Samples Of Dairy Products Research Articles

COAGULASE POSITIVE STAPHYLOCOCCI ENUMERATION AND ENTEROTOXINS DETECTION IN MILK AND DAIRY PRODUCTS FROM CENTRAL ITALY

This study aims at enumerating coagulase positive staphylococci (CPS) in 404 samples of milk and dairy products collected in own-checks or during the official controls from different dairy industries located in Central Italy. These microorganisms were enumerated using ISO 6888-2:1999/Amd. 1:2003 and only when they exceeded 105CFU/g, the presence of any of the seven more common staphylococcal enterotoxins (SEA, SEB, SEC1, SEC2, SEC3, SED and SEE) was also investigated. Own-checks samples resulted always below the detection limit, whereas among those collected by the competent authorities in the framework of official controls, provola (100%) and mozzarella (22.9%) samples were positive to CPS, with mean values of 1.8x102 and 2.8x105 CFU/g respectively. Such values exceeded the maximum limits set by Commission Regulation (EC) No. 2073/2005, resulting in a request of hygiene improvements in the first case; in the second case, the presence of staphylococcal enterotoxins in 8 (2.7%) mozzarella samples out of 298 investigated cheese products was also observed, resulting in their withdrawn from the market. Therefore, this study aims at highlighting that monitoring of CPS incidence in dairy products and subsequent testing of cheeses for enterotoxins when appropriate represent an important tool for public health in order to avoid the occurrence of foodborne outbreaks.

Bacteriological quality and safety of ready-to-consume milk and naturally fermented milk in Borana pastoral area, southern Ethiopia.

Milk and milk products play an important role in the diet of pastoralists in Ethiopia. However, only few studies have been conducted on the microbial contamination of milk and milk products in pastoral areas. Therefore, the objective of the present study was to assess the hygiene and safety of ready-to-consume milk and traditionally produced fermented milk products (yogurt) in Borana. A total of 203 raw milk and milk product samples collected from different points along the milk production and handling chains were tested for Escherichia coli, E. coli O157:H7, and Staphylococcus aureus. E. coli was detected in 51.7% of the analyzed samples with a mean count of 2.5logCFU/ml. The study revealed that 10.8% and 2.5% of the milk and dairy product samples harbor S. aureus and E. coli O157:H7, respectively. Detection of E. coli O157:H7 in ready-to-consume milk has potential health implications for consumers in an area where raw milk consumption is common. To our knowledge, this is the first report of the isolation of E. coli O157:H7 from milk in pastoral systems in Ethiopia.

Biodiversity of lactic acid bacteria isolated from fermented milk products in Xinjiang, China

ABSTRACTFermented dairy products have been produced and consumed for thousands of years in Xinjiang, China. In this study, traditional culture-dependent methods and 16S rRNA gene analyses were performed to analyze the composition of lactic acid bacteria (LAB) from 86 samples of traditional fermented dairy products collected from four regions of Xinjiang. Quantitative polymerase chain reaction (qPCR) was used to quantify Bifidobacterium and Lactobacillus species. The LAB isolates (N = 705) were identified as belonging to seven genera and 26 species or subspecies. The predominant species of all isolates were Lactobacillus (Lb.) delbrueckii subsp. bulgaricus, Lb. fermentum, and Lb. helveticus. The LAB counts of these samples ranged from 5.35 to 10.06 Log CFU/mL. The bacterial counts of seven lactobacilli species and Bifidobacterium ranged from 0.98 ± 0.14 Log CFU/mL (for Lb. sakei from fermented mare milk) to 9.91 ± 0.17 Log CFU/mL (for Lb. helveticus from fermented mare milk). While the microbiota was significantly different between yak and cow milk, there was no significant difference between the Tex and Zhaosu counties. In conclusion, LAB communities in traditional fermented dairy products are complex and differ among local regions within Xinjiang.

Heavy metal residues and health risk assessment in raw milk and dairy products with a trail for removal of copper residues.

