فهرست مطالب mohammad-mehdi soltan dallal

The prevalence of antibiotic resistance has been demonstrated in various food-borne pathogens. Beta-lactam antibiotics are among the first-line antimicrobials that are normally administered in case of gastrointestinal infections. However, Escherichia coli (E. coli) and some other members of Enterobacteriaceae have indicated broad resistance against such antibiotics thanks to extended-spectrum beta-lactamase (ESBL) enzymes. In this research, 216 stool samples have been screened for ESBL-producing E. coli, using phenotypic antibiotic susceptibility tests. ESBL-producing E. coli isolates were further screened for the presence of antibiotic-resistance genes CTX-M, SHV, and TEM. Our isolation experiments resulted in 111 E. coli isolates among which 41 (36.9%) isolates were found as ESBL. Also, 51.2% of the above ESBL isolates harbored blaTEM. Furthermore, 18 (43.9%) and 2 (4.9%) of those ESBL isolates had blaCTX-M and blaSHV genes, respectively.  Our results revealed a detectable prevalence of ESBL E. coli in stool samples collected during food outbreaks. Results of such researches can guide how to control the distribution of drug-resistant pathogens in various environments. In this line, the considerable prevalence of ESBL E. coli seems to have originated from the wide administration of various beta-lactam antibiotics.

Investigating multidrug resistance and TEM and SHV broad-spectrum beta-lactamase genes in Escherichia coli bacteria isolated from patients with urinary tract infections is very useful to improve the treatment of infection and prevent the failure of treatment of urinary tract infections.The aim of this study was to investigate multidrug resistance and TEM and SHV broad-spectrum beta-lactamase genes in Escherichia coli bacteria isolated from patients with urinary tract infections.

In this study, 188 strains of Escherichia coli, which cause urinary tract infections in Alborz province, were studied. Urine samples were cultured on EMB and Blood Agar media. Differential tests were performed for final identification. ESBL-producing strains were identified, PCR was performed to survey the abundance of ESBL-producing genes.

Based on the results of the disk diffusion and Double-disk synergy testS, 82 (43.6%) strains were determined as the final producer of ESBL. out of these isolates, the frequency of SHV, TEM, and CTX genes measured 64.3%, 55.9%, and 21.4%, respectively. These results showed that 12 (14.28%) of Escherichia coli isolated have all genes, 26 (30.95%) had 2 genes and 36 (42.85%) had one gene.

According to the results, it was found that imipenem with the lowest resistance is the best drug in the treatment, and carbapenems are the best drug for treating diseases caused by Escherichia coli. The results of the current study may be useful in replacing ESBL enzyme resistance screening with more modern sensitivity measurement methods such as MIC and Etest.

There is a global threat of methicillin-resistant Staphylococcus aureus (S. aureus or MRSA), which has been regarded as a priority pathogen by the world health organization (WHO). Livestock and its products are the sources of MRSA which can often occur in poor breeding conditions. The present study aims to investigate the prevalence of MRSA and the rate of antibiotic residue in pasteurized and raw farm milk.

This was a cross-sectional study conducted from April to July 2020. 250 samples (200 samples of raw milk in farms around Tehran and 50 samples of pasteurized milk) were cultured to evaluate the occurrence of S. aureus and its antimicrobial susceptibility profile to 7 antimicrobial panels. Hansen Kit was used to monitor antibiotic residue in milk.

63 S. aureus isolates (25.2%) were detected from 250 milk samples. Among 200 raw milk samples, 48 (24%) S. aureus isolates were detected and no strain of S. aureus was isolated from pasteurized milk. The highest rates of resistance belonged to ampicillin (95.8%), amoxicillin/clavulanic acid (87.5%), tetracycline (50%), and cefoxitin (45.8%). Moreover, 43 (17.2%) out of 250 milk samples had antibiotic residue in the antibiotic residue test using Danish Hansen kit.

The present study indicates a high prevalence of subclinical S. aureus in dairy herds in Tehran, Iran. The milk contaminated with S. aureus and MRSA, posed a risk to public health owing to the presence of a phenotype resistant to very common antibiotics

Ecological conditions can change infection routes and increase the risks of outbreaks. The aim of this study is risk assessment of foodborne disease outbreaks based on dispersed regional climatic and demographic variables in Yazd Province, Iran.

In this cross-sectional study, data of temporal climatic parameters and regional demographic factors linked to bacterial foodborne diseases were addressed. A multi-level regression analysis model was used to detect associations between the risk of outbreaks and ecological risk factors; the relationships were verified using (P<0.05).

