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Ohno Y, Rahman MM, Maruyama H, Inoshima Y, Okada A. Exploration of genes associated with induction of the viable but non-culturable state of Campylobacter jejuni. Arch Microbiol 2024; 206:260. [PMID: 38744718 PMCID: PMC11093796 DOI: 10.1007/s00203-024-03980-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/15/2024] [Accepted: 04/25/2024] [Indexed: 05/16/2024]
Abstract
Campylobacter jejuni is known to enter a viable but non-culturable (VBNC) state when exposed to environmental stresses. Microarray and quantitative real-time polymerase chain reaction (qPCR) analyses were performed to elucidate the genes related to the induction of the VBNC state. The C. jejuni NCTC11168 strain was cultured under low-temperature or high-osmotic stress conditions to induce the VBNC state. mRNA expression in the VBNC state was investigated using microarray analysis, and the gene encoding peptidoglycan-associated lipoprotein, Pal, was selected as the internal control gene using qPCR analysis and software. The three genes showing particularly large increases in mRNA expression, cj1500, cj1254, and cj1040, were involved in respiration, DNA repair, and transporters, respectively. However, formate dehydrogenase encoded by cj1500 showed decreased activity in the VBNC state. Taken together, C. jejuni actively changed its mRNA expression during induction of the VBNC state, and protein activities did not always match the mRNA expression levels.
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Affiliation(s)
- Yurina Ohno
- Laboratory of Food and Environmental Hygiene, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Md Matiur Rahman
- Laboratory of Food and Environmental Hygiene, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
- Department of Medicine, Faculty of Veterinary, Animal and Biomedical Sciences, Sylhet Agricultural University, Sylhet, Bangladesh
| | | | - Yasuo Inoshima
- Laboratory of Food and Environmental Hygiene, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
- Education and Research Center for Food Animal Health, Gifu University (GeFAH), Gifu, Japan
- Joint Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan
| | - Ayaka Okada
- Laboratory of Food and Environmental Hygiene, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
- Education and Research Center for Food Animal Health, Gifu University (GeFAH), Gifu, Japan.
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Zhao X, Bhat A, O’Connor C, Curtin J, Singh B, Tian F. Review of Detection Limits for Various Techniques for Bacterial Detection in Food Samples. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:855. [PMID: 38786811 PMCID: PMC11124167 DOI: 10.3390/nano14100855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/07/2024] [Accepted: 05/12/2024] [Indexed: 05/25/2024]
Abstract
Foodborne illnesses can be infectious and dangerous, and most of them are caused by bacteria. Some common food-related bacteria species exist widely in nature and pose a serious threat to both humans and animals; they can cause poisoning, diseases, disabilities and even death. Rapid, reliable and cost-effective methods for bacterial detection are of paramount importance in food safety and environmental monitoring. Polymerase chain reaction (PCR), lateral flow immunochromatographic assay (LFIA) and electrochemical methods have been widely used in food safety and environmental monitoring. In this paper, the recent developments (2013-2023) covering PCR, LFIA and electrochemical methods for various bacterial species (Salmonella, Listeria, Campylobacter, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli)), considering different food sample types, analytical performances and the reported limit of detection (LOD), are discussed. It was found that the bacteria species and food sample type contributed significantly to the analytical performance and LOD. Detection via LFIA has a higher average LOD (24 CFU/mL) than detection via electrochemical methods (12 CFU/mL) and PCR (6 CFU/mL). Salmonella and E. coli in the Pseudomonadota domain usually have low LODs. LODs are usually lower for detection in fish and eggs. Gold and iron nanoparticles were the most studied in the reported articles for LFIA, and average LODs were 26 CFU/mL and 12 CFU/mL, respectively. The electrochemical method revealed that the average LOD was highest for cyclic voltammetry (CV) at 18 CFU/mL, followed by electrochemical impedance spectroscopy (EIS) at 12 CFU/mL and differential pulse voltammetry (DPV) at 8 CFU/mL. LOD usually decreases when the sample number increases until it remains unchanged. Exponential relations (R2 > 0.95) between LODs of Listeria in milk via LFIA and via the electrochemical method with sample numbers have been obtained. Finally, the review discusses challenges and future perspectives (including the role of nanomaterials/advanced materials) to improve analytical performance for bacterial detection.
