Methicillin-resistant Staphylococcus aureus (MRSA) Prevalence in Mastitic Dairy Cows from San Bernardino County, CA
Author:
Elizabeth KurzawinskiMentors:
- Shelton Murinda, Associate Professor of Animal and Veterinary Sciences, California State Polytechnic University Pomona
- Shelton Murinda, Associate Professor of Animal and Veterinary Sciences, California State Polytechnic University Pomona
Mastitis is a costly disease of dairy cows in the United States, caused by various pathogens including the bacteria Staphylococcus aureus. Although Staph. aureus is a common cause of mastitis in dairy cows, few studies have been conducted determining the prevalence of Methicillin-resistant Staphylococcus aureus (MRSA) in mastitic dairy cows, in the United States. The objective of this study is to determine the prevalence of MRSA in mastitic dairy cows from Chino and Ontario, California. 318 milk samples collected from individual cows were isolated on 5%/10% blood agar and purified on tryptic soy agar. There are currently 68 presumptive Staph. aureus isolates (21%) to be confirmed by use of polymerase chain reaction (PCR) to target amplification of the mecA, nuc, coa, and Staphylococcus genus specific 16s rRNA genes associated with MRSA and Staph. aureus. Antibiotic resistance profiles including the antibiotics cefoxitin, oxacillin, and methicillin will be determined for each isolate. Preliminary results suggest a moderately low prevalence of Staph. aureus isolates. If a low prevalence of MRSA in these milk samples from dairy cows should be confirmed, veterinarians will benefit in terms of correct usage of antibiotics to treat dairy cows with mastitis. Major economic losses and human health risks associated with the consumption of raw milk and products manufactured from raw milk, may be reduced as more knowledge is gained related to the prevalence and implications of MRSA.