Significant associations were observed between the outbreaks and age )P<0.001(, community type (P<0.001), temperature (P=0.04), rainfall (P=0.03) and dust pollution (P<0.001) in scattered parts of the province. The maximum rate of outbreaks was seen in spring, while the frequency of the outbreaks increased during April and October, compared to other months of the year (2012–2016).

Consequences have revealed interventions of the environmental exposures in transmissions of microbial agents by complex ecological processes that caused the outbreaks.

Foodborne diseases are a global problem that is spreading day by day. These diseases are one of the most common causes of death in children and the elderly. This study was conducted to investigate the prevalence of water and foodborne diseases in Kurdistan province for six months from April to September 2022. Stool samples from patients were collected in the laboratory in a special container containing 10% formalin preservative. 134 stool samples from 28 food outbreaks from Kurdistan province were analyzed for the type of infected bacteria. The research results were analyzed in SPSS-19 software. Among the 28 outbreaks in Kurdistan province during the two seasons of spring and summer, the highest number of outbreaks was in the summer season with 20 and then in the spring season with 8 outbreaks. The dominant age group was children under 10 years (%21) old and people between 20-30 years old, and the dominant gender group was men. The most common clinical symptoms were nausea, vomiting, abdominal cramps, bloody diarrhea and non-bloody diarrhea. It is important to know the type of bacteria that cause water and foodborne diseases in reducing outbreaks and treatment costs and applying necessary measures for control and prevention.

Today, Foodborne diseases (FBD) are one the important concerns in the world. The indiscriminate and incorrect use of antibiotics has caused resistance in many bacteria, which is a serious threat to public health. This study was conducted on all food-borne outbreaks that occurred in Semnan Province during one year (April to March 2020). The samples were examined for isolation and detection of Salmonella, Shigella, and Escherichia coli O: 157: H7. Data were collected based on a questionnaire and laboratory data. The results of the study were analyzed by SPSS software version 19. The results showed that the prevalence of outbreaks in women (46 %) was higher than in men and children. The age group of 24 to 44 (31.57%) included the most affected cases. The frequency of the outbreak in the city (%57/31) was higher than in the village (%42/69). The incidence of bacterial agents in water was lower than in food and homemade food consumption was lower than takeout food (44/45%). About (73%) of the bacterial abundance belonged to Escherichia coli species. Shigella and Salmonella contamination of food was 2.9%. According to the results of the present study, women are the most vulnerable groups, and consumption of takeout foods and urbanization are important causes of food outbreaks in Semnan province. Also, Salmonella and Shigella can be considered as important causes of diarrhea in Semnan food outbreaks.

The purpose of this study is to determine the viability of enterotoxigenic Escherichia coli (ETEC) in a sample of diarrhea. The investigation focuses specifically on the lt gene and utilizes propidium monoazide (PMA) and quantitative real-time polymerase chain reaction (qPCR) to differentiate between live and dead bacteria.

Propidium monoazide is a chemical that can bind to and inhibit the amplification of free DNA during qPCR analysis. In this study, in addition to analyzing diarrhea samples, artificially spiked samples were used to assess the sensitivity and accuracy of the PMA treatment. The qPCR results were compared to the gold standard of culture-based methods both with and without PMA treatment.

The method’s limit of detection was 8 CFU/mL, and it exhibited linearity from a 10-1 to a 10-9 dilution. The qPCR approach revealed a higher bacterial count than the culture method due to the detection of DNA released from dead bacteria. However, when PMA was employed, the bacterial count was similar to that obtained using colony count agar, which is attributed to the elimination of free DNA during investigation.

The present study developed a PMA-based qPCR approach that enables the detection of live bacterial DNA. This method involves PMA and real-time PCR and offers several advantages, including faster detection times (a few hours vs. several days with the traditional culture method) and the ability to exclusively detect live bacteria without interference from free DNA released by dead bacteria. Additionally, the use of real-time PCR enables precise quantification of the live bacterial load. Overall, this approach is cost-effective, rapid, highly sensitive, and specific, making it a valuable tool for various applications.

Foodborne diseases are caused by eating contaminated food. Yersinia species are among the bacteria involved in food contamination, such as meat, poultry, vegetables, and milk. This study aims to investigate the prevalence and characteristics of Yersinia enterocolitica and Yersinia pseudotuberculosis from raw milk in Tehran.

In this study, 360 samples of raw milk were collected from farms around Tehran and examined according to the FDA method. Then, 25 ml of milk samples were added to 225 ml of Peptone Sorbitol Bile Broth and kept for 10 days at 4 °C for enrichment. After 10 days, 0.5 ml of the sample was added to 0.5 ml of 0.72% KOH solution and 0.54% NaCl. After 30 sec, it was cultured in the selected Cefsulodin-Irgasan-Novobiocin agar (CINagar) medium to remove the normal flora. The plates were stored for 48 h at 28 °C. The suspected Bull's eye colonies were purified and phenotyping tests were carried out on the selected colony. The 20 E API kits were used for confirming identification.

