title: Semi-Quantitative Method for Streptococci Magnetic Detection in Raw Milk.
abstract: 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.
authors.affiliation: INESC-MN Instituto de Engenharia de Sistemas e Computadores-Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal. duarte.margarida72@gmail.com.|CIISA at Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477 Lisbon, Portugal. duarte.margarida72@gmail.com.
authors.forename: Carla
authors.initials: C
authors.lastname: Duarte
authors.affiliation: INESC-ID Instituto de Engenharia de Sistemas e Computadores-Investigação e Desenvolvimento, Rua Alves Redol 9, 1000-029 Lisbon, Portugal. tiagomlcosta@gmail.com.
authors.forename: Tiago
authors.initials: T
authors.lastname: Costa
authors.affiliation: CIISA at Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477 Lisbon, Portugal. carla.n.carneiro@gmail.com.
authors.forename: Carla
authors.initials: C
authors.lastname: Carneiro
authors.affiliation: INESC-MN Instituto de Engenharia de Sistemas e Computadores-Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal. ritasoares18@hotmail.com.
authors.forename: Rita
authors.initials: R
authors.lastname: Soares
authors.affiliation: INESC-MN Instituto de Engenharia de Sistemas e Computadores-Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal. ajitariu@phys-iasi.ro.|Visiting from the National Institute of Research and Development for Technical Physics, 47 Mangeron Blvd, Iasi 700050, Romania. ajitariu@phys-iasi.ro.
authors.forename: Andrei
authors.initials: A
authors.lastname: Jitariu
authors.affiliation: INESC-MN Instituto de Engenharia de Sistemas e Computadores-Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal. scardoso@inesc-mn.pt.|Instituto Superior Técnico, Physics Department, Av. Rovisco Pais, 1049-001 Lisbon, Portugal. scardoso@inesc-mn.pt.
authors.forename: Susana
authors.initials: S
authors.lastname: Cardoso
authors.affiliation: INESC-ID Instituto de Engenharia de Sistemas e Computadores-Investigação e Desenvolvimento, Rua Alves Redol 9, 1000-029 Lisbon, Portugal. msp@inesc-id.pt.
authors.forename: Moisés
authors.initials: M
authors.lastname: Piedade
authors.affiliation: CIISA at Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477 Lisbon, Portugal. ricardobexiga@fmv.ulisboa.pt.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Bexiga
authors.affiliation: INESC-MN Instituto de Engenharia de Sistemas e Computadores-Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal. Paulo.Freitas@inl.int.|International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal. Paulo.Freitas@inl.int.
authors.forename: Paulo
authors.initials: P
authors.lastname: Freitas
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002417:Cattle; D005516:Food Microbiology / Q000379:methods*; D059022:Food Safety; D006801:Humans; D058185:Magnetite Nanoparticles; D044085:Microfluidics; D008892:Milk / Q000382:microbiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013291:Streptococcus / Q000235:genetics / Q000302:isolation & purification; D013292:Streptococcus agalactiae / Q000235:genetics / Q000302:isolation & purification
chemical_list: D058185:Magnetite Nanoparticles
keywords: Streptococcus agalactiae; Streptococcus uberis; immunogenic recognition; magnetic nanoparticle (NP); magnetoresistive sensors; microfluidic; milk