Aim: The study aimed to assess the nature of animal origin Staphylococcus aureus strains. The study has zoonotic importance and aimed to compare virulence between two different hosts, i.e., bovine and ovine origin.

Materials and Methods: Conventional polymerase chain reaction-based methods used for the characterization of S. aureus strains and chick embryo model employed for the assessment of virulence capacity of strains. All statistical tests carried on R program, version 3.0.4.

Results: After initial screening and molecular characterization of the prevalence of S. aureus found to be 42.62% in bovine origin samples and 28.35% among ovine origin samples. Meanwhile, the methicillin-resistant S. aureus prevalence is found to be meager in both the hosts. Among the samples, only 6.8% isolates tested positive for methicillin resistance. The biofilm formation quantified and the variation compared among the host. A Welch two-sample t-test found to be statistically significant, t=2.3179, df=28.103, and p=0.02795. Chicken embryo model found effective to test the pathogenicity of the strains.

Conclusion: The study helped to conclude healthy bovines can act as S. aureus reservoirs. Bovine origin S. aureus strains are more virulent than ovine origin strains. Bovine origin strains have high probability to become zoonotic pathogen. Further, gene knock out studies may be conducted to conclude zoonocity of the bovine origin strains.

Keywords: chicken embryo model, Staphylococcus aureus, virulence, zoonotic agent.

1. Costerton, J.W., Stewart, P.S. and Greenberg, E.P. (1999) Bacterial biofilms: A common cause of persistent infections. Science, 284(5418): 1318-1322. [Crossref]

2. Springer, B., Orendi, U., Much, P., Hoger, G., Ruppitsch, W., Krziwanek, K., Metz-Gercek, S. and Mittermayer, H. (2009) Methicillin-resistant Staphylococcus aureus: A new zoonotic agent? Wien. Klin. Wochenschr., 121(3-4): 86-90. [Crossref] [PubMed]

3. Molla, B., Byrne, M., Abley, M., Mathews, J., Jackson, C.R., Fedorka-Cray, P., Sreevatsan, S., Wang, P. and Gebreyes, W.A. (2012) Epidemiology and genotypic characteristics of methicillin-resistant Staphylococcus aureus strains of porcine origin. J. Clin. Microbiol., 50(11): 3687-3693. [Crossref] [PubMed] [PMC]

4. Frana, T.S., Beahm, A.R., Hanson, B.M., Kinyon, J.M., Layman, L.L., Karriker, L.A., Ramirez, A. and Smith, T.C. (2013) Isolation and characterization of methicillin-resistant Staphylococcus aureus from pork farms and visiting veterinary students. PLoS One, 8(1): e53738. [Crossref]

5. Rahimi, H., Saei, H.D. and Ahmadi, M. (2015) Nasal carriage of Staphylococcus aureus: Frequency and antibiotic resistance in healthy ruminants. Jundishapur. J. Microbiol., 8(10): e22413. [Crossref]

6. O'Toole, G.A. (2011) Microtiter dish biofilm formation assay. J. Vis. Exp., 47: 2437. [Crossref]

7. Polakowska, K., Lis, M.W., Helbin, W.M., Dubin, G., Dubin, A., Niedziolka, J.W., Miedzobrodzki, J. and Wladyka, B. (2012) The virulence of Staphylococcus aureus correlates with strain genotype in a chicken embryo model but not a nematode model. Microb. Infect., 14(14): 1352-1362. [Crossref] [PubMed]

8. Hensen, S.M., Pavicic, M.J.A., Lohuis, J.A.C., de Hoog, J.A.M. and Poutrel, B. (2000) Location of Staphylococcus aureus with in the experimentally infected bovine udder and the expression of capsular polysaccharide Type 5 in situ. J. Dairy Sci., 83(9): 1966-1975. [Crossref]

9. Mork, T., Kvitle, B., Mathisen, T. and Jorgensen, H.J. (2010) Bacteriological and molecular investigations of Staphylococcus aureus in dairy goats. Vet. Microbiol., 141(1-2): 134-141. [Crossref] [PubMed]

