Staphylococci are the most typical bacteria found in cattle with mastitis, either Staphylococcus aureus or coagulase-negative Staphylococci (CNS). The study’s goal was to determine the prevalence of Staphylococci in bovine mastitis, the antimicrobial profile, and evaluate the concentration of pro-inflammatory interleukins (IL-4, IL-6, IL-10) related to the inflammatory response in clinical mastitis by ELISA. S. aureus (54%) and CNS (19%) were detected in 400 samples of milk from both clinical and subclinical bovine mastitis. The S. aureus isolates revealed higher resistance to ampicillin (100%), followed by amoxicillin-clavulanic acid (98.1%), cefotaxime (88.9%), erythromycin (63.2%), cefuroxime (63%), and tetracycline (61.1%). Furthermore, the CNS isolates showed high resistance against amoxicillin-clavulanic acid (100%), followed by ampicillin (94.7%), cefotaxime (89.5%), erythromycin (79.6%), cefuroxime (89.5%), and tetracycline (73.7%). However, the high susceptibility of S. aureus and CNS was observed to imipenem and ciprofloxacin. Furthermore, Cows with clinical mastitis reported high levels of IL-6 in both their serum and their milk. While they have much lower levels of IL-4 and IL-10 than normal ones (P < 0.001). In conclusion, it is recommended that laboratory results be carefully interpreted to avoid antimicrobial therapy for Staphylococci that is not clinically relevant and to ensure the advisable use of antimicrobials. Also, further study on the application of interleukins as therapeutic agents against bovine mastitis should be considered.

Staphylococcus aureus is a major pathogen that affects both people and animals. Staphylococcus aureus causes food poisoning in addition to invasive diseases as arthritis and septicemia. This study was done on 70 chicken samples obtained from 7 different farms of chickens with symptoms of arthritis in Kafr El-sheikh government, Egypt. In this study out of 70 samples of chickens from different farms, 37 (52.8%) samples were recognized as coagulase-positive staphylococci (CoPS) and 33 (47.1%) were recognized as coagulase-negative staphylococci (CoNS). By using the microtitre plate method, seven out of 37 (18.9%) CoPS were positive for biofilm production with variable degrees. The pattern of antibacterial sensitivity of 7 Staphylococcus aureus isolates against 12 commercially available antibiotic discs showed 100 % resistance to oxytetracycline then Amoxicillin (71.43%), Erythromycin (57.14%), Norfloxacin (14.29%), Tetracycline (42.86), Sulphamethoxazole (42.86%), Gentamicin (42.86%), Ampicillin (42.86%), kanamycin (28.57), cephatotin (28.57), doxycycline (0%) and the least was observed with chloramphenicol (0%). seven of positive S. aureus isolates were introduced in order to identify the staphylococcal enterotoxin genes, SEA, SEB, SEC, SED, and SEE and integron by PCR test Which 4 out of 7 isolates (57.1 %) were positive for SEB and SED only while were other isolate were negative for all SE gene. Class 1 integron cassettes were detected in 6 isolates from 7 (85.7%) of tested isolates. In conclusion, this is the first study to report the detection and identification of enterotoxin and class 1 integron in S. aureus isolated from poultry meat of chicken that suffered from arthritis.

OBJECTIVE To determine the concentration of tilmicosin in mammary gland secretions of dairy cows following administration of an experimental preparation once or twice during the dry period (45-day period immediately prior to calving during which cows are not milked) and to evaluate its efficacy for the treatment of cows with intramammary infections (IMIs) caused by Staphylococcus aureus at dry off (cessation of milking; first day of dry period), compared with that of an intramammary infusion of ceftiofur. ANIMALS 172 cows. PROCEDURES Milk samples were collected for microbiological culture 5 days before dry off and at calving and 15 and 30 days after calving. Cows with Staphylococcus IMIs were randomly assigned to receive an experimental preparation of tilmicosin (20 mg/kg, SC) once at dry off (n = 58) or at dry off and again 20 days later (56) or receive a long-acting intramammary preparation of ceftiofur (500 mg/mammary gland; 56) at dry off. Mammary gland secretions were collected from 5 cows in the tilmicosin-treated groups every 5 days after dry off until calving for determination of tilmicosin concentration. RESULTS Mean maximum concentration of tilmicosin in mammary gland secretions ranged from 14.4 to 20.9 μg/mL after the first dose and was 17.1 μg/mL after the second dose. The bacteriologic cure rate was 100% for all 3 treatments. Tilmicosin was detectable for 0 and 18 days after calving in the milk of cows treated with 1 and 2 doses of tilmicosin, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Administration of an experimental preparation of tilmicosin (20 mg/kg, SC) once to dairy cows at dry off might be useful for the treatment of S aureus IMIs.

