This 13-month survey was conducted to estimate the prevalence and counts of foodborne pathogenic bacteria and indicator bacteria on swine carcasses in Sweden. A total of 541 swine carcasses were sampled by swabbing prechill at the 10 largest slaughterhouses in Sweden. Pathogenic Yersinia enterocolitica was detected by PCR in 16% of the samples. The probability of finding Y. enterocolitica increased with increasing counts of Escherichia coli. No samples were positive for Salmonella. The prevalences of Campylobacter, Listeria monocytogenes, and verocytotoxin-producing E. coli were low (1, 2, and 1%, respectively). None of the verocytotoxin-positive enrichments, as determined by a reverse passive latex agglutination assay, tested positive for the virulence genes eaeA or hlyA by PCR. Coagulase-positive staphylococci, E. coli, and Enterobacteriaceae were recovered from 30, 57, and 87% of the samples, respectively, usually at low levels (95th percentiles, 0.79, 1.09, and 1.30 log CFU/cm2, respectively). The mean log level of Enterobacteriaceae was 0.35 log CFU/cm2 higher than that of E. coli on carcasses positive for both bacteria. The mean log level of aerobic microorganisms was 3.48 log CFU/cm2, and the 95th percentile was 4.51 log CFU/cm2. These data may be useful for risk assessment purposes and can serve as a basis for risk management actions, such as the use of E. coli as an alternative indicator organism for process hygiene control.
An increasing trend in human listeriosis cases over the past five years (2005-2009) in Sweden encouraged the authorities to examine the prevalence and levels of Listeria monocytogenes in ready-to-eat (RTE) foods in 2010. The combined results of two surveys are presented: the Swedish part of an EU-wide survey and a national survey. A total of 1590 samples covering three categories of RTE food able to support growth of L. monocytogenes: (i) soft and semi-soft cheeses (mould- and smear-ripened); (ii) heat-treated meat products; and (iii) smoked and gravad fish, were collected at retail outlets and analysed at the end of shelf life. L. monocytogenes was detected in 0.4% of 525 cheese samples, 1.2% of 507 meat-product samples and 12% of 558 fish samples. In the latter category, L. monocytogenes was found in 14% of both gravad and cold-smoked fish samples and in approximately 2% of hot-smoked fish samples. The percentage of cold-smoked or gravad fish testing positive for L. monocytogenes was significantly lower in samples processed in Sweden (8%) than in samples processed in other countries (45%). Levels of L. monocytogenes exceeding 100 cfu/g were found in one (0.2%) of the cheese samples and in three (0.5%) of the fish samples. The high prevalence of contaminated cold-smoked and gravad fish samples suggests that these products constitute the main problem. This has induced the development of a national strategy plan with the aim to halve the prevalence of L. monocytogenes in cold-smoked and gravad fish at retail in Sweden by the end of year 2015.