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Affiliation(s)
- Xinyi Zhao
- School of Food Science and Environmental Health, Technological University Dublin, Grangegorman, D07 ADY7 Dublin, Ireland; (X.Z.); (A.B.); (C.O.); (B.S.)
- FOCAS Research Institute, Technological University Dublin, Camden Row, D08 CKP1 Dublin, Ireland
| | - Abhijnan Bhat
- School of Food Science and Environmental Health, Technological University Dublin, Grangegorman, D07 ADY7 Dublin, Ireland; (X.Z.); (A.B.); (C.O.); (B.S.)
- MiCRA Biodiagnostics Technology Gateway and Health, Engineering & Materials Sciences (HEMS) Research Hub, Technological University Dublin, D24 FKT9 Dublin, Ireland
| | - Christine O’Connor
- School of Food Science and Environmental Health, Technological University Dublin, Grangegorman, D07 ADY7 Dublin, Ireland; (X.Z.); (A.B.); (C.O.); (B.S.)
| | - James Curtin
- Faculty of Engineering and Built Environment, Technological University Dublin, Bolton Street, D01 K822 Dublin, Ireland;
| | - Baljit Singh
- School of Food Science and Environmental Health, Technological University Dublin, Grangegorman, D07 ADY7 Dublin, Ireland; (X.Z.); (A.B.); (C.O.); (B.S.)
- MiCRA Biodiagnostics Technology Gateway and Health, Engineering & Materials Sciences (HEMS) Research Hub, Technological University Dublin, D24 FKT9 Dublin, Ireland
| | - Furong Tian
- School of Food Science and Environmental Health, Technological University Dublin, Grangegorman, D07 ADY7 Dublin, Ireland; (X.Z.); (A.B.); (C.O.); (B.S.)
- FOCAS Research Institute, Technological University Dublin, Camden Row, D08 CKP1 Dublin, Ireland
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Reichelt B, Szott V, Stingl K, Roesler U, Friese A. Detection of Viable but Non-Culturable (VBNC)- Campylobacter in the Environment of Broiler Farms: Innovative Insights Delivered by Propidium Monoazide (PMA)-v-qPCR Analysis. Microorganisms 2023; 11:2492. [PMID: 37894150 PMCID: PMC10609165 DOI: 10.3390/microorganisms11102492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 09/30/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023] Open
Abstract
Campylobacteriosis cases in humans are of global concern, with high prevalence rates in the poultry reservoir considered the most important source of infection. Research findings show Campylobacters' ability to enter a viable but non-culturable (VBNC) state, remaining "viable" but unable to grow on culture media. We explored the persistence of VBNC states in specific environments, particularly at broiler farms, as this state may lead to an underestimation of the present Campylobacter prevalence. For VBNC detection, a propidium monoazide PMA-dye viability qPCR (v-qPCR) was used in combination with cultivation methods. We examined samples collected from broiler farm barns and their surroundings, as well as chicken manure from experimental pens. In addition, the tenacity of culturable and VBNC-Campylobacter was studied in vitro in soil and water. In a total of three visits, Campylobacter was not detected either culturally or by v-qPCR (no Campylobacter DNA) in the environment of the broiler farms. In four visits, however, VBNC-Campylobacter were detected both inside and outside the barns. The overall prevalence in environmental samples was 15.9% for VBNC-Campylobacter, 62.2% for Campylobacter DNA, and 1.2% for culturable C. jejuni. In the experimental pens, no cultivable C. jejuni was detected in chicken manure after 24 h. Strikingly, "VBNC-Campylobacter" persisted even after 72 h. "VBNC-Campylobacter" were confirmed in barn surroundings and naturally contaminated chicken manure. Laboratory studies revealed that VBNC-Campylobacter can remain intact in soil for up to 28 days and in water for at least 63 days, depending on environmental conditions.
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Affiliation(s)
- Benjamin Reichelt
- Institute for Animal Hygiene and Environmental Health, Freie Universität Berlin, 14163 Berlin, Germany; (B.R.)
| | - Vanessa Szott
- Institute of Food Safety and Food Hygiene, Freie Universität Berlin, 14163 Berlin, Germany;
| | - Kerstin Stingl
- Department of Biological Safety, German Federal Institute for Risk Assessment (BfR), 10589 Berlin, Germany
| | - Uwe Roesler
- Institute for Animal Hygiene and Environmental Health, Freie Universität Berlin, 14163 Berlin, Germany; (B.R.)
| | - Anika Friese
- Institute for Animal Hygiene and Environmental Health, Freie Universität Berlin, 14163 Berlin, Germany; (B.R.)
