Association between Chlamydia psittaci seropositivity and abortion in Italian dairy cows.

Although the seroprevalence of Chlamydia psittaci is widespread in Italian dairy herds, its role in inducing genital disorders has not been elucidated. We therefore set up a case-control study to compare seroprevalence to C. psittaci in an aborted-cow population and in a randomly selected control group in the province of Parma (the Po Valley of northern Italy). The true seroprevalence (45%) in aborted cows was significantly higher than that in the control group (24%) (adjusted odds ratio=2.53).     

Use of remote sensing and geographical information systems to identify environmental features that influence the distribution of paramphistomosis in sheep from the southern Italian Apennines

A geographic information system (GIS) was constructed using remote sensing (RS) and landscape feature data together with Calicophoron daubneyi positive survey records from 197 georeferenced ovine farms with animals pasturing in a 3971 km(2) area of the southern Italian Apennines. The objective was to study the spatial distribution of this rumen fluke, identify environmental features that influence its distribution, and develop a preliminary risk assessment model. The GIS for the study area was constructed utilizing the following environmental variables: normalized difference vegetation index (NDVI), land cover, elevation, slope, aspect, and total length of rivers. These variables were then calculated for "buffer zones" consisting of the areas included in a circle of 3 km diameter centered on 197 farms. The environmental data obtained from GIS and RS and from data taken by the veterinarians on the field (stocking rate and presence of streams, springs and brooks on pasture) were analyzed by univariate (Spearman and ANOVA) and multivariate (discriminant) statistical analyses using the farm coprological status (positive/negative) as the dependent variable. Sheep on 32 of the 197 (16.2%) farms, were positive for C. daubneyi, with an average intensity of 52 epg. A multivariate stepwise discriminant analysis model was developed that included moors and heathland, sclerophyllous and coniferous forest vegetation, autumn-winter NDVI and presence of streams, springs and brooks on pasture. The variables entered in the model were also correlated with C. daubneyi positive farms in the univariate tests and are consistent with the environmental requirements of C. daubneyi and its snail intermediate host.     

Neospora caninum in pastured cattle: determination of climatic, environmental, farm management and individual animal risk factors using remote sensing and geographical information systems

A cross-sectional serological survey was conducted on cattle pasturing in an area of the southern Italian Apennines to evaluate the seroprevalence to Neospora caninum, and to investigate the climatic, environmental, farm management, and individual animal factors that influence the distribution of this protozoan. Blood samples were collected from 864 pastured cattle raised on 81 farms. Serum samples were tested for antibodies to N. caninum using an ELISA assay (HerdCheck), IDEXX). A geographical information system (GIS) for the study area was constructed using the following remote sensing (RS) and landscape feature data: autumn-winter, spring and summer normalized difference vegetation index (NDVI), land cover, elevation, slope, aspect, mean rainfall and minimum, mean, and maximum temperature in spring, summer, autumn and winter. Data on each of these features were then extracted for "buffer zones" consisting of the area included in a circle of 3 km diameter centered on the 81 geo-referenced centroids of the main cattle pastures. Climatic and environmental data obtained from RS and GIS and individual animal characteristics and farm management data obtained from a questionnaire were analyzed in relation to N. caninum seropositivity and antibody titres both by linear and logistic regression models. Out of the 81 farms sampled, 63 (77.8%) had at least one tested animal positive for N. caninum. Out of the 864 bovine sera samples, 266 (30.8%) were found to have antibodies to N. caninum. The results of the logistic regression model show that significantly high seroprevalence to N. caninum was found in heifers/steers and adults, in cattle raised on farms having a large number of dogs, and in cattle raised in buffer zones having high minimum temperatures in the spring, and a narrow extension of summer NDVI. In addition, positive linear correlations were found between N. caninum antibody titres and the number of dogs on farm, and the minimum temperature in spring. All the above determined risk factors for N. caninum seroprevalence indicate that horizontal infection resulting from the ingestion of oocysts shed by dogs is the most probable route of N. caninum infection in pastured cattle of the southern Italian Apennines.     

Bacteriologic findings in ostrich (Struthio camelus) eggs from farms with reproductive failures

From January 2001 to December 2002, 543 ostrich eggs were submitted for bacteriologic investigation. The eggs were laid by 387 domesticated ostriches that suffered fertility disorders and that came from 44 farms located in different areas of Northern and Central Italy. Microbiologic investigations showed bacterial isolation in 105 (19.3%) of 543 eggs examined, with a high prevalence of enterobacteria from albumen and yolk. In only a few cases did bacterial isolation result from yolk or albumen alone. An antibiotic sensitivity test was conducted on isolates by the Kirby-Bauer disc diffusion method. This is the first report regarding the microbiologic status of eggs from ostrich farms located in different Italian regions.     

Mycobacterium porcinum strains isolated from bovine bulk milk: implications for Mycobacterium avium subsp. paratuberculosis detection by PCR and culture

In this study, the isolation of 52 mycobactin-independent fast growing mycobacteria from 631 bulk milk samples (8.2%), is reported. These strains, isolated during a bulk milk survey for Mycobacterium avium subsp. paratuberculosis (Map), strongly affected Map detection both by PCR and by culture, as they gave a positive IS900 PCR signal and resulted to totally inhibit the growth of Map when spotted on HEYM slants already inoculated with 200 microl of 10-fold dilutions containing from 5 x 10 to 5 x 10(3)Map cells/ml. 16S rRNA gene sequencing, using the MicroSeq 500 16S rDNA Bacterial Sequencing Kit (Applied Biosystems), was performed on a subset of six strains, identifying Mycobacterium porcinum with 100% homology in all six cases. The 52 strains were characterized by PCR-restriction fragment length polymorphism (RFLP) analysis of the hsp65 gene, which confirmed the identification of M. porcinum for all the isolates. Using specific primers designed on the Map-IS900 sequence and on the M. porcinum sequence determined in this study, a 1385bp sequence from the M. porcinum genome was characterized. This IS900-like sequence showed 82% homology with Map IS900. From our findings the following results emerged: (a) any culture showing one or more M. porcinum colonies represents a potential "false negative" result and should therefore be considered as contaminated; (b) IS900-like elements could be more widespread than was previously thought; (c) IS900 PCR positive results should be interpreted cautiously, as confirmed by the evidence that the primer pair used in this study resulted not to be specific.     

Stress-induced mutagenesis in bacteria

The evolutionary significance of stress-induced mutagenesis was evaluated by studying mutagenesis in aging colonies (MAC) of Escherichia coli natural isolates. A large fraction of isolates exhibited a strong MAC, and the high MAC variability reflected the diversity of selective pressures in ecological niches. MAC depends on starvation, oxygen, and RpoS and adenosine 3',5'-monophosphate regulons; thus it may be a by-product of genetic strategies for improving survival under stress. MAC could also be selected through beneficial mutations that it generates, as shown by computer modeling and the patterns of stress-inducible and constitutive mutagenesis. We suggest that irrespective of the causes of their emergence, stress-induced mutations participate in adaptive evolution.     

Association Between Neospora Caninum Antibodies and Blue Tongue Vaccination in Dairy Cows

Veterinary Research Communications -     

Genome analysis reveals pili in Group B Streptococcus

Pili are essential virulence factors in many Gram-negative bacteria; however, they have not been described in most important Gram-positive pathogens. While screening the sequence of multiple genomes of Group B Streptococcus, we identified protective antigens that formed high molecular weight polymers. Immunogold electron microscopy revealed that the structures have a pilus-like form. These large structures have gone unrecognized in decades of studies of Group B Streptococcus.