Journal articles: 'Impedance microbiology'

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WAWERLA, MONIKA, A. STOLLE, BARBARA SCHALCH, and H. EISGRUBER. "Impedance Microbiology: Applications in Food Hygiene." Journal of Food Protection 62, no. 12 (December 1, 1999): 1488–96. http://dx.doi.org/10.4315/0362-028x-62.12.1488.

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Impedance microbiology is a rapid method that enables qualitative and quantitative tracing of microorganisms by measuring the change in the electrical conductivity. With direct impedance technology, the change in the conductivity of a liquid culture medium serves as a measuring parameter, whereas with indirect impediometry, the change in the electrical conductivity of a reaction solution, which occurs through the absorption of gases from the inoculated bacterial culture, is measured. Most investigations concerning the applicability of impediometry in food microbiology deal with the impedimetric detection or enumeration of Enterobacteriaceae, especially the detection of Salmonella. However, impediometry has been applied to other bacterial groups or species as well. Furthermore, a great number of published findings concern the impedimetric determination of the total bacterial count. The successful application of this fast method on further areas of food hygiene, such as tracing antibiotics and testing additives for their antimicrobiological effect, has also been described. In general the use of impediometry for the application areas stated has been judged positively. However, the time and expense required by the user to optimize the method, the deficits when testing slightly contaminated sample material or determining the bacterial count in those cases in which the microorganisms are sublethally damaged, and the necessity of performing individual calibration for each food category limit the applicability of impediometry.

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Felice, C. J., and M. E. Valentinuzzi. "Medium and interface components in impedance microbiology." IEEE Transactions on Biomedical Engineering 46, no. 12 (1999): 1483–87. http://dx.doi.org/10.1109/10.804577.

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Silley, P., and S. Forsythe. "Impedance microbiology-a rapid change for microbiologists." Journal of Applied Bacteriology 80, no. 3 (March 1996): 233–43. http://dx.doi.org/10.1111/j.1365-2672.1996.tb03215.x.

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KHAYAT, F. A., and G. H. RICHARDSON. "Detection of Abnormal Milk with Impedance Microbiology Instrumentation." Journal of Food Protection 49, no. 7 (July 1, 1986): 519–22. http://dx.doi.org/10.4315/0362-028x-49.7.519.

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Mastitic milk was detected by obtaining conductance measurements using an impedance microbiology Bactomatic 120 SC instrument. Conductance readings separated normal and abnormal milks after 30 min at 25°C when readings differed by more than 2 to 3% and exceeded the variance among instrument module wells. Samples blended from four quarters of a cow indicated milk from one quarter was abnormal if the salt level in the abnormal quarter raised the blend conductivity above that of normal samples and variance among the wells. Either solid or liquid substrates that contained stimulants could be used to accelerate bacterial acid production or reduce impedance detection times and did not affect the ability to detect abnormal milk. However, measurements varied with the volume of sample in the well, suggesting that fixed 1-ml liquid volumes of milk be used. Such volumes would allow detection of abnormal milk and bacterial load on the same sample.

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GLASSMOYER, KIRSTEN E., and SCOTT M. RUSSELL. "Evaluation of a Selective Broth for Detection of Staphylococcus aureus Using Impedance Microbiology." Journal of Food Protection 64, no. 1 (January 1, 2001): 44–50. http://dx.doi.org/10.4315/0362-028x-64.1.44.

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Experiments were conducted to evaluate a selective nutrient broth containing acriflavine and nalidixic acid for detection of Staphylococcus aureus using an impedance microbiological method. Nine species of bacteria, other than S. aureus, were evaluated using the selective broth to determine if these species could be inhibited. A total of 10 ppm of nalidixic acid inhibited the gram-negative species tested, with the exception of Pseudomonas aeruginosa. Similarly, 10 ppm of acriflavine suppressed the Staphylococcus spp. examined; however, S. aureus retained the ability to proliferate. Nutrient broth solution containing 10 ppm of nalidixic acid and 10 ppm of acriflavine (S. aureus impedance broth [SIB]) inhibited multiplication of most of the bacterial species tested and allowed S. aureus to be detected in an average of 16.4 h. Fresh chicken carcass rinses and cooked chicken rinses were inoculated with Escherichia coli and S. aureus and assayed using SIB in conjunction with impedance. Results demonstrated that S. aureus could be detected in less than 11.5 h, although the presence of E. coli decreased detection times. Additionally, impedance assays were conducted using five different poultry products to evaluate the sensitivity of the broth for detecting S. aureus. S. aureus could be detected on poultry products when present at low levels (101 CFU/ml) in less than 24 h. These studies demonstrated that SIB may be used in conjunction with impedance for rapid detection of S. aureus. However, without further modification, this method should not be used for enumeration of S. aureus from samples containing mixed microflora.

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RUSSELL, SCOTT M., DANIEL L. FLETCHER, and NELSON A. COX. "Comparison of Media for Determining Temperature Abuse of Fresh Broiler Carcasses Using Impedance Microbiology." Journal of Food Protection 58, no. 10 (October 1, 1995): 1124–28. http://dx.doi.org/10.4315/0362-028x-58.10.1124.

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Experiments were conducted to determine the ideal medium for detection of temperature abuse of fresh broiler chicken using impedance microbiological techniques. In three separate trials, 15 ready-to-cook broiler chicken carcasses were obtained from the chiller exit of three separate processing plants. Five carcasses were sampled immediately (day 0), 5 carcasses were sampled after temperature abusing at 25°C for 12 h and holding at 3°C for 6 days (temperature abused), and the remaining 5 carcasses were sampled after holding at 3°C for 7 days (day 7 controls). Whole-carcass rinses were diluted by placing 1 ml from each carcass into 9 ml of each of the following media: (1) brain heart infusion broth (BHI), (2) EC broth with 3% added dextrose (ECD), (3) CM medium with 2% added dextrose (CMD), (4) EC broth (EC), and (5) CM medium (CM). The diluted samples were assayed in duplicate at 43°C using impedance microbiological techniques. Once a detection time (DT) was recorded, one ml of the sample was immediately recovered from the module well, diluted to 10−6, 10−7, and 10−8, and spread plated onto plate count agar. Two colonies from each carcass on plates with the highest dilution were randomly selected and identified. Since both gram-positive and gram-negative genera of bacteria were isolated from BHI-cultured carcass rinses and were responsible for changing the impedance of the medium, DTs were variable. EC and ECD media were not suitable for conducting temperature-abuse determinations. Using CMD medium to select for the growth of gram-negative bacteria, specifically E. coli, temperature-abuse determinations were more accurate than using a general medium, such as BHI. CMD appears to be the most effective medium tested to conduct temperature abuse determinations using impedance microbiological techniques.