From 360 raw milk samples, 4 Yersinia isolates (1.1%) including one Y. pseudotuberculosis (0.27%) and three Y. enterocolitica (0.83%) were isolated. In addition to Yersinia, other bacteria such as Klebsiella, Serratia, Citrobacter, and Providencia were isolated from milk samples.

The findings showed that clean tap water and healthy cattle in livestock can be effective in preventing Yersinia contamination. Lack of personal and environmental hygiene could cause food contamination by Yersinia and other intestinal bacteria leading to gastrointestinal infections.

Bacillus cereus is a Gram-positive, rod-shaped, facultative anaerobic, motile, beta-hemolytic, spore forming bacterium commonly The bacteria is commonly found in the environment, is often found in soil and vegetation, and can be present in foods. It can cause foodborne illness worldwide. B. cereus illness is related to many foods - beef, turkey, rice, beans, and vegetables. Specifically, the diarrheal illness is often related to meats, milk, vegetables, and fish. This product may be contaminated with many bacterial pathogens, including Bacillus cereus (4). There are several ways to store vegetables; one way is drying, which is important for several reasons: long-term storage, reducing the volume for the storage, and move products more easily and faster The emetic-type illness is most often associated with rice products, but it has also been associated with other types of starchy products such as potato, pasta, and cheese products (5). Some food-mixtures (sauces, puddings, soups, casseroles, pastries, and salads, have been associated with food-borne illness in general. There are two types of food-borne B. cereus illness. In the first, contaminated food (many types of food, often left at room temperature) makes its way to the small intestine where the toxin, in this case, a large-molecular-weight protein, is released. This can lead to diarrhea, cramps, and sometimes nausea. Usually, vomiting is not present in this form of illness (6, 7). Incubation for the first type is 6 to 15 hours. In the second type, affected food, most often starchy food, and classically, rice, contains a different type of toxin (cereulide, an ionophoric low-molecular-weight dodecadepsipeptide that is pH-stable and heat and protease-resistant). This toxin causes emetic-type B. cereus illness. The incubation period for this type is 30 minutes to 6 hours (9). Bacillus cereus is caused by the ingestion of food contaminated with either the enterotoxigenic B. cereus or with the emetic toxin. In non-gastrointestinal illness, reports of respiratory infections similar to respiratory anthrax have been attributed to B. cereus strains harboring B. anthracis toxin genes (10). The spore of this bacterium is resistant to severe environmental conditions including heat, freezing, drying, and radiation, and may be considered an infectious agent for this bacterium. Changes in diet and lifestyle in recent years and the growing trend of using ready-made products (4). In the gastrointestinal tract (small intestine), vegetative cells, ingested as viable cells or spores, produce and secrete a protein enterotoxin and induce a diarrheal syndrome, whereas emetic toxin, a plasmid-encoded cyclic peptide (cereulide), is produced in food products and ingested as a formed toxin. Dry vegetables it is suitable for the survival quickly multiply at room temperature (12). There are two main types of intestinal illnesses caused by B. cereus. One is diarrheal, and one leads more to nausea/vomiting. B. cereus has also been implicated in infections of the eye, respiratory tract, and in wounds. The pathogenicity of B. cereus, whether intestinal or nonintestinal, is intimately associated with the production of tissue-destructive exoenzymes. Among these secreted toxins are four hemolysins, three distinct phospholipases, an emesis-inducing toxin, and proteases. The specific name, cereus, meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar.Bacillus cereus is one of the most important causes of spore-bearing bacteria such as Bacillus (5, 7, 11). The aim of this study was to isolate and identify Bacillus cereus in bulk and packaged dried vegetables by culture and PCR.

