An in vitro system for the comparison of excision and wet-dry swabbing for microbiological sampling of beef carcasses

The Impact of Cattle Hide Cleanliness Scores on Microbial Contamination of Carcasses During Slaughtering

This study aimed to investigate the effects of cleanliness scoring on the microbiological load of hide and the final contamination of cattle carcasses. Fifty cattle were classified from 1 (clean and dry) to 5 (filthy and wet). Aerobic colony count (ACC) and counts of Enterobacteriaceae (EC) and E. coli (ECC) were determined on the brisket, abdominal midline, rump, groin sites of the hides, and brisket, flank, groin, and hock of the carcasses. On hides, ACC ranged from 3.15±0.13 log cfu/cm2 in category 1 to 8.14±0.21 log cfu/cm2 in category 5. EC and ECC were ranging between 1.13±0.07 and 2.80±0.09 log cfu/cm2, and 1.21±0.05 and 2.15±0.07 log cfu/cm2, respectively. While the mean ACC on the carcasses ranged between 2.18±0.07 and 2.63±0.05 log cfu/cm2 irrespective of the categories, Enterobacteriaceae and E. coli could not be counted due to the detection limits. It was concluded that although the level of bacterial load increased significantly (P<0.001) with the increasing cleanliness category on the hide of the animals, the reflection of this increasing trend on carcasses and different parts of the carcasses were inconsistent and the hygiene provided in the slaughterhouse and processing line was the main factor to reduce cross-contamination during processing.

Bovine lymph nodes as a source of Escherichia coli contamination of the meat

Ground beef contamination with Escherichia coli is usually a result of carcass faecal contamination during the slaughter process. Carcasses are contaminated when they come into contact with soiled hides or intestinal leakage content during dressing and the evisceration processes. A more recent and compelling hypothesis is that, when lymph nodes are present in manufacturing beef trimmings, they can be a potential source of Enterobacteriaceae contamination of ground beef. The aim of this study was to investigate the occurrence of E. coli in lymph nodes from beef carcasses used for ground meat production, in six slaughter plants situated in central Italy A total of 597 subiliac (precrural) lymph nodes were obtained from 597 cattle carcasses and screened for E. coli by culture. Furthermore, E. coli isolates (one per positive carcass) were tested for stx1, stx2 eaeA and hlyA genes that are commonly used to identify and characterise shiga toxin-producing E. coli (STEC). In addition, the E. coli isolates were profiled for antimicrobial susceptibility. A proportion of 34.2% (204/597) carcasses were positive for E. coli. PCR revealed that 29% (59/204) of E. coli possessed stx1 or stx2 which corresponded to 9.9% of the cattle sampled. Moreover, a combination of stx1 or stx2 and eaeA was found in in 4 isolates (2% among E. coli positive samples and 1% among cattle sampled) and a combination of stx1 or stx2 and eaeA and hly in 1 isolate (0.5% and 0.2%). More than 95% of isolates were susceptible to gentamicin, ceftriaxone, cyprofloxacin and cefotaxime while high rates of resistance were recorded for cephalotin, ampicillin, tetracycline, tripe sulfa and streptomycin. The multivariate analysis identified "age" as the factor most closely related to E. coli positivity (either generic E. coli or STEC) in bovine lymph nodes. In conclusion, subiliac lymph nodes represent a source of E. coli for ground beef. These results are of major importance for risk assessment and improving good manufacturing practices during animal slaughter and ground meat production.

A Comparison of 16S rRNA Profiles Through Slaughter in Australian Export Beef Abattoirs

Microbial contamination of beef cattle carcases and subsequent cross-contamination during processing is inevitable and virtually impossible to prevent. The understanding of microbial contamination in the beef industry is currently limited to hypotheses based on traditional microbiological tools. Additionally, the complex structural and functional responses of beef cattle microbial communities to the fragmentation in the supply chain remain unknown. This study used 16S rRNA gene sequencing in combination with traditional microbiology to monitor and compare changes in the microbiota throughout slaughter in an integrated (abattoir A) and a fragmented (abattoir B) beef abattoir in Australia. Briefly, the primary difference between an integrated and a fragmented abattoir is that fragmented abattoirs receive cattle from multiple sources, whereas integrated abattoirs typically receive cattle that has been produced using the same production system and from a limited number of sources. The composition in the bacterial communities varied between the abattoirs, though the presence of the most predominant bacterial species within the microbiota at each abattoir was similar. Lactobacillales (2.4-56.2%) and Pseudomonadales (2.4-59.4%) most notably dominated hides, carcases, and the environment in abattoir B. In abattoir A, Bacteroidales (3.9-43.8%), Lactobacillales (0.0-61.9%), and Pseudomonadales (0.5-72.1%) fluctuated but generally shared the dominance over the rest. Combined results of total viable count (TVC) and 16S rRNA gene profiling indicated that an upward hide pulling system adopted by abattoir B may lead to increased transmission of hide contaminants to post-hide pull carcases. Abattoir B had 3.2 log₁₀CFU/cm² reduction from hide to carcase, where abattoir A had 4.5 log₁₀CFU/cm² reduction. The findings from this study indicated that common beef-associated microbiota exist in varying composition in Australian abattoirs, and 16S rRNA amplicon sequencing is a powerful tool to understand in-depth movement of microbial contaminants.

Analysis of the causes of the seizure and destruction of carcasses and organs in a slaughterhouse in central Italy in the 2010-2016 period

Meat safety and hygiene are fundamental issues for producers and endusers. To achieve these goals, the inspection of carcasses and organs at slaughter is critical. The results of post-mortem inspection are the basis for planning preventive measures against consumer risks and for limiting economic losses. In this retrospective study, the causes of the seizure and destruction of carcasses and organs were analysed at a slaughterhouse in central Italy from 2010 to 2016. 436,646 slaughtered animals were taken into consideration, for a total of 61,799 seizures (73.29% pigs, 23.87% cattle, 2.77% sheep and 0.07% horses). The organs or groups of organs that most frequently showed lesions in pigs were liver (72.38%), heart (10.77%) and pluck (10.20%); in cattle, lungs (64.86%), liver (31.20%) and stomachs (11.63%); in sheep, liver (77.15%), pluck (18.70%) and lung (3.80%); in horses, liver (75.56%), kidney (68.89%) and lung (31.11%). Among the diagnoses, parasitic diseases of the liver (ascariasis and distomatosis) were especially frequent in all species, followed by pericarditis and polyserositis in pigs and diseases affecting the respiratory system in cattle. The data obtained show that postmortem inspection is of fundamental importance for limiting risks for the consumer and ensuring meat safety. It is also evident, even more than ten years after the coming into force of the so-called hygiene package regulations, that the slaughterhouse can still act as an epidemiological observatory to provide the data needed for the development of plans for the control and eradication of the most frequent diseases in the area.

Microbiological Sampling of Carcasses by Excision or Swabbing with Three Types of Sponge or Gauze

Fifty-five bovine, 50 equine, 60 ovine, and 50 porcine carcasses were sampled in a slaughterhouse in eastern Spain. Two samples were taken from each carcass, one using the excision method and the other using the swabbing method. Four different materials were used for swabbing: cellulose, polyurethane, or viscose sponges, and medical gauze. Samples were collected at the end of the process by four different people before the carcasses were taken to the cooler. The samples were examined for total viable bacteria counts (TVCs) and Enterobacteriaceae counts (ECs). The mean TVC for all species sampled by excision was 4.50 log CFU/cm2, which was significantly higher than the 3.53 log CFU/cm2 obtained by swabbing. The TVCs obtained using gauze and the cellulose and polyurethane sponges were significantly higher (P &lt; 0.05) than the corresponding TVCs obtained using viscose sponges. Animal species, the person who collected the samples, and microbiological load also had a significant effect on TVC. ECs were obtained from 82.8% of excision samples, from larger percentages of samples obtained using cellulose or polyurethane sponges or gauze swabs, but from smaller percentages of samples obtained using viscose sponges. The Enterobacteriaceae load significantly influenced the EC. In contrast, animal species and the person who collected the samples had no significant effect. The cellulose sponge, polyurethane sponge, and gauze gave high mean log counts of aerobic bacteria and Enterobacteriaceae, which makes these swab types suitable for use in slaughterhouses for the purpose of assessing production process hygiene.