فهرست مطالب hamdallah moshtaghi

Salmonella is one of the most important bacteria which cause illnesses, may exist in raw foods. The presence of this bacterium in food also causes a decrease in the quality of productions and a decrease in the economic growth. Milk and its products are among the food that may contaminate with Salmonella both primarily and secondarily by employees, water, etc., and transmitted to human. In this study, 100 samples of raw milk and 50 samples of traditional cheese from different parts of Chaharmahal and Bakhtiari province were obtained to isolate and identify Salmonella bacteria using microbiological, and polymerase chain reaction tests. Also, the antibiotic resistance of Salmonella isolates was evaluated by the diffusion disk method. The results of microbiological tests showed that 7 samples were contaminated with salmonella. Suspicious isolates included 5 samples belonging to raw milk and 2 samples belonging to traditional cheeses. The results of PCR test revealed that 3 samples of suspected isolates of raw milk (%3) and 1 sample of suspected isolates of traditional cheese (%2) were S. typhimurium. The results of the antibiogram test on Salmonella isolates showed the highest sensitivity to Gentamicin and Ciprofloxacin, and the highest resistance to Ampicillin, Tetracycline and Trimethoprim sulfamethoxazole antibiotics. According to the results of the present study, raw milk and traditional cheeses are contaminated with Salmonella typhimurium, which are resistant to some antibiotics. Although the contamination of raw milk is removed during the heat treatment steps such as pasteurization, boiling or sterilization, traditional cheeses contaminated with this bacterium are considered a potential risk for the health of consumers. Therefore, the examination of traditional dairy products, especially cheese, in terms of preventing the occurrence of diseases in humans seems to be more necessary.

Pathogenic microorganisms are one of the important factors in contaminating and endangering the safety of foods for consumers, and continuous control of foods in terms of the presence of pathogenic microorganisms can guarantee the health of foods. Yersinia entrocolitica is a foodborne pathogenic bacterium. Raw milk and fresh traditional cheese may be contaminated with this bacterium. Generally, Iranians tend to consume traditional and homemade foods more than industrial products. This issue is especially relevant to milk products such as cheese, butter, and local cream. The purpose of this study was to determine the contamination of raw milk and traditional cheeses produced in Chaharmahal and Bakhtiari province with Yersinia entrocolotica.

A total, of 100 raw milk and 50 traditional cheese samples were obtained randomly from dairy plants and milk collection stations, as well as retail shops. The initial enrichment of the samples was performed in the TSB medium. Then, 100 microliters of the medium was centrifuged and 25 microliters of its sediment was cultured on the special medium of Cefsoludin Irgazan Novobiocin agar (CIN) with supplement (containing Cefsoludin 7.5 mg, Irgasan 0.2 mg and Novobiocin 1.25 mg). Suspicious colonies (red colonies) were identified on the CIN agar and biochemical tests including IMViC, Ureas, and H2S production.DNA extraction was performed by boiling method and polymerase chain reaction (PCR) was performed for the identification of Ali and Yst genes using specific primers (Table 1). Table 1. Characteristics of Primers Used to Identify Yersinia Enterocolitica Genes Antibiotic resistance test was performed by the disk diffusion method on Muller-Hinton agar according to the Clinical and Laboratory Standards Institute (CLSI). Resistance of Yersinia enterocolitica isolates to 7 commonly used antibiotics in treatment including cefixime (5µg), gentamicin (10µg), tryptoprim (5µg), ciprofloxacin (5µg), amoxicillin (10µg), tetracycline (30µg), and sulfamethoxazole (300µg).

Out of 100 samples of raw milk and 50 samples of traditional cheese, 20 samples (13.3%) suspected Yersinia enterocolitica bacteria were isolated. of these, 14 samples (14%) were related to raw milk samples and 6 samples (12%) were related to traditional cheese samples. The results of the PCR test showed that 5 isolates (3.3%) were Y. enterocolitica bacteria, 4 isolates (4%) related to raw milk, and 1 isolate (2%) related to traditional cheese. In addition, in the evaluation of virulence genes, it was found that out of 4 raw milk isolates, 1 isolate carried the Yst gene, 2 isolates carried the Ail gene, and 1 isolate had both genes. Also, 1 isolate of Y. enterocolitica isolated from traditional cheeses carried the Ail gene (Table 2). Table 2. Percentage of Contamination of Raw Milk and Traditional Cheese with Yersinia entrocolitica, (%) The results of antibiogram tests on Yersinia enterocolitica isolates showed the highest resistan.ce to Gentamicin, Trimethoprim, Ciprofloxacin, and Sulfamethoxazole antibiotics, and moderate resistance to cefixime and amoxicillin (Table 3).  Table 3. Antibiotic Resistance Pattern of Yersinia Entrocolitica Isolated from Raw Milk and Traditional Cheese.

In general, the results of the present study and other studies in Iran and the world show that raw milk and traditional cheeses, contaminated with Yersinia enterocolitica, which carry virulence genes and are resistant to some common antibiotics, can endanger the health of consumers.

