Monitoring and Characteristics of Major Mastitis Pathogens from Bulk Tank Milk in Korea

Abstract

In many countries, bulk tank milk (BTM) has been used for examining milk and analyzed as an important part of milk quality assurance programs. The objectives of this study were to investigate milk quality and the presence of major mastitis pathogens in BTM, and to compare the characteristics of BTM by dairy factory or company. A total of 1588 batches of BTM samples were collected from 396 dairy farms of seven dairy factories owned by four companies in Korea. The means of individual bacterial counts (IBC) and somatic cell count (SCC) were 3.7 × 104 cells/mL and 1.1 × 105 cells/mL, respectively, and no significant differences among dairy factories were observed. The most common pathogen was Staphylococcus spp. (60.1%), followed by E. faecalis (53.8%), E. coli (37.6%) and Streptococcus spp. (22.5%). Enterococcus spp. showed the highest resistance to tetracyclines (51.1% to 73.9%) and macrolides (46.5%). S. aureus and coagulase-negative staphylococci (CNS) showed the highest resistance to penicillin (28.4% and 40.2%, respectively), and three (3.2%) S. aureus and seven (3.3%) CNS were also methicillin-resistant. These data show the diverse prevalence and characteristics of major mastitis pathogens among factories, and support the development of strong monitoring and prevention programs of mastitis pathogens by commercial dairy operations.

Diversity and Antimicrobial Resistance in the Streptococcus bovis/Streptococcus equinus Complex (SBSEC) Isolated from Korean Domestic Ruminants

“…In this study, the AMR rates of SBSEC isolated from Korean domestic ruminants were relatively lower than those from other SBSEC isolates of clinical origin and the resistance rates on erythromycin, clindamycin, and tetracycline were estimated to be 2.0% (1/51), 0% (0/51), and 15.7% (8/51), respectively. Moreover, the resistance rates of our SBSEC isolates against the three antibiotics were much lower than those reported previously in various streptococcal species including incompletely classified S. bovis isolated from milk samples in Korea [ 27 , 49 ]. Along with the phenotypic evaluations of AMRs in SBSEC isolates, we also investigated the presence of ARGs associated with resistance to erythromycin, clindamycin, and tetracycline.…”

“…Although S. bovis was synonymized with S. equinus and is currently recognized as the SBSEC, the name is still commonly used in ruminant livestock research [ 49 , 50 , 51 ]. However, researchers in the area have already recognized the physiological and genetic diversities of bovine-origin S. bovis isolates [ 20 , 21 ] and genetic heterogeneity in SBSEC has been described recently, especially in S. equinus isolates [ 22 ].…”

Virulence Variation of Salmonella Gallinarum Isolates through SpvB by CRISPR Sequence Subtyping, 2014 to 2018

“…For cells with less than five factors, we used Fisher’s exact test for a more accurate estimate. Statistically significant differences ( p < 0.05) were verified using post hoc Bonferroni correction, as previously described [ 25 ].…”

Comparative analysis of genetic characterization of β-lactam-resistant Escherichia coli from bulk tank milk in Korea

“…In particular, E. coli one of the more important etiological organisms responsible for bovine mastitis [ 36 ]. Although several studies have reported the characteristics of antimicrobial resistance in E. coli from bovine mastitis in Korea [ 37 – 39 ], to our knowledge, this is the first study to investigate a comparative analysis of β-lactam-resistant E. coli isolated from bulk tank milk in different dairy companies. In Korea, five major dairy companies produce 84% of the total milk and dairy products (ATFIS 2020) [ 40 ], and β-lactam-resistant E. coli isolated from five factories operated by three dairy companies were compared in this study.…”