The impact of incorporating Lactobacillus acidophilus bacteriocin with inulin and FOS on yogurt quality.

The current study aimed to figure out the effect of using a combination of 2% inulin, and 2% Fructo-oligosaccharides (FOS) with Lactobacillus acidophilus and their bacteriocin on some yogurt properties such as coagulation time, extending the shelf life of set yogurt and its microbiological quality, also the acceptance by consumers. The results indicated that coagulation time increased by 22.75% in yogurts prepared with Lactobacillus acidophilus and their bacteriocins compared to the control, and titratable acidity increased gradually in all treatments during storage. Hence control acidity (%) increased from 0.84 ± 0.02A at zero time to 1.23 ± 0.03A after 14 days of cold storage, while treatment (T4) was 0.72 ± 0.01C at zero time and reached 1.20 ± 0.5A after 39 days at the same conditions. The sensory properties showed the superiority of inulin, FOS, and Lactobacillus acidophilus bacteriocin groups. Lactobacillus bulgaricus, Streptococcus thermophiles, and Lactobacillus acidophilus count increased in the treatments compared to the control group, with an extended shelf life to 39 days of storage in the medicines containing lactobacillus acidophilus bacteriocin. Coliforms, Moulds, and yeasts did not detect in the treatments comprising 2% inulin, 2% FOS, and lactobacillus acidophilus bacteriocin for 39 days of refrigerated storage. This study proved that 2% inulin, 2% FOS, and Lactobacillus acidophilus bacteriocin fortification extended the shelf life by more than 5 weeks.

Loads of Coliforms and Fecal Coliforms and Characterization of Thermotolerant Escherichia coli in Fresh Raw Milk Cheese.

The aim of this study was to assess the hygienic status of raw milk cheese and determine the trends of virulence and antimicrobial resistance in thermotolerant Escherichia coli. Two hundred samples of karish, a popular Egyptian fresh raw milk cheese, were analyzed for coliforms and fecal coliforms using a standard most probable number (MPN) technique. Overall, 85% of samples were unsuitable for consumption, as they exceeded Egyptian standards for coliforms (10 MPN/g), and 65% of samples exhibited coliforms at 44.5 °C. Of 150 recovered thermotolerant strains, 140 (93.3%) were identified as E. coli. Importantly, one Shiga toxin-producing E. coli (STEC) strain carrying a striking virulence pattern, stx1-, stx2+, eae-, was detected. Eleven strains (7.8%, 11/140) showed resistance to third-generation cephalosporins. Antibiotic resistance genes included blaSHV, blaCTX-M, qnrS, tet(A), and tet(B), which were present in 4.3%, 2.8%, 0.71%, 2.1%, and 0.71% of isolates, respectively. In conclusion, this study indicated that hygienic-sanitary failures occurred throughout the production process of most retail karish cheese. Furthermore, our findings emphasize the need for adopting third-generation cephalosporin-resistant E. coli as an indicator for monitoring antimicrobial resistance in raw milk cheese to identify the potential public health burden associated with its consumption.

Prevalence of Virulence Determinants among Bacillus cereus Isolated from Milk Products with Potential Public Health Concern.

BACKGROUND AND OBJECTIVE: Bacillus cereus is described as one of the public health pathogen causing severe food poisoning outbreaks worldwide. Accurate surveillance about B. cereus in Egypt is scanty. For this reason, the current study was conducted to determine the prevalence of B. cereus and its virulence genes among milk powder and Ras-cheese products. MATERIALS AND METHODS: Two hundred samples (130 and 70) from milk powder and Ras-cheese, respectively were aseptically collected and cultured onto specific media. The obtained isolates were subjected to mPCR for screening of virulence genes (nhe, cytK, pc-plc, hblD, hbI and ces) among of B. cereus isolates that obtained from milk powder and Ras-cheese. RESULTS: The result revealed that B. cereus was recovered with 6.9 and 8.5% from milk powder and Ras-cheese, respectively. The nhe gene was detected and dominated in all isolates 100% from both products. In milk powder, pc-plc was the most prevalent gene (100%). However, cytK, hblD, hbl and ces genes were prevalent with 55.5, 33.3, 33.3 and 22.2%, respectively. Regarding to Ras-cheese, the prevalence of cytK was (83.33%) while each of hbI, hblD, pc-plc and ces genes were recovered in 50% of tested isolates. CONCLUSION: This result provided an important epidemiological view about the contamination rate and the most prevalent virulence genes of B. cereus in milk products in Egypt.

Enterotoxigenicity and Antibiotic Resistance of Coagulase-Negative Staphylococci Isolated from Raw Buffalo and Cow Milk.

