الفهرس 
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Abstract
6. Summary
The research plan of the current study was divided into 4 sections to achieve the aims of the study.
Firstly, evaluation of the hygienic status of some local abattoirs through determination of aerobic plate, Enterobacteriaceae, coliforms, Staphylococcus aureus, Enterococci, molds, and yeasts counts for various examined samples including meat, water and air samples beside floor, wall, and workers hand swabs.
Secondly, isolation and identification of some indicator pathogenic bacteria including Escherichia coli, Salmonellae, and Enterococcus faecalis beside determination of antibiogram profile of isolated bacteria as well as molecular detection of some virulence and resistance genes in isolated bacteria.
Thirdly, experimental determination of the inhibitory effect of Nanosilver (disinfectant agent) on bacterial isolates recovered throughout the work from the environment of investigated abattoirs by plate diffusion method.
Finally, questionnaire survey and observational study was conducted to analyze data collected from slaughterhouses’ workers in abattoirs under investigation using a structured questionnaire to investigate the role of workers as source of microbial contamination of meat.
This study was conducted in 5 municipal slaughterhouses located in different provinces, Egypt. Abattoirs are manually operated slaughterhouses. They well-constructed with a fence and consisted of a slaughtering hall, quarantine partition, eviscerated rooms, emergency slaughtering room and condemnation room. Slaughtering capacity is around 200 heads of cattle per day. The slaughter operations were started early morning usually at 6:00 am and lasted in 10:00 to 12:00 based on the number of heads admitted for slaughtering. The slaughtering area routinely cleaned at the end of working day.
A total of 300 samples were collected as following: slaughtered meat, water, and air samples beside swabs from floor, wall, and workers hand (50 samples/each). Samples were collected during twice visits per week then labeled and transferred in an icebox to the laboratory of Animal Health Research Institute, Cairo, Dokki, Egypt.
Statistical analytical results of aerobic plate count (APC) of the examined samples during the current study clarified that the highest mean value was recorded in the floor swabs (8.9×105 CFU/g) followed by hand swabs of workers (7.41×105 CFU/g) then wall swabs and air samples (7.2×105 CFU/g) then water samples (5.2×105 CFU/g) and lastly meat samples (1.3×105 CFU/g).
Statistical analytical results of Enterobacteriaceae count (EC) of the examined samples showed that the highest mean value was recorded in the floor swabs (3.2×104 CFU/g) followed by wall swabs (9.3×103 CFU/g) then air samples (6.63×103 CFU/g) then hand swabs of workers (5.33×103 CFU/g) then water samples (3.19×103 CFU/g) and lastly meat samples (9.02×102 CFU/g).
Statistical analytical results of coliforms count (CC) of the examined samples showed that the highest mean value was recorded in the floor swabs (1.65×103 CFU/g) followed by hand swabs of workers (7.23×102 CFU/g) then meat samples (6.10×102 CFU/g) then water samples (4.10×102 CFU/g) then wall swabs (1.72×102 CFU/g) and lastly air samples (1.32×102 CFU/g).
Statistical analytical results of Staphylococcus aureus count of the examined samples showed that the highest mean value was recorded in the floor swabs (7.23×102 CFU/g) followed by hand swabs of workers (6.1×102 CFU/g) then wall swabs (1.32×102 CFU/g) then meat samples (9.5×10 CFU/g) then air samples (6.4×10 CFU/g) and lastly water samples (6.4×10 CFU/g).
Statistical analytical results of Enterococci count of the examined samples showed that the highest mean value was recorded in the wall swabs (6.63×103 CFU/g) followed by hand swabs of workers (5.33×103 CFU/g) then floor swabs (4.25×103 CFU/g) then air samples (3.19×103 CFU/g) then meat samples (3.02×103 CFU/g) and lastly water samples (1.66×103 CFU/g).
Statistical analytical results of molds count of the examined samples showed that the highest mean value was recorded in the floor swabs (1.26×104 CFU/g) followed by wall swabs (9.11×103 CFU/g) then hand swabs (7.87×103 CFU/g) then water samples (5.83×103 CFU/g) then air samples (2.16×103 CFU/g) and lastly meat samples (7.28×102 CFU/g).
Statistical analytical results of yeasts count of the examined samples showed that the highest mean value was recorded in the floor swabs (7.57×103 CFU/g) followed by hand swabs (5.88×103 CFU/g) then wall swabs (3.00×103 CFU/g) then air samples (2.92×103 CFU/g) then meat samples (2.75×103 CFU/g) and lastly water samples (2.60×103 CFU/g).
Results of microbiological examination of the collected samples reflected a clear state of contamination in abattoirs environment that would affect the microbiological quality of the produced meat from these abattoirs that in turn would be harmful for human health. On comparison of various microbiological counts on the investigated meat samples with the Egyptian standards, it was clear that most of samples failed to comply with standards confirming the role of contaminated abattoir environment in the obtained result.