This is a cross-sectional descriptive study from February 2019 to October 2020. In total 160 samples (80 from each of open and packed dried vegetables) were evaluated for the contamination of Bacillus cereus. 25 g of the sample was poured into 225 ml of peptone water and incubated at 37 ° C for 24 hours and then one ml of 0.1 dilutions of the suspension was inoculated into on the specific medium of Bacillus cereus (Scharlau, Spain). (MYP Agar) Mannitol Egg Yolk Polymyxin Agar. For the total count, 10 g of each dried vegetable was added into 90 ml of 0.1% peptone water and then 1 ml of dilutions (10-1, 10-2, 10-3), were inoculated into MYP Agar medium and incubated at 37 ° C for 24 hours.Large pink colonies (no fermentation of mannitol) with a precipitated halo (due to lecithinase production) were considered suspicious colonies. The identification was carried out by catalase and biochemical tests. anaerobic conditions, growth at 45 ° C, lestinase C test, hemolysis B in blood agar with 5% sheep blood, MR-VP test, penicillin sensitivity 10 IU test,and nitrate reduction(13). For molecular analysis, the polymerase chain reaction for the internal transcribed spacer (ITS) gene was used to confirm Bacillus cereus. In order to extract DNA from a pure colony of bacteria, it was cultured in an LB medium and after incubation, the resulting culture was precipitated and the genome was extracted using phenol-chloroform. The quality and quantity of DNA extracted were evaluated by spectrophotometry and electrophoresis. The extracted DNA was frozen at -20 ° C for later use (14). The PCR program consisted of an initial temperature of 94 ° C for 5 min, then 35 cycles consisting of 94 ° C for 30 s, 52 ° for 30 s, and 72 ° for 30 s. PCR reaction was performed in Thermal Cycler (Primus 96, Peqlab Biotechnologie GmbH, Erlangen, Germany). The standard strain of 11778 Bacillus cereus was used as a positive control. The PCR product was electrophoresed in 1% agarose gel at a voltage of 100-80 volts and after staining with ethidium bromide 1 mg/ml was observed and photographed by a gel dock device. Initially, the PCR gradient for the gene was placed in the annealing temperature range of 50 to 60 degrees, which was finally selected at an optimum temperature of 52 degrees (15). Using SPS software, data were analyzed by chi-square test. p<0.05 was considered significant.

The B. cereus contamination were found in 21 (26.25%) and 13 (16.25%) of open and packed dried vegetable samples respectively. There was no statistically significant difference (p>0.05) between contamination rate of B. cereus in open and packed dried vegetable samples. Also, contamination rate of B. cereus was not significantly different (p>0.05) among various kinds of vegetable samples. The results of this study showed that 34 (21.25%) out of 160 samples of dried vegetables were infected with Bacillus cereus by the phenotypic method. PCR results of the ITS gene showed that all 34 strains isolated by culture were also identified by molecular method. In total 7 (4.37%) dill, 5 (3.12%) tarragon, 5 (3.12%) parsley, 5 (3.12%) mint, 6 (3.75%) soup, 4 (2.5%) coriander and 2 (1.25%) turmeric were identified as Bacillus cereus respectively.

Our study showed that despite the supply of packaged dried vegetables, there is still the possibility of microbial contamination, especially by anaerobic bacteria. Although the rate of contamination of dried vegetables in open packaged (13.2%) was more than dried packaged (12.8%).This percentage of contamination probably indicates a lack of hygiene in the drying process in both traditional and industrial forms.

 Breast milk contains nutrients such as carbohydrates, essential fatty acids, proteins, vitamins, minerals, and a source of communal bacteria with probiotic potential that is very effective in the prevention and treatment of neonatal infections. The aim of this study was the evaluation of probiotic properties of lactobacilli in breast milk and their inhibitory effect on pathogenic bacteria of the gastrointestinal tracts.

 In a cross-sectional descriptive study, during 10 months from January to October 2018, 100 breast milk samples were collected by referring to health centers after isolation. Lactobacilli strains were evaluated based on morphological characteristics, catalase, and hot staining tests, survival tests in acidic conditions, and bile salt tolerance to evaluate probiotic properties. Antibiotic resistance of probiotic strains and ability to inhibit pathogenic bacteria was evaluated by well method and growth inhibition zone.

 122 lactobacilli belonging to 12 species were identified from 100 samples of breast milk by phototypical methods. The predominant species belonging to casei and other lactobacilli were Fermentum, Plantarum, and Gasseri, respectively.The highest antibiotic resistance was related to vancomycin (63.15%). The 3 isolates L4, L14 and L16 were able to strongly inhibit all the studied gastrointestinal pathogens.

 Breast milk is a rich source of beneficial probiotic lactobacilli, which can be useful in breast milk for infants who are not breastfed to prevent neonatal infections.

Yersinia is water and foodborne organism that cause human gastroenteritis. This study was done to evaluate the frequency of Yersinia species isolated from children diarrheal samples and chicken meat in Tehran, Iran.

In this descriptive study 250 sample of diarrhea of children referred to the Children's Medical Center, Tehran, Iran and 250 samples of chicken were collected and examined for Yersinia infection during July 2016 to March 2017. Isolation method was performed based on initial enrichment in phosphate buffer for 3 weeks in refrigerator (cooling in c4 +) and then using KOH as secondary enrichment and culture on CIN agar medium. Biotyping method was used to determine pathogenic strains.

