Monitor the freshness of shrimp by smart halochromic films based on gelatin/pectin loaded with pistachio peel anthocyanin nanoemulsion

This paper focuses on the combination of gelatin (Gel), pectin (Pec), and Pistachio peel anthocyanins (PSAs) to develop a halochromic film for food applications (shrimp). The results of spectroscopic properties showed that the film components had proper interaction and compatibility. Furthermore, the addition of PSAs and Pec improved the thermal stability of films. The addition of Pec and PSAs significantly improved the physical properties and mechanical resistance of the films. So that, the permeability to water vapor and oxygen reduced from 2.81 to 2.74 (g‧s-1‧Pa-1‧m-1) and 5.25 to 4.70 (meq/kgO2), respectively. In addition, the strength and flexibility of halochromic film reached 0.7 MPa and 56 % compared to Gel film (0.62 MPa, and 46.96 %). Most importantly, the color changes of the smart film from cherry/pink to yellow/brown, which were proportional to the color changes of the anthocyanin solution at different pHs, were able to monitor the shrimp freshness and spoilage at room (20 °C) and refrigerated (4 °C) temperature for 14 days.

A survey of prevalence and phenotypic and genotypic assessment of antibiotic resistance in Staphylococcus aureus bacteria isolated from ready-to-eat food samples collected from Tehran Province, Iran

BACKGROUND

Resistant Staphylococcus aureus (S. aureus) bacteria are considered among the major causes of foodborne diseases. This survey aims to assess genotypic and phenotypic profiles of antibiotic resistance in S. aureus bacteria isolated from ready-to-eat food samples.

METHODS

According to the previously reported prevalence of S. aureus in ready-to-eat food samples, a total of 415 ready-to-eat food samples were collected from Tehran province, Iran. S. aureus bacteria were identified using culture and biochemical tests. Besides, the phenotypic antibiotic resistance profile was determined by disk diffusion. In addition, the genotypic pattern of antibiotic resistance was determined using the PCR.

RESULTS

A total of 64 out of 415 (15.42%) ready-to-eat food samples were contaminated with S. aureus. Grilled mushrooms and salad olivieh harbored the highest contamination rate of (30%), while salami samples harbored the lowest contamination rate of 3.33%. In addition, S. aureus bacteria harbored the highest prevalence of resistance to penicillin (85.93%), tetracycline (85.93%), gentamicin (73.43%), erythromycin (53.12%), trimethoprim-sulfamethoxazole (51.56%), and ciprofloxacin (50%). However, all isolates were resistant to at least four antibiotic agents. Accordingly, the prevalence of tetK (70.31%), blaZ (64.06%), aacA-D (57.81%), gyrA (50%), and ermA (39.06%) was higher than that of other detected antibiotic resistance genes. Besides, AacA-D + blaZ (48.43%), tetK + blaZ (46.87%), aacA-D + tetK (39.06%), aacA-D + gyrA (20.31%), and ermA + blaZ (20.31%) were the most frequently identified combined genotypic patterns of antibiotic resistance.

CONCLUSION

Ready-to-eat food samples may be sources of resistant S. aureus, which pose a hygienic threat in case of their consumption. However, further investigations are required to identify additional epidemiological features of S. aureus in ready-to-eat foods.

Molecular Detection of Norwalk Virus in Carp Fish and Shrimp Ponds in Khuzestan Province, Iran by RT-PCR Method

Background: Norwalk virus is one of the most common causes of viral gastroenteritis. The aquatic products are potential sources of contamination with this virus. Objectives: The main objective of the study was to investigate the presence of the Norwalk virus in different aquatic animals in Khuzestan provinces, Iran. Materials and Methods: A total of 40 pieces of fish (silver carp, common carp, big head, and grass carp species) and 10 pieces of shrimps were caught from ponds, and the samples were transferred to the laboratory in ice bags. After the separation of the intestine, the content of the intestine was extracted using two sterile filters. Then, the supernatant was used for reverse transcription polymerase chain reaction (RT-PCR) using Calicivirus-specific primers (p289/ p290). Then, Norwalk virus-specific primers (NVp36/NVp35) were detected in Calicivirus positive samples. Results: The results showed 8% (4 samples) and 6% (3 samples) of the samples were infected with Calicivirus (p289/p290 genes) and Norwalk virus (NVp36/NVp35 genes), respectively. Calicivirus positive samples included 2 common carp, 1 silver carp, and 1 shrimp. Norwalk virus-positive samples included 2 common carp and 1 shrimp. In other words, the highest prevalence of virus was observed in aquatic fish feeding from the bottom of the pool. Due to the fact that this species is bred with other species and considering that this virus lives in the gastrointestinal tract, the ingestion of feces of other infected organisms can lead to the increase of this virus in the digestive system of carp. Conclusion: Therefore, due to the importance of Norwalk as a zoonotic agent and the possibility of human infection through consumption of aquatic products, preventive measures such as not using animal manure for fertilization and preventing the growth of phytoplankton in aquaculture ponds and cooking meat properly are suggested.

