In the present study, Fifty random samples of each small-scale (plain yoghurt and kariesh cheese) were collected randomly from different dairy shops and markets in Zagazig city for isolation and identification of Escherichia coli which is considered a good indicator of faecal contamination and a major cause of food poisoning. Identification was done microscopically and biochemically by different biochemical tests (IMVIC).The incidence of E. coli in yoghurt and kariesh cheese samples were 36% and 50%, respectively. Also, the serological identification of E. coli isolates revealed that O26 is the most predominant serogroup by percentagesof27.77% and 28% in both yoghurt and kariesh cheese samples, respectively. Because of its rising resistance to antibiotics, E.coli represents a real threat to human health. Antimicrobial susceptibility testing (AST) was done by disc diffusion method against 10 antimicrobials and the results revealed that E. coli isolates were highly resistant to amoxicillin-clavulanate, ampicillin, Cefotaxime and Ceftazidime, and were highly sensitive to chloramphenicol, Ciprofloxacin and tetracycline. In addition, 83.72%of E. coli isolates showed multi drug resistance (MDR).Bacterial adhesion to food surfaces and the formation of biofilmisa source of food contamination that has an impact on food safety and industry. Micro titer plate assay was used for testing biofilm formation and revealed that 69.77% of E. coli isolates were non-biofilm producers, 9.30% were weak biofilm producers, 20.93%were moderate biofilm producers and none of isolates was strong biofilm producers. Virulence genes of E. coli isolates were identified and characterized by a multiplex PCR assay. The results showed that among the target genes, stx1was most frequently detected by a percentage of81.82%
A total of 100 samples of raw Buffalo milk including (50 from dairy shops and 50 from dairy farms) were collected randomly at Sharkia Governorate for chemical and microbiological evaluation. Chemical assessment of the milk samples collected from dairy shops revealed that the mean values of Fat, Solid Not Fat (SNF), Protein, Lactose and Salts percentages were 6.06±0.36, 9.08±0.23, 3.54±0.09, 4.73±0.14 and 0.74±0.02 respectively, while dairy farm samples were 6.18±0.31, 9.53±0.44, 3.89±0.09, 5.12±0.15 and 0.78±0.03; correspondingly. Microbiological examination revealed that the mean values of faecal coliforms were 2.03×10 6 ± 0.75×10 6 and 1.8×10 6 ± 0.59×10 6 in dairy shops and farms, respectively. The identified species of isolated coliform organisms in both types of milk were Citrobacter diversus (11.3% vs 11.1%) Citrobacter freundii (9.6% vs 9.6%), Enterobacter aerogenes (12.1% vs 9.6%), Enterobacter agglomerans (11.3 vs 10.4%), Enterobacter cloacae (13% vs 11.1%), Klebsila oxytoca (9.6% vs 11.9%), Klebsila pneumoniae (9.6% vs 10.4%) and E.coli (23.5% vs 25.9%); respectively. Mean values of total staphylococci were 4.29×10 6 ± 0.21×10 6 and 8.08×10 6 ± 2.27×10 6 in milk samples of shops and farms respectively. The identified species in both types were S. aureus, S. epidermidis, S. saprophyticus, S. capitis and S. intermedius with percentages of 28% vs 35%, 48% vs 41%, 10% vs 12%, 8% vs 7% and 6% vs 5%; respectively. It was exposed that 8 strains (28.57%) and 10 strains (28.57%) were identified as methicillin-resistant S. aureus that containing mecA gene. In conclusion, high prevalence of different udder pathogens among dairy animals may attributed to the lack of sanitary conditions that adapted in dairy farm. So, restriction to application of hygienic measures in dairy farms as well as quality control and quality assurance programs should be adopted to get safe and good quality raw milk.
In the present study, one hundred samples of raw cow milk were collected randomly from different dairy shops and markets in Zagazig city for isolation and identification of Escherichia coli which is considered a reliable indicator for fecal contamination and an important cause of food poisoning. Identification was done microscopically, biochemically by different biochemical tests (IMVIC) and serologically. The incidence of E. coli in raw milk samples was 47%. Also, the serological identification of E. coli isolates revealed that O26 is the most predominant serogroup by percentage of 21.3%. E. coli pose the greatest threat to human health because of its growing resistance to antibiotics. Antimicrobial susceptibility testing (AST) was done by disc diffusion method against 10 antimicrobials and the results revealed that E. coli isolates were highly resistant to amoxicillinclavulanate, ampicillin, cefotaxime and ceftazidime with percentages of 89.4%, 89.4%, 100.0% and 100.0%, respectively. However, they were highly sensitive to chloramphenicol, ciprofloxacin and tetracycline with percentage of 100.0%, 100.0% and 93.6% respectively. In addition, 89.4% of E. coli isolates showed multi drug resistance (MDR). The ability of bacteria for adherence to food surfaces and biofilm formation is a source of food contamination that affect food safety and industry. Micro titer plate assay used for testing biofilm formation and represented that 78.7% of E. coli isolates were non-biofilm producers, 6.4% were weak biofilm producers, 14.9% were moderate biofilm producers and none of isolates was strong biofilm producers.
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