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Wang F, Wang H, Zhang L, Ji T, Gao Y, Wang Y, Dong S, Gao X. An improved recombinase polymerase amplification assay for the visual detection of Staphylococcus epidermidis with lateral flow strips. Clin Chim Acta 2023; 548:117455. [PMID: 37394163 DOI: 10.1016/j.cca.2023.117455] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/14/2023] [Accepted: 06/20/2023] [Indexed: 07/04/2023]
Abstract
Staphylococcus epidermidis is an opportunistic pathogenic microorganism that is an important cause of cross-infection in hospitals. The development of rapid and effective detection techniques is important for its control. The application of traditional identification and PCR-based methods is limited by their requirements for both laboratory instrumentation and trained personnel. To overcome this issue, we developed a fast detection approach for S. epidermidis that was based on recombinase polymerase amplification (RPA) and lateral flow strips (LFS). First, five pairs of primers were designed for molecular diagnosis using the sesB gene as the target, and were screened for their amplification performance and the formation of primer dimers. Specific probes were then designed based on the best primer pairs screened, which were susceptible to primer-dependent artifacts and generated false-positive signals when used for LFS detection. This weakness of the LFS assay was overcome by modifying the sequences of the primers and probes. The efficacy of these measures was rigorously tested, and improved the RPA-LFS system. Standardized systems completed the amplification process within 25 min at a constant temperature of 37 °C, followed by visualization of the LFS within 3 min. The approach was very sensitive (with a detection limit of 8.91 CFU/μL), with very good interspecies specificity. In the analysis of clinical samples, the approach produced results consistent with PCR and 97.78% consistent with the culture-biochemical method, with a kappa index of 0.938. Our method was rapid, accurate, and less dependent on equipment and trained personnel than traditional methods, and provided information for the timely development of rational antimicrobial treatment plans. It has high potential utility in clinical settings, particularly in resource-constrained locations.
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Affiliation(s)
- Fang Wang
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China; Institute of Clinical Oncology, The Second People's Hospital of Lianyungang City (Cancer Hospital of Lianyungang), Lianyungang 222023, China
| | - Hui Wang
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China
| | - Linhai Zhang
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China
| | - Tuo Ji
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China; Institute of Clinical Oncology, The Second People's Hospital of Lianyungang City (Cancer Hospital of Lianyungang), Lianyungang 222023, China
| | - Yuzhi Gao
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China; Institute of Clinical Oncology, The Second People's Hospital of Lianyungang City (Cancer Hospital of Lianyungang), Lianyungang 222023, China
| | - Yan Wang
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China
| | - Shude Dong
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China.
| | - Xuzhu Gao
- Department of Central Laboratory, The Second People's Hospital of Lianyungang City (Lianyungang Second People's Hospital Affiliated to Kangda College of Nanjing Medical University), Lianyungang 222023, China; Institute of Clinical Oncology, The Second People's Hospital of Lianyungang City (Cancer Hospital of Lianyungang), Lianyungang 222023, China.
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Locatelli C, Gattolin S, Monistero V, Castiglioni B, Moroni P, Addis MF, Cremonesi P. Staphylococcus aureus coa gene sequence analysis can prevent misidentification of coagulase-negative strains and contribute to their control in dairy cow herds. Front Microbiol 2023; 14:1120305. [PMID: 37250045 PMCID: PMC10213915 DOI: 10.3389/fmicb.2023.1120305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 04/24/2023] [Indexed: 05/31/2023] Open
Abstract
Accurate and precise differentiation of staphylococci isolated from milk is of importance for udder health management. In particular, the rapid and specific identification of Staphylococcus aureus plays an essential role in the prevention and treatment programs for bovine mastitis. Plasma gelatinization in coagulase assays is routinely used to discriminate S. aureus from other species by detecting the presence of extracellular free staphylocoagulase. However, rarely occurring coagulase-deficient S. aureus strains can be responsible for clinical and subclinical mastitis cases. By investigating S. aureus isolates from a single herd over a 10-year period we identified the persistence of a phenotypically coagulase-negative S. aureus strain and pinpointed the possible cause to a single base pair deletion in the coa gene sequence. Our results support the need to integrate primary biochemical tests with molecular/sequence analysis approaches for correctly identifying and discriminating atypical S. aureus in bovine herds, as the coagulase test alone may fail to detect persistent mastitis-causing strains.