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SILVA, J. L., C. L. WANG, M. SCRUGGS, P. L. SILVA, and T. KIM. "IMPEDANCE MICROBIOLOGY TO SCREEN VARIOUS ANTIMICROBIALS ON WHOLE AND FILLET CHANNEL CATFISH." Journal of Rapid Methods and Automation in Microbiology 11, no. 2 (October 2003): 153–61. http://dx.doi.org/10.1111/j.1745-4581.2003.tb00037.x.

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Einarsson, Hjorleifur. "Use of Impedance and Optical Density Instruments in Food Microbiology Hjorleifur Einarsson." Journal of AOAC INTERNATIONAL 71, no. 2 (March 1, 1988): 449. http://dx.doi.org/10.1093/jaoac/71.2.449.

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Chang, Tsung Chain, and Ay Huey Huang. "Rapid Differentiation of Fermentative from Nonfermentative Gram-Negative Bacilli in Positive Blood Cultures by an Impedance Method." Journal of Clinical Microbiology 38, no. 10 (2000): 3589–94. http://dx.doi.org/10.1128/jcm.38.10.3589-3594.2000.

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Rapid differentiation of fermentative gram-negative bacilli (fermenters) from nonfermentative gram-negative bacilli (nonfermenters) in positive blood cultures may help physicians to narrow the choice of appropriate antibiotics for empiric treatment. An impedance method for direct differentiation of fermenters from nonfermenters was investigated. The bacterial suspensions (or positive culture broths containing gram-negative bacteria) were inoculated into the module wells of a Bactometer (bioMérieux, Inc., Hazelwood, Mo.) containing 1 ml of Muller-Hinton broth. The inoculated modules were incubated at 35°C, and the change in impedance in each well was continuously monitored. The amount of time required to cause a series of significant deviations from baseline impedance values was defined as the detection time (DT). The percent change of impedance was defined as the change of impedance at the time interval from DT to DT plus 1 h. After testing 857 strains of pure cultures (586 strains of fermenters and 271 strains of nonfermenters), a breakpoint (2.98%) of impedance change was obtained by discriminant analysis. Strains displaying impedance changes of greater than 2.98% were classified as fermenters; the others were classified as nonfermenters. By using this breakpoint, 98.6% (340 of 345) of positive blood cultures containing fermenters and 98% (98 of 100) of positive blood cultures containing nonfermenters were correctly classified. The impedance method was simple, and the results were normally available within 2 to 4 h after direct inoculation of positive blood culture broths.

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Gomez-Sjoberg, R., D. T. Morisette, and R. Bashir. "Impedance microbiology-on-a-chip: microfluidic bioprocessor for rapid detection of bacterial metabolism." Journal of Microelectromechanical Systems 14, no. 4 (August 2005): 829–38. http://dx.doi.org/10.1109/jmems.2005.845444.

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Bancalari, Elena, Paolo D'Incecco, Maria Luisa Savo Sardaro, Erasmo Neviani, Luisa Pellegrino, and Monica Gatti. "Impedance microbiology to speed up the screening of lactic acid bacteria exopolysaccharide production." International Journal of Food Microbiology 306 (October 2019): 108268. http://dx.doi.org/10.1016/j.ijfoodmicro.2019.108268.

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ANDRADE, NELIO J., TRACY A. BRIDGEMAN, and EDMUND A. ZOTTOLA. "Bacteriocidal Activity of Sanitizers against Enterococcus faecium Attached to Stainless Steel as Determined by Plate Count and Impedance Methods." Journal of Food Protection 61, no. 7 (July 1, 1998): 833–38. http://dx.doi.org/10.4315/0362-028x-61.7.833.

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Enterococcus faecium attached to stainless steel chips (100 mm2) was treated with the following sanitizers: sodium hypochlorite, peracetic acid (PA), peracetic acid plus an organic acid (PAS), quaternary ammonium, organic acid, and anionic acid. The effectiveness of sanitizer solutions on planktonic cells (not attached) was evaluated by the Association of Official Analytical Chemists1 (AOAC) suspension test. The number of attached cells was determined by impedance measurement and plate count method after vortexing. The decimal reduction (DR) in numbers of the E. faecium population was determined for the three methods and was analyzed by analysis of variance (P < 0.05) using Statview software. The adhered cells were more resistant (P < 0.05) than nonadherent cells. The DR averages for all of the sanitizers for 30 s of exposure were 6.4, 2.2, and 2.5 for the AOAC suspension test, plate count method after vortexing, and impedance measurement, respectively. Plate count and impedance methods showed a difference (P < 0.05) after 30 s of sanitizer exposure but not after 2 min. The impedance measurement was the best method to measure adherent cells. Impedance measurement required the development of a quadratic regression. The equation developed from 82 samples is as follows: log CFU/chip = 0.2385T2 − 0.96T + 9.35, r2 = 0.92, P < 0.05, T = impedance detection time in hours. This method showed that the sanitizers PAS and PA were more effective against E. faecium than the other sanitizers. At 30 s, the impedance method recovered about 25 times more cells than the plate count method after vortexing. These data suggest that impedance measurement is the method of choice when evaluating the number of bacterial cells adhered to a surface.

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CHABOWSKI, KONRAD, ADAM FELIKS JUNKA, PATRYCJA SZYMCZYK, TOMASZ PIASECKI, ANDRZEJ SIERAKOWSKI, BEATA MĄCZYŃSKA, and KAROL NITSCH. "The application of impedance microsensors for real-time analysis of Pseudomonas aeruginosa biofilm formation." Polish Journal of Microbiology 64, no. 2 (2015): 115–20. http://dx.doi.org/10.33073/pjm-2015-017.