The aim of this study was to investigate the effect of ethanolic and aqueous extracts of shallot on the survival of yogurt starter bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus). Aqueous and ethanolic extracts of shallots were extracted by soaking in distilled water and ethyl alcohol. Then MIC and MBC extracts were obtained for yogurt starter bacteria by microdilution method. Aqueous and ethanolic extracts were added to pasteurized milk at concentrations obtained in the MIC test along with 3% yogurt starter. The inoculated milk was incubated at 45 ° C until pH = 4.4 for 2 hours. After that, the yogurts were cooled to 4 ° C Then, on days 1, 3, 7, and 14, pH, acidity, and LAB count tests were performed on yogurt samples. The results showed that on days 1, 3, 7, and 14, the acidity and pH of the aqueous extract groups were significantly different to the ethanolic and control groups (p <0.05). Also, the lactic acid bacteria count test on days 1, 3, 7, and 14, the aqueous and ethanolic extract groups were significantly different from the control group (p <0.05). The results also showed that the inhibitory effect of aqueous extract of shallot was more on yogurt starter bacteria than ethanolic extract of shallot (p <0.05). In coclussion the revealed that the starter bacteria in yogurt in presence of Shallot extracts were alive and active until day 14 during refrigerator storage, which can transmit the probiotic effects of yogurt and shallots to the consumer.

The present study aimed to determine the prevalence of enterotoxin-producing S.aureus in creamy pastries presented in confectionery in Shahrekord and to determine their antibiotic resistance. One hundred fifty samples were randomly selected from creamy pastries. Microbial tests for isolation of S. aureus were performed by culturing in a nutrient broth and then cultured on a Beards Parker agar and suspected colonies were confirmed by standard complementary tests including gram staining, catalase test, and coagulase. Isolates were tested for presence of enterotoxin genes (A, B, C, D) by Multiplex PCR. Antibiotic resistance was determined by the disk diffusion method. Overall, 38 (25.3%) samples were contaminated with S. aureus. 21 isolates (28%) and 17 isolates (22.7%) were related to summer and winter samples respectively. Thirteen isolates (29%) of S. aureus contained enterotoxin genes. 11 isolates (84. 61%) contained SEA, and 2 isolates (5.3%) contained the SEC gene. Totally, 9 (70%) enterotoxigenic isolates were related to summer and 30% to winter samples. None of the isolates had SEB, SED genes. Four (30%) enterotoxigenic isolates related to creamy pastry and 9 (70%) to creamy bread. Antibiogram test showed that the highest sensitivity to sulfamethoxazole (97.36%) and erythromycin (63.15%). Also, all enterotoxigenic isolates were resistant to penicillin and 95% with SEA gene were resistant to erythromycin and ciprofloxacin.The results of present study revealed that contamination of creamy pastries with S. aureus capable of producing enterotoxin and resistance to some antibiotics.

Shiga Toxin-producing Escherichia coli (STEC) is an important organism known as an emerging zoonotic microorganism causing diseases such as hemorrhagic colitis and Hemolytic Uremic Syndrome (HUS) as well as thrombotic thrombocytopenia in humans. This study aimed to determine the contamination of meat-contact surfaces to STEC and the characterization of the virulence genes of the isolates.

Totally, 111 swab samples were obtained from meat-contact surfaces in slaughterhouses and meat supply centers for 6 months. After the primary enrichment and cultivation on EMB and SMAC environments, sorbitol negative colonies were transferred to differential media and confirmed by specific tests as Escherichia coli. Suspected colonies were evaluated by PCR method to determine the existence of serotype O157: H7and virulence genes such as Stx1, Stx2, eae, and Hly.

E. coli O157 was detected in 14 samples (12.61%), and only 2 isolates (1.8%) were identified as E.coli O157: H7. In PCR, 4 isolates contained Stx1, Stx2, and Hly genes, 2 isolates contained Stx1, eae and Hly genes, 3 isolates contained Stx1 and Hly genes, 1 isolate contained Stx2 and eae genes, 3 isolates contained the Hly gene and 1 isolate did not have any of the virulence genes. Discussion and

Concerning the possibility of the transmission of pathogens such as E.coli O157: H7from contaminated surfaces to carcasses and healthy meat, the lack of attention to the health and care of slaughterhouses and meat supply centers can be concerns for the public health.

Enterohemorrhagic Escherichia coli (EHEC) causes bloody and non-bloody diarrhea, intestinal infection and extraintestinal complications in humans. This study aimed to isolate and evaluate the prevalence of E. coli O157: H7 and other Shiga toxin-producing E. coli (STEC) and identify the virulence genes (stx1, stx2, hly and eaeA) from patients with diarrhea. Also, the antibiotic resistance profile of the isolated strains was evaluated.

A total of 100 stool samples were collected from patients with acute diarrhea referring to the hospital and clinics in Isfahan County, Iran. Phenotypic tests and PCR assay were used for detection of E. coli O157: H7 and other Shiga toxin-producing E. coli. The presence of virulence genes (stx1, stx2, hly and eaeA) were identified by PCR. The antibiotic resistance profile of the isolates was determined using the agar disk diffusion method. The results were analyzed descriptively by Sigma stat version 4 software.

Seventy - eight out of 100 samples (78%) were contaminated with E. coli. E. coli O157 was isolated from five samples (6.4%), of which only two strains (2.56%) were identified as E. coli O157: H7. According to the results, out of two E. coli O157: H7 isolates, one (50%) isolate contained eaeA and two isolates (100%) contained Stx1, Stx2, hlyA genes. Out of three (3.84%) E. coli O157: HN, one of the isolate (33.3%) contained stx1 and, two isolates (66.7%) were positive for hlyA genes. Also, the results revealed that six strains (7.69%) were non-O157: H7 STEC, of which two isolates (33.3%) contained stx1 and four isolates (66.7%) were positive for stx2 and hlyA genes. The results of antibiogram tests revealed that all of the STEC isolates (100%) were sensitive to imipenem followed by kanamycin, gentamicin and nitrofurantoin (91%). High resistance (54.5%) to ampicillin and ciprofloxacin was observed among the STEC isolates.

The results of the current study showed that although the prevalence of E. coli O157: H7 was low among patients with diarrhea, the other STEC strains with relative resistance to antibiotics are more prevalent.