Contamination by Staphylococcus aureus of food produced from animal sources may have diverse and multifactorial causes that depend on geographical distribution. The goal of this study was to isolate and characterise S. aureus strains from contaminated fermented pork sausage, which is a local food of northeastern Thailand. S. aureus strains were isolated from local pork sausage, and the presence of classical enterotoxins was determined by PCR and reversed passive latex agglutination. These results were compared with strains derived from hospitalised patients and healthy carriers. Additionally, production of extracellular enzymes and haemolysin, biofilm formation, and antibiotic susceptibility were assessed. S. aureus was identified in 36 sausage isolates (60%). The strains positive for staphylococcal enterotoxin A were more frequently found in isolates from sausage and healthy carriers than in those from patients. All tested S. aureus strains were positive for DNase, lipase, proteinase, haemolysin, and biofilm formation; notably, strains isolated from food and healthy carriers displayed similar values. Most isolates were resistant to penicillin and ampicillin, while none were to methicillin. Thai fermented pork sausages are associated with a high risk of staphylococcal food poisoning, which may be linked to contamination caused by carriers. Dissemination of knowledge regarding best practices in sanitation and hygiene is important in local communities.

The purpose of this study was to determine the microbiological quality of food fish and its safety for consumers. The study included 24 fish representing grass carp, bighead carp, Siberian sturgeon, and wels catfish. Specimens were collected in winter. Aerobic bacteria, psychrophilic, Enterobacteriaceae, Staphylococcus spp., and E. coli counts were made, and the presence of Salmonella spp., L. monocytogenes, S. aureus, and other coagulase-positive staphylococci was investigated. The microbiological analysis showed a similar level of aerobic, psychrophilic, and Staphylococcus spp. contamination of the four fish species. The Enterobacteriaceae count was higher in the muscles of grass carp and bighead carp than S. sturgeon and wels catfish. No pathogenic bacteria such as Salmonella spp., E. coli, L. monocytogenes, Staphylococcus aureus, or other coagulase positive staphylococci were found in samples of the examined fish species. The fresh fish examined in this study were of good microbiological quality and there was no health risk for consumers.

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is a highly resistant and difficult to cure zoonotic microorganism, which makes up a large part of food toxic infections and has shown high prevalence among pig population all over the world. The aim of the study was to establish the occurrence of MRSA in slaughterhouses, evaluate its antimicrobial resistance, and verify whether there are any differences or similarities with reference to other European countries. Material and Methods: A total of 100 pigs, 105 carcasses, 19 workers, and 24 samples from the environment of several slaughterhouses were examined by conventional microbial and molecular methods. Results: In total, 78 MRSA isolates were found. MRSA prevalence in slaughtered pigs varied from 8.0% to 88.6% depending on the slaughterhouse, reaching higher prevalence in slaughterhouses with higher slaughter capacity. In total, 21.1% of all workers were carriers of MRSA and 6.7% of carcasses were contaminated with MRSA. The 98.2% of MRSA isolates were resistant to penicillin, 89.1% to tetracycline, 60.1% to erythromycin, 65.5% to gentamycin, and 15 different spa types were found, among which spa type t01333 was most widespread. Conclusion: The study indicated that MRSA prevalence and spa types differed according to slaughterhouse slaughter capacity and good hygiene practices. Quite high MRSA occurrence among slaughterhouse workers is one of the main factors which increase pork contamination risk.

Objective—To evaluate whether the application of steam to a variety of surface types in a veterinary hospital would effectively reduce the number of bacteria. Sample—5 surface types.Procedures—Steam was applied as a surface treatment for disinfection to 18 test sites of 5 surface types in a veterinary hospital. A pretreatment sample was obtained by collection of a swab specimen from the left side of each defined test surface. Steam disinfection was performed on the right side of each test surface, and a posttreatment sample was then collected in the same manner from the treated (right) side of each test surface. Total bacteria for pretreatment and posttreatment samples were quantified by heterotrophic plate counts and for Staphylococcus aureus, Pseudomonas spp, and total coliforms by counts on selective media. Results—Significant reductions were observed in heterotrophic plate counts after steam application to dog runs and dog kennel floors. A significant reduction in counts of Pseudomonas spp was observed after steam application to tub sinks. Bacterial counts were reduced, but not significantly, on most other test surfaces that had adequate pretreatment counts for quantification. Conclusions and Clinical Relevance—Development of health-care–associated infections is of increasing concern in human and veterinary medicine. The application of steam significantly reduced bacterial numbers on a variety of surfaces within a veterinary facility. Steam disinfection may prove to be an alternative or adjunct to chemical disinfection within veterinary practices.

