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Microbial Monitoring of a Manufacturing Facility
Published in Philip A. Geis, Cosmetic Microbiology, 2020
To sample hard-to-access interior equipment surfaces (e.g., processing vessels, storage tanks, etc.) that cannot be reached by using a swab or direct contact method, a rinse water sampling technique is used (35). To perform a rinse water method of an interior equipment surface, a volume of sterile water is introduced to flush the interior surfaces of the equipment. A 100-milliliter aliquot of the sterile rinse water is collected as it exits from the flushed equipment. This rinse water aliquot can be tested for microbial count by using a pour plate, membrane filtration, or Most Probable Number (MPN) method to yield a quantitative microbial test result. The advantages in using a rinse water method is that inaccessible areas of manufacturing equipment can be accessed, large interior surface areas can be sampled, and quantitative microbial results can be obtained. Disadvantages of sampling rinse water include lack of suitability for many equipment assessments, not suitable for many applications, extensive manual manipulation is required, and aseptic sample collection and processing techniques which can affect microbial test results.
Water quality and standards
Published in Sandy Cairncross, Richard Feachem, Environmental Health Engineering in the Tropics, 2018
Sandy Cairncross, Richard Feachem
Every country should be equipped with at least one, and usually several laboratories able to carry out, rapidly and routinely, tests for the presence of coliforms and thermotolerant coliforms in drinking water supplies. Two main laboratory methods may be used. First, there is the ‘most probable number’, also called the ‘multiple tube’, method in which the water under consideration is mixed with a nutrient medium (often MacConkey broth) and incubated for a particular time (usually 24 hours) at a particular temperature (usually 37°C for total coliforms and 44°C for thermotolerant coliforms). The production of acid (which turns the purple MacConkey broth yellow) and of gas (which is caught in a small inverted tube within the liquid) are confirmation of the presence of coliform bacteria. A number of test tubes are incubated, containing different volumes of the water under examination, and by observing the number of positive reactions (in other words the production of both acid and gas) it is possible to derive from tables the most probable number (MPN) of coliform bacteria in the original water. This method is described in detail in a number of texts (APHA 2017; AWWA 2014).
Indicators of microbial quality *
Published in Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse, Routledge Handbook of Water and Health, 2015
Manja et al. (1982) first reported the development of a simple, reliable, and low-cost field microbiological test to detect bacteria that produce H2S (including Citrobacter, Salmonella, Clostridium perfringens, Staphylococcus, Klebsiella, and others, though not E. coli). These microorganisms reduce organic sulfur to H2S gas, which then readily reacts with iron to form a black iron precipitate. The H2S test is unable to differentiate between naturally occurring H2S-producing bacteria and those associated with fecal contamination of water. The H2S test has been shown to be largely consistent with other indicators (Khush et al. 2013), though it is often used as a presence/absence or most probable number (MPN) method that may not be directly comparable to membrane filtration-based assays. H2S-producing bacteria may be useful as indicators of diarrheal disease risk (Levy et al. 2012), though additional studies are needed.
From correlation to causality: the case of Subdoligranulum
Published in Gut Microbes, 2020
Matthias Van Hul, Tiphaine Le Roy, Edi Prifti, Maria Carlota Dao, Adrien Paquot, Jean-Daniel Zucker, Nathalie M. Delzenne, Giulio G. Muccioli, Karine Clément, Patrice D. Cani
Subdoligranulum variabile DSM 15176 T was obtained from the Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ). The strain was routinely cultured in yeast extract-peptone medium supplemented with glucose, raffinose and anti-oxidants (detailed composition in supplementary Table 1). Attempts to enumerate S. variabile DSM 15176 T on solid medium failed despite separate autoclaving of phosphate and agar, as well as replacement of agar by gellan gum.39,40 Thus, live and cultivable bacteria were enumerated using most probable number calculation associated to dilution to extinction method: bacterial culture was serially diluted to the appropriate concentrations according to optical density (OD) measurements at 680 nm, then 10 vials per dilution were inoculated with 1 ml of dilution. The number of vials with visible growing within the three following days allowed the calculation of the live bacteria concentration in the culture.41 For the administration to the mice, bacterial culture was centrifuged at 4000 g during 20 min at 4°C. Then supernatant was removed, and the pellet was washed twice in anoxic PBS supplemented with antioxidants and finally resuspended in glycerol (25% vol/vol) and stored at −80°C.
Design of a rotating disk reactor to assess the colonization of biofilms by free-living amoebae under high shear rates
Published in Biofouling, 2018
A. Perrin, P. Herbelin, F. P. A. Jorand, S. Skali-Lami, L. Mathieu
The thermophilic free-living amoebic cells were counted by the most probable number (MPN) approach, described by Pougnard et al. (2002). The MPN approach determines the cell densities of cultivable FLA, both trophozoites and cysts, without discriminating between the two forms. Immediately after sample collection, 5 or 10 replicates of 1 ml each from a 10-fold dilution series were spread on non-nutrient agar (NNA) plates previously overlaid with Escherichia coli. The plates were incubated at 43°C and examined microscopically daily for five days for presence of an amoebic migration front, suggesting the presence of viable thermophilic FLA cells. Every day over the five-day incubation period, all the amoebic migration fronts were observed and the vegetative and cyst forms of the amoebae were identified morphologically under the microscope as recommended by Page (1967) and Adl et al. (2012). To confirm the presence of the genus Naegleria, positive samples were further analyzed to determine induction of flagella formation, using the protocol described by Goudot et al. (2012), by incubating vegetative forms in demineralized water at 37°C for 2 h. The limits of quantification in water and biofilms were 90 FLA l−1 and 0.6 FLA cm−2, respectively.
Loop-mediated isothermal amplification assay as a point-of-care diagnostic tool for Vibrio parahaemolyticus: recent developments and improvements
Published in Expert Review of Molecular Diagnostics, 2019
Karanth Padyana Anupama, Anirban Chakraborty, Iddya Karunasagar, Indrani Karunasagar, Biswajit Maiti
To date, a number of LAMP assays have been developed to detect foodborne pathogens [42], including Salmonella Typhi [43,44], Campylobacter [45], Escherichia coli [46], Helicobacter pylori [47,48] etc. Garrido-Maestu et al. [49] developed a combination of the microfluidic LAMP with gold nanoparticles targeting the invA gene for the detection of Salmonella spp. Various modifications have been made on the LAMP assay, which includes most probable number LAMP (MPN-LAMP), aptamers magnetic capture LAMP, multiplex LAMP (m-LAMP), LAMP-based gold nanoparticles lateral flow biosensor, multiple endonuclease restriction real-time LAMP (MERT-LAMP), reverse-transcriptase LAMP (RT-LAMP) [11,50–52].