Pseudomonas aeruginosa in Dairy Goats: Genotypic and Phenotypic Comparison of Intramammary and Environmental Isolates.

Following the identification of a case of severe clinical mastitis in a Saanen dairy goat (goat A), an average of 26 lactating goats in the herd was monitored over a period of 11 months. Milk microbiological analysis revealed the presence of Pseudomonas aeruginosa in 7 of the goats. Among these 7 does, only goat A showed clinical signs of mastitis. The 7 P. aeruginosa isolates from the goat milk and 26 P. aeruginosa isolates from environmental samples were clustered by RAPD-PCR and PFGE analyses in 3 genotypes (G1, G2, G3) and 4 clusters (A, B, C, D), respectively. PFGE clusters A and B correlated with the G1 genotype and included the 7 milk isolates. Although it was not possible to identify the infection source, these results strongly suggest a spreading of the infection from goat A. Clusters C and D overlapped with genotypes G2 and G3, respectively, and included only environmental isolates. The outcome of the antimicrobial susceptibility test performed on the isolates revealed 2 main patterns of multiple resistance to beta-lactam antibiotics and macrolides. Virulence related phenotypes were analyzed, such as swarming and swimming motility, production of biofilm and production of secreted virulence factors. The isolates had distinct phenotypic profiles, corresponding to genotypes G1, G2 and G3. Overall, correlation analysis showed a strong correlation between sampling source, RAPD genotype, PFGE clusters, and phenotypic clusters. The comparison of the levels of virulence related phenotypes did not indicate a higher pathogenic potential in the milk isolates as compared to the environmental isolates.

Clonal diversity, virulence-associated genes and antimicrobial resistance profile of Staphylococcus aureus isolates from nasal cavities and soft tissue infections in wild ruminants in Italian Alps.

Staphylococcus aureus is a commensal and a pathogenic bacterium that causes a wide variety of diseases in humans and animals with a high impact on public health and the livestock industry. S. aureus virulence pattern, antimicrobial resistance profile and host specialization are of great concern both in livestock and in companion animals. Concerning wild animals, S. aureus carriage and antimicrobial resistance profile has been recently investigated in free-ranging species both in aquatic and terrestrial environment. Here we report genotyping (spa typing, Multilocus Sequence Typing and SCCmec typing), virulence and antimicrobial resistance profile of four S. aureus isolated in Alpine chamois (Rupicapra r. rupicapra) and roe deer (Capreolus capreolus), euthanized due to walking impairment and signs of disorientation. S. aureus was isolated from nasal cavities in both wild ruminant species and in soft tissue infections in chamois. A marked S. aureus genetic heterogeneity was detected: spa type t1523, sequence type 45 (Clonal Complex 45), and spa type t1328, ST22 (CC22) from the nasal cavities and the liver of a chamois kid respectively, t1773, ST700 (CC130) from an adult chamois abscess, and a new sequence type, ST2712, belonging to CC97 from the roe deer nasal cavities. One of the main findings was the confirmation that the t1328, ST22 isolate, obtained from the liver of the chamois kid, was a methicillin-resistant S. aureus (MRSA) harbouring a SCCmec cassette type IV. The set of virulence marker and toxin genes investigated showed profiles characteristic of the S. aureus lineages detected, including those of the human adapted ST (CC) 22 and ST (CC) 45 isolates.

In vitro permissivity of bovine peripheral blood mononuclear cells to bovine viral diarrhoea virus is dependent on the animal specific immune status.

The in vitro permissivity to infection with homologous and heterologous bovine viral diarrhoea virus (BVDV) strains of bovine peripheral blood mononuclear cells (PBMCs) from eight naïve and eight BVDV-1b immune animals was studied. Four reference strains (BVDV-1a NADL, BVDV-1b NY-1, BVDV-2 125 and BVDV-2 890) were selected, based on genotype, prevalence and biotype. Virus neutralizing antibody titres were determined at bleeding and the viral loads were measured in PBMCs by end point titration in cell culture and by real-time PCR. PBMCs from both naïve and immune animals became infected by all BVDV strains tested, although virus titres were lower for immune heifers than naïve ones; the differences were significant for NADL (P<0.05) and 890 (P<0.001) strains. The in vitro model used in this study showed that PBMCs from immune animals are susceptible to re-infection with both homologous and heterologous BVDV strains, albeit at a lower extent than naïve cattle.

