Incidence of multiple sclerosis in the town of Sassari, Sardinia, 1965 to 1985: evidence for increasing occurrence of the disease.

Prevalence studies carried out in Sardinia from 1975 suggest an increasing occurrence of MS. However, it is questionable whether this increase represents a real change in MS incidence or simply reflects longer survival. Data from 79 patients indicated the average annual incidence for the period 1965 through 1985 was 3.4 per 100,000. On December 31, 1985, the prevalence rate was 69 per 100,000. Evaluation of MS temporal trends showed a significant increase in MS incidence during the study period: values ranged around two per 100,000 in the triennial periods 1965-1967, 1968-1970, and 1971-1973, and around five in each triennium from 1977 onward.

Incidence of multiple sclerosis in Macomer, Sardinia, 1912-1981: onset of the disease after 1950.

Intensive search of all cases of MS occurring in the Sardinian commune of Macomer since 1912 indicated that MS was absent up to the early 1950s. All 13 ascertained cases had clinical onset in the years 1952-1981. During this period, the average annual incidence was 4.8 per 100,000; the highest incidence was found in the period 1957-1961, slowly decreasing up to 1981. MS was probably introduced after 1945, when the centuries-old isolation of Macomer ended and the native population came into contact with individuals from high- and medium-risk areas.

Strain typing among enterococci isolated from home-made Pecorino Sardo cheese.

Three molecular techniques (RAPD-polymerase chain reaction analysis, plasmid profile and pulsed-field gel electrophoresis) were used for a preliminary approach to type, at strain level, enterococci isolated from a 24-h-old home-made Pecorino Sardo (protected designation of origin) cheese. A high genetic polymorphism was found. Clusters obtained by the RAPD technique and plasmid profile analysis contained different strains. Pulsed-field gel electrophoresis proved to be an efficient and highly reproducible typing method. In addition, by combining the results from plasmid profile analysis and pulsed-field gel electrophoresis, it was possible to identify closely related strains probably belonging to the same clonal lineage.

Comparison of the incidence of virulence determinants and antibiotic resistance between Enterococcus faecium strains of dairy, animal and clinical origin.

Enterococci are part of the dominant microbiota of several dairy products. They are also present in the gut of humans and animals. Their presence in traditional raw milk cheeses is probably due to faecal contamination of milk during milking. Due to their importance as a cause of nosocomial infections, enterococci are acquiring increased significance. Such infections are becoming more and more difficult to treat as resistance to antibiotics increases. The aim of this investigation was to compare the potential virulence of Enterococcus faecium isolated from different ecological habitats and to establish if strains isolated from dairy products should really be considered as potential pathogens. In the present work, the antibiotic resistance pattern of 40 E. faecium strains isolated from dairy products, 26 E. faecium isolated from ewes' faeces and 28 clinical isolates of the same species was studied, and checks were made to see if known virulence determinants were present. Resistance to 12 different antibiotics commonly used in the treatment of human infections was tested using the broth microdilution method as described by the NCCLS. In addition, polymerase chain reaction (PCR) tests were carried out to see if genes for vancomycin resistance were present. The presence of the aggregation substance (AS) gene, the surface protein gene esp, the accessory colonisation factor ace, the Enterococcus faecalis endocarditis antigen efaA and the gelatinase gelE gene, which are involved in the virulence of enterococci, were also tested by PCR. The results of this study clearly indicate that E. faecium strains isolated from both cheese and sheep faeces are less pathogenic than those isolated from clinical samples. A similar pattern of resistance to antibiotics was observed in both dairy and animal strains. It was also found that there was difference in the kind of virulence determinants present in dairy and clinical isolates, while no virulence traits were found in sheep faeces strains. The results of this study suggest that E. faecium from traditional Sardinian raw milk cheeses should not be considered to be the main source of untreatable nosocomial enterococcal infections in humans in the island of Sardinia.

Genetic diversity of lactococci and enterococci isolated from home-made Pecorino Sardo ewes' milk cheese.