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Biofilms formed by nosocomial pathogens represent a major threat to patients undergoing invasive procedures. As prophylaxis remains the most efficient anti-biofilm option, it is of paramount importance to develop diagnostic tools able to detect biofilm at the early stage of formation. The present study investigates the ability of impedance microsensors to detect Pseudomonas aeruginosa biofilm presence using the impedance spectroscopy method. The measured data were analyzed using Electrical Equivalent Circuit modelling (EEC). It allowed to recognize conduction and polarization phenomena on the sensors surface and in its environment. The impedance assay results, confirmed by means of electron microscopy and quantitative cultures, indicate that specific EEC parameters may be used for monitoring the development of pseudomonal biofilm.

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Felice, Carmelo J., Rossana E. Madrid, Juan M. Olivera, Viviana I. Rotger, and Max E. Valentinuzzi. "Impedance microbiology: quantification of bacterial content in milk by means of capacitance growth curves." Journal of Microbiological Methods 35, no. 1 (February 1999): 37–42. http://dx.doi.org/10.1016/s0167-7012(98)00098-0.

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Miller, Craig, Madison Stiglich, Mark Livingstone, and Jordon Gilmore. "Impedance-Based Biosensing of Pseudomonas putida via Solution Blow Spun PLA: MWCNT Composite Nanofibers." Micromachines 10, no. 12 (December 13, 2019): 876. http://dx.doi.org/10.3390/mi10120876.

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Quantifiable sensing of common microbes in chronic wounds has the potential to enable an objective assessment of wound healing for diagnostic applications. Sensing platforms should be robust, simple, and flexible to provide clinicians with a point-of-care tool. In this work, solution blow spun poly (lactic acid)/multiwalled carbon nanotube nanofiber composites are used to detect the presence and concentration of Pseudomonas putida in vitro using changes in impedance. Impedance microbiology (IM) is a well-documented diagnostic technique used in many applications, including cancer detection, tuberculosis screening and pregnancy tests. Twenty-four hour real-time measurements of the equivalent circuit of three culture media were taken with an inductance, capacitance, and resistance (LCR) meter. Variations in impedance were calculated to correspond to the growth of P. putida. Additionally, instantaneous measurements of bacterial cultures were taken over a one-minute time point to display the fast sensing of bacterial load via IM. This proof-of-concept shows that conductive solution blow spun fiber mats is a valid fabrication technique to develop in situ wound dressing impedance sensors. Study results indicate successful measurement and quantification of bacterial growth in this proof-of-concept study.

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OKIGBO, O. N., and G. H. RICHARDSON. "Detection of Penicillin and Streptomycin in Milk by Impedance Microbiology1,2." Journal of Food Protection 48, no. 11 (November 1, 1985): 979–81. http://dx.doi.org/10.4315/0362-028x-48.11.979.

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A Bactometer 123 impedance instrument detected .001 IU penicillin or streptomycin/ml of sterile milk inoculated with 5% active lactic culture. Results were available in 5 to 10 h. Inactive lactic culture produced results in less than 24 h. Impedance instruments can monitor incoming milk supplies simultaneously for bacterial load, abnormal milk, and antibiotics.

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Mortari, Alessia, Marco S. Nicolò, Andrea Adami, Cristian Collini, Salvatore P. P. Gugliemino, and Leandro Lorenzelli. "Proof of Principle of a Novel Impedance Microbiology Method Based on Bacteriophages Functionalized Paramagnetic Nanobeads." Procedia Engineering 87 (2014): 328–31. http://dx.doi.org/10.1016/j.proeng.2014.11.749.

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Eng, C., and P. Valenstein. "Standardization of yeast inocula with an electronic impedance counter." Journal of Clinical Microbiology 27, no. 10 (1989): 2397–99. http://dx.doi.org/10.1128/jcm.27.10.2397-2399.1989.

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Esfandyarpour, Rahim, Mehdi Javanmard, Zahra Koochak, James S. Harris, and Ronald W. Davis. "Nanoelectronic impedance detection of target cells." Biotechnology and Bioengineering 111, no. 6 (December 28, 2013): 1161–69. http://dx.doi.org/10.1002/bit.25171.

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MOORE, JOHN E., and ROBERT H. MADDEN. "Impediometric Detection of Campylobacter coli." Journal of Food Protection 65, no. 10 (October 1, 2002): 1660–62. http://dx.doi.org/10.4315/0362-028x-65.10.1660.

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The rapid automated bacterial impedance technique (RABIT) was examined as a method for the detection of two wild-type isolates of Campylobacter coli in broth media. Both isolates failed to produce a change in impedance that was sufficient for detection in any combination of six nonselective basal broth media, including Mueller-Hinton broth, nutrient broth no. 2, brain heart infusion broth supplemented with yeast extract (0.5% [wt/vol]), brucella broth, Campy broth supplemented with yeast extract (0.5% [wt/vol]), and Whitley impedance broth, at 37 and 42°C. Although the strains did proliferate in the media, changes in conductivity were very small (ranging from 0 to 1,000 μS) and were not significantly greater than the drift in conductance observed in the control broth medium. Additional work is therefore required to define a nonionic growth substrate that will produce charged ions upon metabolism that are detectable by RABIT.

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KHAYAT, F. A., J. C. BRUHN, and G. H. RICHARDSON. "A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods1." Journal of Food Protection 51, no. 1 (January 1, 1988): 53–55. http://dx.doi.org/10.4315/0362-028x-51.1.53.

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A total of 256 cheese samples were analyzed for coliform plate count using violet red bile agar and for an impedance count using BactometerR Coliform Medium with a correlation coefficient between methods of R=−.91. Fifty-four percent of the samples contained 102 to 107 colony forming units/gram (CFU/g). The highest counts were in cream and fresh cheese products. When 27 Cheddar cheese samples were inoculated with from 102 to 107 CFU of Escherichia coli/g a correlation of R=−.97 was found between methods. Two hundred of the cheese samples were analyzed for Staphylococcus aureus using Baird-Parker medium and impedance count using BactometerR S.aureus Medium. Five samples (2%) contained over 103 CFU/g. The strains isolated were coagulase-positive. When 34 samples of cheese were inoculated with 102 to 107 CFU of staphylococci/g, the correlation between the plate and impedance method was R=0.98.