In this study, 5(2%) isolates from pediatric diarrhea samples and 20 isolates (8%) from chicken meat samples were obtained from Yersiniaenterocolitica. Biotyping of human Yersiniaenterocolitica isolates identified 3 cases of biotype 1A, one case of biotype 1B, one case of biotype 2 and from chicken meat isolates, 16 isolates belonged to biotype 1A and 4 isolates belonged to biotype 1B.

Presence of common pathogenic 1B and non-pathogenic 1A biotypes in pediatric diarrhea samples and chicken meat can indicate the cause of diarrhea in children.

Resistance to a wide range of beta-lactam family antibiotics is due to the emergence of new beta-lactamases among bacterial strains. The aim of the present study was to determine the prevalence of ESBLs in Klebsiella speices isolated from raw and pasteurized school
milk using phenotypic and genotypic methods. 

In a descriptive cross-sectional study, 200 samples of raw and pasteurized school milk were analyzed for the presence of Klebsiella spp. Samples were grown on Hektoen enteric agar medium. Suspected colonies of Klebsiella spp. were confirmed running differential tests. For the initial screening of ESBL producing organisms, the Disk Diffusion Agar method (DDA) was used. Final confirmation was done using PCR.

Out of 200 samples tested, 44 isolates were identified as Klebsiella, 32 isolates (72.7%) from raw and 12 (27.3%) from pasteurized school milk. In general, 14 (31.8%) isolates that were resistant to at least ceftazidime or cefotaxime antibiotics were selected for confirmatory testing.In Multiplex PCR assay, 6 (3%) isolates were screened for the confirmatory test (5 raw and 1 pasteurized school milk). Out of 6 isolates, 4 (2%) and 1 (0.5%) isolates contained TEM and DHA genes, and 2 (1%) and 1 (0.5%) isolates contained SHV and CITM genes, respectively.

It is difficult to identify the enzymes producing strains through the phenotypic tests; therefore, the inclusion of molecular probes using universal primers along with phenotypic tests can be used for the detection of these types of resistance, which play a major role in infection control.

 Phage therapy could be used as an alternative method to antibiotic treatments. The purpose of this study was to evaluate the antibacterial activities of isolated lytic bacteriophage against ciprofloxacin-resistant strain of Salmonella infanits in vitro conditions.

 The standard strain of Salmonella infantis  and its specific bacteriophage was isolated by soft agar method. Phage susceptibility to heat and pH was evaluated by the Double-Layer Agar method.  In vitro assay was carried out on human epithelial type 2 (HEp-2) cells to investigate the effect of bacteriophage on the cytotoxic and invasion of Salmonella infantis to human epithelial cells.

 Head and tail morphology of bacteriophages against Salmonella infantis were identified by transmission electron microscopy and assigned to the Myoviridae family. The results of the double-layer agar assay showed that the titer of bacteriophages was 1.8×107 PFU/ml. bacteriophage was stable at 4 C and the best quantification of bacteriophage was determined at pH=8. The isolated bacteriophage was specific for Salmonella infantis and had no lytic activity against other pathogenic bacteria. In the evaluation of the binding and invasion of Salmonella infantis to the HEp-2 cell line, as expected, the lytic activity of specific bacteriophage was observed following inoculation.

 Additional studies are needed for better understanding of the interaction between phage, microorganisms and human host before applying phage therapy on a large scale.

The use of amniotic membrane has been suggested in the treatment of infectious keratitis for its intrinsic anti-infective properties probably mediated by its antiinflammatory effects. The aim of this study was to investigate the effect of amniotic membrane transplantation (AMT) along with ciprofloxacin to cure the primary stages of Pseudomonas keratitis.

In total, 28 rabbits were selected and divided in four groups as follows: group 1 as control, group 2 with amniotic membrane, group 3 with ciprofloxacin, and group 4 with amniotic membrane combined with ciprofloxacin. About 0.05 cc suspension of Pseudomonas aeruginosa, 27853 ATCC was injected into corneal stroma.

The results showed groups of AMT, AMT + ciprofloxacin, and ciprofloxacin had 0% perforation while the control group had 85.6%. Average infiltration of 5.5 mm was observed in ciprofloxacin group, 5 mm in AMT + ciprofloxacin group, 24 mm in AMT group, and finally 23.75 mm for control. Amniotic membrane showed to be effective in prevention of cornea perforation as well as remission of Pseudomonas keratitis. There was no significant difference between ciprofloxacin groups in comparison with ciprofloxacin + AMT group. However, regarding the anti-inflammatory effect, the process of improvement of inflammation in ciprofloxacin + AMT group was faster.

Transplantation of amniotic membrane in the primary stages of Pseudomonas keratitis treatment remarkably prevents the disease and it can be used to control its process.

Campylobacter is one of the most important pathogens causing bacterial gastroenteritis, which is usually transmitted through the food of animal origin. This study was done to evaluate the status of Campylobacter in diarrheal food outbreaks compared to other microbial agents.

