Use of computerized image analysis to quantify staphylococcal adhesion to canine corneocytes: does breed and body site have any relevance to the pathogenesis of pyoderma?

An optimized system of computerized image analysis was used to investigate variations in the adherence of Staphylococcus intermedius to canine corneocytes from four different breed groups and six different anatomical sites. S. intermedius showed significantly greater adherence to the head and neck compared with the dorsum, but adherence to the limb, axilla and groin did not differ from other sites. Furthermore, there was significantly greater adherence of S. intermedius to corneocytes from the dorsum, forelimb, axilla and groin of Boxers and Bull Terriers than Spaniels and Hounds. S. intermedius, and also Pseudomonas aeruginosa, exhibited abundant adherence, which was significantly greater than Staphylococcus aureus, Streptococcus canis, Klebsiella pneumoniae and Escherichia coli. In addition, S. intermedius adherence demonstrated a sigmoid dose-response curve with increasing bacterial concentration. These results suggest that S. intermedius adheres to canine corneocytes by a specific receptor-ligand interaction and adheres to the skin of some breeds more avidly than others. However, variations in adherence between body regions would not account for the predilection sites of canine bacterial pyoderma.     

Emergence of a New Cucurbit-Infecting Begomovirus Species Capable of Forming Viable Reassortants with Related Viruses in the Squash leaf curl virus Cluster

ABSTRACT Cucurbit leaf curl virus (CuLCV), a whitefly-transmitted geminivirus previously partially characterized from the southwestern United States and northern Mexico, was identified as a distinct bipartite begomovirus species. This virus has near sequence identity with the previously partially characterized Cucurbit leaf crumple virus from California. Experimental and natural host range studies indicated that CuLCV has a relatively broad host range within the family Cucurbitaceae and also infects bean and tobacco. The genome of an Arizona isolate, designated CuLCV-AZ, was cloned and completely sequenced. Cloned CuLCV-AZ DNA A and B components were infectious by biolistic inoculation to pumpkin and progeny virus was transmissible by the whitefly vector, Bemisia tabaci, thereby completing Koch's postulates. CuLCV-AZ DNA A shared highest nucleotide sequence identity with Squash leaf curl virus-R (SLCV-R), SLCV-E, and Bean calico mosaic virus (BCaMV) at 84, 83, and 80%, respectively. The CuLCV DNA B component shared highest nucleotide sequence identity with BCaMV, SLCV-R, and SLCV-E at 71, 70, and 68%, respectively. The cis-acting begomovirus replication specificity element, GGTGTCCTGGTG, in the CuLCV-AZ origin of replication is identical to that of SLCV-R, SLCV-E, and BCaMV, suggesting that reassortants among components of CuLCV-AZ and these begomoviruses may be possible. Reassortment experiments in pumpkin demonstrated that both reassortants of CuLCV-AZ and SLCV-E A and B components were viable. However, for CuLCV-AZ and SLCV-R, only one reassortant (SLCV-R DNA A/CuLCV-AZ DNA B) was viable on pumpkin, even though the cognate component pairs of both viruses infect pumpkin. These results demonstrate that reassortment among sympatric begomovirus species infecting cucurbits are possible, and that, if generated in nature, could result in begomoviruses bearing distinct biological properties.     

Prevalence of papillomatous digital dermatitis among culled adult cattle in the southeastern United States

OBJECTIVE: To determine prevalence of papillomatous digital dermatitis (PDD) among culled adult dairy and beef cattle in the southeastern United States. ANIMALS: 815 cattle examined during 4 visits to a slaughterhouse. PROCEDURE: The left hind foot of each animal was examined for gross lesions of PDD. Breed and sex of the animals were recorded. Lesions were examined histologically for pathologic changes and bacteria, especially spirochetes. RESULTS: 22 of 76 (29%) dairy cattle and 29 of 739 (4%) beef cattle had gross lesions of PDD. Detection of lesions was not associated with sex of dairy cattle, but male beef cattle were more likely to have lesions of PDD than were female beef cattle. Histologically, acute and chronic lesions were seen; the most severe changes were localized to the stratum corneum. Spirochetes were seen in lesions from 31 of 51 (61%) cattle. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that PDD is common among culled adult cattle. Prevalence was higher in culled adult dairy cattle than in culled adult beef cattle.     