This study was conducted to determine the residues of Lead (Pb), Cadmium (Cd), and Copper (Cu) in different types of raw milk and dairy products, and to estimate the dietary intake of such metals, as well as to evaluate the potential health hazards of these metals to peoplethrough consuming milk and dairy products. On the other hand, we made a trial to remove copper residues using the adsorption properties of the resin. Therefore, a total of 120 random samples of milk and dairy products, including 80 samples of raw milk of different species from different dairy shops, and farms in Sharkia Governorate, Egypt, in addition to 20 samples for each of UHT milk and Kariesh cheese, werecollected. Pb and Cu residues in the examined samples ranged from 1.85–2.78, 0.009–0.81ppm respectively, while Cd was detected only in raw goats' milk and kariesh cheese samples.Moreover, it is worth clarifying thatPb recorded the highest levels in the examined samples since most of the samples were over the permissible level of 0.1 mg/kg established by Egyptian Standard. Human health risk associated with consuming milk and other examined dairy products was identified using Target Health Quotient (THQ) showed that Pb is the most dangerous element measured in these products as its value was more than one in mostof the samples. In the present study, the performance of IMAC HP resin was assessedfor the firsttime for removal of Cu ions from artificially contaminated raw cows' milk, although it is used extensively to purify water from heavy metals. It was noticed that the removal efficiency of Cu ions increased with higher resin concentration, and increasing time, as the maximum removal percent (76.89%) was achieved by using 0.8 g/L. IMAC HP resin after 45 min. Finally, it was concluded that this type of resin is suitable for the adsorption of Cu ions from artificially contaminated raw milk.

Aluminum in Artisanal Dairy Products: Occurrence, Residues Level, Estimated Intake and Target Hazard Quotient

Aluminum is non-essential element for humans and is considered to be a toxic metal. dairy products are a major constituent of the daily diet, and its contamination with Aluminum may constitute a serious impact on consumers’ health. One hundred dairy products samples (butter, Damietta cheese, Kareish cheese and plain yoghurt) 25 each were collected randomly from artisanal producers at Damanhur city, West Delta, Egypt to be analyzed for aluminum (Al) concentration using Flame Atomic Absorption Spectrophotometer. Aluminum was detected in examined samples of butter, Damietta cheese, Kareish cheese and plain yoghurt by 24%, 36%, 20% and 28% with mean concentrations (µg/kg) of 144.28, 232.76, 236.58 and 131.08, respectively. Consumption of raw milk in the area under investigation contributes to 1.44% (butter), 8.53% (Damietta cheese), 8.67% (Kareish cheese) and 3.05% (plain yoghurt) of the provisional tolerable weekly intake (PTWI). The target hazard quotient (THQ) of Al metal via artisanal dairy products consumption was less than one. Therefore, regarding aluminum contamination, the results indicated that consumption of artisanal dairy products does not pose health hazard to local residents in Damanhur city, West Delta, Egypt. An effective control measures(e.g. HACCP and ISO series) must be applied to decrease contamination of dairy products with Al.

Heavy metals in raw milk and some dairy products at local markets

A total of seventy-five random samples of dairy products (15 each ofraw cow's milk, raw buffalo's milk, condensed milk, baby formula, andmilk powder) were collected from different markets and pharmacies atDamanhour, Behera governorate, Egypt. All examined samples wereanalyzed by Atomic Absorption Spectrophotometer to determine heavymetals residues namely such as Lead (Pb), Cadmium (Cd), Aluminum (Al),Chromium (Cr), and Nickel (Ni). The results obtained revealed that highlytoxic metals lead (Pb) and cadmium (Cd) were detected above therecommended daily intake, While aluminum (Al), chromium (Cr), andnickel (Ni) were detected below the recommended daily intake as Leadlevels in raw cow milk, raw buffalo milk, condensed milk, baby formulaand milk powder were (0.11 ± 0.038 , 0.14 ± 0.040, 0.20 ± 0.049, 0.21 ±0.052, and 0.27 ± 0.054), Cadmium levels were (0.03 ± 0.021, 0.09 ±0.037, 0.11 ± 0.044, 0.12 ± 0.036, and 0.17 ± 0.046), Aluminum levelswere (0.15 ± 0.078, 0.162 ± 0.062, 0.23 ± 0.077, 0.24 ± 0.086, and 0.26 ±0.066), Chromium levels were (0.06 ± 0.05, 0.073 ± 0.04, 0.11 ± 0.046,0.21 ± 0.062, and 0.20 ± 0.061), and Nickel levels were (0.00, 0.025 ±0.015, 0.04 ± 0.03, 0.05 ± 0.023, and 0.093 ± 0.04), respectively. Publichealth significance of heavy metals was discussed.