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Affiliation(s)
- Clara Locatelli
- Department of Veterinary Medicine and Animal Sciences, Università degli Studi di Milano, Lodi, Italy
- Laboratorio di Malattie Infettive degli Animali, Università degli Studi di Milano, Lodi, Italy
| | - Stefano Gattolin
- Italian National Research Council, Institute of Agricultural Biology and Biotechnology, Lodi, Italy
| | - Valentina Monistero
- Department of Veterinary Medicine and Animal Sciences, Università degli Studi di Milano, Lodi, Italy
- Laboratorio di Malattie Infettive degli Animali, Università degli Studi di Milano, Lodi, Italy
| | - Bianca Castiglioni
- Italian National Research Council, Institute of Agricultural Biology and Biotechnology, Lodi, Italy
| | - Paolo Moroni
- Department of Veterinary Medicine and Animal Sciences, Università degli Studi di Milano, Lodi, Italy
- Laboratorio di Malattie Infettive degli Animali, Università degli Studi di Milano, Lodi, Italy
- Quality Milk Production Services, Animal Health Diagnostic Center, Cornell University, Ithaca, NY, United States
| | - Maria Filippa Addis
- Department of Veterinary Medicine and Animal Sciences, Università degli Studi di Milano, Lodi, Italy
- Laboratorio di Malattie Infettive degli Animali, Università degli Studi di Milano, Lodi, Italy
| | - Paola Cremonesi
- Italian National Research Council, Institute of Agricultural Biology and Biotechnology, Lodi, Italy
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High Virulence and Multidrug Resistance of Escherichia coli Isolated in Periodontal Disease. Microorganisms 2022; 11:microorganisms11010045. [PMID: 36677337 PMCID: PMC9863014 DOI: 10.3390/microorganisms11010045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/12/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Periodontal disease is caused by different gram-negative anaerobic bacteria; however, Escherichia coli has also been isolated from periodontitis and its role in periodontitis is less known. This study aimed to determine the variability in virulence genotype, antibiotic resistance phenotype, biofilm formation, phylogroups, and serotypes in different emerging periodontal strains of Escherichia coli, isolated from patients with periodontal disease and healthy controls. E. coli, virulence genes, and phylogroups, were identified by PCR, antibiotic susceptibility by the Kirby-Bauer method, biofilm formation was quantified using polystyrene microtiter plates, and serotypes were determined by serotyping. Although E. coli was not detected in the controls (n = 70), it was isolated in 14.7% (100/678) of the patients. Most of the strains (n = 81/100) were multidrug-resistance. The most frequent adhesion genes among the strains were fimH and iha, toxin genes were usp and hlyA, iron-acquisition genes were fyuA and irp2, and protectin genes were ompT, and KpsMT. Phylogroup B2 and serotype O25:H4 were the most predominant among the strains. These findings suggest that E. coli may be involved in periodontal disease due to its high virulence, multidrug-resistance, and a wide distribution of phylogroups and serotypes.
