Effects of source and washing of erythrocytes on growth of bacterial pathogens from the bovine mammary gland.
Effects of source and washing of RBC on quantitative growth and hemolytic zone sizes of common bacterial pathogens of the bovine mammary gland were evaluated. Blood samples used to prepare the blood agar media were obtained from 10 adult dairy cows, 10 dairy calves, and 10 sheep. Hemolytic zone sizes produced by Staphylococcus aureus were significantly (P less than 0.01) larger on blood agar prepared with washed RBC than on blood agar prepared with nonwashed RBC, regardless of RBC source. With the exception of Corynebacterium bovis, growth of all bacteria was equivalent or significantly higher on medium prepared with washed RBC, compared with that on medium prepared with nonwashed RBC, regardless of RBC source. Significantly higher numbers of C bovis (P less than 0.01) and Streptococcus agalactiae (P less than 0.01) were isolated on medium prepared with washed cow RBC. Significantly higher numbers of Str uberis (P less than 0.01) and S aureus (P less than 0.05) were isolated on medium prepared with washed sheep RBC and washed calf RBC, respectively. Growth of Escherichia coli was not affected by the RBC source. Seemingly, RBC used in the preparation of medium should be washed. The source of RBC, as well as inter-animal variation, also should be considered in the quality control of medium.
Shearer
J K
JK
Department of Preventive Medicine, College of Veterinary Medicine, University of Florida, Gainesville 32610.
Brown
M B
MB
Reed
P A
PA
D000818:Animals; D001419:Bacteria / Q000254:growth & development*; D002417:Cattle; D003352:Corynebacterium / Q000254:growth & development; D003470:Culture Media; D004912:Erythrocytes; D004926:Escherichia coli / Q000254:growth & development; D005260:Female; D008321:Mammary Glands, Animal / Q000382:microbiology*; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000382:microbiology; D013211:Staphylococcus aureus / Q000254:growth & development; D013291:Streptococcus / Q000254:growth & development; D013292:Streptococcus agalactiae / Q000254:growth & development
D003470:Culture Media