High diversity of genetic lineages and virulence genes of Staphylococcus aureus isolated from dairy products in Tunisia

Staphylococcus aureus can produce staphylococcal enterotoxins (SEs) in foods and cause staphylococcal food poisoning. Milk and dairy products are foodstuffs among the most frequently associated with staphylococcal food poisoning. It is also relevant to consider that the transmission of S. aureus is possible either by direct contact with animals or through contaminated food as milk or cheese. The aim of this study was to determine the genetic lineages and the genotypes of antibiotic resistance and virulence factors of S. aureus isolates recovered of different dairy products in Tunisia. We collected 136 samples of various traditional and commercial dairy products in different areas in Tunisia. Bacterial isolates were identified by conventional methods (Gram staining, catalase test, oxidase test, DNase production, and ability to coagulate rabbit plasma). The antimicrobial resistance profile and the virulence gene content were investigated. Molecular typing was performed by spa-typing, agr-typing and pulse-field gel electrophoresis (PFGE). Twenty six (19.2%) of the total analyzed samples (N = 136) were contaminated by methicillin-sensitive S. aureus (MSSA). Antimicrobial sensitivity assays have shown that MSSA isolates exhibit a resistance rate of 73.1% to penicillin, 23.1% to tetracyclin, 19.2% to kanamycin, 15.4% to amikacin, and 3.9% to gentamicin. Furthermore, the following toxin encoding genes have been identified among MSSA: luk ED (24 isolates), luk M (2), see (3), sel (3), sea (2), sej (1), sec (1), seb (1), and tst (1). Results of molecular characterization and phylogenetic relations analysis revealed a considerable genetic diversity. Thirteen different spa-types were detected among the 26 isolated MSSA. S. aureus was attributed to the agr type I (16 isolates), II (2), III (2), and non-typables (6). Sixteen different electrophoretic profiles were revealed. Dairy products could constitute a reservoir of virulent and antibiotic-resistant Staphylococcus aureus.

Identification of blaVIM, blaIMP and blaSPM-1 Metallo-β-Lactamase Genes in Bacillus subtilis Strains Isolated From Raw Milk and Cheese Samples

Introduction: Studies on bacterial resistance to common antibiotics are often based on bacteria isolated from patients, with less attention towards foodborne bacteria. This study aimed to investigate the antibiotic resistance pattern and the presence of metallo-β-lactamase (MBL) genes viz blaVIM, blaIMP, and blaSPM-1, in the Bacillus subtilis strains isolated from raw milk and cheese samples. Methods: A total of 100 raw milk and cheese samples (50 of each) were collected from the centers of production and distribution of dairy products in Ardabil city in 2017. Bacillus subtilis colonies susceptible to antibiotics were identified by conventional methods. Kirby-Bauer method was used to measure the antibiotic susceptibility and MBL E-test technique was used for detecting MBL enzymes. Presence of blaVIM, blaIMP, and blaSPM-1 MBL genes in the bacterial strains was investigated using PCR. Results: The results showed that 25 (59.52%) isolates from raw milk samples and 16 (43.24%) isolates from cheese samples produced MBL enzyme. The MBL-producing isolates exhibited high level (100%) of antibiotic resistance, except for cefixime (67.40%) and cefotaxime (64.60%). All MBL-producing isolates expressed blaVIM gene, while blaIMP and blaSPM-1 genes were not detected. Conclusion: Based on our results, molecular detection of MBL genes can be used as a complementary method along with common phenotypic diagnostic methods in the samples of dairy products, tested positive for MBL.

Antimicrobial resistance and genotyping of vacA, cagA, and iceA alleles of the Helicobacter pylori strains isolated from traditional dairy products

