Mastitis resulting from mammary gland infection is a common and painful disease associated with lactation. In addition to the impact on human and animal health, mastitis causes substantial economic losses in the dairy industry. Staphylococcus aureus is a frequent cause of mastitis worldwide. Despite significant progress in understanding S. aureus pathogenesis in general, much remains to be learned regarding virulence factors relevant in the context of mastitis. In mammary gland infections, it is not fully understood which metal acquisition systems are required for S. aureus survival. To help understand molecular mechanisms by which S. aureus might acquire essential metals, such as iron, within lactating mammary glands, S. aureus mutants were tested for growth defects in vitro. A low-iron media (TMM) was created and supplemented with differing iron sources relevant to mastitis infection such as host iron-binding proteins lactoferrin and transferrin. Mutants were grown in the various iron sources to determine which genes were involved with iron acquisition for each specific media tested. Results show that a double knock-out (∆htsA/sirA::ba) involved with two iron siderophore receptors and the ATPase, fhuC::ba, which powers those receptors are essential for growth in media supplemented with human lactoferrin, while mutants involved with the iron siderophore Staphyloferrin B (sbnE::ba) and its specific receptor (sirA::ba) proved important for growth in bovine lactoferrin. Additionally, S. aureus mutants were grown in bovine and human milk. Significant growth defects in human milk were found for mutants involved with zinc (znuBC::ba) and manganese (psaA::ba) acquisition. Iron limitations leading to growth defects were also found in ∆htsA/sirA::ba and fhuC::ba grown in human milk. Growth defects in bovine milk were seen for psaA::ba but not zinc genes. Growth of the fhuC mutant was shown to be significant, but not the double knock-out, indicating that iron acquisition in bovine milk does not involve the SirABC or HtsABC siderophore receptors. A mutant involved in purine synthesis, purH::ba, was also shown to have a significant growth defect in bovine milk. The importance of S. aureus metal acquisition has been well established, but there is a significant need to research these multifaceted processes further. Increased understanding of how metal acquisition facilitates bacterial survival in the lactating mammary gland can provide therapeutic targets for more effective mastitis prevention and treatment.

To asses the short- and medium-term breastfeeding effects on women´s postpartum health a prospective cohort study was performed with a base-line questionnaire at 1-5 days post partum and a follow-up questionnaire at 5-6 months pp. The sample consisted of two groups: the formula-feeding group (n = 15) and the breastfeeding group (n = 69). 1-5 days after delivery painful perineum (44.2%), backache (24.4%) and sore nipples (23.3%) were the most common complaints in the total sample whereas 5-6 months after delivery tiredness/ exhaustion (49.4%), haemorrhoids (27.7%) and painful perineum (24.1%) were on top of the list of complaints. During the first five days after delivery 28.6% of the whole breastfeeding group had sore nipples, at month 5-6 this proportion had raised to 34.8%. A large proportion (20.3%) of the breastfeeding group developed mastitis in the five months after delivery. Increase of complaints within the first 5-6 months after delivery tended to be higher in the breastfeeding group. Women who continued breastfeeding and introduced complementary foods within 5-6 months tended to have a worse subjective health status than the formula group and the group of exclusively breastfeeding mothers. In the Formula group the SOC-Score declined from 52.7 to 48.7. In the breastfeeding group the SOC-Score increased from 50.9 to 51.6. Besides wide spread health problems like exhaustion, haemorrhoids, painful perineum and backache, many breastfeeding women additionally have to deal with sore nipples and mastitis. On the other hand there is evidence that women can profit from breastfeeding in the sense of mastering a challenge, which is expressed in a higher SOC-Score comparing to formula feeding women.

Bovine mastitis, or inflammation of the mammary gland, has substantial economic and animal welfare implications. A genetic basis for mastitis resistance traits is recognized and can be used to guide selective breeding programs. The discovery of regions of the genome associated with mastitis resistance, and knowledge of the underlying molecular mechanisms responsible, can facilitate development of efficient mastitis control and therapeutic strategies. The objectives of this dissertation research were to identify sites of genetic variation associated with mastitis resistance, and to define the contributions of the milk-secreting epithelial cells to mammary gland immune responses and mastitis resistance. Twenty seven regions of the bovine genome potentially involved in mastitis resistance were identified in Holstein dairy cattle. Additionally, this research demonstrates a role of bovine mammary epithelial cells in mastitis resistance, and provides guidance for the use of an in vitro model for mastitis studies. Primary bovine mammary epithelial cells from mastitis-resistant cows have differential expression of 42 inflammatory genes compared with cells from mastitis-susceptible cows, highlighting the importance of epithelial cells in mastitis resistance. Bovine mammary epithelial cells display both similarities and differences in pro-inflammatory gene expression compared to fibroblasts, and their expression of inflammatory genes is influenced by administration of the enzyme phospholipase A2. The growth potential of milk-derived bovine mammary epithelial cells in vitro can be extended, facilitating their use in mastitis studies, by transfection with a viral protein. Collectively, this research contributes to current knowledge on bovine mastitis resistance and in vitro models.