Neutrophils are present in milk of cows as a means of suppressing invading pathogens during mastitis. However, the manner by which neutrophils traverse the secretory epithelia is still not clear: do they diapedese between epithelial cells or do they kill epithelial cells to gain entry into milk? We investigated the process of bovine neutrophil diapedesis across bovine mammary gland epithelium in vitro. The bovine mammary epithelial cell line MAC-T, grown on collagen-coated filters, formed a confluent monolayer with characteristic tight junctions, basal-apical polarity, and functional barriers to the dye trypan blue. Neutrophils added on the apical surface of the monolayer were stimulated to diapedese across the epithelium by the addition of Staphylococcus aureus (10(7) colony-forming units/ml) to the basal compartment. Light and transmission electron microscopy revealed the series of events for neutrophil transmigration: accumulation of neutrophils on the surface of epithelial monolayer; projection of pseudopods into intercellular junctions and movement of neutrophils between adjacent epithelial cells; and reapproximation of the lateral epithelial cell membranes and reformation of the apical tight junctions after neutrophils crossed the epithelium. Morphologically, epithelial cell damage caused by neutrophil diapedesis was not evident. This in vitro model provides a two-dimensional epithelial sheet by which neutrophil diapedesis can be qualitatively studied under defined conditions. Results of the study suggest a major mode by which bovine neutrophils diapedese across the alveolar epithelia into milk during mastitis.

The main objective of the study reported here was to generate a panel of monoclonal antibodies (MAB) to bovine neutrophil surface antigens, and to identify MAB that modulate neutrophil chemotaxis, respiratory burst, and phagocytosis. A further objective was to study MAB reactivity with resting and activated neutrophils, to identify activation antigens and adhesion molecules. A panel of 14 MAB was generated by producing murine hybridomas. Neutrophils incubated with MAB at 4 C for 2 hours were used in chemotaxis, respiratory burst, and phagocytosis assays. Chemotaxis was evaluated in Boyden chambers, using Escherichia coli endotoxin-activated fetal bovine serum as the chemoattractant. Respiratory burst was determined by measuring chemoluminescence of neutrophils incubated with 5-amino-2,3-dihydro-1,4-phthalazinedione, and serum opsonized zymosan. Phagocytosis was determined by flow cytometry, using fluorescein-labeled Staphylococcus aureus. The MAB S7G8, S5F8G10, S7E10, and S5F8B8 enhanced chemotaxis (to > 125% of control). The MAB S7E10 and S8D9 enhanced respiratory burst activity (to > 125% of control), whereas MAB S2G8, S4G10, S8G10, and S5F8B8 caused inhibition (to < 75% of control). The MAB S2G8, S4G10, S8G10, and S5F8G10 enhanced phagocytosis (to > 125% of control). Chemotaxis, respiratory burst, and phagocytosis values of neutrophils not bound with MAB served as controls for comparison. The MAB binding for nonactivated neutrophils (at 4 C) ranged from 9 to 100%, and for activated neutrophils (at 37 C; at 37 C with phorbol myristate acetate) from 90 to 100%. Binding of MAB S4F5, S5F8B8, S6C6, S7E10, S8D9, and S5F8G10 increased when neutrophils had been incubated at 37 C. Binding of these MAB was further increased after incubation with phorbol myristate acetate (100 ng/ml) at 37 C, indicating recognition of activation antigens by MAB. The MAB generated in this study appeared to be potential candidates for studying mechanisms of neutrophil function and for enhancing neutrophil function in vitro and in vivo.

Sixteen Holstein cows were used to test the effect of postmilking teat treatment on colonization and intramammary infection by Staphylococcus aureus on chapped teats. Treatments were (1) chapping the teat and using 1% I2/10% glycerin postdip solution, (2) 1% I2/10% glycerin postdip solution on nonchapped teats, (3) chapping the teat and using 10% glycerin postdip solution, (4) chapping the teat and not using a postdip solution. All mammary glands were free of S aureus teat skin colonization and intramammary infection at the start of the study. Teats selected for chapping were dipped in 1N NaOH prior to 3 applications of S aureus broth culture; cultures were applied at 12-hour intervals on all teats. Treatments were applied after each milking for 30 days and were initiated after the second broth dip. Teat skin swab specimens and milk samples were collected before treatment application. Teat skin condition was scored daily. Nonchapped teats (treatment 2) did not support skin or orifice colonization by S aureus. Treatment-1 teats healed most rapidly and supported less colonization in skin and orifice than did treatment-3 and -4 teats. Teat skin scores and skin colonization were lower for treatment-3 than treatment-4 teats. A correlation between teat skin colonization and teat skin conditions was found. Two intramammary infections were found in treatment-4 quarters and 1 in a treatment-3 quarter. On the basis of our findings, we concluded that poor teat skin condition will more readily support S aureus colonization, that a dip of 1% I2 with glycerin helped reduce S aureus colonization and was associated with faster healing, and that glycerin in teat dips may be of value in preventing colonization by S aureus and in promoting healing.