AbstractDairy products play a considerable role in transmission of Helicobacter pylori. The current study was done to assess phenotypic characters of antimicrobial resistance and genotyping pattern of vacA, cagA, and iceA alleles among the H. pylori strains isolated from dairy products. Eight‐hundred dairy samples were collected and cultured. Antimicrobial resistance and genotyping patterns were assessed using disk diffusion and polymerase chain reaction, respectively. Thirty‐one out of 800 (3.87%) traditional dairy product samples were positive for H. pylori. Cheese (11.53%) samples had the highest incidence of H. pylori, while yoghurt (1.11%) had the lowest. Helicobacter pylori strains harbored the highest incidence of resistance against ampicillin (93.54%), amoxicillin (93.54%), tetracycline (90.32%), erythromycin (80.64%), and metronidazole (77.41%). VacA s1a (90.32%), m1a (90.32%), s2 (80.64%) and m2 (77.19%), cagA (51.61%), and iceA1 (32.25%) were the most routinely identified genotypes. S1am1a (67.74%), s2m1a (64.51%), and s1am2 (51.61%) were the most routinely identified genotyping pattern. Simultaneous presence of vacA, cagA, and iceA genotypes in antimicrobial resistant H. pylori strains indicates important public health issue regarding the consumption of dairy products. However, additional researches are required to find molecular genetic homology and other epidemiological aspects of H. pylori in dairy products.Practical applicationsDue to the high consumption rate of dairy samples, they should have a high microbial quality. Foods with animal origins and especially dairy samples are considered as a probable source of Helicobacter pylori infections. The incidence of contamination of dairy samples by H. pylori is fairly high, and nearly all of the isolates exhibited resistance against several types of antimicrobials and harbored pathogenic vacA, cagA, and iceA genotypes, so the risk of probable foodborne diseases caused by H. pylori in such products should not be neglected. Additionally, dairy samples may act as a reservoir of H. pylori with ability to transfer antimicrobial resistance and virulent genotypes.

Retracted: Prevalence of Toxoplasma gondii and Neospora caninum in different types of raw milk and traditional dairy product samples

AbstractThe current investigation was done to examine the prevalence of Toxoplasma gondii and Neospora caninum in raw milk and traditional dairy samples. Eight‐hundred and eighty samples were collected and subjected to DNA extraction and nested PCR for detection of T. gondii B1 and N. caninum Nc5 genes. Seventy out of 880 (7.95%) and 80 out of 880 (10%) samples were positive for T. gondii and N. caninum, respectively. Simultaneous prevalence of T. gondii and N. caninum in studied samples was 4.20%. Prevalence of T. gondii and N. caninum in raw milk and traditional dairy samples were 6% and 10.60% and 10.52% and 9.21%, respectively. Traditional cheese and butter (15.00%) had the highest prevalence of T. gondii. Raw bovine (24.00%) had the highest prevalence of N. caninum. Boost prevalence of parasites in samples revealed an important public health threat regarding the consumption of raw milk and traditional dairy.Practical applicationsDue to the high consumption rate of milk and dairy products, they should have a high microbial quality. Toxoplasma gondii and Neospora caninum are two closely related protozoa with considerable zoonotic importance regarding the consumption of raw milk and traditional dairy products. The current research represents that raw milk and traditional dairy samples may be the sources of T. gondii and N. caninum transmission into the human population.

Optimization of a modified QuEChERS method by means of experimental design for multiresidue determination of pesticides in milk and dairy products by GC–MS

The aim of this study is to determine optimum extraction and clean up conditions for different pesticide residues in milk and dairy products by using GC–MS. A Box-Behnken design with 3-level 4-variable followed by Plackett-Burman screening design was employed in order to optimize significant variables of the modified QuEChERS method. After the determination of optimal experimental conditions, the proposed method was validated according to SANCO guideline. The method presented recoveries between 72.5% and 120.0% for 25 pesticides, which is satisfactory when one considers the performance criteria detailed in this guideline. The repeatability and within-laboratory reproducibility ranged from 0.95 to 14.62% and from 1.45 to 17.94%, respectively. Also, the method allowed the determination at low detection limits within short analysis time (<17.5 min). Consequently, application of the developed method to milk and dairy products samples revealed that this method is suitable for routine multi-residue pesticides analysis in terms of high accuracy, precision and efficient.