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Kleiss, T., J. Albrecht, T. Putallaz, and J. L. Cordier. "Impedance measurement of the microbial flora in dairy-based desserts." Journal of Microbiological Methods 22, no. 2 (May 1995): 131–37. http://dx.doi.org/10.1016/0167-7012(94)00069-j.

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BYRNE, R. D., J. R. BISHOP, and J. W. BOLING. "Estimation of Potential Shelf-life of Pasteurized Fluid Milk Utilizing a Selective Preliminary Incubation." Journal of Food Protection 52, no. 11 (November 1, 1989): 805–7. http://dx.doi.org/10.4315/0362-028x-52.11.805.

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Selective preliminary incubation, followed by bacterial enumerations or detection techniques, was used to indicate potential shelf-life of pasteurized fluid milk. Commercial whole milk samples, stored at 7°C, were analyzed for bacterial and biochemical parameters and potential shelf-life using daily organoleptic evaluation. Prior to analysis, each sample was subjected to the following preliminary incubations: milk alone, milk with benzalkonium chloride, milk and broth, milk and broth with benzalkonium chloride, and milk and a dairy gram-negative broth. The following bacterial enumerations were conducted: Psychrotrophic Bacteria Count, modified Psychrotrophic Bacteria Count (Petrifilm and agar methods), and Moseley Keeping Quality test (Petrifilm and agar methods). Catalase detection (headspace pressure and flotation time) and impedance detection times were also determined. Initial Standard Plate and Coliform counts (Petrifilm and agar methods) were conducted on each fresh sample but were not used for shelf-life prediction. Many of the preliminary incubations, in conjunction with enumeration or detection combinations, (especially modified Psychrotrophic Bacteria Count and impedance microbiology) gave good correlations to shelf-life (−0.89 and 0.91, respectively). Thus, these methods could be used to indicate the potential shelf-life of pasteurized fluid milk.

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MOSTELLER, T. M., and J. R. BISHOP. "Sanitizer Efficacy Against Attached Bacteria in a Milk Biofilm." Journal of Food Protection 56, no. 1 (January 1, 1993): 34–41. http://dx.doi.org/10.4315/0362-028x-56.1.34.

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Pseudomonas fluorescens, Yersinia enterocolitica, and Listeria monocytogenes were shown to readily attach to both rubber and Teflon® surfaces. Sanitizer efficacy testing done in the laboratory with nonadherent bacteria could lead to false assumptions as to the sanitizer's true effectiveness under processing conditions where cells may be attached. The objectives in this study were: (a) evaluate the efficacy of in-use concentrations of sanitizers on bacteria attached to gasket materials, (b) compare bacterial attachment to rubber and Teflon® gaskets, (c) examine different methods of enumeration, and (d) compare sanitizer efficacy on attached and suspended bacteria. The goal reduction for all of the sanitizers tested was ≥3 log cycles or 99.9%. Results indicated that iodophor, hypochlorite, acid anionic, peroxyacetic acid, fatty acid, and quaternary ammonium sanitizers failed to provide an adequate reduction in the numbers of attached bacteria at levels of 104 to 105/mm2 in most cases. The test organisms attached in slightly higher numbers to the rubber surface versus Teflon®. Plate counts, impedance microbiology, and the direct epifluorescent filter technique were tested as methods of enumeration. Impedance microbiology was the best method of enumeration, since it allowed the estimation of both reversibly and irreversibly attached bacteria. The efficacy of sanitizers versus a bacterial suspensions resulted in a ≥ 5 log-cycle reduction. The same concentrations were relatively ineffective against the attached bacteria. The goal reduction was reached on the Teflon® surface with the iodophor, hypochlorite, and fatty acid sanitizers with a log-cycle reduction in the number of Yersinia enterocolitica of 3.09, 3.19, and 3.31, respectively. Pseudomonas fluorescens was reduced by 3.16 on both the rubber and Teflon® surfaces when exposed to the hypochlorite sanitizer.

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Dai, Meng, Xue-Chao Liu, Hao-Ting Li, Can-Hua Xu, Bin Yang, Hang Wang, Xue-Tao Shi, Xiu-Zhen Dong, and Feng Fu. "EIT Imaging of Intracranial Hemorrhage in Rabbit Models Is Influenced by the Intactness of Cranium." BioMed Research International 2018 (November 19, 2018): 1–10. http://dx.doi.org/10.1155/2018/1321862.

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Electrical impedance tomography (EIT) has been shown to be a promising, bedside imaging method to monitor the progression of intracranial hemorrhage (ICH). However, the observed impedance changes within brain related to ICH differed among groups, and we hypothesized that the cranium intactness (open or closed) may be the one of potential reasons leading to the difference. Therefore, the aim of this study was to investigate this effect of open or closed cranium on impedance changes within brain in the rabbit ICH model. In this study, we first established the ICH model in 12 rabbits with the open cranium and in 12 rabbits with the closed cranium. Simultaneously, EIT measurements on the rabbits’ heads were performed to record the impedance changes caused by injecting the autologous nonheparinized blood into cerebral parenchyma. Finally, the regional impedance changes on EIT images and the whole impedance changes were analyzed. It was surprisingly found that when the cranium was open, the impedance of the area where the blood was injected, as well as the whole brain impedance, decreased with the amount of blood being injected; when the cranium was closed, while the impedance of the area where blood was not injected continued to increase, the impedance of the area where blood was injected decreased within 20s of the blood being injected and then remained almost unchanged, and the whole brain impedance had a small fall and then notably increased. The results have validated that the cranium completeness (open or closed) has influences on impedance changes within brain when using EIT to monitor ICH. In future study on application of EIT to monitor ICH, the cranium completeness should be taken into account for establishing an ICH model and analyzing the corresponding EIT results.

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DURAN, GIANNA M., and DOUGLAS L. MARSHALL. "Rapid Determination of Sanitizer Concentration Using Impedance-Based Methods." Journal of Food Protection 65, no. 9 (September 1, 2002): 1422–27. http://dx.doi.org/10.4315/0362-028x-65.9.1422.