10. Dubey, D., Rath, S., Sahu, M.C., Pattnaik, L., Debata, N.K. and Padhy, R.N. (2013) Surveillance of infection status of drug resistant Staphylococcus aureus in an Indian teaching hospital. Asian Pac. J. Trop. Dis., 3(2): 133-142. [Crossref]

11. Gharsa, H., Slama, K.B., Gomez-Sanz, E., Lozano, C., Zarazaga, M., Messadi, L., Boudabous, A. and Torres, C. (2015) Molecular characterization of Staphylococcus aureus from nasal samples of healthy farm animals and pets in Tunisia. Vector Borne Zoonotic Dis., 15(2): 109-115. [Crossref] [PubMed]

12. Haran, K.P., Godden, S.M., Boxrud, D., Jawahir, S., Bender, J.B. and Sreevatsan, S. (2012) Prevalence and characterization of Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus, isolated from bulk tank milk from Minnesota dairy farms. J. Clin. Microbiol., 50(3): 688-695. [Crossref] [PubMed] [PMC]

13. Kumar, R., Yadav, B.R. and Singh, R.S. (2011) Antibiotic resistance and pathogenicity factors in Staphylococcus aureus isolated from mastitic Sahiwal cattle. J. Biosci., 36(1): 175-188. [Crossref]

14. Fagundes, H., Barchesi, L., Filho, A.N., Ferreira, L.M. and Oliveira, C.A.F. (2010) Occurrence of Staphylococcus aureus in raw milk produced in dairy farms in Sao Paulo state, Brazil. Braz. J. Microbiol., 41(2): 376-380. [Crossref]

15. Thaker, H.C., Brahmbhatt, M.N. and Nayak, J.B. (2013) Isolation and identification of Staphylococcus aureus from milk and milk products and their drug resistance patterns in Anand, Gujarat. Vet. World, 6(1): 10-13. [Crossref]

16. Duran, N., Ozer, B., Duran, G.G., Onlen, Y. and Demir, C. (2012) Antibiotic resistance genes and susceptibility patterns in staphylococci. Indian J. Med. Res., 135(3): 389-396. [PubMed] [PMC]

17. Gefen, O. and Balaban, N.Q. (2009) The importance of being persistent: heterogeneity of bacterial populations under antibiotic stress. FEMS Microbiol. Rev., 33(4): 704-717. [Crossref] [PubMed]

18. Lee, S.H.I., Mangolin, B.L.C., Goncalves, J.L., Neeff, D.V., Silva, M.P., Cruz, A.G. and Oliveira, C.A.F. (2014) Biofilm producing ability of Staphylococcus aureus isolates from Brazilian dairy farms. J. Dairy Sci., 97(3): 1812-1816. [Crossref] [PubMed]

19. Cha, J.O., Yoo, J.I., Yoo, J.S., Chung, H.S., Park, S.H., Kim, H.S., Lee, Y.S. and Chung, G.T. (2013) Corrigendum to "investigation of biofilm formation and its association with the molecular and clinical characteristics of methicillin-resistant Staphylococcus aureus". Osong Public Health Res. Perspect., 4(5): 225-232. [Crossref] [PubMed] [PMC]

20. Mulcahy, M.E., Geoghegan, J.A., Monk, I.R., O'Keeffe, K.M., Walsh, E.J., Foster, T.J. and McLoughlin, R.M. (2012) Nasal colonisation by Staphylococcus aureus depends upon clumping factor B binding to the squamous epithelial cell envelope protein loricrin. PLoS Pathog., 8(12): e1003092. [Crossref]

21. Anderson, C., Gripenland, J. and Johansson, J. (2015) Using the chicken embryo to assess virulence of Listeria monocytogenes and to model other microbial infections. Nat. Protoc., 10(8): 1155-1164. [Crossref] [PubMed]