This study was focused on the isolation of Campylobacter spp. from swabs of poultry and pork carcasses, and environmental swab samples from poultry and pork processing plants. The study aimed to investigate the prevalence of Campylobacter spp. in the processing of poultry and pork in Russian processing plants and to compare it with the European baseline data on Campylobacter prevalence.

Environmental samples were taken using sterile sponges (3M TM, Saint Paul, 110 Minnesota, USA). Samples were transported at 4 °C to the laboratory and processed within 24 h.

The isolation of Campylobacter spp. was performed according to ISO 10272-1 (2017). Environmental samples were performed according to ISO 18593 (2018). They were taken using sterile sponges from 100 cm² and homogenized in 100 mL of Bolton broth (Merck, Germany). Swabs of poultry and pork carcasses were homogenized for 20 s with 225 mL of Bolton broth. The samples were incubated at 41.5 °C for 44 h under a microaerobic atmosphere. Campylobacter isolation was done on modified charcoal cefoperazone deoxycholate agar (mCCDA) (Merck, Germany) and selective agar Preston under microaerobic conditions at 41.5 °C for 44 h. Confirmation of presumptive colonies was performed according to the ISO 10272-1 (2017) principles – typical colonies were seeded on blood agar (Oxoid, UK) and incubated at 41.5 °C for 24 h and then confirmed using biochemical tests (Oxoid, UK).

StatPlus 6.2.2.0 Software (AnalystSoft) was used. Tukey’s test for the comparison of means was performed using the same program. The significance level was defined at p <0.05.

A total of 47 Campylobacter isolates were obtained from 107 environmental samples and poultry carcasses (40.2%): 87.2% were identified as C. jejuni whereas 12.8% were identified as C. coli (Figure 1).

Table 1 shows the presence of Campylobacter at different stages of poultry processing. After evisceration, Campylobacter spp. was detected in 62.7% of the equipment and environmental samples. From positive samples of Campylobacter spp. 84.3% of C. jejuni and 15.7% C. coli was observed. The predominance of C. jejuni over C. coli has been shown by other authors (Sánchez et al., 2017). In that study, the abundances of C. jejuni and C. coli were 94.5% and 5.5%, respectively. These results confirmed those reported by Lee et al. (2017) that the greatest contamination rates were after evisceration. According to Facciolà et al. (2017) during slaughter, the main critical points for poultry carcass contamination were identified by plucking, gutting, and final washing. Other authors described slaughtering and evisceration as critical points of Campylobacter contamination (Gruntar et al., 2015; Sasaki et al., 2013).

Campylobacter spp. was not detected after deboning and cutting, but it was found after packaging. The Campylobacter spp. isolated during packaging was identified as C. jejuni.

It is also an important contamination point due to the possible intestinal ruptures that can occur during the mechanical removal of the intestines (Perez-Arnedo and Gonzalez-Fandos, 2019). Moreover, 50% of the investigated cloacal swabs samples were Campylobacter positive. These two stages can be related to each other and can cause cross-contamination of carcasses. Also, 5 mg of caecal content can increase the number of Campylobacter on eviscerated broiler carcasses (Berrang et al., 2004). These findings support the idea of cross-contamination from contaminated equipment and work surfaces to carcass. Studies are confirming the genetic identity of the strains contaminating slaughterhouse equipment and meat products (Elvers et al., 2011; Prachantasena et al., 2016).

Thirty-three percent of the investigated carcasses were Campylobacter positive. All Campylobacter positive samples from cloacal swabs, carcasses, and necks were identified as C. jejuni.

However, in our research, the prevalence of Campylobacter was significantly (p <0.05) higher after evisceration than in carcasses. It is very important to decrease Campylobacter prevalence in poultry meat, because although Campylobacter spp. do not replicate in food (Corry and Atabay, 2001), a low dose can cause an infection (Vidal et al., 2014).

C. coli was detected in five environmental samples after evisceration and in the leg of one poultry sample.

A total of nine Campylobacter isolates were obtained from 116 environmental samples and pork carcasses (7.8%): 33.3% of them were identified as C. jejuni whereas 66.7% were identified as C. coli (Figure 1). As reported in previous studies, C. jejuni prevailed in the poultry farm compared to the lower presence of C. сoli (Pepe et al., 2009; Peyrat et al., 2008; Wieczorek et al., 2015).

Table 2 shows the presence of Campylobacter at different stages of pork processing. After splitting and evisceration, Campylobacter spp. was detected in 7.4% of the equipment and environmental samples. A significant difference (p <0.05) in positive Campylobacter samples was found between poultry and pork evisceration. The prevalence of positive Campylobacter samples in poultry processing was significantly (p <0.05) higher than in pork processing. From two positive samples of Campylobacter spp, C. jejuni was observed. Environmental and equipment samples after removal of skin, deboning, and cutting were investigated. One of them was identified as C. jejuni, another one as C. coli.

Pork carcasses (neck, leg, belly, skin) were also investigated for the prevalence of Campylobacter spp. Almost all pork carcasses were Campylobacter positive, and all of them were identified as C. coli.

Our results confirm those reported by others, who found the predominant species of Campylobacter in pigs was C. coli (Fosse et al., 2009, Horrocks et al., 2009; Varela et al., 2007). While the reservoirs of Campylobacter are recognised as both poultry and pigs (Quintana-Hayashi and Thakur, 2012), C. coli is the main species found in pigs (Avrain et al., 2004). Authors also reported that control of this microorganism must rely on careful food processing and storage of pork (Varela et al., 2007). A factor that is associated with an increased risk of Campylobacter in pork is a high level of contamination in farms. Bacteriological study results showed that 77% of the piglets and 100% of the fattening pigs were infected with high levels of contamination, but Campylobacter was not detected after deboning (Minvielle et al. 2007). The authors also note the importance of animal selection, transportation to the slaughterhouse, and time spent in the slaughterhouse (Hald, Sommer and Skovgård ,2007).

The application of strict biosecurity measure proved to be effective in preventing the Campylobacter spp. contamination. There are: cleaning and disinfection of the plant equipment; a control of the entry of persons, birds, rodents or other animals; an insect control; water control; waste control (Hansson et al., 2007; Guerin et al., 2007; Nesbit et al., 2001).

It was previously reported that survival during storage and under stress factors, such as microaerophilic conditions, Campylobacter in food products could be aerotolerant. Interestingly, a greater prevalence of aerotolerant strains (80%) was found among C. coli isolates as compared to C. jejuni isolates (6%); these strains were previously isolated from retail chicken meat, chicken livers, chicken gizzards, turkey, pork, and beef liver samples (Karki et al., 2018).

Many studies describe the antibiotic resistance of Campylobacter strains (Noormohamed and Fakhr, 2014). The increasing trend of antimicrobial resistance among Campylobacter strains indicates a high risk of new outbreaks (Geissler et al., 2017).

Further studies are needed to investigate the antimicrobial resistance profile and aerotolerance of isolated Campylobacter strains. Potential approaches for the control of Campylobacter in processing poultry and pork plants are also necessary.