Bacteriological evaluation of freshly slaughtered chicken carcasses

Poultry is a food that has been highly appreciated by man since time immemorial. It is an important, low cost source of animal protein, rich in nutrients, phosphorus, other minerals, and B-complex vitamins (FAO 2010). Chicken carcasses have higher pathogenic and spoilage bacterial counts than most other foods, where carcass can be contaminated at several points throughout the processing operation during scalding, de-feathering and evisceration as well as cross contamination from other birds and processing equipment. Several indicators can be useful to evaluate hygiene level of meat such APC and total psychrotrophic counts. Total Enterobacteriaceae count and total coliforms count are more frequently used to assess enteric contamination and commonly used in slaughterhouses as indicators of faecal as well as environmental contamination (Gonzalez and Domingues, 2006). Moreover, total staphylococci count and Staphylococcus aureus counts, which are present on hand, mucous membrane and skin of man, birds and animals, are good indicators of poor personal hygiene, poor handling and temperature control (Rindhe et al., 2008). Contamination of poultry meat with foodborne pathogens remains an important public health issue, where many food poisoning bacteria contaminate chicken meat (Mbata, 2005). Therefore, the present study aimed to evaluate the bacteriological quality of some freshly slaughtered chicken carcasses through Determination of APC, Psychrotrophic count, Enterobacteriaceae count Coliform counts, total Staphylococci count, and isolation and identification of Salmonella, S. aureus, E. coli O157:H7, Listeria monocytogenes and Clostridium perfringens.

A grand total of one hundred random samples of chicken carcasses (slaughtered, plucked and eviscerated) were collected from local commercial retail shops in  BeniSuef city. The collected samples were kept in separate plastic bags, transferred directly to the laboratory in an insulated ice box under complete aseptic conditions without any delay to evaluate their bacteriological quality.

Twenty five grams of the examined samples were removed by sterile scissors and forceps after surface sterilization by hot spatula, transferred to a sterile polyethylene bag, and 225 ml of 0.1 % sterile buffered peptone water were aseptically added to the content of the bag. Each sample was then homogenized in a blender at 2000 rpm for 1-2 minutes to provide a homogenate of 1/10 dilution. One ml from the original dilution was transferred with sterile pipette to another sterile test tube containing 9 ml of sterile buffered peptone water 0.1 % and mixed well to make the next dilution, from which further decimal serial dilutions were prepared. The prepared dilutions were subjected to the following examinations.

It was done using standard plate count agar media.

It was done using standard plate count agar media.

It was done using violet red bile glucose agar media (VRBG).

It was done using violet red bile agar media (VRB).

It was done using Baird Parker agar media.

It was done using Rappaport Vassilidis broth and Xylose Lysine Desoxycholate (XLD) agar.

It was done using E.coli broth supplemented with novobiocin and sorbitol MacConkey agar media.

It was done using cooked meat medium and Tryptose-sulfite-cycloserine (TSC) agar containing egg yolk emulsion.

It was done using buffered Listeria enrichment broth and Oxford agar media.

Table (1) and Fig.(1) reported that APC (log cfu/g) in the examined samples varied from 4.30 to 7.85 with a mean value of 6.18 ± 0.67. The total psychrotrophic count varied from <1 to 5.00 with an average value of 3.31 ± 1.33 , the total coliforms varied from <1 to 4.95 with an average value of 2.07 ± 1.87, the total staphylococci count varied from <1 to 4.90 with a mean value of 3.50 ± 1.68 and S. aureus count varied from 0 to 4.60 with an average value of 2.71 ± 1.67. Results given in table (2) showed that the incidences of isolated Salmonellae, St.aureus, E. coli and listeria monocytogenes were 12, 73, 4 and 6 %.

Clostridium perfringens failed to be detected in the examined samples. Regarding the results in table (3) the incidence of pathogenic E. coli serotypes isolated from the examined chicken carcasses were E. coli O55 (50%) and E. coli O86A (50%). Table (4) reported that Salmonellae could be identified serologically as S.typhimurium (41.70%), S. virchow (41.70%) and S. enteric (16.60%).

