Virulence genes and pulsed-field gel electrophoresis profiles of Shiga toxin-producing Escherichia coli isolated from different food samples and patients with acute diarrhea.

Background and Objectives: Escherichia coli O157: H7 is one of the most important causes of hemorrhagic colitis, and hemolytic uremic syndrome. The present study aimed to isolate E. coli O157: H7 from foods and patients with hemorrhagic colitis, and identify Shiga toxin genes, phylogenetic comparison, and antibiotic resistance of the isolates. Materials and Methods: In total 400 samples, including patients stool and food were taken in Isfahan-Iran province. Phenotypic tests and PCR were performed to identify Shiga toxin-producing E. coli. The isolated strains were compared phylogenetically by PFGE. Agar disk diffusion was performed to identify the antibiotic resistance of the isolates. Results: Totally, 5 isolates of fecal samples were E. coli O157, but only 2 isolates carried H7 gene. Also, 9 isolates of E. coli O157 were isolated from food samples that 3 isolates were E. coli O157: H7. The isolates carried stx1, stx2, hlyA and eaeA genes. Also, E. coli non-O157: H7 identified from samples that contained stx1, stx2, hlyA genes. The highest susceptibility to imipenem and the highest resistance to ampicillin and ciprofloxacin were observed. There was a similarity of 100% between the E. coli O157: H7 strains isolated from patients and raw milk and minced beef samples. Conclusion: Serotypes other than the O157 of E. coli are more prevalent in patients and food. The E. coli O157: H7 isolates from patients had 100% genetic similarity with minced meat and cow milk isolates, which indicates cattle are the most important reservoir of this bacterium in Iran.

Detection of genes encoding enterotoxins (SEA-D) in Staphylococcus aureus strains isolated from workers' nasal samples and creamy pastries of Shiraz confectioneries.

Background and Objectives: Staphylococcus aureus is responsible for the majority of food poisoning all around the world. Nasal carriers of S. aureus and foodstuffs need for handling are important sources and vehicles to transmit this pathogen to ready-to-eat foods. According to hygienic standards, confectioners should not be contaminated with S. aureus. This study aimed to detect nasal carriers and creamy pastries contaminated with enterotoxigenic S. aureus in confectioneries of Shiraz, Iran. Materials and Methods: From the confectioneries of Shiraz city, 27 places in the north, south, center, west, and east areas were selected randomly then 100 creamy pastries samples and 117 nasal swabs were collected. Bacteriological and biochemical tests were performed to isolate S. aureus. The polymerase chain reaction (PCR) test was used to identify the virulence and enterotoxins genes of the S. aureus isolates. Agar disk diffusion was performed to find out the antibiotic resistance of the isolates. Results: Results revealed that 16.24 and 33 percent of workers and creamy pastries were contaminated with S. aureus respectively. Also, 100%, 37%, 58%, and 6% of nasal samples harbored femA, mecA, sea, and sec genes respectively. According to the results 97%, 70%, 54.5%, and 6% of creamy pastries isolates harbored femA, mecA, sea, and sec genes respectively. No isolate carried seb and sed genes. The results also showed that 41.5% of nasals and 5.5% of creamy pastry isolates harbored both sea and sec genes. The sea was the most common enterotoxin gene observed in nasal and creamy pastries. The results of the antimicrobial resistance test showed that 68.42% of nasal and 48.48% of creamy pastry isolates were resistant to cefocxitn (FOX) respectively. Both nasal (89%) and creamy pastry (82%) isolates presented the highest resistance to penicillin (P) and the most sensitivity to trimethoprim-sulphamethoxazole (SXT) (94%). Most of the isolates were sensitive to erythromycin (E), aztreonam (AZM), tetracycline (TE), trimethoprim (TMP), and ciprofloxacin (CP). Isolates of S. aureus harboring multi-enterotoxin genes were resistant to more antibiotics than others. Conclusion: The presence of enterotoxigenic S. aureus in the workers' nasal samples and creamy pastries of Shiraz confectioneries was high which is a potential public health hazard.