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Chlorine, iodophor, and quaternary ammonium solutions of various concentrations were assayed with rapid test kits and with three Bactometer impedimetric test codes (the impedance, conductance, and capacitance test codes). An initial study was conducted to determine which test code was most suitable for each sanitizer. Impedance was shown to be the best for sodium hypochlorite solutions, conductance for iodophor solutions, and capacitance for quaternary ammonium solutions. When Bactometer results were compared with test kit results, linear regression revealed strong correlations for all three sanitizer solutions. For sodium hypochlorite concentrations of 0 to 100 ppm and 100 to 1,000 ppm, R2 values of 0.87 and 0.99, respectively, were obtained. For iodophor concentrations between 25 to 150 ppm, an R2 value of 0.95 was obtained. For quaternary ammonium compound concentrations of 100 to 1,000 ppm, an R2 value of 0.94 was obtained. The impedimetric methods proved to be simple and rapid (6 min) alternatives for measuring concentrations of the sanitizer solutions with a high level of certainty (P < 0.0002). The Bactometer will save time when multiple samples are tested.

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Slanina, H., A. König, H. Claus, M. Frosch, and A. Schubert-Unkmeir. "Real-time impedance analysis of host cell response to meningococcal infection." Journal of Microbiological Methods 84, no. 1 (January 2011): 101–8. http://dx.doi.org/10.1016/j.mimet.2010.11.004.

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BULLOCK, R. D., and D. FRODSHAM. "Rapid impedance detection of salmonellas in confectionery using modified LICNR broth." Journal of Applied Bacteriology 66, no. 5 (May 1989): 385–91. http://dx.doi.org/10.1111/j.1365-2672.1989.tb05107.x.

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Timms, S., K. O. Colquhoun, and C. R. Fricker. "Detection of Escherichia coli in potable water using indirect impedance technology." Journal of Microbiological Methods 26, no. 1-2 (July 1996): 125–32. http://dx.doi.org/10.1016/0167-7012(96)00903-7.

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BISHOP, J. R., and C. H. WHITE. "Estimation of Potential Shelf-life of Pasteurized Fluid Milk Utilizing Bacterial Numbers and Metabolites." Journal of Food Protection 48, no. 8 (August 1, 1985): 663–67. http://dx.doi.org/10.4315/0362-028x-48.8.663.

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A study was conducted on use of bacterial numbers and their metabolites, and any possible interaction thereof, as estimators of the potential shelf-life of pasteurized fluid milk. Whole and skim milk samples were obtained on the day of processing. Samples of each milk were inoculated in duplicate with 0, 1,000, or 100,000 bacteria/ml with a pure strain of Pseudomonas fluorescens P27. Samples, stored at 7°C, were analyzed for microbiological and bioichemical parameters every 5 d for up to 20 d, with organoleptic evaluations conducted on a daily basis. On days of analysis, each sample was subjected to various preliminary incubations. Bacterial enumerations conducted were psychrotrophic bacteria count, standard plate count, gram-negative bacteria count, and modified psychrotrophic bacteria count. Lipopolysaccharide (endotoxin) concentrations, degree of proteolysis and impedance detection were also determined. All bacterial enumerations and proteolysis were significantly related to potential shelf-life of pasteurized fluid milk (whole, skim, and combined) but were of little predictive value. Endotoxin concentration and impedance detection were highly significantly related to shelf-life, and provided predictive regression equations. Using combined data from whole and skim milk, impedance detection resulted in the preferred prediction equation suitable for pasteurized fluid milks.

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Park, Yangkyu, Hyeon Woo Kim, Joho Yun, Seungwan Seo, Chang-Ju Park, Jeong Zoo Lee, and Jong-Hyun Lee. "Microelectrical Impedance Spectroscopy for the Differentiation between Normal and Cancerous Human Urothelial Cell Lines: Real-Time Electrical Impedance Measurement at an Optimal Frequency." BioMed Research International 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/8748023.

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Purpose. To distinguish between normal (SV-HUC-1) and cancerous (TCCSUP) human urothelial cell lines using microelectrical impedance spectroscopy (μEIS). Materials and Methods. Two types of μEIS devices were designed and used in combination to measure the impedance of SV-HUC-1 and TCCSUP cells flowing through the channels of the devices. The first device (μEIS-OF) was designed to determine the optimal frequency at which the impedance of two cell lines is most distinguishable. The μEIS-OF trapped the flowing cells and measured their impedance at a frequency ranging from 5 kHz to 1 MHz. The second device (μEIS-RT) was designed for real-time impedance measurement of the cells at the optimal frequency. The impedance was measured instantaneously as the cells passed the sensing electrodes of μEIS-RT. Results. The optimal frequency, which maximized the average difference of the amplitude and phase angle between the two cell lines (p<0.001), was determined to be 119 kHz. The real-time impedance of the cell lines was measured at 119 kHz; the two cell lines differed significantly in terms of amplitude and phase angle (p<0.001). Conclusion. The μEIS-RT can discriminate SV-HUC-1 and TCCSUP cells by measuring the impedance at the optimal frequency determined by the μEIS-OF.

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Puttaswamy, Sachidevi, Byung-Doo Lee, Ashley Jurgensmeyer, Anne Baumstummler, Kathleen Souza, and Shramik Sengupta. "Multi-frequency Microchannel Electrical Impedance(m-EIS) Method for the Rapid Detection of Proliferating Microorganisms, and their Rapid Quantification." Journal of Pure and Applied Microbiology 11, no. 3 (September 30, 2017): 1219–37. http://dx.doi.org/10.22207/jpam.11.3.01.

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KANAYEVA, DAMIRA A., RONGHUI WANG, DOUGLAS RHOADS, GISELA F. ERF, MICHAEL F. SLAVIK, STEVE TUNG, and YANBIN LI. "Efficient Separation and Sensitive Detection of Listeria monocytogenes Using an Impedance Immunosensor Based on Magnetic Nanoparticles, a Microfluidic Chip, and an Interdigitated Microelectrode." Journal of Food Protection 75, no. 11 (November 1, 2012): 1951–59. http://dx.doi.org/10.4315/0362-028x.jfp-11-516.

