Aims: To determine the prevalence, seasonal variation and virulence characteristics of Escherichia coli O157:H7 in lambs presented for slaughter in Ireland.
Methods and Results: Over a 13‐month period, pre‐ and postchill carcass swabs, faeces and fleece samples from 1600 lambs were examined for the presence of E. coli O157:H7. Escherichia coli O157:H7 was isolated from 5·75% (23/400) of fleece samples, 1·5% (6/400) of pre‐ and 1% (4/400) of postchill carcass swabs but was not isolated in faeces (0/400). The present study detected no evidence of seasonal variation. Polymerase chain reaction analysis showed that both the vt1 and vt2 genes associated with clinical illness were carried by five of the E. coli O157:H7 isolates, while 24 of the remaining isolates carried the vt2 gene only. Phage typing detected four different subtypes: PT 32 (48·48%), PT 8 (12·12%), PT 31 (12·12%) and PT 21/28 (12·12%).
Conclusions: Escherichia coli O157:H7 is present in lambs at slaughter in Irish abattoirs and the virulence profiles of these isolates reveals that they are potentially harmful to humans.
Significance and Impact of the Study: The present study provides crucial information indicating that sheep may be a significant contributing source to human E. coli O157:H7 infection.
Aims: The aim of this study was to investigate changes in Salmonella and total viable count (TVC) survival on beef carcass surfaces stored for 72 h under different combinations of relative humidity (i.e. RH 75% or 96%) and temperature (5°C or 10°C).
Methods and Results: The influence of low water activity (aw) and temperature on the survival and growth of Salmonella enterica serovar Typhimurium DT104 and the aerobic mesophilic flora on meat pieces from different sites on beef carcasses was investigated, under controlled conditions (75% or 96% RH; 5 or 10°C) in an environmental cabinet. Salmonella counts declined during storage at low aw (75% RH) conditions at 5°C or 10°C. Salmonella counts increased during storage at high aw (96% RH) at 10°C only. At 5°C, TVCs increased during storage at high aw, but not at low aw. TVCs increased on all samples from carcasses stored at high or low aw at 10°C, except those samples taken from areas of surface fat.
Conclusions: This suggests that substrate composition dictates growth rates under low aw conditions. The results are discussed in terms of the possible protective effects of substrate osmolyte accumulation in bacterial survival and/or growth.
Significance and Impact of the Study: The data obtained in this study provides useful insights on the influence of aw and temperature on pathogen survival on meat surfaces at chill temperature.
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