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Sandwich Fluorescence Detection of Foodborne Pathogen Staphylococcus aureus with CD Fluorescence Signal Amplification in Food Samples. Foods 2022; 11:foods11070945. [PMID: 35407032 PMCID: PMC8997861 DOI: 10.3390/foods11070945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/16/2022] [Accepted: 03/21/2022] [Indexed: 12/15/2022] Open
Abstract
Timely detection of Staphylococcus aureus (S. aureus) is critical because it can multiply to disease−causing levels in a matter of hours. Herein, a simple and sensitive DNA tetrahedral (Td) fluorescence signal amplifier with blue carbon quantum dots (bCDs) was prepared for sandwich detection of S. aureus. bCD was modified at the apex of Td, and an aptamer on Td was used to accurately identify and “adsorb” the amplifier to the surface of S. aureus. Atomic force microscopy (AFM) demonstrates the successful preparation of this signal amplifier. The fluorescence intensity emitted in this strategy increased 4.72 times. The strategy showed a stronger fluorescence intensity change, sensitivity (linear range of 7.22 × 100–1.44 × 109 CFU/mL with a LOD of 4 CFU/mL), and selectivity. The recovery rate in qualified pasteurized milk and drinking water samples was 96.54% to 104.72%. Compared with simple aptamer sandwich detection, these fluorescence signal amplifiers have improved fluorescence detection of S. aureus. Additionally, this fluorescent signal amplification strategy may be applied to the detection of other food pathogens or environmental microorganisms in the future.
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Shen Y, Nie J, Kuang L, Zhang J, Li H. DNA sequencing, genomes and genetic markers of microbes on fruits and vegetables. Microb Biotechnol 2020; 14:323-362. [PMID: 32207561 PMCID: PMC7936329 DOI: 10.1111/1751-7915.13560] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/01/2020] [Accepted: 03/02/2020] [Indexed: 12/20/2022] Open
Abstract
The development of DNA sequencing technology has provided an effective method for studying foodborne and phytopathogenic microorganisms on fruits and vegetables (F & V). DNA sequencing has successfully proceeded through three generations, including the tens of operating platforms. These advances have significantly promoted microbial whole‐genome sequencing (WGS) and DNA polymorphism research. Based on genomic and regional polymorphisms, genetic markers have been widely obtained. These molecular markers are used as targets for PCR or chip analyses to detect microbes at the genetic level. Furthermore, metagenomic analyses conducted by sequencing the hypervariable regions of ribosomal DNA (rDNA) have revealed comprehensive microbial communities in various studies on F & V. This review highlights the basic principles of three generations of DNA sequencing, and summarizes the WGS studies of and available DNA markers for major bacterial foodborne pathogens and phytopathogenic fungi found on F & V. In addition, rDNA sequencing‐based bacterial and fungal metagenomics are summarized under three topics. These findings deepen the understanding of DNA sequencing and its application in studies of foodborne and phytopathogenic microbes and shed light on strategies for the monitoring of F & V microbes and quality control.
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Affiliation(s)
- Youming Shen
- Institute of Pomology, Chinese Academy of Agricultural Sciences/Laboratory of Quality & Safety Risk Assessment for Fruit (Xingcheng), Ministry of Agriculture and Rural Affairs/Quality Inspection and Test Center for Fruit and Nursery Stocks (Xingcheng), Ministry of Agriculture and Rural Affairs, Xingcheng, 125100, China
| | - Jiyun Nie
- Institute of Pomology, Chinese Academy of Agricultural Sciences/Laboratory of Quality & Safety Risk Assessment for Fruit (Xingcheng), Ministry of Agriculture and Rural Affairs/Quality Inspection and Test Center for Fruit and Nursery Stocks (Xingcheng), Ministry of Agriculture and Rural Affairs, Xingcheng, 125100, China.,College of Horticulture, Qingdao Agricultural University, Qingdao, 266109, China
| | - Lixue Kuang
