THE ROLE OF EQUIPMENT THAT HAS DIRECT CONTACT WITH THE CARCASE IN THE SPREAD OF SALMONELLA IN A BEEF ABATTOIR

Counts of Salmonella were performed by the most probable number technique on 16 articles of abattoir equipment having direct contact with the carcase. Forty samples were collected from each article over 21 months. The contamination rate of these articles with salmonellae varied from nil % for a saw used to quarter the sides to 47.5% for stainless steel tables and hooks. Mesh gloves were also highly contaminated, salmonellae being isolated from 32.5% of gloves on the slaughter floor and 40% of those in the boning room. Salmonella counts ranged from 1.0 to 3,663 organisms per article. Mesh gloves, cutting boards and stainless steel tables were found to have counts that were at times greater than 1,000 salmonellae per article.     

Pesticide residues in foodstuffs in Great Britain; organochlorine pesticides,organophosphorus pesticides and fumigant residues in home-produced and imported wheat

Residue levels of organochlorine pesticides, organophosphorus pesticides, fumigants and bromide were determined in home-produced and imported wheat during the period October 1978 to April 1979. A total of 281 samples was analysed of which 133 contained low levels of carbon tetrachloride, 112 contained low levels of gamma-HCH and 26 contained low levels of malathion. One sample contained a residue of carbon tetrachloride, and another a residue of 1,2-dichloroethane, both of which were above the Codex Alimentarius guide-line levels. No other residue approached the proposed Codex Alimentarius maximum residue limits.     

A single radial haemolysis technique for the measurement of antibody to Mycoplasma bovis in bovine sera.

A single radial haemolysis in gel technique is described for assaying antibody to Mycoplasma bovis (M agalactiae subsp bovis) in bovine sera. The test, which should be particularly useful for screening large numbers of serum samples, is sensitive, simple to perform and highly reproducible.     

Sulfonamide-associated keratoconjunctivitis sicca and corneal ulceration in a dysuric dog

Long-term sulfonamide therapy for a urinary tract disorder was believed to have caused toxicosis of the lacrimal gland, and subsequently, dry eyes. Initial topical treatment of the ulcers may have potentiated the dry eye condition. The dog was referred with negligible tear production and bilateral corneal ulcers. Diagnostic evaluation of the urinary tract indicated reflex dyssynergia, a neurologic disorder causing functional urinary tract obstruction. The combination of appropriate topical and surgical therapy of the eyes, discontinuation of sulfonamide treatment, and initiation of bethanechol in the treatment of reflex dyssynergia all contributed to return of a normal tear film. Any combination of systemic and/or topical therapy may affect lacrimal secretion. The clinician must be cognizant of the potential effects that systemic medication, particularly antimicrobial drugs and drugs affecting the autonomic nervous system, may have on lacrimal secretions.     

Cloning and expression of bovine and porcine interleukin-2 in baculovirus and analysis of species cross-reactivity

The cDNAs encoding bovine and porcine interleukin-2 (IL-2) have been expressed using the baculovirus Autographa californica nuclear polyhedrosis virus as a vector in insect cells. Insect cells infected with recombinant viruses secreted bovine and porcine IL-2 into the culture medium, with biological activities for maintaining the proliferation of homologous cells. When the activities of these two IL-2 proteins and commercially available human IL-2 were tested on heterologous cells differences were found. Recombinant bovine (rb)IL-2 only supported the growth of bovine lymphocytes and was not active on human, mouse or porcine lymphocytes. Recombinant porcine (rp)IL-2 and recombinant human (rh)IL-2 supported the proliferation of human, bovine, porcine and murine cells. However, the proliferative response of human lymphocytes to rpIL-2 was only 50% of that seen with rhIL-2. Sequence differences at the predicted p55 and p75 contact binding sites may explain this.     