Mastitis, an infection of the mammary gland, is the most common and expensive animal health problem for the dairy industry and affects every dairy farm to some degree. This disease complex is painful for dairy cows, increases the on-farm use of antibiotics, presents a threat to milk quality and is a waste of time, money and milk production. Each year, the dairy industry loses as much as a billion dollars to mastitis. Many cows will experience mastitis at least once during a lactation cycle and some animals will develop recurring mastitis episodes in a single mammary quarter. These mastitic quarters can be difficult to manage during the lactation cycle. Cessation of production in the quarter while continuing to milk the other three can be a beneficial management decision in this scenario. However, the current methods available for cessation of lactation in a single quarter are limited. This study investigated the use of casein hydrolysate as a non-antibiotic option for causing cessation of lactation in a quarter. From this preliminary study we were able to apply our results to another aspect of mastitis prevention, which is the routine use of intramammary antibiotics at the end of the lactation cycle. This management practice is known as dry treatment and is a standard practice in the dairy industry with many years of proven efficacy against clearing infections present at the end of the lactation cycle. Increasing pressure from consumers to decrease antibiotic use in food production animals has caused this practice to come under scrutiny. This secondary study investigated the use of casein hydrolysates as a nonantibiotic alternative to standard antibiotic dry cow treatment. Overall, these studies demonstrated that casein hydrolysate has some efficacy in inducing mammary involution of a single quarter mid-lactation and also potentially as an alternative dry cow treatment. None of the animals treated in these studies displayed any symptoms of pain or discomfort, and all treated quarters resumed milk production after the next calving. Additionally, all antimicrobial milk tests on treated animals were negative. Casein hydrolysates may be a useful management tool for milk quality and animal health within the dairy industry.

