Molecular and proteomic identification of Arthrobacter gandavensis isolated from cows with subclinical mastitis in a dairy farm

Aims: The genus Arthrobacter is a pleomorphic and heterogeneous Gram-positive bacteria mainly isolated from the soil, only two species of Arthrobacter have been reported worldwide as pathogens of veterinary importance. This paper aims to report the isolation and identification of the Arthrobacter gandavensis from cows with subclinical mastitis at a dairy farm in the savanna of Bogota, Colombia. Methodology and results: A total of 209 milk and skin samples were taken from cows with and without subclinical mastitis, nasal swabs from workers and the environment. All samples were cultured in blood and MacConkey agar and identified by 16S rRNA gene sequencing and mass spectrometry MALDI TOF-MS. From the isolates identified, 33 corresponded to Staphylococcus spp., nine to the Enterobacteriaceae family and seven from Arthrobacter spp. (only identified by MALDI-ToF MS). The A. gandavensis isolates were obtained from six different positive cows for the California mastitis test, all with a matching pattern corresponding to Arthrobacter gandavensis strain DSM N: 15046, isolated from milk from cows with subclinical mastitis in Belgium. Analysis of the 16S rRNA gene showed 100% genetic similarity with sequences of A. gandavensis previously reported in the NCBI databases. Conclusion, significance and impact of study: The identification by MALDI-ToF-MS and molecular, as shown in this report, is important to provide data that allow us to approach the actual ecology of the opportunistic pathogens of subclinical mastitis, especially in regions where the infection is endemic.