The aim of this study was to evaluate the antimicrobial activity and determine the minimum bactericidal concentration (MBC) of the essential oils derived from Origanum vulgare (oregano), Melaleuca alternifolia (tea tree), Cinnamomum cassia (cassia), and Thymus vulgaris (white thyme) against Salmonella Typhimurium, Salmonella Enteritidis, Escherichia coli, Staphylococcus aureus and Enterococcus faecalis. The study also investigated the ability of these different bacterial strains to develop adaptation after repetitive exposure to sub-lethal concentrations of these essential oils. The MBC of the essential oils studied was determined by disc diffusion and broth dilution methods. All essential oils showed antimicrobial effect against all bacterial strains. In general, the development of adaptation varied according to the bacterial strain and the essential oil (tea tree > white thyme > oregano). Therefore, it is important to use essential oils at efficient bactericidal doses in animal feed, food, and sanitizers, since bacteria can rapidly develop adaptation when exposed to sub-lethal concentrations of these oils.

Objective: To determine the pharmacokinetics of a commercial formulation of doxycycline hyclate after IM administration of a single dose to sheep. Animals: 11 healthy domestic sheep. Procedures: For each sheep, doxycycline was administered as a single dose of 20 mg/kg, IM. Blood samples were obtained prior to and for 84 hours after doxycycline administration. Plasma concentrations of doxycycline were determined via high-performance liquid chromatography with UV detection. Pharmacokinetic data were analyzed with noncompartmental methods. Results: Mean ± SD values for pharmacokinetic parameters included maximum plasma concentration (2.792 ± 0.791 μg/mL), time to reach maximum plasma concentration (0.856 ± 0.472 hours), mean residence time (91.1 ± 40.78 hours), elimination half-life (77.88 ± 28.45 hours), and area under the curve (65.67 ± 9.877 μg•h/mL). Conclusions and Clinical Relevance: Results indicated that doxycycline had prolonged absorption and elimination in sheep after IM administration. A daily dose of 20 mg/kg would be sufficient to reach effective plasma concentrations against Chlamydia spp (minimum inhibitory concentration, 0.008 to 0.031 μg/mL) and Staphylococcus aureus (minimum inhibitory concentration, 0.12 μg/mL). Doxycycline administered IM could be an option for therapeutic use in sheep, although further studies are needed.

The effect of a novel bovine mastitis trivalent vaccine, containing Staphylococcus aureus capsular polysaccharide type 5 (T5), 8 (T8), and 336 (T336), on lymphocyte subpopulations, antibody production, and neutrophil phagocytosis was evaluated. Twenty pregnant heifers were immunized with either the trivalent alone, trivalent emulsified in Freund's incomplete adjuvant (FICA), trivalent in aluminum hydroxide, or adjuvant only (FICA). Immunization was done 30 d before the expected calving date followed by 2 boosts in a 2-week interval. Compared to FICA, serum antigen-specific immunoglobulin (Ig)G1 and IgG2 were significantly increased in all the vaccinated groups before parturition and sustained until 3 wk postpartum. In comparison with the trivalent alone, formulation with either adjuvant enhanced production of IgG2, but not IgG1. Immune sera, which contained the highest amount of antibodies, slightly increased neutrophil phagocytosis to the 3 serotypes of killed S. aureus, but most of the differences were not significant due to large variation between the cows. The percentage of CD4+ lymphocyte was significantly higher in vaccinated groups than that of FICA 4 wk after the primary immunization. In comparison with FICA, cows inoculated with trivalent vaccine and adjuvants had an increased percentage of CD8+ lymphocytes at 2 time points, 2 wk before and after calving. Our results indicated that the whole cell trivalent vaccine, with or without adjuvants, is able to elicit antibody responses specific to the 3 capsular polysaccharide antigens. The increase of T8-specific IgG2 was more noticeable when the vaccine was emulsified with adjuvants.