AIMS: To assess the intraspecific genetic diversity of lactococci and enterococci isolated from 24-h, 1- and 2-month-old home-made Pecorino Sardo ewes' milk cheese. METHODS AND RESULTS: Two molecular techniques, plasmid profiling and pulsed-field gel electrophoresis, were used in order to type the isolates at strain level. The present study revealed that the lactococcal and enterococcal microbial populations of home-made Pecorino Sardo cheese were complex, not only 24 h after manufacture, but also after 1 and 2 months of ripening. The genetic diversity at subspecies level ranged from 58 to 80% during the three periods examined. The study also showed that the strains that dominated in the first stage of ripening were not necessarily predominant in the later periods. A high number of strains isolated at 24 h were still present in the mature cheese, but many of the genotypes were only found in the cheese after 1 or 2 months. CONCLUSIONS: The results showed a high intraspecific genetic diversity in the natural microbial population colonizing home-made Pecorino Sardo cheese. Two molecular techniques are necessary for a thorough and precise typing at strain level in order to better distinguish between closely related isolates and between isolates that probably belong to the same clonal lineage. SIGNIFICANCE AND IMPACT OF THE STUDY: The genetic complexity observed in the present study is of particular relevance in the preservation of the natural microflora of traditional Protected Designation of Origin raw milk cheeses, as well as in the selection of new starter strains for the dairy industry.

Genotypic and phenotypic heterogeneity among lactococci isolated from traditional Pecorino Sardo cheese.

Twenty-nine Lactococcus lactis isolates from one traditional 24 h-old Pecorino Sardo cheese were characterized phenotypically, technologically and genotypically in order to assess the biodiversity within this wild microbial population. Two DNA-based techniques, plasmid profiling and PFGE, were used for the genetic typing of the isolates. All 29 isolates were characterized at strain level and eight different genotypes were recognized. In addition, by combining the results from plasmid profile analysis and PFGE, it was possible to identify closely related isolates probably belonging to the same clonal lineage. The dominant biotype was identified in the 24 h-old cheese, as were the strains believed to act as starters for the curd. Atypical lactococci, able to grow in 6.5% NaCl, were isolated. The results suggest that wild bacterial populations should be preserved in order to protect the traditional raw milk cheeses, and to select new starter strains for the dairy industry.

Sardinia, a high-risk area for multiple sclerosis: a prevalence and incidence study in the district of Alghero.

Findings from small descriptive studies carried out in the last few years in Sardinia suggest that this region is now of high rather than medium risk for multiple sclerosis. It is uncertain whether this high prevalence reflects a different approach in case finding over time or a true change in disease occurrence. We report the results of a prevalence and incidence survey conducted in the district of Alghero, a community of 78,000 people in northwest Sardinia. Based on data from 31 patients, the average annual incidence for the period 1971 through 1980 was 4.1 per 100,000. On December 31, 1980, the prevalence rate was 59 per 100,000. The results support the view that Sardinia is now a high-risk area for multiple sclerosis, and further suggest a rise in the occurrence of the disease in recent years.

Epidemiology of multiple sclerosis in Northwestern Sardinia: further evidence for higher frequency in Sardinians compared to other Italians.

The Sardinians are an ethnically homogeneous population, having a genetic structure quite different from that of all other Italian and European populations. All epidemiological studies carried out in Sardinia since 1975 indicate that this Mediterranean island shows twice the prevalence of multiple sclerosis (MS) compared to continental Italy, but the size of the Sardinian communities so far surveyed has been too small to draw definitive conclusions. To overcome this draw-back, we have studied the frequency of MS in a well-defined area of north-western Sardinia, with a population of about 270,000 in the 1991 census. Based on 276 MS cases, the prevalence on December 31st, 1991, was 102.6 per 100,000. The incidence, averaging 2 per 100,000 in the period of 1962 to 1971, rose to 5 in the period from 1977 to 1991. The present study confirms the higher frequency of MS among Sardinians compared to other Italian populations. Genetic, linguistic and historical data suggest a role of environmental and genetic factors in determining the notable difference in MS risk between Sardinia and the rest of Italy.

Multiple sclerosis epidemiology in Sardinia: evidence for a true increasing risk.

OBJECTIVES: To update prevalence and incidence rates of MS among Sardinians. MATERIALS AND METHODS: The present work is a "spider" kind of population based survey, conducted over the interval 1968-97, on patients with MS (Poser criteria) living in the province of Sassari, Northern Sardinia (454,904 population). RESULTS: A crude total prevalence rate of 144.4 per 100,000, an onset-adjusted prevalence rate of 149.7 per 100,000 and an average annual incidence rate of 8.2 for the period 1993-7 were found. CONCLUSION: Repeated epidemiological assessments of MS in Sardinia over decades have shown that the island is at high risk for MS. The present work highlights that MS incidence in Sardinia has been increasing over time. Although a substantial and widely spread improvement in MS case ascertainment can be postulated as the reason for such observations, a comparison between our data and those recently reported from a more industrialized province in Northern Italy seems to prove an at least partially real increase in MS risk among Sardinians and favours the hypothesis of a MS "Sardinian focus" as related to its latitude.