Minimum Inhibitory Concentrations for Selected Antimicrobial Agents Against Organisms Isolated from the Mammary Glands of Dairy Heifers in New Zealand and Denmark

Abstract

Minimum inhibitory concentrations were determined for selected antimicrobial agents against 872 bacteria isolated from intramammary infections in heifers in New Zealand (n = 401) and Denmark (n = 471). These values were reported in micrograms per milliliters. Antimicrobial agents tested against isolates from New Zealand were penicillin, cloxacillin, cephapirin, ceftiofur, novobiocin, enrofloxacin, erythromycin, and pirlimycin. The minimum inhibitory concentrations that inhibit 90% of the strains tested for these antimicrobial agents with Staphylococcus aureus were 4.0, 0.5, 0.5, 2.0, 1.0, 0.25, 0.5, and 1.0, respectively. The minimum inhibitory concentration values that inhibit 90% of the strains tested against the Staphylococcus spp. ranged from 0.5 to 1.0 for all antimicrobics. The minimum inhibitory concentrations against streptococci were < or = 0.06, 0.5, 0.13, 0.13, 4.0, 1.0, 0.13, and < or = 0.06, respectively. Antimicrobial agents tested against isolates from Denmark included penicillin, ampicillin, oxacillin, cephalothin, ceftiofur, penicillin plus novobiocin, erythromycin, and pirlimycin. Against S. aureus, the minimum inhibitory concentrations were 0.13, 0.5, 0.5, 0.5, 1.0, 0.25, 0.5, and 0.5, respectively. The minimum inhibitory concentrations against Staphylococcus spp. were 0.25, 0.25, 0.5, 0.5, 1.0, < or = 0.06, 0.13, 1.0, and 0.5, respectively. The minimum inhibitory concentrations against the streptococci were < or = 0.06, 0.13, 0.5, 0.5, 1.0, < or = 0.06, 0.13, 0.5, and 0.5, respectively. Minimum inhibitory concentration values for staphylococci from New Zealand and Denmark were similar to values reported for US isolates. Streptococci from New Zealand and Denmark had lower minimum inhibitory concentration values than did US isolates. Only ceftiofur and enrofloxacin were active against the Gram-negative bacilli.

Identification of Cronobacter spp (enterobacter sakazakii) from raw milk and environmental samples of dairy farms

“…New pathogens include bacteria of Cronobacter genus (formerly Enterobacter sakazakii), which is especially dangerous for babies up to a year. These microorganisms are opportunistic pathogens that can cause serious infections (necrotizing colitis and meningitis) in neonates after consumption of PIF and mortality ranges from 40 % to 80 % [2,5,11,23,24].…”

“…were not isolated from the feces of cattle, the soil of the farm and water, but they were isolated from other objects such as animal feed, indicating a possible source of the pathogen in the animal's body. A number of studies have found that bacteria Cronobacter spp were identified from the udder of cows with mastitis, and from dairy equipment for the production of dairy products [24].…”

Identification of Enterobacter sakazakii in raw milk for dry infant formula production

“…Salmon и др. (1998) выявляли бактерии E. sakazakii с выделений вымени больных маститом ко-ров [13]. H. L. Muytjens (1990), M. C. Kandhai (2010) и др.…”

Molecular identification of coagulase-negative staphylococci isolated from bovine mastitis and detection of β-lactam resistance

“…There are differences in pathogenicity between the coagulase-positive and coagulase-negative staphylococcal (CoNS) species. As a group, CoNS have traditionally been considered to be of minor pathogenicity, although in recent years they are increasing in importance as causes of bovine mastitis resulting in tissue damage, decrease in milk production and persistent bovine intramammary infections [2], and have been isolated from milk samples collected from cows with clinical and subclinical mastitis in several countries [3][4][5] .…”