Study on Potential Clostridium Botulinum Growth and Toxin Production in Parma Ham.

The objective of this study was to investigate Clostridium botulinum growth and toxin production in the industrially manufactured Italian Parma ham. The study focuses on the Parma ham production phase identified as maximum risk to C. botulinum proliferation, i.e. the transition from cold phase (salting and resting) to a phase carried out at temperature between 15 and 23°C (drying). A preliminary in vitro test was carried out in order to verify the capability of 6 C. botulinum strains (1 type A, 4 type B, and 1 type E strains) to grow in conditions of temperature, pH and NaCl concentration comparable to those of the beginning stage of ham drying. Five C. botulinum strains grew at 20°C and pH 6, four strains produced toxin when inoculated at a concentration equal to 103 cfu/mL at NaCl concentration of 4%, while when the inoculum concentration was 10 cfu/mL, NaCl concentration of 3% resulted the toxin-genesis limiting factor. An experimental contamination with a mixture of the 5 C. botulinum strains selected by the preliminary in vitro test was performed on 9 thighs inoculated at the end of the resting phase. The study was designed to evaluate the potential growth and toxin production in extremely favourable conditions for the bacterium. Type B proteolytic C. botulinum toxin was produced after 14 days of incubation at 20°C in 2 thighs characterised by high weight, low number of days of resting and anomalous physiochemical characteristics [one for very low NaCl concentration (1.59%), the other for elevated pH (6.27) and both for high water activity values (>0.970)]. The results of this research confirm that the cold resting step is a critical phase in the production process of Parma ham for the investigated hazard. Based on the present study, the long resting phase adopted in the manufacturing of Parma ham is proven effective to prevent the growth of C. botulinum, an event which could not otherwise be excluded if the hams were processed under less stringent technological conditions.

Abortion in cattle due to infection with Staphylococcus lugdunensis.

An aborted fetus of 7 months gestation, the associated placenta, and a single blood sample from the dam were submitted for diagnostic investigation to the diagnostic laboratory of the Lombardy and Emilia-Romagna Experimental Zooprophylactic Institute in Parma, Italy. The serum was negative for Neospora caninum, Coxiella burnetii, Chlamydophila abortus, Bovine herpesvirus 1 (BHV-1), Bovine viral diarrhea virus (BVDV), Brucella abortus, and Brucella melitensis. Fetal tissues and placental cotyledons were pooled and tested by polymerase chain reaction (PCR) for the presence of BHV-1, Bovine herpesvirus 4, BVDV, N. caninum, C. burnetii, Chlamydophila spp., Schmallemberg virus, and Leptospira interrogans. All PCR assays were negative. Bacteriological examinations performed on the fetal organs revealed a pure growth of Staphylococcus lugdunensis in all organs cultured. In human beings, S. lugdunensis is responsible for community-acquired and nosocomial infections, in both immunocompetent and immunocompromised patients. In veterinary medicine, the pathogenic potential of S. lugdunensis has not been fully investigated. The incidence of S. lugdunensis is regarded as being underreported because it could be easily misidentified as Staphylococcus aureus. The current report documents the ability of S. lugdunensis to cause abortion in cattle, indicating the need for accurate diagnostic procedures to identify this emerging and zoonotic pathogen whose incidence is likely underestimated in both human and veterinary medicine.

Concurrent vaccinations against PCV2 and PRRSV: study on the specific immunity and clinical protection in naturally infected pigs.

The present study aims at evaluating the efficacy of the concurrent PCV2 and PRRS vaccinations in comparison with single vaccinations and placebo in pigs exposed to both natural viral infections. Four groups of pigs (200 animals each) at 4 weeks of age were considered. Pigs from group A were concurrently vaccinated with a modified live PRRSV-1-based vaccine and a genotype a-based PCV2 subunit (Cap) vaccine via the intramuscular route. Animals from groups B and C were vaccinated with PRRSV and PCV2 vaccines alone, respectively, and group D was inoculated with the adjuvant alone. Clinical score (morbidity), mortality and average daily weight gain (ADWG) were evaluated. Viraemia, virus-specific ELISA antibodies and cell-mediated immunity (CMI) as IFN-γ secreting cells by ELISpot were detected. The clinical signs associated with PRRSV infection lasted from 8 to 16 weeks while those related to PCV2 infection from 5 months of age. The results showed that the concurrent vaccinations reduced clinical signs and increased the preventive fraction (40.4%) and the ADWG. In concurrently vaccinated pigs, the probability of dying due to infection, especially in association with PCV2 viraemia was reduced 3-fold. PRRSV viraemia was not reduced by vaccination but lower and shorter PCV2 viral load was detected in both concurrently and single PCV2-vaccinated pigs. Despite the presence of maternally derived antibodies, animals showed a prompt seroconversion after vaccination and PCV2 natural infection. Moreover, maternal immunity did not interfere with the development of the specific cellular IFN-γ SC response in single and concurrently vaccinated animals. The study demonstrates that concurrent PRRSV+PCV2 vaccination has no interference with the development of the specific humoral and cell-mediated immunity and it is associated with clinical protection upon natural challenge.