The effect of iron sulfate nanoparticles and their fortified bread on Wistar rats and human cell lines.

BACKGROUND: Ferrous sulfate nanoparticles (FSNPs) were synthesized and characterized to mitigate the undesirable effects of ferrous sulfate bulk particles (FSBPs) as a supplement or fortificant in health/food industries. METHODS: The toxicity of FSNPs and FSBPs was evaluated against AGS, PLC/PRF/5, and HGF1-PI 1 cell lines. Then, Wistar rats were fed three levels of FSNPs and FSBPs fortified-bread. Growth performance, hematological parameters, and histopathological changes in treated rats were assessed after 21 days. RESULTS: High concentrations of FSNPs (3.125 and 6.25 mM) increased the necrosis of AGS cells. A low level of FSNPs (1.57 mM) did not affect the viability of cells after 72 h. Fibroblasts did not show apoptosis and necrosis after exposing 1.57 mM of FSNPs. In rats, 9 mg elemental iron of FSNPs/day enhanced hemoglobin, PCV, and ferritin values and increased the body weight gain (p < 0.05). FSNPs fortified-bread induced no clinical symptom or histopathological lesion in rats. CONCLUSION: FSNPs affect cells in a dose-dependent manner. The results indicate that FSNPs at the low level do not have adverse effects on normal fibroblasts and rats. Significant weight gain in rats having a low level of FSNPs compared to the FSBPs indicates the negligible toxicity of FSNPs at low concentrations.

Prevalence and antibiotic resistance profile of Shiga toxin-producing Escherichia coli isolated from diarrheal samples.

BACKGROUND AND OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Effect of edible composite film based on chitosan and cumin essential oil-loaded nanoemulsion combined with low-dose gamma irradiation on microbiological safety and quality of beef loins during refrigerated storage.

This research was conducted to assess the combined effect of chitosan (Ch) film containing cumin essential oil nanoemulsion (CNE) and low-dose gamma irradiation (GI) at 2.5 kGy on microbiological safety and quality of beef loins during 21 days of chilled storage. The growth of mesophilic and psychrophilic bacteria, Enterobacteriaceae, and lactic acid bacteria were retarded in all treated groups (Ch, GI, Ch + CNE, Ch + GI, and Ch + CNE + GI groups) compared to control group during storage time. The treatments also slowed down the increasing level of total volatile basic nitrogen and pH during storage, while irradiation increased the levels of thiobarbituric acid reactive substances and protein carbonyls in beef loins. All treatments except Ch were effective to control the growth of inoculated pathogenic bacteria, including Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella typhimurium, in loin samples. The combination of Ch + CNE + GI was the most effective treatment to control the population of microbial flora and inoculated pathogens, slow down some physicochemical changes, and enhance the storage life of beef loins. As a result, the combination of active chitosan film and low-dose gamma irradiation can ensure microbiological safety and is suggested for long time preservation of beef during chilled storage.

Phenotypic and genotypic characterization of antibiotic-resistant in Escherichia coli isolates from patients with diarrhea.

