Screening method for Staphylococcus aureus identification in subclinical bovine mastitis from dairy farms

Vet World Vol.10 July-2017 Article-1

Research Article

Veterinary World, 10(7): 721-726

https://doi.org/10.14202/vetworld.2017.721-726

Natapol Pumipuntu¹, Suphang Kulpeanprasit¹, Sirijan Santajit¹, Witawat Tunyong¹, Thida Kong-ngoen¹, Woranich Hinthong², and Nitaya Indrawattana¹

1. Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
2. Faculty of Medicine and Allied Health, HRH Princess Chulabhorn College of Medical Science Bangkok, Thailand.

Background and Aim: Aim of this study was to compare and assess the screening method, Mannitol fermentation test (Mannitol salt agar [MSA]), and deoxyribonuclease (DNase) test, for S. aureus identification in milk samples.

Materials and Methods: A total of 224 subclinical bovine mastitis milk samples were collected from four provinces of Thailand and determined S. aureus using conventional method and also subjected to the screening test, MSA and DNase test. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) among both tests were analyzed and compared to the tube coagulase test (TCT), as reference method. Immunological test by latex agglutination and molecular assay by determined spa gene were also used to identify and differentiate S. aureus.

Results: A total of 130 staphylococci were isolated by selective media, Gram-stain, and catalase test. The number of S. aureus which identified using TCT, MSA and DNase test were 32, 102, and 74 isolates, respectively. All TCT results were correlated to results of latex agglutination and spa gene which were 32 S. aureus. MSA showed 100% sensitivity, 28.57% specificity, 31.37% PPV, and 100% NPV, whereas DNase showed 53.13% sensitivity, 41.84% specificity, 22.97% PPV, and 73.21% NPV. DNase test showed higher specificity value than MSA but the test presented 26.79% false negative results whereas no false-negative result from MSA when comparing to TCT.

Conclusion: MSA had a tendency to be a good preference for screening S. aureus because of its high sensitivity and NPV. The result from this study will improve a choice to use a screening test to diagnose S. aureus of veterinary field for prompt disease controlling and effective treatment. Keywords: bovine mastitis, deoxyribonuclease test, mannitol fermentation test, screening methods, Staphylococcus aureus.

Keywords: bovine mastitis, deoxyribonuclease test, mannitol fermentation test, screening methods, Staphylococcus aureus.

How to cite this article: Pumipuntu N, Kulpeanprasit S, Santajit S, Tunyong W, Kong-ngoen T, Hinthong W, Indrawattana N (2017) Screening method for Staphylococcus aureus identification in subclinical bovine mastitis from dairy farms, Veterinary World, 10(7):721-726.

Received: 09-02-2017 Accepted: 12-05-2017 Published online: 01-07-2017

Corresponding author: Nitaya Indrawattana E-mail: nitaya.ind@mahidol.ac.th

DOI: 10.14202/vetworld.2017.721-726

Copyright: Pumipuntu, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.