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4
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Knipper AD, Göhlich S, Stingl K, Ghoreishi N, Fischer-Tenhagen C, Bandick N, Tenhagen BA, Crease T. Longitudinal Study for the Detection and Quantification of Campylobacter spp. in Dairy Cows during Milking and in the Dairy Farm Environment. Foods 2023; 12:foods12081639. [PMID: 37107434 PMCID: PMC10137412 DOI: 10.3390/foods12081639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/06/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
Campylobacteriosis outbreaks have repeatedly been associated with the consumption of raw milk. This study aimed to explore the variation in the prevalence and concentration of Campylobacter spp. in cows' milk and feces, the farm environment and on the teat skin over an entire year at a small German dairy farm. Bi-weekly samples were collected from the environment (boot socks), teats, raw milk, milk filters, milking clusters and feces collected from the recta of dairy cows. Samples were analyzed for Campylobacter spp., E. coli, the total aerobic plate count and for Pseudomonas spp. The prevalence of Campylobacter spp. was found to be the highest in feces (77.1%), completely absent in milking equipment and low in raw milk (0.4%). The mean concentration of Campylobacter spp. was 2.43 log10 colony-forming units (CFU)/g in feces and 1.26 log10 CFU/teat swab. Only a single milk filter at the end of the milk pipeline and one individual cow's raw milk sample were positive on the same day, with a concentration of 2.74 log10 CFU/filter and 2.37 log10 CFU/mL for the raw milk. On the same day, nine teat swab samples tested positive for Campylobacter spp. This study highlights the persistence of Campylobacter spp. for at least one year in the intestine of individual cows and within the general farm environment and demonstrates that fecal cross-contamination of the teats can occur even when the contamination of raw milk is a rare event.
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Affiliation(s)
- Anna-Delia Knipper
- Department of Biological Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Steven Göhlich
- Department of Biological Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Kerstin Stingl
- Department of Biological Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Narges Ghoreishi
- Department Exposure, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Carola Fischer-Tenhagen
- Center for Protection of Experimental Animals, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Niels Bandick
- Department of Biological Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Bernd-Alois Tenhagen
- Department of Biological Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Tasja Crease
- Department of Biological Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
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Change of Campylobacter, Escherichia coli and Salmonella counts in packaged broiler breast meat stored under modified atmosphere and vacuum conditions at 4 and 10 °C based on cultural and molecular biological quantification. Food Control 2022. [DOI: 10.1016/j.foodcont.2022.109337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Dubovitskaya O, Seinige D, Valero A, Reich F, Kehrenberg C. Quantitative assessment of Campylobacter spp. levels with real-time PCR methods at different stages of the broiler food chain. Food Microbiol 2022; 110:104152. [DOI: 10.1016/j.fm.2022.104152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 09/08/2022] [Accepted: 09/20/2022] [Indexed: 11/26/2022]
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Current methodologies and future direction of Campylobacter isolation and detection from food matrices, clinical samples, and the agricultural environment. J Microbiol Methods 2022; 201:106562. [PMID: 36049611 DOI: 10.1016/j.mimet.2022.106562] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/25/2022] [Accepted: 08/25/2022] [Indexed: 12/27/2022]
Abstract
Campylobacter spp. are the leading cause of bacterial foodborne infections in both developed and developing countries. The food commodities primarily attributed to campylobacteriosis include raw milk, poultry, seafood, and fresh produce. Furthermore, insects, animal/bird fecal material, and agricultural water have been shown to be the sources of Campylobacter contamination in these commodities. Both established and emerging species of Campylobacter have been recovered from food and environmental sources. Therefore, optimal detection and isolation of Campylobacter spp., including the emerging species, is critical for improved surveillance, prevention, and traceback of Campylobacter outbreaks. This review focuses on the existing variability in Campylobacter enrichment and isolation procedures used by researchers and regulatory agencies worldwide, for various matrices. Additionally, the challenges associated with developing and validating new culture, molecular, and immunological methods for rapid and sensitive Campylobacter detection are discussed.
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Chicken Skin Decontamination of Thermotolerant Campylobacter spp. and Hygiene Indicator Escherichia coli Assessed by Viability Real-Time PCR. Pathogens 2022; 11:pathogens11060706. [PMID: 35745559 PMCID: PMC9230925 DOI: 10.3390/pathogens11060706] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/31/2022] [Accepted: 06/10/2022] [Indexed: 11/17/2022] Open
Abstract
Thermotolerant Campylobacter spp. are fecal contaminants of chicken meat with serious implications for human health. E. coli is considered as hygiene indicator since, in contrast to Campylobacter. spp., the bacterium is generally present in the avian gut. Stress exposure may transiently cease bacterial division. Therefore, colony forming units (CFU) may underestimate the infection risk of pathogens. We developed a viability real-time PCR (v-qPCR) for the quantification of viable E. coli targeting the uidA gene, encoding β-glucuronidase, which is usually detected for phenotypic species identification. The short- and long-term effects of decontaminating chicken skin on the survival of both C. jejuni and an ESBL-producing E. coli were evaluated by CFU and v-qPCR. The results showed that freezing and storage in cool conditions are potentially underestimated by CFU but not by v-qPCR. The effect of treatment with peroxyacetic acid on survival was consistently detected by CFU and v-qPCR. v-qPCR analysis detected bacterial survival upon the application of lactic acid, which awaits further analysis. Interestingly, both bacteria showed similar kinetics of inactivation upon the application of reduction strategies, suggesting that E. coli might be a complementary hygiene indicator. We conclude that v-qPCR can improve food safety under the consideration of some limitations.
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de Klerk JN, Robinson PA. Drivers and hazards of consumption of unpasteurised bovine milk and milk products in high-income countries. PeerJ 2022; 10:e13426. [PMID: 35646485 PMCID: PMC9135038 DOI: 10.7717/peerj.13426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 04/21/2022] [Indexed: 01/14/2023] Open
Abstract
Introduction The consumption of dairy products contributes to health, nutrition, and livelihoods globally. However, dairy products do not come without microbiological food safety risks for consumers. Despite this risk, common hygiene measures in high-income countries, particularly pasteurisation, ensures that milk is safe, and is indeed frequently mandated by law. Nevertheless, over the past two decades, there has been a global increase in the number of consumers in high-income developed countries actively seeking out unpasteurised milk in liquid and product forms for perceived nutritional and health benefits, and improved taste. The often-anecdotal claims upon which consumers make such choices are not all supported by scientific evidence; however, some recent research studies have investigated (and in some cases demonstrated) the positive impact of unpasteurised milk consumption on the prevalence of asthma, atopy, rectal cancer and respiratory illness. Methods To investigate the significance of unpasteurised milk and milk product consumption for human health in high-income countries, outbreak data between the years 2000 and 2018 were obtained for the United States of America, Canada, the European Union, the United Kingdom, Japan, New Zealand and Australia, which were then categorized into three World Health Organisation subregions: AMR A, EUR A and WPR A. Outbreak dynamic variables such as pathogens, the place of consumption, numbers of outbreaks and deaths per million capita, the average number of cases per outbreak and regulations were described and analysed using R Studio. To provide an overview of unpasteurised milk-related disease outbreaks, a rapid evidence review was also undertaken to establish an overview of what is known in the current literature about hazards and drivers of consumption. Results Foodborne outbreaks associated with unpasteurised dairy consumption have risen in high-income countries over the period 2000 to 2018, with Campylobacter spp. being the most common aetiological agent responsible, followed by Escherichia coli and Salmonella spp. The most common places of consumption are on farms or in households, indicating individuals choose to drink unpasteurised milk, rather than a widespread distribution of the product, for example, at social events and in schools. Further study is needed to better understand contributing factors, such as cultural differences in the consumption of dairy products. Conclusion There are several observable health benefits linked to consuming raw milk, but outbreaks associated with unpasteurised milk and milk products are on the rise. It cannot be definitively concluded whether the benefits outweigh the risks, and ultimately the decision lies with the individual consumer. Nevertheless, many countries have regulations in place to protect consumer health, acknowledging the definite risks to human health that unpasteurised dairy foods may pose, particularly from microbial hazards.