Fig. (1): Mean values of bacterial counts (log10cfu/g) in the examined chicken carcasses

Microbial contamination of poultry carcasses is a natural result of different procedures necessary to produce retailed products from living birds. Most of bacterial contaminants are non pathogenic; however, poultry are known to harbour a large number of bacteria that are pathogenic to human being (Zhang et al., 2001). Several indicators can be useful to evaluate hygiene levels during meat slaughtering process. Aerobic plate count (APC) is commonly used to evaluate the hygiene of the entire meat production process. Nearly similar results were reported by Santosh Kumar et al. (2012) (6.23 log cfu/g), Sengupta et al.(2012) (6.39 log cfu/g) and Omorodion and Odu (2014) (5.96 log cfu/g) .On the other hand, higher counts were reported by Barbuddhe et al. (2003) (7.34 log cfu/g), Huong et al. (2009) (11.1 logcfu/g) and Bhandari et al. (2013) (7.24 log cfu/g). Lower counts were reported by Rindhe et al. (2008) (3.67 log cfu/g), Chaudhry et al. (2011) (5.07 log cfu/g), high numbers is a good indication of poor hygiene and poor temperature control. Higher percentage of Salmonella were reported by Abdellah et al. (2009) (57%), Huong et. al. (2009) (62.79%), Bhandari et al. (2013) (46.2%) and Lertworapreecha et. al. (2013) (67.5%). Moreover, Joshi and Joshi (2010) reported that Salmonella was isolated from all examined chicken carcasses (100%). On contrary, Salmonella was isolated in low percentage from chicken carcasses as reported by Cohen et al. (2007) (1.6%), Abdellah et al.(2008) (2.08%) , Colmegna et al. (2009) (1.1%) and Kozacins et al. (2012) (7.46%) . On the other hand, Salmonella could not be isolated from chicken carcasses as reported byVaidya et al. (2005) , Lindblad et al.(2006) , Selvan et al. (2007), Shaltout, F.A.(2009) and Javadi and Safarmashaei (2011). Presence of salmonellae in chicken meat may be attributed to the healthy state of the living bird which carries salmonellae, bad hygienic conditions during slaughtering, cross contamination either from other birds, instruments, machines, workers, scalding tanks, defeathering machines, crop removal, manual evisceration , during slaughter, intestinal contents can spill and contaminate the muscle and organs of the chicken, which is the important source of presence of Salmonella in meat and chilling tanks (Paiao et al., 2013). E.coli O157:H7 failed to be detected in the examined samples. Such results agree with results reported by Baran and Gulmez (2000) , Joa et al.(2004),Hajian et al. (2012) and Kalin et al.(2012). On the other hand, E.coli O157:H7 was isolated in low percents byAkkaa et al. (2006) (1.05%) and Kiranmayi and Krishnaiah (2010) (2%). On contrary, higher results were obtained by Chang et al. (2013) (40%). Although E.coli0157:H7 is mostly found in ruminant animal and it is occasionally associated with other livestock and various foods of animal origin, experience suggests that it is rare in poultry ,whether in the live birds or on processed products (Mbata 2005) .

Similar prevalence of L. monocytogenes was reported Kozacinski et al. (2006) (3%), Colmegna et al. (2009) (3%) and Kozacins et al. (2012) (4.5 %). Lower percentages were reported by Molla et al. (2004) (1.9%) and Cohen et al. (2007) (0.5%). L. monocytogenes is an important foodborne pathogen, which has been isolated from many natural environments, such as water, soil, sewage, mud, gut of poultry and feces Yeh (2004), Donnelly et al. (1992) and Nickelson and Finne, 1992). It is considered an environmental contaminant, therefore, cross contamination easily occurs in traditional shops during preparation of chicken carcasses ready to be sold. 

Clostridium perfringens (C.perfringenes) failed to be isolated from examined samples. Such results agrees with Shaltout (2009). On Contrary, C. perfringens was isolated in higher percentages by Hall and Angelotti (1965) (58%), Miwa et al. (1998) (84%), Singh et al. (2005) (70.4%) and Nowell et. al. (2010) (66%). On the other hand, other studies could detect C.perfringens in lower percentages as Craven et al. (2003) (4%), Cohen et al. (2007) (7.2%) and Thangamani and Subramanian (2012) (3.81%).The organism is an obligate anaerobe that is relatively tolerant to oxygen and can be found in low numbers in the alimentary tract of poultry. When present in meat, growth is favoured by conditions in which oxygen has been dispelled. However, growth of the organisms cannot occur if the meat is held below 15OC, the problem is easily avoided by refrigerated storage. Regarding all the discussed results, chicken carcasses could be contaminated in all stages of production starting from the live bird carrying microorganisms during transportation to the slaughter house, during stages of slaughtering, bleeding, scalding, defeathering, evisceration, washing and storage. Therefore, good hygienic practices should be followed in every step of processing.

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