This descriptive study was performed on 305 diarrheal swab samples from 102 food outbreaks during six months from spring to the end of summer 2018. Presence of Campylobacter species were assessed according to the protocol of the General Directorate of Laboratory Affairs.

Out of 305 samples, 8 (2.6%) were identified as Campylobacter species, 3 (37.5%) Campylobacter and 5 (62.5%) Campylobacter coli. The epidemiology of the outbreaks showed that female (54.5%), average age of 16-30 years (28.2%), consumption of salads and vegetables (16.1%) and living in the cities (59.7%) were the most cases.

This study showed that in addition to classic pathogens such as Salmonella, Shigella, Escherichia coli, attention also should be paid to Campylobacter bacteria. In addition, recognizing epidemiological factors can play an important role in preventing and controlling food outbreaks.

This study aimed to evaluate antibiotic resistance profiles and presence of virulence genes among Salmonella enterica serovar Enteritidis (S. Enteritidis) isolated from patients with gastroenteritis in various regions of Iran. Moreover, genetic relatedness among the strains was assessed by pulsed-field gel electrophoresis (PFGE). From April through September 2017, 59 Salmonella strains were isolated from 2116 stool samples. Of these strains, 27 S. Enteritidis were recovered. These strains were subjected to disk diffusion tests, polymerase chain reaction (PCR) for detection of virulence genes (invA, hilA, pefA, rck, stn, ssrA, ssaR, sefA, spvC, sipA, sipC, sopB, sopE, and sopE2), and PFGE. High prevalence of resistance towards cefuroxime (n = 20, 74.1%) and ciprofloxacin (n = 13, 48.2%) were demonstrated. All tested strains possessed invA, hilA, sefA, sipA, sopB, and sopE. The least prevalent virulence gene was rck (n = 6; 22.2%). Based on combinations of virulence genes, 12 virulotypes were observed. The most common virulotype was VP2 (n = 12; 44.4%), harboring all of the virulence genes except for rck. PFGE typing showed only two distinct fingerprints among tested strains. Each fingerprint had completely different virulotypes. Notably, VP4 (harboring all genes except for rck and spvC) was only presented in pulsotype A, while VP2 was confined to pulsotype B. S. Enteritidis strains were derived from a limited number of clones, suggesting that it is highly homogenous. Future works should consider combinations of other genotyping methods together with larger sample sizes from more diverse sources.

Autophagy is a highly conserved mechanism in eukaryotic cells which removes the dysfunctional organelles from the cell. Autophagy has immense physiological and pathological roles in cells. There are a variety of reports showing the dual function of autophagy as a tumor suppression and promotion phenomenon. Therefore, targeted therapy approaches like virotherapy can be a promising cancer treatment. Vesicular stomatitis virus (VSV) is a well-known oncolytic virus which mutations in its matrix (M) protein including M51R, make it a better candidate for oncotargeting. Moreover, beclin-1 is one of the key regulators of autophagy and also apoptosis.

In the present study, the level of autophagy markers such as beclin-1 and LC3 were investigated concerning the apoptosis process induction by VSV M-protein. Two colorectal cancer cell lines HCT116 and SW480 and one normal colon epithelial cell line (FHC) which expressing VSV M51R mutant M-protein were compared regarding autophagy versus apoptosis. All experiments were conducted at least in triplicate.

The results showed that the elevated level of caspase 3 and reduced amount of beclin-1 in transfected SW480 cells may be an acceptable description for apoptosis.

In HCT116 cells domination of autophagy, plays a supportive mechanism for the cells to survive in response to M51R M-protein stress. Suppression of autophagy as an adjunct can be a promising way to eliminate resistance to cancer treatment. We have quantitively evaluated the Beclin-1 and LC3-II as autophagy markers, Future evaluation of these two along with other markers like P62 will reduce the limitations of this study.

One of the major sources of Listeria monocytogenes, as the causative agent of invasive listeriosis, is raw milk. The aim of the present study was to detect Listeria monocytogenes in raw milk samples collected from dairy stores in Tehran, Iran, 2019.

A total of 100 raw milk samples were assessed using cultural techniques. Furthermore, antimicrobial resistance profiles of the Listeria isolates were assessed against eight antimicrobials using disc diffusion method. Results and

Listeria spp., including Listeria grayi (5%), Listeria ivanovii (3%) and Listeria monocytogenes (2%), were detected in 10% of the samples. Listeria monocytogenes isolates were susceptible to major antimicrobials used for the treatment of listeriosis with no multidrug resistances. The highest frequencies of resistance were seen against streptomycin (60%), gentamicin (50%) and tetracycline (50%). In conclusion, potential risks of listeriosis still threaten consumers of the raw milk in Tehran.