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Listeria monocytogenes continues to be a major foodborne pathogen that causes food poisoning, and sometimes death, among immunosuppressed people and abortion among pregnant women. In this study, magnetic nanoparticles with a diameter of 30 nm were functionalized with anti–L. monocytogenes antibodies via biotin-streptavidin bonds to become immunomagnetic nanoparticles (IMNPs) to capture L. monocytogenes in a sample during a 2-h immunoreaction. A magnetic separator was used to collect and hold the IMNPs–L. monocytogenes complex while the supernatants were removed. After the washing step, the nanoparticle–L. monocytogenes complex was separated from the sample and injected into a microfluidic chip. The impedance change caused by L. monocytogenes was measured by an impedance analyzer through the interdigitated microelectrode in the microfluidic chip. For L. monocytogenes in phosphate-buffered saline solution, up to 75% of the cells in the sample could be separated, and as few as three to five cells in the microfluidic chip could be detected, which is equivalent to 103 CFU/ml of cells in the original sample. The detection of L. monocytogenes was not interfered with by other major foodborne bacteria, including E. coli O157:H7, E. coli K-12, L. innocua, Salmonella Typhimurium, and Staphylococcus aureus. A linear correlation (R2 = 0.86) was found between the impedance change and the number of L. monocytogenes in a range of 103 to 107 CFU/ml. Equivalent circuit analysis indicated that the impedance change was mainly due to the decrease in medium resistance when the IMNPs–L. monocytogenes complexes existed in mannitol solution. Finally, the immunosensor was evaluated with food sample tests; the results showed that, without preenrichment and labeling, 104 and 105 CFU/ml L. monocytogenes in lettuce, milk, and ground beef samples could be detected in 3 h.

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NIEUWENHOF, F. F. J., and J. D. HOOLWERF. "Impedance Measurement as an Alternative to the Plate Count Method for Estimating the Total Count of Bacteria in Raw Milk." Journal of Food Protection 50, no. 8 (August 1, 1987): 665–68. http://dx.doi.org/10.4315/0362-028x-50.8.665.

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An improved impedance method is described with a good standard deviation of repeatability (sm = 0.05 log unit) and a fair standard deviation of the estimate of the plate count from the detection time [(sy)x = 0.33 log unit]. Compared with the standard deviation of repeatability of the plate count method (0.07 log unit), the standard deviation of repeatability of the impedance method described is a significant improvement. The impedimetric experiments were done with a Bactometer M123. The detection times as measured by this instrument were compared with the plate counts at 30°C for samples of raw refrigerated farm milk. With this technique a good indication of the microbiological quality of raw milk can be obtained within 15 h.

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JAWAD, GHAZALA M., TODD MARROW, and JOSEPH A. ODUMERU. "ASSESSMENT OF IMPEDANCE MICROBIOLOGICAL METHOD FOR THE DETECTION OF ESCHERICHIA COLI IN FOODS." Journal of Rapid Methods and Automation in Microbiology 6, no. 4 (December 1998): 297–305. http://dx.doi.org/10.1111/j.1745-4581.1998.tb00210.x.

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Chiriacò, Maria, Ilaria Parlangeli, Fausto Sirsi, Palmiro Poltronieri, and Elisabetta Primiceri. "Impedance Sensing Platform for Detection of the Food Pathogen Listeria monocytogenes." Electronics 7, no. 12 (November 23, 2018): 347. http://dx.doi.org/10.3390/electronics7120347.

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A great improvement in food safety and quality controls worldwide has been achieved through the development of biosensing platforms. Foodborne pathogens continue to cause serious outbreaks, due to the ingestion of contaminated food. The development of new, sensitive, portable, high-throughput, and automated platforms is a primary objective to allow detection of pathogens and their toxins in foods. Listeria monocytogenes is one common foodborne pathogen. Major outbreaks of listeriosis have been caused by a variety of foods, including milk, soft cheeses, meat, fermented sausages, poultry, seafood and vegetable products. Due to its high sensitivity and easy setup, electrochemical impedance spectroscopy (EIS) has been extensively applied for biosensor fabrication and in particular in the field of microbiology as a mean to detect and quantify foodborne bacteria. Here we describe a miniaturized, portable EIS platform consisting of a microfluidic device with EIS sensors for the detection of L. monocytogenes in milk samples, connected to a portable impedance analyzer for on-field application in clinical and food diagnostics, but also for biosecurity purposes. To achieve this goal microelectrodes were functionalized with antibodies specific for L. monocytogenes. The binding and detection of L. monocytogenes was achieved in the range 2.2 × 103 cfu/mL to 1 × 102 with a Limit of Detection (LoD) of 5.5 cfu/mL.

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PLESS, P., K. FUTSCHIK, and E. SCHOPF. "Rapid Detection of Salmonellae by Means of a New Impedance-Splitting Method." Journal of Food Protection 57, no. 5 (May 1, 1994): 369–76. http://dx.doi.org/10.4315/0362-028x-57.5.369.

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An Impedance-Splitting method is proposed for the rapid detection of salmonellae in foods. The measuring System, BacTrac™ 4100, permits the registration of changes, caused by bacterial metabolism, not only of the impedance of the culture medium but also of changes in the ionic layers at the measuring electrodes, which has advantages in case of high salt concentrations. These changes are expressed as percentage decreases of the initial values, M-value and E-value, respectively. Food samples were pre-enriched 14 to 16 h at 37°C in peptone water by addition of mannitol, which facilitated the detection of salmonellae on selective culture media. Following this, 0.1 mi of the preenrichment culture was transferred to 9.9 ml of Impedance-Splitting Salmonellae (ISS) medium which consisted of magnesium chloride (hydrated), malachite green oxalate, novobiocin, phosphate buffer, mannitol, peptone and yeast extract. Despite the high magnesium chloride concentration in this medium, salmonellae produced changes of the E-value up to 100%, while the changes in M-values were limited to a few percent. The impedance changes were automatically recorded during incubation in the measuring system for up to 22 h at 40°C, and the time required to exceed a threshold value of 15% (E reaction time) was evaluated. Comparative testing of the ISS method with standard cultural analysis of 250 unknown food samples showed high sensitivity and selectivity in detecting salmonellae. From all of the 122 Salmonella-positive samples, the largest number (119) was obtained by the ISS method, as compared to that obtained by conventional testing with the selenite-cystine (106), Rappaport Vassiliadis soya (95), Rappaport Vassiliadis (92) and tetrathionate brilliant green medium (64). Six samples were false positive by Enterobacter cloaceae. One strain each of Salmonella enteritidis PT8 and Salmonella panama were not recorded. The ISS method is very suitable as a screening test, all the more since a negative investigation result will be obtained within 38 h. In view of the practicability, this method is superior to the enzyme-immunological and molecular-biological procedures.

