Lack of hygiene and puerperal mastitis are common causes of bacterial diseases in nursing neonates. The aim of this study was to isolate microorganisms from milk samples of healthy female Jindo dogs with suckling puppies and to investigate antimicrobial susceptibility against the isolated bacteria. Milk samples were collected from 120 udders of 12 lactating Jindo dogs that were 2~4 years old without any clinical diseases including mastitis. Bacteria were isolated from 64 milk samples (53.3%), either singly (76.6%) or in combination (23.4%). Staphylococcus (S.) spp. was the most common microorganisms (74.7%) isolated from canine milk, followed by Haemophillus spp. (10.9%), Streptococcus spp. (9.6%), Gardnerella spp. (2.4%) and Moraxella spp. (2.4%). The most frequently isolated organism was S. warneri (31.3%). Antimicrobial susceptibility of these bacteria was tested with 17 antimicrobial agents by Kirbyand Bauer standardized disc diffusion method. Results indicated that bacteria isolated from healthy canine milk were mostly susceptible to amoxicillin-clavulanic acid, cephalothin and ceftiofur, but were resistant to erythromycin, neomycin and tetracycline.

Objective—To evaluate enterotoxin production, enterotoxin gene distribution, and genetic diversity of Staphylococcus aureus in milk obtained from cows with subclinical mastitis. Sample—Milk samples obtained from 350 cows (1,354 mammary glands) on 11 Wisconsin dairy farms. Procedures—Of 252 S aureus isolates obtained from 146 cows, 83 isolates (from 66 cows with subclinical mastitis) were compared genotypically by use of pulsed-field gel electrophoresis and via PCR identification of toxic shock syndrome toxin 1 (TSST-1) and classical S aureus enterotoxin genes (sea, seb, sec, sed, and see). Results—Among the 83 S aureus isolates, ≥ 1 enterotoxin genes were identified in 8 (9.6%). Enterotoxin gene distribution was as follows: TSST-1, 7 isolates (8.4%); sec, 5 isolates (6.0%); and sed, 2 isolates (2.4%). Enterotoxin genes sea, seb, and see were not identified. Twelve pulsotypes and 5 subtypes were identified among the 83 isolates; 5 of the 12 pulsotypes were represented by only 1 isolate. In cows of 1 herd, only a single S aureus pulsotype was detected; in cows on most other farms, a variety of pulsotypes were identified. One pulsotype was recovered from 4 farms (n = 23 cows) and another from 5 other farms (16). Isolates with an enterotoxin gene were represented by 6 pulsotypes. Conclusions and Clinical Relevance—S aureus classical enterotoxins and TSST-1 were rarely recovered from milk samples obtained from cows with subclinical mastitis in Wisconsin. Diverse pulsotypes of S aureus were detected within and among farms, indicating that different strains of S aureus cause subclinical mastitis in dairy cows.

Objective—To compare results for 3 commercially available microbiological media plates with those for standard bacteriologic testing of bovine milk. Sample—Milk samples from postpartum cows and cows with a high somatic cell count (SCC) or clinical mastitis (CM). Procedures—Sample-ready Staphylococcus culture medium (SRSC) plates were used to detect Staphylococcus aureus in milk samples obtained from postpartum cows and cows with a high SCC or CM. Rapid coliform count (RCC) plates were used to detect coliforms in milk samples obtained from cows with CM. Aerobic count (AC) plates were used to detect streptococci in CM samples. Fresh mastitic milk samples were frozen and then thawed to evaluate the effects of freezing for the SRSC and RCC plates. The effects of dilution (1:10) of samples were determined. Agreement of results between the commercially available plates and standard bacteriologic testing was evaluated. Results—The ability of SRSC plates to detect S aureus in milk samples was highest with diluted samples from postpartum cows and cows with a high SCC or CM. Sensitivity of the RCC plate for detection of coliforms was highest with diluted mastitic milk samples. The AC plates had a poor positive predictive value for detection of streptococci in mastitic milk samples. Freezing increased S aureus detection. Conclusions and Clinical Relevance—Overall, the SRSC and RCC plates were accurate, were easy to use, and yielded results comparable to those of standard bacteriologic testing for the detection of S aureus and coliforms in bovine milk.

A monitoring program for melamine in milk and feed was conducted in response to global melamine alertness in the year 2008. Two screening methods were adopted i.e., a liquid chromatography triple quadrupole tandem mass spectrometry (LC-MS/MS) and enzyme-linked
immunosorbent assay (ELISA). The liquid chromatography method developed by several international research centers was adapted. This method consisted of an initial extraction with 10%trichloroacetic acid (TCA) for milk samples or 60% methanol/water for feed samples, followed by a series of centrifugation, dilution and filtration steps. Melamine was analysed in the chromatographic program using a zwitterionic HILIC LC column. Electrospray ionisation in positive ion mode was used. The quantity of melamine
present was determined with a calibration curve consisting of sample extracts from milk or feed fortified from 25 to 50 ppb that were taken through the extraction procedure. The ranges of recovery from
fortified raw milk samples (n=20) and feed samples (n=21) was 70–80% and 68%, respectively. The limit of detection was estimated at 10 ppb for both matrixes. Milk samples were found negative for melamine,
however 4.5% of feed samples were found to contain the compound at concentrations between 1 to 5 ppm.