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Niu C, Zhang Y, Zhang Y. Evaluation of a Most Probable Number Method for Detection and Quantification of Legionella pneumophila. Pathogens 2022; 11. [PMID: 35890033 DOI: 10.3390/pathogens11070789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/02/2022] [Accepted: 07/07/2022] [Indexed: 11/17/2022] Open
Abstract
The detection and enumeration of Legionella pneumophila (L. pneumophila) in water is crucial for water quality management, human health and has been a research hotspot worldwide. Due to the time-consuming and complicated operation of the plate culture method, it is necessary to adopt a fast and effective method for application. The present study aimed to comprehensively evaluate the performance and applicability of the MPN method by comparing its qualitative and quantitative results with the GB/T 18204.5-2013 and ISO methods, respectively. The qualitative results showed that 372 samples (53%) were negative for both methods; 315 samples (45%) were positively determined by the MPN method, compared with 211 samples (30%) using GB/T 18204.5-2013. The difference in the detection rate between the two methods was statistically significant. In addition, the quantitative results showed that the concentration of L. pneumophila by the MPN method was greater than ISO 11731 and the difference was statistically significant. However, the two methods were different but highly correlated (r = 0.965, p < 0.001). The specificity and sensitivity of the MPN method were 89.85% and 95.73%, respectively. Overall, the results demonstrated that the MPN method has higher sensitivity, a simple operation process and good application prospects in the routine monitoring of L. pneumophila from water samples.
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López A, Baguer B, Goñi P, Rubio E, Gómez J, Mosteo R, Ormad MP. Assessment of the methodologies used in microbiological control of sewage sludge. Waste Manag 2019; 96:168-174. [PMID: 31376961 DOI: 10.1016/j.wasman.2019.07.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 06/28/2019] [Accepted: 07/14/2019] [Indexed: 06/10/2023]
Abstract
Sewage sludge usually contains potentially polluting substances such as heavy metals, organic pollutants and various organisms including bacteria, protozoa, helminths, viruses and algae, some of which may be pathogenic. Certain of these pathogens could be transferred to the soil if the sludge is used on agricultural or land recovery applications. For its application on agricultural land, sewage sludge must comply with the limits established in the legislation, which in Europe does not include quality standards regarding microbiological parameters. Nevertheless, the presence of pathogens could limit its agricultural use, as it could pose a risk to human, animal and environmental health. This study compares 4 different methodologies used in microbiological analysis in order to identify the most efficient and reliable method on determining bacteria in sewage sludge. Escherichia coli and Enterococcus faecium are used as bacterial indicators. The results obtained in this work indicate that results obtained with three different plate count methods cannot be comparable with those obtained with the MPN method. The membrane filtration method is recommended for its high precision and sensitivity, both in low and high bacterial loads. It is also concluded that it would be necessary to establish the quality standard in concordance with the method used.
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Affiliation(s)
- A López
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain.
| | - B Baguer
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain
| | - P Goñi
- Department of Microbiology, Preventive Medicine and Public Health, Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Faculty of Medicine, University of Zaragoza, Calle Domingo Miral, 50009 Zaragoza, Spain
| | - E Rubio
- Department of Microbiology, Preventive Medicine and Public Health, Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Faculty of Medicine, University of Zaragoza, Calle Domingo Miral, 50009 Zaragoza, Spain
| | - J Gómez
- Navarra de Infraestructuras Locales S.A (NILSA), Avenida Barañain 22, 31008 Pamplona, Spain
| | - R Mosteo
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain
| | - M P Ormad
- Water and Environmental Health Research Group, Environmental Sciences Institute (IUCA), Department of Chemical Engineering and Environmental Technologies, School of Engineering and Architecture, University of Zaragoza, Calle María de Luna 3, 50018 Zaragoza, Spain
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