Detection of capsular polysaccharide (CP) in milk of cows with natural intramammary infection caused by Staphylococcus aureus was attempted. Five quarters of 5 cows harboring S aureus strains that produce type-8 CP were selected. Using an ELISA with a monoclonal antibody, type-8 CP was not detected in extracts prepared from fresh milk collected aseptically. By contrast, CP was easily detectable after incubation of infected milk at 38 C for 20 hours. Quantitation of CP in extracts from incubated milk samples by use of ELISA indicated a great variation of CP expression by strains. Although an incubation step was necessary to detect CP, results of the study indicate that CP may be expressed in vivo during intramammary infection caused by S aureus.

Phagocytic and oxidative metabolic activities of bovine blood neutrophils were determined in the presence of glycolytic (NaF) and cytoskeletal (colchicine, cytochalasin B, and prostaglandin E1) inhibitors. Phagocytosis and postphagocytic oxidative metabolic activity, measured by nitroblue tetrazolium reduction, were determined using zymosan, Escherichia coli, Staphylococcus aureus, or Streptococcus agalactiae. Sodium fluoride (1.25 micromolar to 1.25 mM concentrations) did not significantly (P greater than 0.05) inhibit phagocytosis of S aureus and Str agalactiae, whereas phagocytosis of zymosan and E coli was significantly (P less than 0.05) inhibited only at 1.25 mM concentration. Colchicine at 1.25 nM to 1.25 micromolar conce ntrations significantly inhibited phagocytosis of zymosan and E coli, but not of S aureus and Str agalactiae. Cytochalasin B at 1.25 nM to 1.25 micromolar concentrations significantly inhibited phagocytosis of zymosan and all 3 bacteria, whereas prostaglandin E1 was noninhibitory at similar concentrations. Nitroblue tetrazolium reduction, in general, was not significantly affected by NaF and cytoskeletal inhibitors.

The tarsocrural joints of 11 horses were inoculated with 1.2 to 2.16 x 10(6) viable Staphylococcus aureus organisms susceptible to a trimethoprim-sulfadiazine (TMP-SDZ) combination with minimal inhibitory concentration (MIC) of 0.25 microgram of TMP/ml and 4.75 microgram of SDZ/ml. Antimicrobial treatment consisted of oral administration of a TMP-SDZ combination-30 mg/kg of body weight given once daily (group-1 horses) or 60 mg/kg given as 30 mg/kg every 12 hours (group-2 horses). Paired serum and synovial fluid samples were obtained before intra-articular inoculation with the S aureus, after inoculation with S aureus but before antimicrobial treatment, and after inoculation at various hourly intervals after oral administration of the TMP-SDZ combination. The TMP-SDZ combination was administered daily in the 2 dosages for 21 days. Samples were collected after day 3 of repetitive drug administration so that drug steady-state concentration would have been achieved. Serum and synovial fluid samples were analyzed for TMP and SDZ concentrations. Administration of the TMP-SDZ combination at a dosage of 30 mg/kg once daily was not effective in maintaining TMP or SDZ concentrations above the MIC of TMP-SDZ for the S aureus (0.25 and 4.75 microgram/ml for TMP and SDZ, respectively) in the infected synovial fluid or in maintaining adequate TMP concentration in the serum. The alternative use of the TMP-SDZ combination at a dosage of 60 mg/kg given as 30 mg/kg every 12 hours was effective in maintaining serum and synovial fluid concentrations of TMP and SDZ that were greater than the MIC for the infective organism. Sulfadiazine concentration was significantly (P less than or equal to 0.05) lower in the infected synovial fluid sample than that in the corresponding serum sample. We concluded that administration of 60 mg of TMP-SDZ/kg given as 30 mg/kg every 12 hours is more effective than 30 mg/kg given once daily for the treatment of equine infectious arthritis caused by organisms for which the MIC of TMP-SDZ is less than or equal to 0.25-4.75 microgram/ml.