Staphylococcal food poisoning is considered to be one of the most common foodborne illnesses worldwide. Because milk is rich in nutrients and its neutral pH, it leads to the growth of various bacteria. To date, the correlation between enterotoxigenic potential in Staphylococcus species and antimicrobial resistance (AMR), using bioinformatics analysis in buffalo and cow raw milk and the possible health risks from these bacteria, has not been examined in Egypt. A total of 42 Staphylococcus isolates representing 12 coagulase-positive staphylococci (Staphylococcus aureus and Staphylococcus intermedius) and 30 coagulase-negative staphylococci (Staphylococcus capitis, Staphylococcus xylosus, Staphylococcus carnosus, Staphylococcus saccharolyticus, and Staphylococcus auricularis) were isolated. An assay of the antimicrobial resistance phenotypes indicated low resistance against vancomycin (9.5%). The blaZ gene was associated with penicillin G and methicillin resistance and not with sulbactam + ampicillin. The presence of the gene ermB presented the correlation with erythromycin resistance and tetK with tetracycline resistance (correlation index: 0.57 and 0.49, respectively), despite the absence of the same behavior for ermC and tetM, respectively. Interestingly, the gene mecA was not correlated with resistance to methicillin or any other ß-lactam. Correlation showed that slime-producing isolates had more resistance to antibiotics than those of nonslime producers. The multiple correlations between antibiotic resistance phenotypes and resistance genes indicate a complex nature of resistance in Staphylococcus species. The antimicrobial resistance could potentially spread to the community and thus, the resistance of Staphylococcus species to various antibiotics does not depend only on the use of a single antimicrobial, but also extends to other unrelated classes of antimicrobials.

Molecular characterization of Escherichia coli isolated from cheese and biocontrol of Shiga toxigenic E. coli with essential oils.

The current research was carried out to study the incidence of Escherichia coli (E. coli) in Egyptian cheese (Kariesh and Ras) and molecular characterization of certain E. coli virulence genes (stx1, stx2, eaeA, hlyA and fimH) using multiplex PCR technique. Biocontrol of E. coli with essential oils (clove and thyme oil) was also studied. A total of 150 random samples of Kariesh and Ras cheese (75 each) were collected from various areas in Governorate of Menoufia. According to our results, the frequency of E. coli isolated from Kariesh and Ras cheese was 16% and 5.3%, respectively. Serological identification classified the E. coli strains into two groups, enterohemorrhagic E. coli (EHEC) serogroup (O26: H11, O91: H21, O111: H2 and O103: H2). While the enterotoxigenic E. coli (ETEC) serogroup were detected as O125: H21 which is the most prevalent strain. O171: H2, O86 and O119: H6 belonging to enteropathogenic E. coli (EPEC). The most prevalent gene detected in E. coli strains was stx1 (87.5%) followed by stx2 (86%), fimH (75%), hlyA (50%) and eaeA (25%) genes. Concerning the antimicrobial activity with essential oils, thyme oil (1%) is considered as the bactericidal effect against E. coli (ATCC35150) with improved the sensory evaluation than clove oil (1%). In conclusion, Kariesh and Ras cheese are extremely tainted with pathogenic E. coli strains, which represent a strong hazard on the human health.

Substantial Virulence Genes among Brucella melitensis Field Strains Isolated from Cattle in Egypt.

BACKGROUND AND OBJECTIVE: The economic losses due to brucellosis as well as its potential public health in human worldwide encourage more researches to find novel pathways for effective control methods of the disease. The objective of this study was to investigate the most prevalent Brucella strains obtained from cattle and their virulence genes. MATERIALS AND METHODS: Three hundred small-holders cows in Menoufia governorate, Egypt, were screened for brucellosis using rose bengal test (RBT) and confirmed by complement fixation test (CFT). Milk samples and supra-mammary lymph nodes of serologically positive cows were collected for bacteriological isolation and identification. The obtained isolates were genotyped using PCR and their virulence genes (omp25, omp31, manA, manB, virB and znuA) were screened. RESULTS: The prevalence rate of bovine brucellosis was 15 (5%), 11 (3.6%) and 7 (2.33%) by RBT, CFT and bacteriological examination, respectively. The seven isolates were identified and genotyped as Brucella melitensis biotype3. Furthermore, the molecular detection of substantial virulence genes revealed that manA, manB, omp25 and omp31 genes were detected in all tested B. melitensis strains. Meanwhile, the virB genes were detected in 4 strains and the znuA genes were detected in 3 strains among the isolated B. melitensis strains. CONCLUSION: It was concluded that B. melitensis biotype3 was the pre-dominant Brucella spp. as well as omp25, omp31, manA and manB were the most common related-virulence genes which assumed to play a worthy function in the pathogenesis of brucellosis.