Semi-Quantitative Method for Streptococci Magnetic Detection in Raw Milk

Biosensors

Ricardo Bexiga¹  Carla Carneiro¹  Tiago Costa²  Moisés Piedade²  Carla Duarte³  Susana Cardoso³  Andrei Jitariu³  Rita Soares³  Paulo Freitas³ 

[1] CIISA at Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477 Lisbon, Portugal;INESC-ID Instituto de Engenharia de Sistemas e Computadores—Investigação e Desenvolvimento, Rua Alves Redol 9, 1000-029 Lisbon, Portugal;INESC–MN Instituto de Engenharia de Sistemas e Computadores—Microsistemas e Nanotecnologias, Rua Alves Redol 9, 1000-029 Lisbon, Portugal;

关键词: magnetoresistive sensors;    magnetic nanoparticle (NP);    Streptococcus agalactiae;    Streptococcus uberis;    milk;    immunogenic recognition;    microfluidic;   

DOI  :  10.3390/bios6020019

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown