To efficiently prevent and treat bovine mastitis and minimize its effect on the dairy industry, a sensitive, rapid, and specific test is required for identifying the mastitis-causing pathogens. In this study, a biochip capable of detecting 7 common species of mastitis-causing pathogens, including Corynebacterium bovis, Mycoplasma bovis, Staphylococcus aureus, and the Streptococcus spp. S. agalactiae, S. bovis, S. dysgalactiae, and S. uberis, within 6 hr was developed. The technique is based on DNA amplification of genes specific to the target pathogens and consists of 4 basic steps: DNA extraction of bacteria, polymerase chain reaction, DNA hybridization, and colorimetric reaction. To examine the accuracy and specificity of this biochip, a preliminary test with 82 random quarter milk samples were analyzed and compared with results from conventional microbiological methods conducted simultaneously. Results from all but 1 sample analyzed by the biochip were in agreement with those analyzed by bacteriology. The biochip could be a feasible tool for rapidly diagnosing mastitis-causing pathogens in milk and providing information for a more effective treatment to cure mastitis.
1 March 2009 in Journal of Zoo and Wildlife Medicine
Hematologic analyses are useful for the monitoring of animal health and diseases and for the differentiation of physiologic processes for clinicians and conservationists. In order to establish hematology reference values for the Chinese striped-necked [corrected] turtle (Ocadia sinensis) and to produce an accurate baseline of clinical laboratory data for O. sinensis with regard to sex and season, 50 (24 males and 26 females) adult captive individuals of O. sinensis were studied. Blood samples from the jugular veins of the turtles were collected in January, April, June, and November. Data were analyzed using repeated measures analysis of variance for significant (P < 0.05) variation by sex, season, and the interaction between sex and season. Significant sex differences were observed for the parameters of packed cell volume, eosinophil count, heterophils and monocytes ratio, total protein, albumin, uric acid, aspartate aminotransferase, alanine aminotransferase, triglycerides, cholesterol, and alkaline phosphatase. Marked seasonal variation was noted in all parameters except mean cell hemoglobin, monocytes and heterophils ratio, and creatinine. Differences between sexes and seasons were primarily associated with the reproductive cycle. Heterophils had a strong positive reaction and eosinophils had a moderate positive reaction to benzidine peroxidase stain. Thrombocytes had a positive reaction to periodic acid-Schiff stain. Surface morphologic study using scanning electron microscopy of blood cells showed that white blood cells of O. sinensis had no distinctive surface characteristics.
Antibiotic therapy is the primary treatment for bovine mastitis, but the drawbacks of this strategy include poor cure rate and economic losses from the need to discard milk with antibiotic residues. Unfortunately, few other treatment options are currently available for mastitis. Failure of antibiotic treatments is often attributed to formation of bacterial biofilms and abscesses in the mammary gland tissue, which lead to chronic infections that are difficult to eradicate and drive recurrent disease. A major mastitis-causing pathogen (MCP) associated with biofilms in bovine mastitis is Staphylococcus aureus. In this study, we demonstrate that octanoic acid has broad-spectrum microbicidal activity against MCPs and effectively inhibits S. aureus biofilm formation in milk (>50% inhibition at 3.13 mM). Octanoic acid effectively clears biofilms (95% eradication at 1X minimum bactericidal concentration, MBC) and infrequently induces S. aureus small colony variants (SCVs) that may cause recurrent mastitis. Additionally, octanoic acid rapidly kills persistent biofilm cells and cells with antibiotic tolerance (within 4 h). In contrast, antibiotics treated at >100X MBC cannot eradicate biofilms but do induce SCVs and antibiotic-tolerant cells. These effects may accelerate the transition from biofilm to chronic infection. Thus, octanoic acid exhibits bactericidal action against S. aureus biofilms, and it is less likely than antibiotic therapy to induce persistent cells and pathogen tolerance. Moreover, octanoic acid acts additively with antibiotics against S. aureus, and it attenuates tetracycline-induced virulence factor gene expression in S. aureus cells. According to these data, octanoic acid may prevent the pathological progression of bovine mastitis and offer a new strategy for treating the condition.