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Affiliation(s)
- Joanna N. de Klerk
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Philip A. Robinson
- Department of Animal Health, Behaviour and Welfare, Harper Adams University, Newport, Shropshire, United Kingdom
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10
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Boleratz BL, Oscar TP. Use of
ComBase
data to develop an artificial neural network model for nonthermal inactivation of
Campylobacter jejuni
in milk and beef and evaluation of model performance and data completeness using the acceptable prediction zones method. J Food Saf 2022. [DOI: 10.1111/jfs.12983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Bethany L. Boleratz
- US Department of Agriculture, Agricultural Research Service, Chemical Residue and Predictive Microbiology Research Unit, Center for Food Science and Technology University of Maryland Eastern Shore Princess Anne Maryland USA
| | - Thomas P. Oscar
- US Department of Agriculture, Agricultural Research Service, Chemical Residue and Predictive Microbiology Research Unit, Center for Food Science and Technology University of Maryland Eastern Shore Princess Anne Maryland USA
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Taghizadeh M, Nematollahi A, Bashiry M, Javanmardi F, Mousavil M, Hosseini H. The global prevalence of Campylobacter spp. in milk A systematic review and meta-analysis. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2022.105423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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12
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Stingl K, Heise J, Thieck M, Wulsten IF, Pacholewicz E, Iwobi AN, Govindaswamy J, Zeller-Péronnet V, Scheuring S, Luu HQ, Fridriksdottir V, Gölz G, Priller F, Gruntar I, Jorgensen F, Koene M, Kovac J, Lick S, Répérant E, Rohlfing A, Zawilak-Pawlik A, Rossow M, Schlierf A, Frost K, Simon K, Uhlig S, Huber I. Challenging the "gold standard" of colony-forming units - Validation of a multiplex real-time PCR for quantification of viable Campylobacter spp. in meat rinses. Int J Food Microbiol 2021; 359:109417. [PMID: 34624596 DOI: 10.1016/j.ijfoodmicro.2021.109417] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 08/01/2021] [Accepted: 09/18/2021] [Indexed: 11/26/2022]
Abstract
Campylobacter jejuni is the leading bacterial food-borne pathogen in Europe. Despite the accepted limits of cultural detection of the fastidious bacterium, the "gold standard" in food microbiology is still the determination of colony-forming units (CFU). As an alternative, a live/dead differentiating qPCR has been established, using propidium monoazide (PMA) as DNA-intercalating crosslink agent for inactivating DNA from dead, membrane-compromised cells. The PMA treatment was combined with the addition of an internal sample process control (ISPC), i.e. a known number of dead C. sputorum cells to the samples. The ISPC enables i), monitoring the effective reduction of dead cell signal by the light-activated DNA-intercalating dye PMA, and ii), compensation for potential DNA losses during processing. Here, we optimized the method for routine application and performed a full validation of the method according to ISO 16140-2:2016(E) for the quantification of live thermophilic Campylobacter spp. in meat rinses against the classical enumeration method ISO 10272-2:2017. In order to render the method applicable and cost-effective for practical application, the ISPC was lyophilized to be distributable to routine laboratories. In addition, a triplex qPCR was established to simultaneously quantify thermophilic Campylobacter, the ISPC and an internal amplification control (IAC). Its performance was statistically similar to the two duplex qPCRs up to a contamination level of 4.7 log10Campylobacter per ml of meat rinse. The limit of quantification (LOQ) of the alternative method was around 20 genomic equivalents per PCR reaction, i.e. 2.3 log10 live Campylobacter per ml of sample. The alternative method passed a relative trueness study, confirming the robustness against different meat rinses, and displayed sufficient accuracy within the limits set in ISO 16140-2:2016(E). Finally, the method was validated in an interlaboratory ring trial, confirming that the alternative method was fit for purpose with a tendency of improved repeatability and reproducibility compared to the reference method for CFU determination. Campylobacter served as a model organism, challenging CFU as "gold standard" and could help in guidance to the general acceptance of live/dead differentiating qPCR methods for the detection of food-borne pathogens.