Multinucleated giant cells with an osteoclast phenotype derived from caprine peripheral blood mononuclear cells.

Formation of multinucleated giant cells (MGCs) by macrophage fusion is a typical cytopathic effect of lentiviral replication in caprine monocytes and MGC formation from cultured caprine peripheral blood mononuclear cells (PBMCs) has been considered to be diagnostic for small ruminant lentivirus (SRLV) infection. In this study, formation of MGCs was observed after 7-14 days when PBMCs were cultured from healthy goats free from SRLV infection. These MGCs expressed tartrate-resistant acid phosphatase, calcitonin receptor, integrin αVß3, cathepsin K and matrix metalloproteinase 9 and were able to resorb bone in vitro in the absence of RANKL and macrophage colony stimulating factor, consistent with an osteoclast phenotype.

Genetic analysis of small ruminant lentiviruses following lactogenic transmission.

Lactogenic transmission plays an important role in the biology of lentiviruses such as HIV and SIV or the small ruminant lentiviruses (SRLV). In this work we analyzed the characteristics of viruses that goats, naturally infected with two strains of SRLV, transmitted to their kids. The spectrum of viral genotypes transmitted was broader and the efficiency of transmission greater compared to their human and simian counterparts. The newly described A10 subgroup of SRLV was more efficiently transmitted than the B1 genotype. The analysis of a particular stretch of the envelope glycoprotein encompassing a potential neutralizing epitope revealed that, as in SIV, the transmitted viruses were positively charged in this region, but, in contrast to SIV, they tended to lack a glycosylation site that might protect against antibody neutralization. We conclude that the physiology of the ruminant neonatal intestine, which permits the adsorption of infected maternal cells, shaped the evolution of these particular lentiviruses that represent a valid model of lactogenic lentivirus transmission.

Down-regulatory effect of alpha 1-acid glycoprotein on bovine neutrophil degranulation.

In this paper, the possible involvement of the acute phase protein alpha(1)-acid glycoprotein (AGP) in the local immunomodulation of inflammation was investigated. The dose response of bovine neutrophils to AGP as to mobilization of primary and secondary granules was studied. It was found that AGP fulfils a protective role against spontaneous exocytosis of secondary, but not primary, granules. This downregulatory effect is much more evident when degranulation is challenged with Zymosan activated serum (ZAS). AGP activity is dose-dependent, the acute phase concentration being more active than the physiological one. Carbohydrate moiety of AGP was found to be critical, since experimentally desialylated protein does not maintain its exocytosis-modulatory activity. The fact that AGP may modulate the degranulation of neutrophils confirms the hypothesis that AGP is heavily involved in the fine tuning of neutrophil activity in the inflammatory environment.

Large-scale screening of the in vitro susceptibility of Prototheca zopfii towards polyene antibiotics.

A large scale screening of the in vitro susceptibility of 105 strains of Prototheca zopfii to a panel of polyene antibiotics (amphotericin B, nystatin, primaricin and filipin) was conducted. Strains studied were isolated from dairy-associated environments in five different localities. Groups 1-4 included strains recovered from four separate regions of Italy, while group 5 included isolates from Belgium. Amphotericin B and primaricin exhibited the highest activity, with th MIC90 ranging from 4 and 8 microg/ml, respectively. On the other hand, the MIC90 of nystatin and filipin were from two to four times higher. Two strains were resistant to all four polyenes tested. The above results are compared with those in the literature and the importance of carrying out large-scale screening surveys to assess polyene susceptibility patterns within the species P. zopfii is discussed.