Research of Fatty Acid Composition of Samples of Bio-Drink Made of Camel Milk

Adequate nutrition is the most important determinant of the human health. Taking into account this factor, development of the technology for special purpose dairy products based on camel milk using probiotic starter cultures that will have the ability to destroy toxic metabolites, produce amino acids, volatile fatty acids and synthesize vitamins is the urgent task. In connection with the objective set, we have developed 4 samples of dairy products based on camel milk, and examined fatty acid composition thereof on the basis of the Scientific Research Institute of Biotechnology FSBEI HE Kemerovo Institute of Food Science and Technology (University). In the scientific article four samples of the product based on milk are considered. The first sample of the fermented Bacterial leaven of thermophilic lactic acid lactococcus, propionic acid and acetic acid bacteria and Bacterial leaven of thermophilic lactic acid sticks АНВ. The second sample was prepared using Bacterial leaven of thermophilic lactic acid sticks АВ and Bacterial leaven of thermophilic lactic acid lactococcus, propionic acid and acetic acid bacteria. The third sample fermented Bacterial leaven of thermophilic lactic acid sticks Бн and Bacterial leaven of thermophilic lactic acid sticks АНВ. The fourth sample prepared with the addition of Bacterial leaven of thermophilic lactic acid sticks АВ and Bacterial leaven of thermophilic lactic acid sticks Бн. Using the method of chemical ionization with positive and negative ions recording on a chromatographic mass-spectrometer, we determined the content of saturated and unsaturated fatty acids in the samples studied. High content of these acids was found in samples № 1 and № 2. In samples 3 and 4, the acid content was low.

Cronobacter sakazakii and Microbiological Parameters in Dairy Formulas Associated With a Food Alert in Chile.

The objective of this study was to evaluate the presence of Cronobacter sakazakii and microbiological parameters in dairy products associated with a food alert. Ninety dairy product samples were analyzed, including seven commercial brands and two product types (liquid and powdered) from four countries. Aerobic plate count (APC) and Enterobacteriaceae count were performed according to Chilean standards. Cronobacter spp. and C. sakazakii were identified by polymerase chain reaction real time amplification of rpoB and cgcA genes and the genotype by multilocus sequence typing. Eighty-eight percent of dairy products showed APC higher than the detection limit. Fifty percent of liquid commercial brand samples contained APC: 2.6, 2.3, 1.1, and 2.9 CFU/mL in brands A, C, E, and G, respectively. Results for powdered commercial brands were 3.0, 3.6, and 5.7 CFU/g in brands B, D, and F, respectively. Maximum count (5.7 CFU/g) occurred in brand F dairy product manufactured in Chile. Enterobacteriaceae were found in 55% of the samples, 64% in liquid and 51% in powdered commercial brands. In 50% of brands B, D, and E, samples contained 2.9, 2.8, and 2.7 log CFU/g, respectively. Only liquid commercial brands from the United States had Enterobacteriaceae values between 0.1 and 4.5 CFU/mL. Seventeen suspicious strains were isolated and nine were identified as Enterobacter spp. Only eight suspicious strains from four powdered commercial brands (Chile and Singapore) were confirmed as C. sakazakii by rpoB and cgcA gene amplification and fusA sequencing. C. sakazakii prevalence in the analyzed samples was 8.8%. There were 11% of powdered milk brands that contained APC between 4.0 and 4.7 log CFU/g and 55% of the samples contained Enterobacteriaceae. C. sakazakii was found in dairy products manufactured in Chile and Singapore. On the basis of this information, the Chilean Ministry of Health (RSA) decreed a national and international food alert and recalled all the product batches that resulted positive in the present study from supermarkets and pharmacies.

Aptamer functionalized magnetic nanoparticles for effective extraction of ultratrace amounts of aflatoxin M1 prior its determination by HPLC

Aptamers, due to the inherently high selectivity towards target analytes, are promising candidate for surface modification of the nanoparticles. Therefore, aptamer-functionalized magnetic nanoparticles (AMNPs) was prepared and used to develop a magnetic solid-phase extraction procedure for clean-up of milk and dairy products samples before measuring the aflatoxin M1 (AFM1) contents by the high-performance liquid chromatography. The prepared sorbent was characterized by different instrumental methods such as FT-IR, FESEM, TEM, EDX and AGFM. The AMNPs was used in extraction and pre-concentration of ultratrace amounts AFM1 from local milk samples. The amount of sorbent, elution volume, extraction time, and salt addition were optimized. Based on the results, calibration plot is linear over the 0.3 to 1 ng·L−1 and 5 to 50 ng·L−1 AFM1 concentration ranges. The limits of detection of the developed method were obtained 0.2 ng·L−1 which is the smallest value that has been reported up to now. The results show that this new superior sorbent has a large potential to simplify the complex matrix of the samples and can used for detection, preconcentration and accurate determination of ultratrace amounts of the AFM1 from milk and dairy products.

