedience and cost efficiency as well as to automate the detection and the data registration, we applied the highly selective Z-broth culture media and redox potential monitoring to detect P. aeruginosa from water. The Z-broth is based on only a few, stable chemicals that provide consistency of quality and long shelf life. It limits growth to P. aeruginosa and, thus, eliminates the need for subsequent microbiological identification steps of the European Standard procedure defined in ISO 16 266:2006 (2018). A redox potential monitor was used in this work, that simultaneously recorded 64 sample curves and automatically marked positive samples reliably within 24 hours after sample initialization. In comparison, the standard method requires additional tests that prolongs identification to some days. Practical applicability and reliability of the method in this paper was demonstrated by testing a total of 739 water samples of which 222 were tap water, 342 well water and 145 had been taken from swimming pools.It is considered this method is well suited to process large numbers of samples for purposes of detecting P. aeruginosa contamination with relative ease, little cost in shortened time. Using Z-broth in combination with redox potential monitoring can be recommended for central laboratories for routine testing of drinking water for live P. aeruginosa presence. As well, using this method for testing of fluids and surfaces for P. aeruginosa contamination would be advantageous in such environments as the hospital industry, swimming pools and spas, where cleaning routines and P. aeruginosa transmission prevention protocols could be made much more resultful and cost-effective due to ease and speed of processing both spot check and water samples.HighlightsA method was applied for detection of viable Pseudomonas aeruginosa in 739 water samples.Redox potential monitoring of Z-broth cultures exclusively registered growth of P. aeruginosa.The method is highly selective, reliable and partly automated, with lower labor costs.The method is suited for testing of water and hospital environments for P. aeruginosa.