BACKGROUND AND OBJECTIVES: Escherichia coli is a common enteric pathogen of human and livevestock. Antibiotic resistance is the main concern of public health. The aim of this study was to detect this bacterium in stool samples of diarrheal patients and identify the phenotypic and genotypic characterizations of antibiotic-resistant isolates such as dfrA1, sul1, citm, tetA, qnr, aac(3)-IV in Shahrekord. MATERIALS AND METHODS: Two hundred fifty diarrheal stool samples from patients were collected. Microbiological and biochemical examinations were done to detect E. coli. Phenotypic and genotypic antibiotic resistance of the isolates were determined using dick diffusion method and polymerase chain reaction (PCR), respectively. RESULTS: Among 114 E. coli isolates, the least resistance was for gentamicin (0%) and the most resistance was for trimethoprim (79.8%). The resistance to sulfamethoxazole, ciprofloxacin, ampicillin, and tetracycline were 71.05%, 10.5%, 52.63%, and 3.5% respectively. The results of PCR assay revealed that 10 isolates contain sul1, 49 isolates harbor citm, 8 isolates tetA, 36 isolates dfrA1, 11 isolates qnr genes but there was no isolate with aac(3)-IV gene. In comparison between phenotypic and genotypic of the isolates revealed that citm, tetA, dfrA1, qnr, sul1, aac(3)-IV genes covered 42.98%, 7.01%, 31.57%, 9.64%, 8.7%, 0% of the antibiotic resistance, respectively. CONCLUSION: Our results revealed that all isolates harbor one or more antibiotic resistance genes and that the PCR is a fast practical and appropriate method to determine the presence of antibiotic resistance genes.

PCR detection of Vibrio cholerae, Escherichia coli, and Salmonella sp. from bottled drinking water in Iran.

INTRODUCTION: The quality of drinking water has an important role in human health. This study was aimed to detect Escherichia. coli, Salmonella sp. and Vibrio cholerae from bottled drinking waters produced in Iran. METHODOLOGY: A total of 240 samples of bottled water of different brands were collected for testing between March 2015 to December 2015 in Shahrekord-Iran. Samples were examined by polymerase chain reaction (PCR) combined with culture methods for the detection of E. coli, Salmonella sp., and V. cholerae. RESULTS: The results of PCR revealed that the uidA gene from E. coli, IpaB gene from Salmonella sp, and epsM gene from V. cholerae were detected in 6 (2.5%), 1 (0.4 %), 0 (0%) of the samples, respectively. But in culture methods, only E. coli 5 (2.1%) were isolated from the samples. The contamination with E. coli was significantly higher (P < 0.05) in water produced during the hot seasons than the cold seasons. CONCLUSIONS: This study confirmed the presence of Escherichia coli as the main microorganism in bottle drinking water in Iran. Also, our study showed that PCR can be used as a screening method for monitoring the enteric pathogens in drinking water.

Molecular characterization and antibiotic resistance of enterotoxigenic and entero-aggregative Escherichia coli isolated from raw milk and unpasteurized cheeses.

The aim of this study was to determine the occurrence of enterotoxigenic and enteroaggregative Escherichia coli strains and antibiotic resistance of the isolates in raw milk and unpasteurized cheese. Out of 200 samples of raw milk and 50 samples of unpasteurized cheeses, 96 and 24 strains of E. coli were isolated, respectively. Polymerase chain reaction (PCR) was used to detect the genes encoding heat-stable enterotoxin a (STa), heat-stable enterotoxin b (STb), heat labile toxin (LT) and enteroaggregative heat-stable toxin1 (EAST1). Twelve out of 120 (10.00%) isolates harbored the gene for EAST1, 2(1.66%) isolates were detected as producing STb and LT toxins and 12 (10.00%) strains contained STb and EAST1 genes. None of the strains contain the STa gene. All of the strains were tested for antibiotic resistance by disk diffusion method. Disks included: ciprofloxacin (CFN), trimetoprim-sulfamethoxazole (TSX), oxytetracycline (OTC), gentamicin (GMN), cephalexin (CPN), nalidixic acid (NDA) and nitrofurantoin (NFN), ampicillin (AMP), neomycin (NEO) and streptomycin (STM). Among 120 isolated strains of E. coli, the resistance to each antibiotics were as follows: OTC100%, CPN 86.00%, NDA 56.00%, NFN 42.00%, GMN 30.00%, TSX 28.00%, CFN 20%, AM 23.40% and STM 4.25%. None of the isolates were resistant to NEO. The present data indicate that different resistant E. coli pathogens may be found in raw milk and unpasteurized cheese. It poses an infection risk for human and transferring the resistant factors to microflora of the consumers gut.