The prevalence of pathogenic bacteria and antimicrobial resistance in milk of Ettawa Grade goat

Ettawa Grade (PE) are potentially developed goats to produce milk and meat. Milk is food of animal that is rich in nutrients, but it is a perishable food easily contaminated by microorganisms. Contaminated pathogenic bacteria in milk can decrease the quality and has an organoleptic effect on milk, as well as endangers human health. Milk contaminated with bacteria antimicrobial resistance (AMR) in which is resistant to antibiotics, may adversely affect the response to treatment with antibiotics in humans when suffering from infectious diseases and using antibiotics in therapy. In this study Ettawa Grade's samples of fresh milk and other dairy products were taken from some of the goat farms in Yogyakarta Sleman district. The samples were tested for the presence of pathogenic bacteria and for its resistance to several kinds of antibiotics. In this study 35 Ettawa Grade's samples of fresh milk and other dairy products (fresh milk, milk powder, ice cream, and yoghurt) were taken from some of the goat farms in Sleman district-Yogyakarta. The samples were tested for the presence of pathogenic bacteria and for its resistance to several kinds of antibiotics. The result of the prevalence of pathogenic bacteria in goat fresh milk and other dairy products was 15% Escherichia coli and had multi resistance to multiple antibiotics, namely ampicillin, colistin sulphate, cefixime, kanamycin, oxytetracycline, tetracycline and sulfonamide.

Evaluation of the Effect of Probiotics Isolated from Traditional Dairy Products on the Expression of Stx1 and Stx2 Genes of Verotoxigenic Escherichia coli (VTEC) in Laboratory Conditions

Background: Lactobacilli are commonly used organisms in the production of probiotics. Objectives: The present study was conducted to examine the effect of probiotics isolated from dairy products on the expression of Stx1 and Stx2 genes in verotoxigenic E. coli (VTEC). Methods: This experimental study was conducted during April and January 2016 in East Azerbaijan, Iran. At first, Hundred samples of traditional dairy products were collected. Then, using standard phenotypic and genotypic methods, the Lactobacillus casei (L. casei) and lactobacillus (L. plantarum) were studied. Subsequently, these strains were examined along with the pathogenic bacteria strain of Escherichia coli (E. coli) (O157: H7) by neighboring cultivation. After extraction of mRNA, the expression of these genes was determined using real- time PCR. Results: The results revealed that L. casei reduces the expression of Shiga toxin (Stx1 and Stx2) genes more compared to L. plantarum (P = 0.001). Moreover, it was found that both Lactobacilli reduce the expression of Stx1 genes more than Stx2. Conclusions: Probiotics could be used to prevent and control intestinal diseases caused by E. coli.

The antimicrobial activity of probiotic bacteria Escherichia coli isolated from different natural sources against hemorrhagic E. coli O157:H7.

BackgroundDiarrheal diseases have been seen in all geographical areas throughout the world. Therefore, considering treatment, could be deemed a necessary action.ObjectiveThe aim of this study was to determine the antimicrobial effect of probiotic bacterial strains isolated from different natural sources against 2 pathotypes of pathogenic E. coli.MethodsThis cross-sectional study of Martyr Chamran University of Ahvaz was carried out from December 2013 to July 2014. A total of 13 probiotic colonies isolated from 20 samples of traditional dairy products including (yogurt, cheese, milk) and 20 samples of vegetables including carrots and cabbages (red and white) of which 5 isolates were selected to evaluate the antimicrobial effect against 2 Escherichia coli pathotypes, randomly. Antimicrobial effect was evaluated using two methods: disk diffusion and well diffusion tests and measuring growth inhibition zones of probiotics against 2 pathotypes of pathogenic E. coli.ResultsObtained results showed growth inhibition effects of all 5 probiotic strains against Escherichia coli pathotypes in both used methods. All selected strains showed considerable antimicrobial effect on Escherichia coli O157:H7 strain, but had no inhibitory effect against Enterohemorrhagic Escherichia coli.ConclusionThis study demonstrated considerable antimicrobial effect against E. coli O157:H7 strain. Due to this, characteristic and similar antimicrobial effects of probiotics bacteria, increasing use of the probiotics as a natural and modern method for prevention of different diseases is recommended.

Antagonistic effect of isolated probiotic bacteria from natural sources against intestinal Escherichia coli pathotypes.