The effects of 3 days of glucocorticoid administration on bovine blood neutrophil expression of L-selectin and CD18, and on the health status of mammary glands subclinically infected with Staphylococcus aureus were measured in 9 lactating Holsteins. The experiment was a 3 x 3 Latin square cross-over design, with 3 glucocorticoid treatments switched among groups of 3 cows/treatment during 3 periods. Treatments consisted of a vehicle (control, 10 ml of excipient/cow/d), cortisol (7.5, 15, and 7.5 mg/cow on days 1, 2, and 3, respectively), and dexamethasone (0.04 mg/kg of body weight/cow/d for total daily dosages that ranged from 21.6 to 33.2 mg). Blood samples for immunostaining and flow cytometric analysis of L-selectin and CD18 and leukograms, as well as foremilk samples for determination of S aureus shedding somatic cell counts, protein and fat percentages, and daily milk yields were collected repeatedly before, during and after treatment days. Dexamethasone caused a profound, acute, short-lived down-regulation of L-selectin on neutrophils, which correlated in time to leukocytosis, mature and immature neutrophilias, increased shedding of S aureus in infected glands, and onset of high percentages of fat and protein and decreased milk yields. Dexamethasone also caused profound but delayed down-regulation of neutrophil CD18, which reached nadir simultaneously with reappearance of L-selectin-bearing neutrophils, normalized blood neutrophil counts, markedly high foremilk somatic cell counts and protein percentage, decreased S aureus shedding in milk, and finally, expression of clinical mastitis in some infected quarters. Each of these variables had returned to control (vehicle) values by the ninth (and last) sample collection day. Although cortisol treatment also decreased expression of L-selectin and CD18 on neutrophils, dosages used in this study were not sufficient to alter the number of circulating cells or to convert subclinical mammary gland infections to clinical mastitis. These results suggest that mammary gland health status can be altered by sudden exposure of blood neutrophils to glucocorticoids, because these steroid hormones caused profound down-regulation of the adhesion molecules that direct neutrophil margination and migration through the vascular endothelium. The results also reinforce the potential disease risk of treating infected animals with potent synthetic glucocorticoids, such as dexamethasone.

Ten healthy first- and second-lactation Holstein cows were observed from 1 week before to 1 week after calving and at postpartum day 30 to determine polymorphonuclear neutrophil (PMN) functional variation and immunoglobulin binding profiles. Blood and mammary PMN were obtained 3 times weekly and within 24 hours of calving. Functional traits measured included phagocytosis of Stapbylococcus aureus and in vitro chemotaxis through micropore filters in a Boyden chamber. Additionally, PMN were evaluated for endogenous binding of IgG1, IgG2, IgA, and IgM before and after in vitro chemotaxis. Exogenous binding of the same isotypes was determined after incubation in pooled colostrum, purified immunoglobulin, and pooled sera. Phagocytosis results indicated a significant and transient increase in percentage of milk PMN with associated, rather than phagocytosed, bacteria for 1 week after calving. Blood PMN phagocytosis was not significantly different during this period. Though total chemotaxis was essentially unchanged, the percentage of PMN that were unable to complete migration increased substantially on the day of calving, an effect that disappeared by postpartum day 4. A significant (P < 0.01) positive correlation (r = 0.29) between percentage of PMN migrating completely through the micropore filter and percentage of blood PMN with associated bacteria was observed. Changes were not observed in endogenous immunoglobulin binding, with the exception of a peak in relative fluorescence intensity for IgG1 on the day of calving; this disappeared within 2 days after calving. Correlations between relative intensities of IgG2, and IgM, and percentage of mammary neutrophils phagocytosing were 0.37 and 0.70. Exogenous binding of antibody to blood neutrophils before chemotaxis was generally accomplished most effectively by pooled colostrum, whereas use of pooled sera markedly reduced binding and percentage and intensity of IgM in all cases. Binding of all isotypes was slightly higher before than after calving. Incubation of blood neutrophils in isotypes G1, G2, A, and M after chemotaxis yielded lower immunoglobulin binding among all isotypes, particularly IgM. Fluctuations in neutrophil function were observed immediately around parturition, and these changes correlated strongly with endogenous immunoglobulin-binding profiles.

