Enumeration of Escherichia coli Cells on Chicken Carcasses as a Potential Measure of Microbial Process Control in a Random Selection of Slaughter Establishments in the United States

Abstract

To evaluate whether the number of Escherichia coli bacteria in carcass rinses from chicken slaughter establishments could be monitored for the purpose of microbial process control, we drew a random sample from 20 of 127 large USDA-inspected operations. In 2005, every 3 months, two sets of 10 carcass rinses, 100 ml each, were collected from establishments, netting 80 sample sets from the rehang and postchill stages. E. coli and Campylobacter numbers and Salmonella prevalence were measured. Mixed-effect models were used to estimate variance of mean log 10 E. coli cell numbers of 10-carcass rinse sample sets. Relationships between E. coli and Campylobacter and Salmonella were examined. For 10-carcass rinse sets, at both the rehang and postchill stages the mean log 10 E. coli CFU/ml fit the logistic distribution better than the normal distribution. The rehang overall mean log 10 E. coli was 3.3 CFU/ml, with a within-sample set standard deviation of 0.6 CFU/ml. The overall postchill mean log 10 E. coli was 0.8 CFU/ml, with 13 establishments having mean log 10 E. coli CFU/ml values of less than 1.0 and 7 having mean values of 1.2 or more. At the midpoint separating these establishments, a mean log 10 E. coli CFU/ml of 1.1, the within-sample set standard deviation was 0.5 CFU/ml, with smaller standard deviations as means increased. Postchill sample sets with mean log 10 E. coli counts less than or equal to 1.1 CFU/ml had lower overall prevalence of Salmonella and mean log 10 Campylobacter CFU/ml than sample sets with higher means. These findings regarding reductions in E. coli numbers provide insight relevant to microbial process control.Regulatory food microbiology standards are defined and enforced with the intent of protecting public health and maintaining consumer confidence in the safety of the food supply. Resource demands (22) and legal constraints (21) have hindered the U.S. Department of Agriculture (USDA) from enforcing its current Salmonella performance standard (3). For this reason, in 2004 the USDA requested guidance from its national scientific advisory committee on the possible use of E. coli numbers to monitor sanitary conditions during poultry slaughter (12). The committee acknowledged that, if valid, such a performance standard could facilitate inspection of slaughter processing establishments. The committee recommended studies to define how E. coli numbers vary in poultry carcass rinses during poultry processing by processing stage, time of year, and geographic region and with respect to foodborne pathogens.The widespread presence and high numbers of generic E. coli bacteria on poultry entering the slaughter establishment (2,5,14) are suitable characteristics for an indicator organism used to monitor microbial control processes. The ease and lower cost (5, 13) of E. coli enumeration also allow more observations than can be made when comparable resources are allocated for Campylobacter or Salmonella testing (15).Regulatory agencies and food manufacturers have recognized the potential utility of E. col...

Biophysical Evaluation of Food Decontamination Effects on Tissue and Bacteria

“…If this is not clear, then reduction efficiency may be influenced both by treatment dose and the susceptibility of the bacteria to the treatment. Traditionally the efficiency of a decontamination method is determined by the counting of CFUs dislodged from the sample by performing a carcass wash. 6,[8][9][10] However, our results suggest that bacteria not exposed to the surface treatment are also likely not to be removed by the carcass rinse. This observation leads to an important consideration regarding any results obtained only from carcass rinse and CFU counts; the observed decreases in recovered CFUs reflect only the reduction in the fraction of bacteria, which are accessible to both treatment and CFU recovery.…”

“…The retrieving of cell CFU of E. coli from skin samples was performed as described by Altekruse et al 9 . However, due to the small samples sizes, the protocol was slightly modified.…”

“…For example, three examples of carcass rinses include variations in rinse fluid from 100 to 400 ml and the rinse process from scrubbing the chicken for 2-3 min to gently swinging the bag in a 60-cm arc for 1 min. 6,[8][9][10] These different approaches to the retrieval of bacteria from skin samples, may although similar in some respects result in significantly different levels of retrieval. In addition, when employing CFU counts, the bacteria are only categorized as viable or not in the subsequent enumeration procedure, thus omitting any information on the state of the cells left on the food stuff subsequent to decontamination.…”

Self-Monitoring Microbiological Criteria for the Assessment of Hygienic Procedures During Chicken Slaughtering

“…In addition, based on this analysis it becomes clear that there is a need to consider additional microbiological criteria to assess the hygienic procedures in chicken slaughterhouses. Even presenting low microbiological counts in some key steps of slaughtering, the frequencies of chicken carcass samples with counts higher than reference values indicate an absence of proper control of hygienic procedures, jeopardizing the processing steps of slaughterhouses and indicating the need for corrective measures in the process (Altekruse et al, 2009;Heggum et al, 2015;i Sala et al, 2015;Stannard, 1997). Table 6 presents the microbiological counts recorded in the samples obtained from the processing environment of Sl1, Sl2, and Sl3.…”

Scientific Opinion on the public health hazards to be covered by inspection of meat (poultry)

“…However, the presence of generic E. coli at high levels indicates the presence of intestinal material, which is considered to be a measure of slaughter hygiene (Ghafir et al, 2008;Habib et al, 2012;USDA, 1996). Altekruse et al (2009) evaluated whether the number of E. coli bacteria in carcass rinses from chicken slaughter establishments could be monitored for the purpose of microbial process control and made conclusions supporting the use of E. coli as a specific indicator of faecal contamination in the context of process hygiene.…”