The most common enterohemorrhagic Escherichia coli strain is the O157: H7 serotype, which is one of the most important intestinal pathogens and can cause complications such as hemorrhagic colitis, hemolytic uremic syndrome and acute renal failure. The aim of this study was to evaluate the enterohemorrhagic Escherichia coli causing molecular outbreaks of foodborne illness in Iran.

In this descriptive cross-sectional study, 189 fecal swab specimens were examined during April to September 2018. All suspected isolates were tested for biochemical tests. The isolates were confirmed by molecular PCR and evaluated by antimicrobial susceptibility tests.

From 189 stool swab samples studied, 98 Escherichia coli isolates were detected based on phenotypic tests. Most of the outbreaks occurred in summer and the prevalence of enterohemorrhagic Escherichia coli was 24.5%, which 4% of them were non-O157H7. Most patients were between 1 and 12 years of age and the highest antibiotic resistance to cotrimoxazole and chloramphenicol was observed at 80% and 79%, respectively.

This study showed an increase in enterohemorrhagic Escherichia coli with 24.5% and an increase in antibiotic resistance to the antibiotics of chloramphenicol, cotrimoxazole and carbapenems. Increased resistance to imipenem and meropenem antibiotics makes it difficult to treat beta-lactamase-resistant strains.

Foodborne diseases are a major problem worldwide. The epidemiological investigations in many parts of the world have shown an increase in infections caused by Salmonella serovars. Furthermore, the emergence of drug resistance among them has become a major global concern and awareness of the resistance patterns of Salmonella could be very useful in treatment of diseases.

This study aimed to investigate Salmonella serotypes in foodborne outbreaks by sequencing of ITS region of 16S-23SrRNA gene and to determine their antimicrobial susceptibility pattern.

A total of 614 diarrheal stool samples were collected from 173 foodborne outbreaks in different provinces of Iran during one year. Identification of Salmonella was carried out by phenotypic and molecular (16s-23srRNA gene detection) methods and antibiotic susceptibility was performed using disc diffusion method.

Out of 614 samples, 18 isolates were identified as Salmonella of which 16 (88.9%) isolates were Salmonella Enteritidis and 2 (11.1%) isolates as Salmonella Paratyphi A. All isolates were sensitive to ceftazidime, and high resistance was seen with nalidixic acid with 14 (77.8%) isolates.

Increasing antibiotic resistance in many bacterial pathogens such as Salmonella has been a major threat for human health. Therefore, identifying the antibiotic resistance patterns of Salmonella serovars may help in treatment of the associated infections.

Dental plaque is a biofilm that is formed on the surface of the tooth. Carious lesions are caused by inappropriate ecological changes in microbial flora of the plaque biofilm. In this study, the effect of Lactobacillus casei bacteriocin, isolated from dairy products, was investigated on Streptococcus salivarius biofilm formation.

In this experimental study, MRS Broth and MRS Agar medium were used to isolate three strains of Lactobacillus casei probiotic from milk samples under microaerophilic conditions. The initial identification of Lactobacillus casei was performed by sugar fermentation and other biochemical tests. Then, 16SrRNA encoding gene was confirmed by PCR and sequenced. At last, Bacteriocin was isolated by ammonium sulfate sedimentation and its molecular weight was measured by SDS-PAGE and the antimicrobial activities were investigated. The Streptococcus salivarius were isolated from dental plaque and phenotypically and biotypically identified. Molecular confirmation of the isolates was performed using gtfK specific gene by PCR. The ability to form Streptococcus salivarius biofilm and the effect of bacteriocin on biofilm formation were measured by microtiter plate.

After partial purification of Lactobacillus casei probiotic from dairy products, two LC3 and LC1 protein samples formed bands (35-40 kDa and about 75 kDa, respectively). The supernatant fluid from the cultivation of Lactobacillus casei and bacteriocins showed antibacterial effects against Streptococcus salivarius isolates from dental plaque and the formation of biofilm by this bacterium.

According to this study, bacteriocin and supernatant fluid from Lactobacillus casei cultures could inhibit the growth of Streptococcus salivarius and also reduced biofilm formation, so, it could be used in oral care products.

The potential of Streptococcus mutans for biofilm formation makes it one of the main organisms causing dental caries. Various preventive strategies have been applied to reduce tooth decay.

In the current study, we aimed to isolate S. mutans bacteriophages from sewage and to investigate their effects on the expression of the genes involved in bacterial biofilm formation in dental caries.