BackgroundProbiotics are live microorganisms which are beneficial bacteria that are normal flora of the digestive system which, in determined amounts, show beneficial effects on host health, and can balance gastrointestinal microflora. Digestive tract diseases such as diarrhea are one of the major causes of child mortality in developing countries. Different pathotypes of Escherichia coli cause diarrhea that affects children, therefore reduction of these colonization strains in humans or animals can decline gastrointestinal disorders such as diarrhea.ObjectiveThe aim of this study was to determine the antimicrobial effect of probiotic bacterial strains isolated from different natural sources against 4 pathotypes of pathogenic E. coli using disk and well diffusion methods.MethodsThis cross-sectional study was conducted from December 2013 to July 2014 on Martyr Chamran University in Ahwaz city. A total of 13 probiotic colonies isolated from 20 samples of traditional dairy products including yogurt, cheese and milk, and 20 samples of vegetables including carrots and cabbages (red and white), of which 5 isolates were selected to determine the antimicrobial effect against 4 Escherichia coli pathotypes, randomly. The antimicrobial effect was evaluated using two methods: disk diffusion and well diffusion tests and measuring growth inhibition zones of probiotics against 4 pathotypes of pathogenic E. coli.ResultsObtained results showed growth inhibition effects of all 5 probiotic strains against Escherichia coli pathotypes in both used methods. But in comparison Lactobacillus plantarum had higher growth inhibitory effects in both methods.Conclusionresults of this study demonstrated high antimicrobial effect of probiotic bacteria against pathogenic Escherichia coli strains. It indicated a positive and beneficial role of probiotics in human health and prevention of illness.

The prevalence and antimicrobial resistance of Listeria spp in raw milk and traditional dairy products delivered in Yazd, central Iran (2016)

Listeria monocytogenes is an important foodborne pathogen which its data in Iranian dairy products is limited. A total of 545 samples of traditional dairy products (raw milk, traditional cheese, traditional butter, traditional curd, and traditional ice cream) were collected from traditional dairy shops located in Yazd, Iran. L. monocytogenes was isolated, and positive samples were confirmed by polymerase chain reaction. Antibiotic sensitivity test was conducted to determine the antibiotic resistance. Listeria species were isolated from 11.7% samples. 4.03% samples were identified as L. monocytogenes, 5.6% as L. innocua, 1.8% as L. seeligeri, and 0.18% L. murrayi. All L. monocytogenes isolates were resistant to tetracycline, chloramphenicol, penicillin, and amoxicillin/clavulanic acid. Consumption of raw milk and its traditional products prepared inadequate heat treatment and the lack of appropriate control measures might lead to serious health problems. As our results show, the Iranian food safety authorities should set up an effective standard to screen all susceptible food for the presence of Listeria spp.

Influence of milk product type and its initial contamination on the efficiency of different methods for detection of Salmonella Enteritidis, Listeria monocytogenes and Escherichia coli O157:H7

This paper investigates differences in efficacy of isolating pathogenic bacteria Salmonella Enteritidis, Listeria monocytogenes and Escherichia coli O157:H7 between conventional cultivation (ISO method) and immunomagnetic separation (IMS method) related to the types of dairy products and initial numbers of bacteria. Different milk products (dairy pudding- vanilla or chocolate ; a mixture of yoghurt and pudding ; solid, liquid and fruit yoghurt ; AB culture - with or without fruit ; cheese spread) were intentionally contaminated with different numbers (≈10 and ≈30) of live cells of the observed bacteria per mL. The obtained results showed that the classical ISO procedure still represents an equally adequate method for the detection of S. Enteritidis and L. monocytogenes in dairy products as well as the IMS method. However, the ISO method was found to be inefficient for determination of E. coli O157:H7 when the initial contamination was low (≈10 live cells per mL). In such cases, even the IMS method appeared to be inefficient when used for fermented dairy products analysis. Fermented dairy products in contrast to the non-fermented ones, still represent a challenge for the development of routine detection methods, especially for S. Enteritidis, whilst the detection of L. monocytogenes and E. coli O157:H7 has improved by introducing the IMS method. The largest difference in the ability to detect bacteria in dairy product samples with reference to the initial number of bacteria by both methods was in the detection of E. coli O157:H7. The choice of broth (non- selective fluid broth vs. selective fluid broth) did not matter in the in the detection of S. Enteritidis and L. monocytogenes by applying the IMS procedure. However, for the detection of E. coli O157:H7 the application of modified tripton-soya broth with novobiocin (mTSB+Nb) has proved to be superior when compared to using the buffered peptone water (BPW). The presented results may be of importance as a scientific basis for future determination of standard methods related to laboratory detection of pathogens in dairy products.