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Osipyants, A. I., D. M. Hushpulyan, and D. A. Sakharov. "Measurement of EGTA-Mediated Barrier Impairment by Impedance Spectroscopy." Biotekhnologiya 37, no. 1 (2021): 95–100. http://dx.doi.org/10.21519/0234-2758-2021-37-1-95-100.

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For the widespread use of in vitro models of barrier tissues in practice, it is necessary to develop approaches to the automation of cultivation and monitoring of the state of cells. Impedance spectroscopy is a promising and informative method for assessing the state of cell barriers. In this work, the dynamics of electrical parameters in an in vitro model of the intestinal barrier with a high temporal resolution has been studied using impedance spectroscopy. For the first time, the detailed kinetics of changes in TEER, electrical capacitance and additional resistance of a monolayer of Caco-2 cells at various EGTA concentrations was recorded. It was demonstrated that spontaneous restoration of the integrity of the cell barrier is possible in the presence of 2 mM EGTA in the medium, which begins approximately 6 h after the compound addition. A strong increase in TEER was also found immediately after the addition of EGTA, which probably depended on the EGTA concentration and can be explained by a decrease in intracellular conductance due to the closure of transmembrane channels. impedance spectroscopy, intestine, TEER, electrical capacitance, EGTA The study was funded by the Russian Science Foundation (project 16-19-10597).

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Amorim, Lara R. P., Joana G. L. Silva, Paul A. Gibbs, and Paula C. Teixeira. "Application of an Impedimetric Technique for the Detection of Lytic Infection ofSalmonellaspp. by Specific Phages." International Journal of Microbiology 2009 (2009): 1–6. http://dx.doi.org/10.1155/2009/259456.

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This study was performed to evaluate the adaption of the impedimetric method to detect the lytic infection bySalmonella-specific bacteriophages and to provide a higher selectivity to this rapid method in detectingSalmonellaspp. by using specific agents. Three bacteriophages and twelve strains ofSalmonellaspp. were tested. Each of the twelve strains was used separately to inoculate TSB together with each one of the phages. The inoculum concentration was between 106and 107 cfu/mL, at a cell: phage ratio of 1 : 100. From the sample analysis, based on conductance (G) measurements (37°C), the infection could be detected, by observation of both detection-time delay and distinct curve trends. The main conclusions were that kinetic detection by impedance microbiology with phage typing constitutes a method of determining whether a test microorganism is sensitive to the bacteriophage and a method to evaluate whether a lytic bacteriophage is present in a sample, by affecting bacterial growth rate/metabolic change.

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Martin, J. F., and J. O. Hearnsberger. "Evaluation of Impedance Microbiology for Rapid Assessment of Shelf-Life and Quality of Processed Channel Catfish,Ictalurus punctatus." Journal of Applied Aquaculture 3, no. 3-4 (June 1994): 353–62. http://dx.doi.org/10.1300/j028v03n03_11.

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FERNÁNDEZ-ESCUDERO, I., I. CARO, J. MATEO, J. TEJERO, and E. J. QUINTO. "Low Variability of Growth Parameters among Six O157:H7 and Non-O157:H7 Escherichia coli Strains." Journal of Food Protection 77, no. 11 (November 1, 2014): 1988–91. http://dx.doi.org/10.4315/0362-028x.jfp-14-209.

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Five Escherichia coli O157:H7 strains and one nonpathogenic E. coli strain were used. All strains were cultured in brain heart infusion broth and were inoculated in 16-well disposable module cassettes of a Bactometer impedance system. Two initial concentrations were obtained in the wells: 1.37 × 103 and 1.36 × 105 CFU/ml. The impedance measurements were monitored for 72 h at 5, 10, or 15°C, 48 h at 20°C, and 24 h at 25, 30, 35, 40, 45, 50 or 55°C. The lag time and the generation time of each culture were calculated from the detection time data. The coefficients of variation between the strains' growth parameters were low (0.009 to 0.105 for generation time and 0.074 to 0.475 for lag time). An F test showed no significant differences between strains at 5 or 1% confidence levels.

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Zhang, Jun, Yi Zhang, Yang Li, Ruimin Chen, K. Kirk Shung, Grace Richter, and Qifa Zhou. "Correlation of IOP with Corneal Acoustic Impedance in Porcine Eye Model." BioMed Research International 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/2959717.

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Purpose. The aim of this study is to correlate the intraocular pressure (IOP) change with the acoustic impedance of the cornea, in order to propose a noncontact and noninvasive method for IOP monitoring.Methods and Materials. A highly focused transducer (frequency 47-MHz; bandwidth 62%) was made to measure the echo from the anterior and posterior surfaces of intact porcine eyes, respectively. A multilayered transmission and reflection model was used to calculate the acoustic impedance. The linear relationship between acoustic impedance and intraocular pressure was analyzed by statistical method.Result.During pressure elevation from 10 mm Hg to 50 mm Hg, the mean acoustic impedance of the posterior cornea increased from 1.5393 to 1.5698 MRayl, which showed a strong linear correlation (R=0.9849;P=0.0022). Meanwhile, the mean value of the anterior cornea increased from 1.5399 to 1.5519 MRayl, and a less significant correlation was observed (R=0.7378;P=0.0025).Conclusion. This study revealed a linear correlation between intraocular pressure and acoustic impedance of the cornea, thus demonstrating a potentially important method to noninvasively measure the intraocular pressure in vivo.

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REVOL-JUNELLES, ANNE-MARIE, ROMARIC MIGUINDOU-MABIALA, DELPHINE ROGER-MAIGNÉ, and JEAN-BERNARD MILLIÈRE. "Behavior of Escherichia coli Cells and Bacillus cereus Spores on Poplar Wood Crates by Impedance Measurements." Journal of Food Protection 68, no. 1 (January 1, 2005): 80–84. http://dx.doi.org/10.4315/0362-028x-68.1.80.

