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Two formulations of chicken summer sausages [100% hand deboned chicken meat (HDCM) and 85% HDCM and 15% chicken hearts (HDCM-CH)] were prepared with a nonpediocin-producing (PED-) Pediococcus acidilactici starter culture and inoculated with 10(4) or 10(7) cfu of a five-strain mixture of Listeria monocytogenes/g of batter. Sausages were fermented to pH 5.0 (11 h), cooked to an internal temperature of 66.5 C, cold-showered, and stored at 4 C (60 days) and 30 C (7 days). For both formulations and inoculation levels, L. monocytogenes populations decreased 1.3 to 1.8 log10 cfu/g by the end of fermentation. No L. monocytogenes organisms were recovered from sausages (by enrichment) following the cook and shower or storage at 4 or 30 C. In contrast, P. acidilactici increased .7 to 1.2 log10 cfu/g during fermentation, and < 10(2) cfu/g remained after the cook and shower and storage at 4 and 30 C. In a second set of experiments, sausages (HDCM) were prepared with a PED- or a pediocin-producing (PED+) P. acidilactici starter culture and challenged with the L. monocytogenes mixture (10(7) cfu/g). The PED- culture reduced numbers of L. monocytogenes 1.2 log10 cfu/g during fermentation, whereas L. monocytogenes numbers declined 2.6 log10 cfu/g in the presence of the PED+ culture. Although acid production by both starter cultures was equivalent, greater inhibition of L. monocytogenes by the PED+ compared with the PED- starter culture was attributed to in situ production of pediocin. Pediococcal starter cultures and proper cooking eliminated L. monocytogenes from sausages and established that PED+ cultures provide an additional hurdle against poultry-related listeriosis.

The aim of this study was to determine whether the contents of farm eggs in Trinidad are contaminated with Salmonella and if transovarian transmission occurs. 750 fresh eggs from 10 farms supplying 75% of the country's eggs were cultured for Salmonella. Salmonella was found on the egg shells' surfaces from all farms, and in the egg contents from three farms. Isolates were obtained from the cultures of the contents and shells of nine (1.2%) and 35 (4.66%) eggs, respectively (p0.005). Serotypes found in the contents were S. enteritidis (0.8%; deduced to be contaminated by transovarian transmission) and S. typhimurium (0.4%); those isolated from the shells (contaminated by faecal transmission) were S. typhimurium (3.06%), S. enteritidis (0.67%), S. ohio (0.27%), S. cerro (0.27%), S. infantis (0.27%) and S. heidelberg (0.13%). This study provides the first evidence for Salmonella and, more importantly, S. enteritidis, in eggs in Trinidad. This is of major public health significance because S. enteritidis infected eggs appear normal and the organism is difficult to detect and control. The consumption of these eggs may increase the risk of Salmonella infection. Food safety practices, particularly the thorough cooking (or = 70 degrees C) of all egg dishes and the refrigeration (10 degrees C) of shell eggs and egg dishes, are recommended.

The pulsed-field technique of clamped homogeneous electric field electrophoresis was employed to characterize and size genomic DNA of three pediocin-producing (Ped+) and two non-pediocin-producing (Ped-) strains of Pediococcus acidilactici. Comparison of genomic fingerprints obtained by digestion with the low-frequency-cleavage endonuclease AscI revealed identical restriction profiles for four of the five strains analyzed. Summation of results for 10 individually sized AscI fragments estimated the genome length to be 1,861 kb for the four strains (H, PAC1.0, PO2, and JBL1350) with identical fingerprints. Genomic analysis of the pediocin-sensitive, plasmid-free strain P. acidilactici LB42 with the unique fingerprint revealed nine AscI fragments and a genome length of about 2,133 kb. Ped- (JBL1350) and Ped+ (JBL1095) starter cultures (one each) were used to separately prepare turkey summer sausage coinoculated with a four-strain Listeria monocytogenes mixture (ca. 10(5) CFU/g). The starter cultures produced equivalent amounts of acid during fermentation, but counts of L. monocytogenes were reduced to a greater extent in the presence of the Ped+ starter culture (3.4 log10 unit decrease) than in the presence of the Ped- starter culture (0.9 log10 unit decrease). Although no listeriae were recovered from sausages following the cook/shower, appreciable pediocin activity was recovered from sausages prepared with the Ped+ strain for at least 60 days during storage at 4 degrees C. The results of this study revealed genomic similarities among pediococcal starter cultures and established that pediocins produced during fermentation provide an additional measure of safety against listerial proliferation in turkey summer sausage.