Cytologic and bacteriologic responses, and changes in cytokine activity were evaluated in secretions of Staphylococcus aureus-infected mammary glands after treatment of heifers with recombinant bovine interferon gamma (rbIFN gamma) or interleukin 2 (rbIL-2). Two groups of 4 heifers each, experimentally infected with 10(7) colony-forming units (CFU) of S aureus, were injected in 2 quarters via the teat canal, with 10(5) U of rbIFN gamma (trial 1) or 7.5 X 10(5) U of rbIL-2 (trial 2) 2 weeks after experimentally induced infection; control quarters received phosphate-buffered saline solution. Mammary secretion samples were taken on days 0, 1, 2, 3, 4, 7, and 14 after cytokine infusion. Secretions were diluted 1:10 and used to perform somatic cell counts (SCC), differential cell counts, and CFU enumerations, and to determine the number of leukocytes expressing major histocompatibility complex class-II (MHC II) antigens. In addition, mammary secretion samples taken on days 0, 1, and 2 were processed to obtain skimmed milk for evaluation of rbIFN gamma- and rbIL-2-like activities. Treatment with rbIFN gamma did not influence SCC, or differential or bacteria counts, or the number of leukocytes expressing MHC II antigens. However, rbIL-2 stimulated leukocytosis, which may have reduced bacteria counts early in the trial; treatment with this cytokine also increased the neutrophil, macrophage, lymphocyte, and eosinophil counts in secretions. Similarly, numbers of MHC II-positive leukocytes were greater in rbIL-2-treated quarters vs controls. Compared with day 0, IFN gamma-like activity was increased on only day 1 in both trials. Interleukin-2-like activity was not influenced in the rbIFN gamma trial, but was increased on days 1 and 2 in the rbIL-2 trials. Results indicated that neither cytokine may have had a major influence on the course of established S aureus infections. However, the increased SCC in rbIL-2-treated quarters may have accounted for the reduction in CFU throughout the trial after treatment with this cytokine. Greatest cytokine-like activity was observed on day 1; however, the consequences of cytokine activity, such as the sustained eosinophilia after rbIL-2 treatment, were detected over the 14-day trial period, indicating possible prolonged action.

Ten Holstein cows were fed a selenium-deficient (SeD) diet containing 0.04 mg of Se/kg of dry matter for 3 months before and throughout their first lactation. A selenium-supplemented (SeS) group of 10 cows was fed an additional 2 mg of Se/head/d to increase dietary Se concentration of the dry matter to approximately 0.14 mg/kg of body weight. An intracisternal challenge exposure of 40 to 60 colony-forming units (CFU) of Staphylococcus aureus was administered into 1 or 2 quarters of the udder of each trial cow at about the twenty-second week of lactation. Blood Se concentration (microgram/ml +/ - SEM) at the time of challenge exposure was 0.035 +/- 0.002 in SeD and 0.139 +/- 0.006 in SeS cows. Infections were established in 14/16 of the challenge-exposed quarters in SeD and 16/19 of the challenge-exposed quarters in SeS cows. The infection in 1 quarter of each Se group cleared without treatment by the end of the 8-week trial period. Log10 peak bacterial concentrations in milk from infected SeD quarters (5.04 +/- 0.25 CFU/ml) were higher (P < 0.05) than those of infected SeS quarters (4.40 +/- 0.12 CFU/ml). Log10 peak somatic cell count (SCC) in milk from infected SeD quarters (7.18 +/- 0.08 cells/ml) did not differ from that of SeS quarters (7.17 +/- 0.05 cells/ml). Peak bacterial concentrations were attained sooner (P < 0.05) in SeD quarters (9.5 +/- 4.0 days) than in SeS quarters (20.7 +/- 3.1 days). Similarly, peak SCC were reached earlier (P < 0.05) in SeD (4.3 +/- 1.1 days) than in SeS quarters (13.3 +/- 3.8 days). The Se groups did not differ significantly with respect to peak milk concentrations of bovine serum albumin or IgG1. Throughout the 8-week trial, the Se groups did not differ significantly in milk bacterial concentration, SCC, bovine serum albumin, or IgG1. Selenium status did not affect the percentage of challenge exposures resulting in infection, duration, or severity of experimentally induced S aureus mastitis.