Treatment of Beef Hides with Cetylpyridinium Chloride Solution to Reduce Contamination before Slaughter of Beef Cattle

<p>It has long been known that beef and dairy cattle are a primary reservoir of E. coli O157:H7. Faith et al. (1996) and Hancock et al. (1994) showed that fecal material acts as the vehicle of transmission of E. coli O157:H7 from animal to animal and from animal to human. Gill et al. (1999) showed that carcass contamination is most likely to occur during the dehiding process when the exterior hide surface accidentally roles over and contaminates the previously sterile carcass surface. The present studies were conducted to identify chemical interventions that could potentially be used on the hide surface to minimize pathogenic contamination.</p>
<p>Although not federally approved for food contact surfaces, cetylpyridinium chloride (CPC) has reduced bacterial counts on beef carcasses by as much as 6 log CFU/cm2 (Cutter et al., 2000). In addition, Ransom et al. (2002) demonstrated that CPC reduced E. coli O157:H7 populations by 4.8 and 2.1 log CFU/cm2, respectively on beef adipose tissue and beef trimmings.</p>
<p>When CSU preliminary studies were first initiated, populations of E. coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes were reduced by 6 to 7 log CFU/cm2 on hide surfaces; however, we realized that the residual CPC in the plated sample was preventing the bacteria from growing on the agar plates. Thus, subsequent studies were conducted using Dey-Engley Broth, which immediately stops the antimicrobial action of CPC.</p>
<p>Hide samples were cut to approximately 50 cm2, then inoculated with 8 log CFU/ml of a five-strain cocktail of E. coli O157:H7. Following inoculation, the bacteria were allowed 30 minutes to attach to the hide surface. After attachment, the samples were dipped and rotated in the CPC solution for 30 seconds; then, neutralizing broth was added to stop the antimicrobial activity of CPC. Bacterial populations were reduced immediately following treatment and, in general, reductions in E. coli O157:H7 and total bacterial populations were observed following the 30 second CPC treatment period. The effectiveness of CPC increased as the time following 30-second treatment period increased. For example, the reduction of E. coli O157:H7 increased from 2.1 log CFU/cm2 after the 30-second treatment time to 3.3 log CFU/cm2 after 30 minutes following the original CPC treatment (Table 1). Each sample from each time period was plated in duplicate and replicated twice.</p>
<p>A second study was conducted to determine if the length of exposure time in the CPC solution would affect the survival of both pathogen and total bacterial populations on the hide surfaces. Increasing the length of time before neutralization after 30 seconds of exposure during treatment application, increased (P < 0.05) the reduction of both pathogen and total bacterial populations by 0.9 log CFU/cm2. Moreover, increasing the length of expose to the CPC solution, increased (P < 0.05) the effectiveness of CPC on E. coli O157:H7 and total bacterial populations.</p>
<p>Unfortunately, the most commonly reported data on hides is for prevalence, rather than logarithmic quantification, of E. coli O157:H7, thus the level of pathogenic bacteria on beef hides during entry to the harvest facility is currently unknown. Further investigation of CPC on live animal hides is warranted and could prove to be beneficial in reducing the potential for bacterial contamination and ultimately foodborne illness.</p>