- Institute of Pomology, Chinese Academy of Agricultural Sciences/Laboratory of Quality & Safety Risk Assessment for Fruit (Xingcheng), Ministry of Agriculture and Rural Affairs/Quality Inspection and Test Center for Fruit and Nursery Stocks (Xingcheng), Ministry of Agriculture and Rural Affairs, Xingcheng, 125100, China
| | - Jianyi Zhang
- Institute of Pomology, Chinese Academy of Agricultural Sciences/Laboratory of Quality & Safety Risk Assessment for Fruit (Xingcheng), Ministry of Agriculture and Rural Affairs/Quality Inspection and Test Center for Fruit and Nursery Stocks (Xingcheng), Ministry of Agriculture and Rural Affairs, Xingcheng, 125100, China
| | - Haifei Li
- Institute of Pomology, Chinese Academy of Agricultural Sciences/Laboratory of Quality & Safety Risk Assessment for Fruit (Xingcheng), Ministry of Agriculture and Rural Affairs/Quality Inspection and Test Center for Fruit and Nursery Stocks (Xingcheng), Ministry of Agriculture and Rural Affairs, Xingcheng, 125100, China
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García-Cano I, Rocha-Mendoza D, Ortega-Anaya J, Wang K, Kosmerl E, Jiménez-Flores R. Lactic acid bacteria isolated from dairy products as potential producers of lipolytic, proteolytic and antibacterial proteins. Appl Microbiol Biotechnol 2019; 103:5243-5257. [PMID: 31030287 PMCID: PMC6570704 DOI: 10.1007/s00253-019-09844-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 04/08/2019] [Accepted: 04/10/2019] [Indexed: 01/21/2023]
Abstract
Regular consumption of fermented dairy products helps maintain a healthy microbiota and prevent gut dysbiosis-linked diseases. The lactic acid bacteria (LAB) present in food enhance the digestibility of proteins, moderate the release of fatty acids, and support human health through inhabiting the gastrointestinal tract. These desirable properties of LAB are attributed, in part, to their metabolic processes involving enzymes such as lipases, proteases, and antibacterial proteins. The LAB strains presenting higher enzymatic activities may offer improved functionality for applications in foods. The first aim of this work was to isolate and identify LAB from diverse dairy products and select those with enhanced enzymatic activities. Secondly, this work aimed to investigate the subcellular organization and identity of these enzymes after semi-purification. Out of the total 137 LAB strains isolated and screened, 50.3% and 61.3% of the strains exhibited lipolytic and proteolytic activities, respectively. Seven strains displaying high enzymatic activities were selected and further characterized for the cellular organization of their lipases, proteases, and antibacterial proteins. The lipolytic and proteolytic activities were exhibited predominantly in the extracellular fraction; whereas, the antibacterial activities were found in various cellular fractions and were capable of inhibiting common undesirable microorganisms in foods. In total, two lipases, seven proteases, and three antibacterial proteins were identified by LC-MS/MS. Characterization of LAB strains with high enzymatic activity has potential biotechnological significance in fermentative processes and in human health as they may improve the physicochemical characteristics of foods and displace strains with weaker enzymatic activities in the human gut microbiota.
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Affiliation(s)
- Israel García-Cano
- Department of Food Science and Technology, Parker Food Science and Technology Building, The Ohio State University, Columbus, OH, 43210, USA
| | - Diana Rocha-Mendoza
- Department of Food Science and Technology, Parker Food Science and Technology Building, The Ohio State University, Columbus, OH, 43210, USA
| | - Joana Ortega-Anaya
- Department of Food Science and Technology, Parker Food Science and Technology Building, The Ohio State University, Columbus, OH, 43210, USA
| | - Karen Wang
- Department of Food Science and Technology, Parker Food Science and Technology Building, The Ohio State University, Columbus, OH, 43210, USA
| | - Erica Kosmerl
- Department of Food Science and Technology, Parker Food Science and Technology Building, The Ohio State University, Columbus, OH, 43210, USA
| | - Rafael Jiménez-Flores
- Department of Food Science and Technology, Parker Food Science and Technology Building, The Ohio State University, Columbus, OH, 43210, USA.