Isolation and identification of E. coli were performed, and it was observed that the highest isolation rate was obtained from floor swabs (14%) followed by meat samples (12%) then air samples (10%) and lastly wall swabs, hand swabs and water samples (8% for each). Moreover, serotyping of the recovered isolates clarified the presence of various serotypes including enterohemorrhagic serotypes (O111: H4, O128: H2, and O127: H6) and enterotoxigenic serotypes (O44: H18 and O125: H21) with different rates.
In addition, antibiogram pattern of the recovered E. coli isolates (n=30) obtained from different examined samples clarified that isolates were resistant to Cefotaxime (100%), Vancomycin and Amoxiclav (80%), then Rifampin (66.7%) while it was found that all isolates were sensitive to Gentamycin (100%) then Ciprofloxacin (80%) and Linezolid (66.7%).
Molecular detection of some virulence genes in selected E. coli isolates (n=10) obtained from different examined samples was employed. It was found that Stx1 gene was detected in 1 isolate, Stx2 gene was detected in 1 isolate, eaeA gene was detected in 5 isolates. On the other hand, molecular detection of some resistance genes in the same selected E. coli isolates (n=10) clarified that blaCMY2 gene was detected in 4 isolates and iss gene was detected in 8 isolates.
Isolation and identification of Salmonellae were performed, and it was observed that the highest isolation rate was obtained from hand swabs (8%) followed by meat samples (6%) then floor and wall swabs, and water samples (4% for each) while Salmonella could not be isolated from air samples. Moreover, serotyping of the recovered isolates (n=13) clarified the presence of various serotypes including S. Enteritidis, S. Typhimurium, S. Heidelberg, and S. Virchow with different rates. In addition, PCR was employed successfully for confirmation of the obtained isolates through detection of invA gene of Salmonella strains. Antibiogram pattern of the recovered Salmonella isolates (n=13) clarified that isolates were resistant to Amikacin and Ciprofloxacin (76.9%) then Vancomycin (53.8%), while it was found that 92.3% of isolates were sensitive to Gentamycin and Linezolid.
Occurrence of Enterococci as an indicator organism was investigated. It was recorded that the overall rate of isolation of Enterococci from the examined samples was 12% (36 isolates out of 300 samples) and the highest rate of isolation were recorded in floor swabs (24%) followed by air samples (14%) then wall swabs and air samples (12% for each) and lastly meat samples (4%). In addition, 20 Enterococcus faecalis isolates were identified biochemically out of 36 isolates of Enterococci in the examined samples. Moreover, PCR was employed successfully to confirm the identification of E. faecalis isolates by detection of 16S rRNA specific for E. faecalis.
Also, antibiogram pattern of E. faecalis (n =20 isolates) obtained from different examined samples was carried out. It was found that E. faecalis were resistant to Cefotaxime (60%), Amikacin and Linezolid (55 %), Rifampin (50%), Amoxiclav (45%) and Gentamycin and Vancomycin (40%) while it was observed that 80% of isolates were sensitive to Ciprofloxacin. Finally, molecular detection of Vancomycin resistance gene A (vanA) in the 20 isolates to E. faecalis was performed by PCR and vanA gene was amplified at 885 bp in 8 isolates only with percentage of 40%.
The inhibitory effect of Nanosilver on some bacterial isolates recovered throughout the work from the environment of investigated abattoirs was investigated by plate diffusion method. The recorded result showed that 50 PPM nanosilver was the lowest concentration that inhibited the growth of S. Enteritidis while 12.5 PPM up to 25 PPM was the lowest concentration that inhibited the growth of Shiga toxin producing E. coli (STEC) and E. faecalis.
Questionnaire survey and observational study was conducted to collect data on slaughterhouses’ workers (n=50) in abattoirs under investigation using a structured questionnaire.
Firstly, analysis of sociodemographic characteristics of the workers revealed that 90% of workers were males and the age group ranged from 15 to 30 years scored the highest level (48%) followed by the age group more than 30 years (38%) and lastly the age group less than 15 years (14%).
Analysis of data about the level of education clarified that 24% of workers were informal (had no education), 42% had primary education only, 34% had secondary education while none of them had a higher education degree. Also, analysis of data about the service duration clarified that 52% of workers had a duration service ranged from 1 to 5 years and 48% had more than 5 years of experience. In addition, only 5% informed that they had received a kind of training on meat hygiene practices and finally, none of them informed that they made periodical medical checkup.
To investigate the role of slaughterhouses’ workers in contamination of meat by different organisms, some meat handling practices of the slaughterhouses’ workers were recorded and analyzed. It was observed that only 12% of workers were using a clean white coat, only 24% washed their hands between activities during work, only 14% used soap for hand washing, 42% used of the same knife for offal and meat.