Abstract
Mastitis is a disease in dairy cattle that damage the milk chain. It was aimed identify the major causative agents of bovine mastitis in small dairy farms by producing an antibiogram and analysis of milk quality. Methods: During the summer, 280 dairy cows were examined on a farm located in Camapuã, MS, Brazil. The farm had a concrete milking facility and used cleaning and disinfection of the udder before and after milking to control mastitis. For assess microbial resistance, two samples of milk per cow were collected biweekly between January and March. The antibiotics sulfazotrim (25 μg), penicillin (10 μg), streptomycin (10 μg), vancomycin (30 μg), chloramphenicol (30 μg), tetracycline (30 μg), amoxicillin (10 μg), and gentamycin (10 μg) were used. Results: A total of 17.14% of the animals were positive for the California Mastitis Test (CMT). The identification of the pathogens revealed that Staphylococcus aureus accounted for 41.65% of the isolated organisms and Escherichia coli for 37.5%. Our results showed only sulfazotrim and chloramphenicol had effective results for both Gram-negative and Gram-positive bacteria. The isolated strains presented high resistance to the other tested antibiotics. Conclusions: sulfazotrim (25 μg) and chloramphenicol (30 μg) can be used to disinfect the udder of dairy cows.
Highlights
Mastitis is a common and costly disease in dairy cattle that affects the profitability of the milk chain due to a reduction in milk yield, high amounts of discarded milk, treatment costs, and other factors
Most of the occurrences of mastitis are caused by bacteria, which are generally classified as either environmental or contagious (Gonçalves et al, 2018)
Clinical or subclinical mastitis caused by S. aureus tends to become chronic and has a low response to conventional antibiotics due to its intracellular localization in epithelial cells of the mammary gland (Dego et al, 2002; Leitner et al, 2003)
Summary
Mastitis is a common and costly disease in dairy cattle that affects the profitability of the milk chain due to a reduction in milk yield, high amounts of discarded milk, treatment costs, and other factors It can be present in both clinical and subclinical forms. Clinical or subclinical mastitis caused by S. aureus tends to become chronic and has a low response to conventional antibiotics due to its intracellular localization in epithelial cells of the mammary gland (Dego et al, 2002; Leitner et al, 2003). This infection is related to the absence of an immune response, which involves different host and bacterial agents (Zecconi et al, 2005). Mastitis caused by E. coli can be treated in a few days and is characterized by pain, inflammation of one or all of the mammary quarters, fever, and milk with clots and an abnormal appearance (Oviedo-Boyso et al, 2007)
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