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Dry poplar wood crates and glass surfaces (bottoms of Pyrex flasks) were contaminated with aqueous suspensions of Escherichia coli Collection de l'Institut Pasteur (CIP) 54.8 cells or Bacillus cereus CIP 78.3 spores. After different periods of storage at 25°C, the number of cells still present on both surfaces was determined by impedance microbiology. The physical and chemical properties of the wood greatly and rapidly decreased the number of cells. After 4 h of contact time, B. cereus residual metabolic activity corresponded to less than 10% of the initial inoculum level. With a low inoculum level of 2.4 × 102 E. coli cells, sterility of the wood was obtained after a contact time of 24 h. With a higher inoculum level of 106 E. coli cells, only a few viable bacteria, corresponding to the metabolic activity of four cells, could be recovered after a prolonged contact time of 145 h. Conversely, under the same conditions of storage, when bacteria were deposited on inert and nonporous materials such as glass surfaces, growth occurred. After 24 h of contact time at 25°C, bacterial populations were about 109 cells for E. coli and 107 cells for B. cereus. Under our experimental conditions after a prolonged contact time, wood exhibited growth-inhibiting properties and cells were no longer metabolically active. These results indicate that the potential for cross-contamination of foods stored directly in contact with previously contaminated poplar wood crates is low under our experimental conditions.

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JUNKA, ADAM F., ADRIANA JANCZURA, DANUTA SMUTNICKA, BEATA MĄCZYŃSKA, ANNA SECEWICZ, JOANNA NOWICKA, MARZENNA BARTOSZEWICZ, and GRAŻYNA GOŚCINIAK. "Use of the Real Time xCelligence System for Purposes of Medical Microbiology." Polish Journal of Microbiology 61, no. 3 (2012): 191–97. http://dx.doi.org/10.33073/pjm-2012-024.

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Roche's xCelligence impedance-measuring instrument is one of a few commercially available systems of such type. According to the best knowledge of authors, instrument was tested so far only for eukaryotic cell research. The aim of this work was to estimate xCELLigence suitability for the microbiological tests, including (i) measurement of morphological changes in eukaryotic cells as a result of bacterial toxin activity, (ii) measurement of bacterial biofilm formation and (iii) impact of antiseptics on the biofilm structure. To test the infuence of bacterial LT enterotoxin on eukaryotic cell lines, Chinese Hamster Ovary (CHO) cell line and reference strain Escherichia coli ATTC 35401 were used. To investigate Roche's instrument ability to measure biofilm formation and impact of antiseptics on its development, Staphylococcus aureus ATTC6538 reference strain was used. The data generated during the experiments indicate excellent ability of xCelligence instrument to detect cytopathic effect caused by bacterial LT endotoxin and to detect staphylococcal biofilm formation. However, interpretation of the results obtained during real-time measurement of antiseptic's bactericidal activity against staphylococcal biofilm, caused many difficulties. xCelligence instrument can be used for real-time monitoring of morphological changes in CHO cells treated with bacterial LT enterotoxin and for real-time measurement of staphylococcal biofilm formation in vitro. Further investigation is necessary to confirm suitability of system to analyze antiseptic's antimicrobial activity against biofilm in vitro.

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Tang, Biyu, Wanzhi Wei, Jian Yin, Xiaoyin Liu, Hongxia Xiang, and Bo Kong. "A monitoring technique of piezoelectric impedance analysis used in Tea Polyphenols (TP) antimutagenic characteristics." Journal of Microbiological Methods 70, no. 3 (September 2007): 535–41. http://dx.doi.org/10.1016/j.mimet.2007.06.010.

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Donaghy, J. A., and R. H. Madden. "Impedance detection of Salmonella in processed animal protein and meat." International Journal of Food Microbiology 16, no. 3 (July 1992): 265–69. http://dx.doi.org/10.1016/0168-1605(92)90087-j.

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Zhang, Jinzhong, Wanzhi Wei, Youan Mao, and Liyuan Chai. "Monitoring of Bio-Oxidation Process of Ferrous Ion by Using Piezoelectric Impedance Analysis." Current Microbiology 43, no. 2 (March 6, 2001): 83–88. http://dx.doi.org/10.1007/s002840010265.

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PRIEGO, R., L. M. MEDINA, and R. JORDANO. "Bactometer System versus Traditional Methods for Monitoring Bacteria Populations in Salchichón during Its Ripening Process." Journal of Food Protection 74, no. 1 (January 1, 2011): 145–48. http://dx.doi.org/10.4315/0362-028x.jfp-10-244.

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The performance of the Bactometer system (an impedimetric microbial monitoring system) compared with traditional methods (microbial colony counts) for monitoring bacterial populations (lactic acid bacteria [LAB], Enterobacteriaceae, and coliforms) was studied in 90 samples of an experimental salchichón (a type of Spanish ripened dry sausage) during its ripening process. The population quantitations were carried out with fresh sausage, semiripened sausage (14 days of ripening), and finished product (28 days of ripening). The results showed a high correlation between the traditional microbial colony count (in CFU per gram) and the impedance detection time: −0.98, −0.97, and −0.94 for coliforms, Enterobacteriaceae, and LAB, respectively (P < 0.01). Considering the results obtained with regard to the enumeration of populations of Enterobacteriaceae, coliforms, and LAB in salchichón during its ripening process, the advantages of impedance with respect to plate counts for monitoring the microbial dynamics of ripening processes are notable, especially in its time-saving aspects: between 19 and 21 h in the case of Enterobacteriaceae, between 7 and 20 h for coliforms, and between 32 and 46 h for LAB.

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Wu, J. J., A. H. Huang, J. H. Dai, and T. C. Chang. "Rapid detection of oxacillin-resistant Staphylococcus aureus in blood cultures by an impedance method." Journal of clinical microbiology 35, no. 6 (1997): 1460–64. http://dx.doi.org/10.1128/jcm.35.6.1460-1464.1997.

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Li, C. ,. M. "Impedance labelless detection-based polypyrrole protein biosensor." Frontiers in Bioscience 10, no. 1-3 (2005): 2518. http://dx.doi.org/10.2741/1716.

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Journal articles on the topic 'Impedance microbiology'

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