Mycoplasmas are a group of bacteria which are small in size, lack a cell wall, and have small genomes in comparison to other bacteria. The members of the group that are pathogenic utilize several mechanisms to evade the host's immune system. These processes affect surveillance and control mechanisms such as serologic testing and vaccination. Many of these organisms cause diseases of livestock, which heavily impact production parameters such as weight gain, milk yield, and egg production. Mycoplasmas also cause disease in people. Mycoplasma spp. can cause mastitis, metritis, pneumonia, and arthritis. The currently documented routes of transmission of Mycoplasma spp. are through fomites and by direct animal contact. The existence of environmental sources for Mycoplasma spp. and their role in transmission are poorly characterized. Mycoplasma spp. (confirmed as M. bovis using PCR) was found in recycled bedding sand from a dairy experiencing an outbreak of mycoplasma mastitis. The possibility of a persistent environmental source of Mycoplasma spp. in recycled bedding sand was further investigated using recycled sand from the dairy. Study objectives included determining factors associated with the persistence of Mycoplasma spp. in recycled bedding sand and the duration of survival of mycoplasmas in the sand. We also evaluated 2 disinfectants at 2 different concentrations each for the elimination of Mycoplasma spp. from contaminated sand. Mycoplasma spp. survived in the sand pile intermittently over a period of 8 months. The concentration of Mycoplasma spp. within the sand pile was directly related to temperature and precipitation. The survival of Mycoplasma spp. at a greater than expected range of temperatures suggests the formation of a biofilm. Ideal temperatures for replication of Mycoplasma spp. occurred between 15 °C and 20 °C. Moisture in the sand and movement of the sand pile also appeared to play a role in replication of mycoplasmas. Sodium hypochlorite (0.5%) and chlorhexidine (2%) were efficacious in eliminating Mycoplasma spp. from contaminated bedding sand. Recycled bedding sand could be an environmental source of Mycoplasma spp. infections, including M. bovis, in dairy cows. Future studies should investigate the contribution of this environmental source to the epidemiology of mycoplasma infections in dairy cattle and other ruminants.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第13218号 / 論医博第2165号 / 新制||医||1033(附属図書館) / 京都大学大学院医学研究科内科系専攻 / (主査)教授 溝脇 尚志, 教授 黒田 知宏, 教授 鈴木 実 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Conventional bacteriological methods to establish bacterial burden and distribution in infected tissues in vivo animal models typically require extensive bacteriological procedures and therefore are time consuming. An alternative approach has been suggested to use optical markers, such as luciferases, to labeled pathogens and monitor their progress and distribution in real time. The objective of the work presented in this document was to validate the use of Biophotonic Imaging (BI) through in vitro studies as a first step toward the development of in vivo models to study infectious disease in the bovine. For example, the feasibility of detecting bioluminescent Escherichia coli (E. coli-lux) from within the different bovine reproductive tract segments was studied. Up to 17 % transference of photonic emissions (PE) was detected through the reproductive tract, suggesting that in vivo or in situ models may provide a novel approach for in real time screening of uterine infections in large farm animal models. Further in vitro research conducted toward the development of approaches for non invasive detection of lux-bacteria in bovine mastitis models demonstrated that detection through the bovine mammary gland might be limited due to tissue thickness and density. However, imaging of Staphylococcus aureus (S. aureus)-lux presence in teat-end skin wound in vitro models demonstrated promising results. Furthermore, trials demonstrated that imaging of lux-bacteria in milk samples, as means to estimate bacterial cell numbers (CFU), represent an efficient model to monitor bacterial progression in vivo mastitis models. According to these findings, the efficacy of an intramammary antimicrobial agent was evaluated in real time using S. aureus-lux in vivo mastitis models conducted in lactating dairy cows. Photonic emissions from milk samples collected from challenged quarters with S. aureus-lux resulted to be an excellent predictor of CFU, as demonstrated by the high and positive correlation (0.99; P < 0.0001) between CFU and PE. In addition, BI provided in real time information regarding spatial distribution of S. aureus-lux in infected mammary gland quarters ex vivo. Collectively, this date positions BI as novel and promising tool to improve current bacteriological methods to better understand pathogenesis of bovine mastitis infections.

No description available.

Research to determine the impact of PTA<SUB>SCS</SUB> on incidence of mastitis, daughter response to infection, and other measures of daughter performance was conducted using data on 1st, 2nd, and 3rd lactation Holsteins obtained from the Virginia Tech herd and from VA DHI herds. Overall correlation of PTA<SUB>SCS</SUB> to lactation average SCS ranged from 0.13 to 0.17 across all data sets. Correlations between PTA<SUB>SCS</SUB> and 1st lactation SCS measures were higher than those between PTA<SUB>SCS</SUB> and SCS in later parities, but higher correlations were found between 2nd and 3rd lactation SCS measures than between 1st and later parities. Correlation of lactation average SCS and incidence of clinical mastitis was 0.41. Regression of lactation average SCS and averages of test day SCS measures on PTA<SUB>SCS</SUB> was significant in 1st, 2nd, and 3rd lactations. All significant relationships were linear and equal or close to 1.0. Relationships between PTA<SUB>SCS</SUB> and number of cases of clinical mastitis (.79), number of treatments (2.0), number of days treated (7.0), changes in SCS from beginning to end of a lactation (-.26), and the slope of changes in test day SCS with DIM (5.9x10-4) were significant only in 1st lactation. No significant relationships between PTA<SUB>SCS</SUB> and measures of clinical mastitis or variation in test day SCS measures were found in 2nd or 3rd lactations. Heavy cull rates imposed on 1st lactation cows in the Virginia Tech herd explained lack of significance in the later parities in the herd study, but results in following analyses indicated that measures of SCS in 1st and later parities may be two different, but correlated, traits. The greatest impact of PTA<SUB>SCS</SUB> on measures of daughter performance and profit was the negative relationship between PTA<SUB>SCS</SUB> and herd life. Increased PTA<SUB>SCS</SUB> resulted in the decreased ability to survive involuntary culling, and thus decreased opportunity for lifetime yield and profit. Selection on PTA<SUB>SCS</SUB> should be an effective method of reducing incidence of clinical mastitis, lactation average SCS, and variation in SCS, or response to infection. The response, however, may be different in 1st lactation than in later parities. / Master of Science

No description available.