SUMMARYThis report summarizes studies on 1699 foodborne outbreaks, in Italy, reported to the Istituto Superiore di Sanitai (ISS) (the National Institute of Health of Italy, Rome) during the period 1991-4. The most frequently reported foodborne outbreaks were caused by salmonellae (81 %), in particular by Salmonella enteritidis and non-serotyped group D salmonella (34% and 33 % of the total salmonella outbreaks, respectively). A vehicle was implicated in 69 % of the salmonella outbreaks; eggs were implicated in 77 % of the outbreaks for which a vehicle was identified or suspected. Salmonella strains isolated in 54 outbreaks were studied for phenotypic and genotypic characteristics. The isolates belonged to S. enteritidis (50 outbreaks), S. typhimurium (three outbreaks) and S. hadar (one outbreak). In the S. enteritidis outbreaks, phage type 4 was most frequently isolated (64-8 %), followed by phage type 1 (14-8 %). The virulence plasmid of 38 megadaltons was found in many different phage types of S. enteritidis.

This paper focuses on the history of the two systems that have been adopted in Italy for the surveillance of Salmonellosis and describes their respective characteristics. Both systems have been subsequently modified: (1) The National Laboratory-based Surveillance System (NLSS) which was created in 1967 for Enteropathogenic Bacteria and subsequently, in 1992, became part of the European computerised Laboratory-based Surveillance System of Salmonellae isolates, the SALM-NET (Salmonella network); (2) The National Infectious Disease Reporting System (NIDRS) which was set up in the 1930s, revised in 1990 and has been used, since 1994, along with the Infectious Disease Informative System (IDIS). The results obtained with the different surveillance systems are presented: (1) The number of isolates from the laboratory surveillance from 1973 to 1997 are described. Total Salmonellae isolates have a slope with an increasing trend from 4372 isolates in 1973 to 15,041 isolates in 1988 drastically dropping to 5479 isolates in 1990 and increasing again to 13,596 isolates in 1993. Attention is given particularly to the epidemiology of S. enteritidis in Italy which increased progressively since 1982 (225 isolates) to 5435 isolates in 1994. S. typhimurium showed a slightly increasing trend in the period 1973-1988 (from 1694 to 3383 isolates) then decreased for reaching again previous levels. S. typhi showed a marked reduction from 573 isolates in 1973 to 33 isolates in 1996. On the contrary, other less frequent serotypes increased. (2) The number of cases of Salmonellosis reported during 1971-1997 are also presented. Other Infections by Salmonellae increased from 12,516 cases in 1976 (renamed Non Typhoidal Salmonellosis in 1990) to more than 20,000 cases in 1992. The number of cases of Typhoid Fever and Infections by S. paratyphi are also described. Particular attention has to be paid to the parallel trends of Salmonellosis using both surveillance systems: number of isolates and number of cases, particularly comparing Other Infections by Salmonellae and total Salmonellae isolates: after the 1992-1993 peak, an initial decrease was observed.

In recent years, Salmonella enteritidis has become an increasingly important public health problem in Italy. In some parts of the country, the fraction of total human salmonella isolates accounted for by S. enteritidis has risen from 3-4% in the mid-1980s to more than 30% in 1990. Between 1990 and 1991, the number of reported S. enteritidis outbreaks increased more than sixfold. The 33 outbreaks reported in 1991 occurred in seven contiguous regions in northern and central Italy and were clustered in time between June and October: in the majority, products containing raw or undercooked shell eggs were implicated. Five of the egg-related outbreaks that occurred within a 30 kilometre radius over a 7-week period were investigated in detail. A phage type 1 strain containing a 38.9 MDa plasmid appeared responsible for three of the outbreaks, while in the remaining two a phage type 4 strain, also with a 38.9 MDa plasmid was isolated. Efforts are being made to enhance epidemiological surveillance and laboratory evaluation, and the use of pasteurized eggs has been recommended for high-risk populations.

In this paper we report the distribution of Salmonella Typhi isolates in Italy and their resistance patterns to antibiotics. The data were collected by the Italian SALM-NET surveillance system in a pilot retrospective study of the period 1980-96. Data on drug-resistance were available for 82 isolates out of 176 S. Typhi isolated in Italy. Of these 82 isolates, 32 (39%) were resistant or intermediate to 1 or more antibiotics. Eight isolates were resistant and 7 intermediate to streptomycin; 4 isolates were resistant to ampicillin alone or in association with other antibiotics; only 2 strains (1 isolated in Lombardia in 1993 and the other 1 in Lazio in 1994) were resistant to chloramphenicol, and 2 (isolated in Sardegna and Piemonte in 1995 and 1996, respectively) showed intermediate resistance to chloramphenicol. The strains showing resistance to 3 or more antibiotics were very scarce: 1 (with 5 complete resistances) was isolated in Lazio in 1994, and another 1 (with complete resistance to 10 antibiotics and intermediate resistance to 2 antibiotics) was isolated in Molise in 1988. In conclusion, besides the routine activities to control typhoid fever, an accurate and continuous surveillance is necessary in order to quickly identify multidrug-resistant (MDR) S. Typhi strains and prevent their spread, even though their level, in our country, is still quite low.

During 1994, 603 cases of bacterial meningitis were reported in Italy. Seventy-five percent of cases with determined etiology was due to three agents: Neisseria meningitidis (33.4%), Streptococcus pneumoniae (23.4%) and Haemophilus influenzae (18.6%). The majority of cases due to N. meningitidis and H. influenzae occurred in subjects below five years of age (35.7% and 84.8%, respectively) while S. pneumoniae accounted for 52.8% of meningitis cases in subjects older than 44 year of age. The estimated incidence of N. meningitidis on the national population in 1994 was 0.27 per 100,000. Serogroup B accounted for 62.5% of the serotyped isolates, group C for 23.1%, group A for 7.2%, group W135 for 3.6%, group Y for 1.8%. All tested meningococcal strains were susceptible to penicillin as well as to rifampin. Incidence of meningococcal meningitis in 1994 has been low suggesting that its relative importance compared to other bacteria causing meningitis is likely to change in the future. Therefore, extended surveillance on bacterial meningitis by other etiological agents has to be maintained and implemented in order to undertake the appropriate control measures and evaluate their effect.