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Affiliation(s)
- Kerstin Stingl
- German Federal Institute for Risk Assessment (BfR), Department of Biological Safety, National Reference Laboratory for Campylobacter, Berlin, Germany.
| | - Janine Heise
- German Federal Institute for Risk Assessment (BfR), Department of Biological Safety, National Reference Laboratory for Campylobacter, Berlin, Germany
| | - Maja Thieck
- German Federal Institute for Risk Assessment (BfR), Department of Biological Safety, National Reference Laboratory for Campylobacter, Berlin, Germany
| | - Imke F Wulsten
- German Federal Institute for Risk Assessment (BfR), Department of Biological Safety, National Reference Laboratory for Campylobacter, Berlin, Germany
| | - Ewa Pacholewicz
- German Federal Institute for Risk Assessment (BfR), Department of Biological Safety, National Reference Laboratory for Campylobacter, Berlin, Germany; Wageningen Bioveterinary Research, Lelystad, the Netherlands
| | - Azuka N Iwobi
- Bavarian Health and Food Safety Authority (LGL), Oberschleissheim, Germany
| | | | | | - Sandra Scheuring
- Bavarian Health and Food Safety Authority (LGL), Oberschleissheim, Germany
| | - Huong Quynh Luu
- National Institute of Veterinary Research (NIVR), Hanoi, Viet Nam
| | | | - Greta Gölz
- Freie Universitaet Berlin, Institute of Food Safety and Food Hygiene, Berlin, Germany
| | | | - Igor Gruntar
- University of Ljubljana, Institute of Microbiology and Parasitology, Ljubljana, Slovenia
| | - Frieda Jorgensen
- Public Health England, Food, Water and Environmental Laboratory - Porton, Salisbury, United Kingdom
| | - Miriam Koene
- Wageningen Bioveterinary Research, Lelystad, the Netherlands
| | - Jasna Kovac
- The Pennsylvania State University, Department of Food Science, State College, PA, United States
| | - Sonja Lick
- Max Rubner-Institute (MRI), Department of Safety and Quality of Meat, Kulmbach, Germany
| | | | - Annika Rohlfing
- Impetus GmbH & Co. Bioscience KG, Microbiology, Bremerhaven, Germany
| | - Anna Zawilak-Pawlik
- Hirszfeld Institute of Immunology and Experimental Therapy, PAS, Microbiology Department, Wroclaw, Poland
| | - Marko Rossow
- State Office for Consumer Protection Saxony-Anhalt, Department of Food Safety, Halle (Saale), Germany
| | | | | | | | | | - Ingrid Huber
- Bavarian Health and Food Safety Authority (LGL), Oberschleissheim, Germany
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Bouju-Albert A, Saltaji S, Dousset X, Prévost H, Jaffrès E. Quantification of Viable Brochothrix thermosphacta in Cold-Smoked Salmon Using PMA/PMAxx-qPCR. Front Microbiol 2021; 12:654178. [PMID: 34335490 PMCID: PMC8316974 DOI: 10.3389/fmicb.2021.654178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/17/2021] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was to develop a rapid and accurate PMA-qPCR method to quantify viable Brochothrix thermosphacta in cold-smoked salmon. B. thermosphacta is one of the main food spoilage bacteria. Among seafood products, cold-smoked salmon is particularly impacted by B. thermosphacta spoilage. Specific and sensitive tools that detect and quantify this bacterium in food products are very useful. The culture method commonly used to quantify B. thermosphacta is time-consuming and can underestimate cells in a viable but not immediately culturable state. We designed a new PCR primer set from the single-copy rpoC gene. QPCR efficiency and specificity were compared with two other published primer sets targeting the rpoC and rpoB genes. The viability dyes PMA or PMAxx were combined with qPCR and compared with these primer sets on viable and dead B. thermosphacta cells in BHI broth and smoked salmon tissue homogenate (SSTH). The three primer sets displayed similar specificity and efficiency. The efficiency of new designed rpoC qPCR on viable B. thermosphacta cells in SSTH was 103.50%, with a linear determination coefficient (r2) of 0.998 and a limit of detection of 4.04 log CFU/g. Using the three primer sets on viable cells, no significant difference was observed between cells treated or untreated with PMA or PMAxx. When dead cells were used, both viability dyes suppressed DNA amplification. Nevertheless, our results did not highlight any difference between PMAxx and PMA in their efficiency to discriminate viable from unviable B. thermosphacta cells in cold-smoked salmon. Thus, this study presents a rapid, specific and efficient rpoC-PMA-qPCR method validated in cold-smoked salmon to quantify viable B. thermosphacta in foods.