Eighty-one dental plaque samples were collected. Then to isolate and identify S. mutans, bacterial culture media and molecular tests were used. Moreover, the biofilm formation capability of the isolated S. mutans was determined. Also, lytic bacteriophages were isolated from raw urban sewage, and phage morphology was determined by transmission electron microscopy (TEM). Real-time PCR was used to assess the effects of the isolated bacteriophages on the expression of the genes involved in biofilm formation.

Overall, 32 (39.5%) samples were positive for the presence of S. mutans. All of the isolates contained the gtfD gene. The frequencies of other genes were as follows: gtfB (17, 53.12%), gtfC (19, 53.37%), SpaP (13, 40.62%), and luxS (23, 17.87%). The isolated S. mutans bacteria presented different ranges of biofilm formation ability. Based on TEM results, two sewage-isolated bacteriophages, belonging to Siphoviridae and Tectiviridae families, were able to prevent biofilm formation up to 97%.

Our findings indicate that phage therapy can be an optional way for controlling biofilm development and reducing the colonization of teeth surface by S. mutans.

Fruit juices are an important part of modern diets that can infect various gastrointestinal tract infections if infected with pathogenic bacteria. The aim of this study was to determine the Frequency of Yersinia enterocolitica in traditional fruit juices shop in southern part of Tehran.

This was a descriptive cross-sectional study, 100 samples of fruit juice including orange juice, mango, carrot, apple and celery(5 samples from each fruit juice shop) were collected from south of Tehran and examined according to the national standard of Iran number 2946 and 9236 for Escherichia coli, Salmonella, Shigella and Yersinia enterocolitica. Data were analyzed using descriptive statistics and SPSS19 software. 

The rate of contamination by Yersinia enterocolitica was 2% followed by Escherichia coli 25%, Shigella 14% and Salmonella 1% respectively. The Escherichia coli were isolated from all the tested fruit juice samples, Shigella in carrot and celery, and Yersinia enterocolitica in mango and apple and Salmonella in carrot juice.

The results of this study suggest more attention and regular checking should be paid in preparation of juices in order to minimize the rate of 
contaminations to public health.

Listeria monocytogenes show high mortality among pregnant women and newborns. This study aimed to detect L. monocytogenes in pregnant women with a history of abortion and assess the serotypes, antibiotic susceptibility patterns, and its resistance genes.

Overall, 400 vaginal swabs were taken from pregnant women with a history of abortion in the past few years in a tertiary care hospital in Tehran, Iran, during 2015-2018. Antibiotics susceptibility to a panel of 10 antibiotics was determined using the standard disk diffusion method and the isolates serotyped by the agglutination method. The antimicrobial-resistant isolates were also screened for the presence of tetM, ermB and dfrD genes by PCR.

Overall, 22 L. monocytogenes isolates were identified. High rates of resistance were observed for trimethoprim (50%; n=11), sulphamethoxazole (50%; n=11), tetracycline (45.45%; n=10) and gentamicin (36.36%; n=8). From 22 L. monocytogenes isolates, 13 (59.10 %), 5 (22.73%), 3 (13.63%) and 1 (4.54%) belonged to serotypes 4b, 1/2a, 1/2b, and 3c, respectively. The genetic determinant tetM was detected in 70% of the tetracycline-resistant isolates. Out of 11 trimethoprim-resistant isolates, 27.27% isolates contained dfrD. Moreover, the ermB gene was found in 83.33% of the erythromycin-resistant isolates.

Ampicillin and partly penicillin consider to be suitable antimicrobial agents to treat human listeriosis. Moreover, due to resistance against many antibiotics, it is necessary to continue monitoring and managing antimicrobial resistance.

Clostridium perfringens is an anaerobic bacterium, commonly present in retail foods. Its enterotoxin-producing ability, short generation time, ability to grow at elevated temperatures, and spore-forming ability, allows it to survive in food-processing temperatures, and cause foodborne illness. The aim of study was to screen dehydrated vegetables contaminated with cpe and cpa carrying C.perfringens.

This is descriptive-analytical study, was carried out on 140 samples (70 unpacked and  70 packed) dehydrated vegetables collected from different areas of Tehran. Samples were inoculated on peptone and sulfite polymyxin sulfadiazine (SPS) agar for enrichment. The enrichment culture was then incubated on anaerobic condition for 48 hours. The black colonies were selected for identification test and PCR. The bacterial colonies were identified by biochemical tests, and duplex PCR was performed for α-toxin (cpa) and enterotoxin (cpe) genes.

 In general 13 samples (9.3%) were identified as C. perfringens using phenotypic methods, all of the isolates were also positive for cpa but negative for cpe gene. The contamination rate for packed vegetables was 12.8% and for unpacked was 5.7%.

Our finding showed that contamination of packed dehydrated vegetables was higher than unpacked; this might be due to drying as well as packaging process. We found that these isolates were negative for enterotoxin.