A clinical case of mastitis caused by Prototheca zopfii in a cow from a dairy herd located in the region of Zona da Mata, Minas Gerais State, was studied. The cow showed clinical signs of mastitis in both front mammary quarters and marked reduction on milk production. Following the diagnosis the animal was accompanied for 11 months. Milk samples collected at days l, 7, 30, 39, 49, 65, 326 and 331 were cultured. The last two exams were conducted at 7 and 12 days after calving. The P. zopfii strains were resistant in vitro to: ampicillin, kanamycin, cephalothin, enrofloxacin, streptomycin, gentamycin, neomycin, oxacillin, penicillin G, sulfonamides and trimethoprim/sulfamethoxazole. The strains showed sensitivity in vitro to a natural extract made of citrous seed, commercially available. The smallest concentration that completely inhibited the growth of the organisms was 1:500. The infected glands were treated intrammamary, with an extract preparation of a 1:200 dilution in 0.85%(p/v) NaCl containing 1:30,000 thimerosal as preservative. Doses of 20ml were applied daily, during seven days. After this period, P. zopfii was still isolated from milk samples, although in smaller numbers. The treatment was resumed for a period of 15 days. At day 39 after diagnosis the infected quarters were cultured negative and microbiological exams carried out from day 39 onward resulted negative. The milk production returned to levels as before infection. Naturally infected milk samples were kept frozen (-20°C) and viable P. zopfii were recovered until 38 days under this condition.
bovine mastitis; Prototheca zopfii; therapy; citrous seed extract