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Alsulami TS, Zhu X, Abdelhaseib MU, Singh AK, Bhunia AK. Rapid detection and differentiation of Staphylococcus colonies using an optical scattering technology. Anal Bioanal Chem 2018; 410:5445-5454. [DOI: 10.1007/s00216-018-1133-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 04/23/2018] [Accepted: 05/07/2018] [Indexed: 02/08/2023]
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Gao X, Yao X, Zhong Z, Jia L. Rapid and sensitive detection of Staphylococcus aureus assisted by polydopamine modified magnetic nanoparticles. Talanta 2018; 186:147-153. [PMID: 29784342 DOI: 10.1016/j.talanta.2018.04.046] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 04/08/2018] [Accepted: 04/15/2018] [Indexed: 10/17/2022]
Abstract
Pathogens cause significant morbidity and mortality to humans. Thus, development of fast and reliable methods for detection and identification of pathogens is urgently needed to increase protection level of public health and ensure the safety of consumers. Herein, a rapid and sensitive method has been developed for Staphylococcus aureus (S. aureus) detection based on the dual role of polydopamine modified magnetic nanoparticles (PDA@Fe3O4 NPs) combined with polymerase chain reaction (PCR) and capillary electrophoresis (CE). The core-shell type structure PDA@Fe3O4 NPs were prepared, which are spherical, about 152 ± 20 nm in diameter and the PDA shell is about 17.5 ± 1.6 nm. PDA@Fe3O4 NPs play a dual role including efficient capture of bacteria and extraction of DNA. In the pH range of 3.0-7.0, the capture efficiency of S. aureus by PDA@Fe3O4 NPs was more than 95% in 5 min. The adsorption capacity of the PDA@Fe3O4 NPs for S. aureus is 1.2 × 108 cfu mg-1. The efficient capture and concentration of bacteria from large volumes of samples by PDA@Fe3O4 NPs avoids the time-consuming culture-enrichment prior to PCR. Interestingly, PDA@Fe3O4 NPs were also found to be efficient adsorbents for extraction of genomic DNA from pathogens based on the electrostatic interaction. The process can be finished in 25 min. The PDA@Fe3O4 NPs based solid phase extraction combined with PCR and CE allows for detecting the order of 102 cfu mL-1S. aureus in tap water and orange juice samples. The whole process takes < 5.5 h. The developed method would provide a promising platform for rapid and sensitive detection of pathogens.
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Affiliation(s)
- Xiaomei Gao
- Ministry of Education Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
| | - Xin Yao
- Ministry of Education Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
| | - Zitao Zhong
- Ministry of Education Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
| | - Li Jia
- Ministry of Education Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China.
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Osmani Bojd M, Kamaladini H, Haddadi F, Vaseghi A. Thiolated AuNP probes and multiplex PCR for molecular detection of Staphylococcus epidermidis. Mol Cell Probes 2017; 34:30-36. [PMID: 28461258 DOI: 10.1016/j.mcp.2017.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/17/2017] [Accepted: 04/28/2017] [Indexed: 02/05/2023]
Abstract
The emergence of nanotechnology in biology helps to apply the gold nanoparticle probes for fast and accurate identification of pathogens compared to the time-consuming and non-precise phenotypic methods. In this study, two molecular methods have been established for the accurate identification of staphylococcus epidermidis from other coagulase-negative staphylococci. Multiplex PCR was performed using designed primers for Gmk2 and pta housekeeping genes, and SESB specific gene of S. epidermidis. Colorimetric detection by gold nanoparticle probes was carried out using two 20-base thiolated probes designed based on the sequence of pta housekeeping gene of S. epidermidis. The specificity of multiplex PCR and colorimetric assays were determined using genomic DNA of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii as negative controls and no alteration was detected. To investigate the sensitivity of the primers and gold nanoparticle probes, different concentrations of the extracted DNA from S. epidermidis were used. Based on the results, the minimum required quantity of target DNA for multiplex PCR amplification was 1 ng/μL and for color and absorption alteration of solution in colorimetric assay was 20 ng/μL. Our results revealed that both methods were sufficiently specific and sensitive to detect S. epidermidis.