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Lazou TP, Gelasakis AI, Chaintoutis SC, Iossifidou EG, Dovas CI. Method-Dependent Implications in Foodborne Pathogen Quantification: The Case of Campylobacter coli Survival on Meat as Comparatively Assessed by Colony Count and Viability PCR. Front Microbiol 2021; 12:604933. [PMID: 33732219 PMCID: PMC7956984 DOI: 10.3389/fmicb.2021.604933] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 02/01/2021] [Indexed: 11/28/2022] Open
Abstract
The aim of the present study was to address method-dependent implications during the quantification of viable Campylobacter coli cells on meat over time. Traditional colony counting on selective and non-selective culture media along with an optimized viability real-time PCR utilizing propidium monoazide-quantitative PCR (PMA-qPCR), spheroplast formation and an internal sample process control (ISPC), were comparatively evaluated for monitoring the survival of C. coli on fresh lamb meat during refrigeration storage under normal atmospheric conditions. On day zero of three independent experiments, lamb meat pieces were artificially inoculated with C. coli and then stored under refrigeration for up to 8 days. Three meat samples were tested on different days and the mean counts were determined per quantification method. An overall reduction of the viable C. coli on lamb meat was observed regardless of the applied quantification scheme, but the rate of reduction followed a method-dependent pattern, the highest being observed for colony counting on modified charcoal cefoperazone deoxycholate agar (mCCDA). Univariate ANOVA indicated that the mean counts of viable C. coli using PMA-qPCR were significantly higher compared to Columbia blood agar (CBA) plating (0.32 log10 cell equivalents, p = 0.015) and significantly lower when mCCDA was compared to CBA plating (0.88 log10 CFU, p < 0.001), indicating that selective culture on mCCDA largely underestimated the number of culturable cells during the course of meat storage. PMA-qPCR outperformed the classical colony counting in terms of quantifying both the culturable and viable but non-culturable (VBNC) C. coli cells, which were generated over time on meat and are potentially infectious and equally important from a public health perspective as their culturable counterparts.
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Affiliation(s)
- Thomai P Lazou
- Laboratory of Hygiene of Foods of Animal Origin - Veterinary Public Health, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Athanasios I Gelasakis
- Laboratory of Anatomy and Physiology of Farm Animals, Department of Animal Science, School of Animal Biosciences, Agricultural University of Athens, Athens, Greece
| | - Serafeim C Chaintoutis
- Diagnostic Laboratory, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Eleni G Iossifidou
- Laboratory of Hygiene of Foods of Animal Origin - Veterinary Public Health, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Chrysostomos I Dovas
- Diagnostic Laboratory, Faculty of Health Sciences, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
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How to Evaluate Non-Growing Cells-Current Strategies for Determining Antimicrobial Resistance of VBNC Bacteria. Antibiotics (Basel) 2021; 10:antibiotics10020115. [PMID: 33530321 PMCID: PMC7912045 DOI: 10.3390/antibiotics10020115] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/19/2021] [Accepted: 01/22/2021] [Indexed: 12/17/2022] Open
Abstract
Thanks to the achievements in sanitation, hygiene practices, and antibiotics, we have considerably improved in our ongoing battle against pathogenic bacteria. However, with our increasing knowledge about the complex bacterial lifestyles and cycles and their plethora of defense mechanisms, it is clear that the fight is far from over. One of these resistance mechanisms that has received increasing attention is the ability to enter a dormancy state termed viable but non-culturable (VBNC). Bacteria that enter the VBNC state, either through unfavorable environmental conditions or through potentially lethal stress, lose their ability to grow on standard enrichment media, but show a drastically increased tolerance against antimicrobials including antibiotics. The inability to utilize traditional culture-based methods represents a considerable experimental hurdle to investigate their increased antimicrobial resistance and impedes the development and evaluation of effective treatments or interventions against bacteria in the VBNC state. Although experimental approaches were developed to detect and quantify VBNCs, only a few have been utilized for antimicrobial resistance screening and this review aims to provide an overview of possible methodological approaches.
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