Semi-Quantitative Method for Streptococci Magnetic Detection in Raw Milk
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INESC–MN Instituto de Engenharia de Sistemas e Computadores—Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal
2
CIISA at Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477 Lisbon, Portugal
3
INESC-ID Instituto de Engenharia de Sistemas e Computadores—Investigação e Desenvolvimento, Rua Alves Redol 9, 1000-029 Lisbon, Portugal
4
Visiting from the National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd, Iasi 700050, Romania
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Instituto Superior Técnico, Physics Department, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
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International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal
*
Author to whom correspondence should be addressed.
Academic Editor: Domenico Caputo
Biosensors 2016, 6(2), 19; https://doi.org/10.3390/bios6020019
Received: 21 March 2016
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Revised: 15 April 2016
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Accepted: 21 April 2016
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Published: 27 April 2016
(This article belongs to the Special Issue Advances in Lab-on-Chip Devices)
Bovine mastitis is the most costly disease for dairy farmers and the most frequent reason for the use of antibiotics in dairy cattle; thus, control measures to detect and prevent mastitis are crucial for dairy farm sustainability. The aim of this study was to develop and validate a sensitive method to magnetically detect Streptococcus agalactiae (a Group B streptococci) and Streptococcus uberis in raw milk samples. Mastitic milk samples were collected aseptically from 44 cows with subclinical mastitis, from 11 Portuguese dairy farms. Forty-six quarter milk samples were selected based on bacterial identification by conventional microbiology. All samples were submitted to PCR analysis. In parallel, these milk samples were mixed with a solution combining specific antibodies and magnetic nanoparticles, to be analyzed using a lab-on-a-chip magnetoresistive cytometer, with microfluidic sample handling. This paper describes a point of care methodology used for detection of bacteria, including analysis of false positive/negative results. This immunological recognition was able to detect bacterial presence in samples spiked above 100 cfu/mL, independently of antibody and targeted bacteria used in this work. Using PCR as a reference, this method correctly identified 73% of positive samples for streptococci species with an anti-S. agalactiae antibody, and 41% of positive samples for an anti-GB streptococci antibody.
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Keywords:
magnetoresistive sensors; magnetic nanoparticle (NP); Streptococcus agalactiae ; Streptococcus uberis ; milk; immunogenic recognition; microfluidic
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MDPI and ACS Style
Duarte, C.; Costa, T.; Carneiro, C.; Soares, R.; Jitariu, A.; Cardoso, S.; Piedade, M.; Bexiga, R.; Freitas, P. Semi-Quantitative Method for Streptococci Magnetic Detection in Raw Milk. Biosensors 2016, 6, 19. https://doi.org/10.3390/bios6020019
AMA Style
Duarte C, Costa T, Carneiro C, Soares R, Jitariu A, Cardoso S, Piedade M, Bexiga R, Freitas P. Semi-Quantitative Method for Streptococci Magnetic Detection in Raw Milk. Biosensors. 2016; 6(2):19. https://doi.org/10.3390/bios6020019
Chicago/Turabian StyleDuarte, Carla, Tiago Costa, Carla Carneiro, Rita Soares, Andrei Jitariu, Susana Cardoso, Moisés Piedade, Ricardo Bexiga, and Paulo Freitas. 2016. "Semi-Quantitative Method for Streptococci Magnetic Detection in Raw Milk" Biosensors 6, no. 2: 19. https://doi.org/10.3390/bios6020019
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