A model to determine sampling strategies and milk inoculum volume for detection of intramammary Staphylococcus aureus infections in dairy cattle by bacteriological culture

A model was developed to evaluate the effects that methods of obtaining milk samples and culture inoculum volumes had on the sensitivity of microbiological culture to detect Staphylococcus aureus intramammary infections (IMI). An assumption was made that milk from mammary quarters infected with S. aureus only contains bacteria intermittently. A modified sine wave function was used to model this intermittent shedding pattern. Specifications for the components of the shedding cycle used in this function were based on quantitative culture results from 54 experimentally infected S. aureus quarters, sampled daily for a period of 30–49 days. The components of the shedding cycle were length in days, peak number of CFU shed per milliliter of milk, and length of time in the cycle when no shedding occurred. These components were used to estimate the model's predicted distribution of S. aureus CFU ml⁻¹ milk when individual quarter milk samples were cultured for S. aureus. The sensitivity of culture for several sampling methods was then calculated. The model predicted that culture of a single quarter milk sample had a sensitivity ranging from 60 to 87% for detection of S. aureus IMI depending on inoculum volume. Quarter milk samples taken on day 1 and repeated either on day 3 or day 4, and cultured separately using 0.1 ml of milk for culture inoculum, were predicted to have sensitivities of 90–95% and 94–99%, respectively. Other milk-sampling strategies examined included culture of a composite milk sample (equal-volume mixture of milk from four separate mammary quarters ) and pooled milk samples in which samples from different milkings (either quarter or composite samples) were mixed together and then cultured. The range of predicted sensitivities of these other sampling strategies was 30–97%. Factors having the greatest impact on the sensitivity of culture, in order of importance were: the type of milk sample, the volume of milk cultured, and the time interval between repeated milk sample collection strategies.     

Experimental reproduction of septicemic pasteurellosis in feedlot lambs: bacteriologic and pathologic examinations

Septicemic pasteurellosis (SP) was induced in feedlot lambs. Twenty-eight lambs, randomly allotted into 7 groups, were given combinations of 3 treatments: (i) immunosuppression using hydrocortisone solubilized in dimethyl sulfoxide, (ii) rapid changes in feed, from 100% roughage to 90% concentrate, and (iii) oral inoculation of Pasteurella haemolytica biotype T. Feed changes and immunosuppression by hydrocortisone were needed for the production of SP. Pasteurella haemolytica inoculation was not necessary for induction of SP in all cases, indicating an endogenous source of infection. Clinical pathologic, bacteriologic, and gross and microscopic pathologic findings of induced SP were similar to those described for naturally occurring SP in lambs. Infection of lambs with P haemolytica biotype T via the gastrointestinal tract is discussed as a possible step in the pathogenesis of SP in feedlot lambs.     

Use of polysulphated glycosaminoglycan in equine lameness

Four cases of equine lameness were treated with intra-articular polysulphated glycosaminoglycan. Two, two-year-old flat racers were treated conservatively after traumatic injury. They subsequently became lame owing to the formation of new bone and osteophytes. Two older steeplechasers were lame owing to degenerative joint disease. The four horses were treated with intra-articular injections of polysulphated glycosaminoglycans and, after three or four injections, they became clinically sound and were able to continue racing with varying degrees of success.     

The (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) colorimetric assay for the quantitation of Actinobacillus pleuropneumoniae cytotoxin.

Using swine neutrophils as target cells, two MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) colorimetric assay systems, one with and one without phorbol 12-myristate 13-acetate (PMA) stimulation were established for the quantitation of Actinobacillus pleuropneumoniae cytotoxin. The MTT assays were optimized for the number of neutrophils, incubation time, and PMA concentration by a series of experiments. The optimal conditions were 25 x 10(4) cells/well incubated for four hours for the assay system without PMA stimulation, and 12.5 x 10(4) cells/well incubated for two hours for the assay system with PMA stimulation. One culture supernatant of a toxigenic Pasteurella multocida strain and five A. pleuropneumoniae cytotoxin preparations produced from three A. pleuropneumoniae strains were used to test assay reproducibility. Results showed both assays were reproducible with a coefficient of variation ranging from 7.8 to 18% for the assay system without PMA stimulation and from 10.7 to 18.2% for the assay system with PMA stimulation. The PMA-stimulated assay had 40 to 60-fold higher sensitivity than the nonstimulated MTT assay. The MTT assay also was applied to the measurement of neutralizing antibody titers against A. pleuropneumoniae cytotoxin.