Variation in the colour of broiler breast fillets in the UK

1. The normal range in colour of broiler breast muscle was assessed using an objective (instrumental) measure of colour in portioned breast fillets at a commercial processing plant. In addition, the relationship between colour and ultimate muscle pH (pH(ult)) was also examined. 2. Considerable variation in colour was evident although minimal inter-flock variation was found. The exceptions were 2 free range flocks which produced breast fillets significantly lighter and less red. 3. Extremes of colour are likely to be discriminated against at the point of purchase. 4. A clear relationship between pH(ult) and L* values was found which provides more evidence for the existence of a PSE like condition in broiler breast meat.     

In vitro elution of gentamicin, amikacin, and ceftiofur from polymethylmethacrylate and hydroxyapatite cement

OBJECTIVE: To compare the elution characteristics of ceftiofur and liquid and powdered gentamicin and amikacin from polymethylmethacrylate (PMMA) and from hydroxyapatite cement (HAC). METHODS: PMMA and HAC beads in triplicate were impregnated with various amounts and formulations of antibiotics. Beads were immersed in 5 mL of phosphate buffered saline that was replaced at 1, 3, 6, and 12 hours, and 1, 2, 3, 5, 7, 10, 14, 18, 22, 26, and 30 days. The eluent was stored at -70 degrees C until assayed within 2 weeks by microbiological assay (gentamicin and amikacin) or capillary electrophoresis (ceftiofur). RESULTS: Rate of elution for all beads was greatest within the first 24 hours. Cumulative release of total antibiotic dose from beads over 30 days was significantly greater from HAC than PMMA. Antibiotic elution was directly related to the amount of antibiotic incorporated into the cement. Powdered and liquid forms of gentamicin had similar elution rates from PMMA. Elution of amikacin from PMMA beads was greater when the powdered form was used compared with liquid amikacin. Eluent concentrations of ceftiofur were similar to those of the aminoglycosides during the first 3 to 7 days but then decreased precipitously by comparison. CONCLUSIONS: Elution of antibiotics from HAC was greater than from PMMA. Gentamicin- and amikacin-impregnated PMMA and HAC released bactericidal concentrations of antibiotic for at least 30 days. Ceftiofur-impregnated PMMA or HAC is unlikely to provide long-term bactericidal concentrations. CLINICAL RELEVANCE: Gentamicin and amikacin elute effectively from PMMA and HAC.     

Estimation of rates of recombination and migration in populations of plant pathogens

ABSTRACT A method of estimating the frequency of recombination in field populations of ascomycete fungi is presented. This is a development of a technique described by J. Zhan, C. C. Mundt, and B. A. McDonald, in which field plots were inoculated with isolates of Mycosphaerella graminicola of known genotypes and then, later, the proportions of the fungal populations in the plots that originated as recombinant progeny of matings between the inoculated isolates or as immigrants from the local population were estimated. It is argued that J. Zhan, C. C. Mundt, and B. A. McDonald's method is inappropriate in terms of its approach to statistical inference and that the lack of confidence intervals for rates of recombination (r) or immigration (m) is a further weakness. An improvement to their method would involve the use of inoculated isolates that can be clearly distinguished from the local population, for instance, by the use of DNA markers. There should also be sufficient markers for there to be a negligible probability that progeny of matings between inoculated isolates will have the same genotype as either of their parents. With this experimental design, estimates of r and m can be found by a standard maximum likelihood method, while confidence intervals for the parameters can be estimated by a simple bootstrap procedure. The method appears to be about an order of magnitude more efficient than are the existing ways of estimating the frequency of recombination in ascomycete fungi.     

Blood lead levels of wild Steller's eiders (Polysticta stelleri) and black scoters (Melanitta nigra) in Alaska using a portable blood lead analyzer.

Sea duck populations are declining in Alaska. The reasons for the decline are not known; environmental lead exposure is one suspected cause. Thirty wild Steller's eider ducks (Polysticta stelleri) and 40 wild black scoter ducks (Melanitta nigra) were tested for blood lead levels using a portable blood lead analyzer (LeadCare; ESA, Inc., Chelmsford, Massachusetts 01824, USA). Sixty-seven and one-tenth percent of the sea ducks had undetectable blood lead levels, 30.0% had values indicating normal or background lead exposure, and 2.9% had values indicating lead exposure. None of the birds had values indicating lead toxicity, and no birds demonstrated clinical signs of toxicity. Birds in areas with higher human population density had higher blood lead levels than those in less densely populated areas. This is the first time a portable blood lead analyzer has been utilized with sea ducks in a field setting. Because it provides immediate results, it is valuable as a screening tool for investigators carrying out surgical procedures on birds in the field as well as establishing baseline blood lead data on sea ducks. Lead exposure does occur in wild sea ducks, and the study indicates that additional research is needed in order to determine the role environmental lead plays in declining sea duck populations.