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Affiliation(s)
- Mahsa Osmani Bojd
- Department of Biology, Faculty of Basic Sciences, University of Zabol, Zabol, Iran
| | - Hossein Kamaladini
- Department of Biology, Faculty of Basic Sciences, University of Zabol, Zabol, Iran.
| | - Fatemeh Haddadi
- Department of Biology, Faculty of Basic Sciences, University of Zabol, Zabol, Iran
| | - Akbar Vaseghi
- Young Researchers and Elite Club, Ardabil Branch, Islamic Azad University, Ardabil, Iran
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Chandrashekhar KM, Isloor S, Veeresh BH, Hegde R, Rathnamma D, Murag S, Veeregowda BM, Upendra HA, Hegde NR. Limit of detection of genomic DNA by conventional PCR for estimating the load of Staphylococcus aureus and Escherichia coli associated with bovine mastitis. Folia Microbiol (Praha) 2015; 60:465-72. [PMID: 25773783 DOI: 10.1007/s12223-015-0384-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 03/02/2015] [Indexed: 01/15/2023]
Abstract
Detection of mastitis-associated bacteria can be accomplished by culturing or by molecular techniques. On the other hand, rapid and inexpensive methods to enumerate bacterial load without culturing can be better achieved by molecular methods. Staphylococcus aureus and Escherichia coli are the predominant bacterial pathogens associated with bovine mastitis. Here, we describe the application of conventional PCR for the limit of detection (LOD) of genomic DNA of S. aureus and E. coli based on single-copy genes. The selected genes were thermonuclease (nuc), aureolysin (aur), and staphopain A (scpA) for S. aureus and β-D-glucuronidase A (uidA), cytochrome d oxidase (cyd), and rodA (a gene affecting cell shape and methicillin sensitivity) for E. coli. The LOD was 5.3, 15.9, and 143 pg for aur, nuc, and scpA genes, corresponding to S. aureus genomic copies of 1.75 × 10(3), 5.16 × 10(3), and 4.71 × 10(4), respectively. The LOD was 0.45, 12.3 and 109 pg for uidA, rodA and cyd genes, corresponding to E. coli genome copies of 8.91 × 10(1), 2.43 × 10(3), and 2.16 × 10(4), respectively. Application of uidA and aur PCRs to field strains revealed that as low as approximately 100 genome copies of E. coli and 1000-10,000 copies of S. aureus could be detected. This study is the first to report LOD of genomic DNA using conventional PCR for aur and scpA genes of S. aureus, and rodA and cyd genes of E. coli. The results should be useful for developing assays to assess bacterial load in milk and to determine the load that contributes to subclinical or clinical mastitis.
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Affiliation(s)
- K M Chandrashekhar
- Department of Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, Hebbal, Bengaluru, 560024, India
| | - Shrikrishna Isloor
- Department of Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, Hebbal, Bengaluru, 560024, India
| | - B H Veeresh
- Department of Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, Hebbal, Bengaluru, 560024, India
| | - Raveendra Hegde
- Institute of Animal Health and Veterinary Biologicals, Karnataka Veterinary Animal and Fisheries Sciences University, Hebbal, Bengaluru, 560024, India
| | - D Rathnamma
- Department of Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, Hebbal, Bengaluru, 560024, India
| | - Shivaraj Murag
- Institute of Animal Health and Veterinary Biologicals, Karnataka Veterinary Animal and Fisheries Sciences University, Hebbal, Bengaluru, 560024, India
| | - B M Veeregowda
- Department of Microbiology, Karnataka Veterinary Animal and Fisheries Sciences University, Hebbal, Bengaluru, 560024, India
| | - H A Upendra
- Institute of Wildlife Veterinary Research, Kudige, Kodagu, 571232, India
| | - Nagendra R Hegde
- Ella Foundation, Genome Valley, Turkapally, Shameerpet Mandal, Hyderabad, 500078, India.
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