Modeling the Effects of Citrus sinensis Essential Oil and Nitrite on Growth Probability of Clostridium botulinum Type A in Broth Media

Background:

Nitrite is a multifunctional food additive used for control of toxigenic Clostridium botulinum in foodstuffs. However, there is a growing concern about the carcinogenic and teratogenic effects of nitrite. The present research was done to assess the effects of Citrus sinensis essential oil and nitrite on the growth probability of C. botulinum type A using predictive mathematical modeling technique in broth media.

Methods:

Essential oil of C. sinensis was collected using Clevenger. Multifactorial design included diverse C. sinensis, nitrite and NaCl concentrations and also different pH ranges and storage temperatures were arranged in BHI broth medium. C. botulinum type A strains were then inoculated and their growth model was analyzed.

Results:

The synergistic inhibitory effects of nitrite and C. sinensis were significant (P<0.05). C. sinensis (0.045%) and nitrite (20 ppm) strongly decreased the growth of C. botulinum (log P%= - 2.2 versus log P%= 1.15). Decreasing temperature up to 25°C significantly affected growth probability of C. botulinum (P<0.05). Increasing NaCl concentration up to 3% did not cause any significant differences in the growth of C. botulinum (P= 0.062). Bacterial growth in broth media was completely inhibited at pH 5.5 and also in media contained C. sinensis (0.045%) and nitrite (60 ppm) at pH 6.5 (log P%= -3.76).

Conclusion:

Using certain concentrations of C. sinensis essential oil with other suboptimal factors (pH and temperature) and nitrite can control the growth of C. botulinum in broth media.

Effects of Citrus sinensis Essential Oil and Intrinsic and Extrinsic Factors on the Growth and ToxinProducing Ability of Clostridium botulinum Type A

Background: Considering the high fatality of botulism, the control of Clostridium botulinum and its neurotoxins has clinical importance. In this regard, using chemical preservatives, natural essential oils (Eos), and changes in the growth predisposing factors of bacteria are suitable methods to control the growth and toxin producing of C. botulinum in foods. Objective: The current survey was done to assess the effects of Citrus sinensis EO and intrinsic and extrinsic factors on the growth and toxin producing of C. botulinum type A. Materials and Methods: In this experiment with a factorial design, C. sinensis EO (0.0%, 0.015%, 0.03%, and 0.045%), nisin (0, 500, and 1500 IU/mL), nitrite (0, 20, and 60 ppm), pH (5.5 and 6.5), storage temperature (25 and 35° C), and sodium chloride (NaCl, 0.5% and 3%) were used to assess bacterial growth in the brain heart infusion medium. Finally, the mouse bioassay method was also used to assess toxicity. Results: Clostridium sinensis EO with a concentration of 0.045%, as well as the reduction of pH and temperature could significantly delay the growth of bacteria (P≤0.05) in contrast to the use of NaCl and nisin alone. However, all concentrations of sodium chloride (NaCl), nisin, and C. sinensis EO (< 0.045%) in interaction with each other, especially in combination with nitrite, showed good synergistic effects. Conclusion: These results suggested that using certain concentrations of C. sinensis EO and nisin, along with other suboptimal factors caused a significant decrease in the nitrite contents of foods with a significant reduction in the growth and toxin-producing ability of C. botulinum.

Phenotypic and Genotypic Assessment of Antibiotic Resistance and Genotyping of vacA, cagA, iceA, oipA, cagE, and babA2 Alleles of Helicobacter pylori Bacteria Isolated from Raw Meat

BACKGROUND

Foodstuffs with animal origins, particularly meat, are likely reservoirs of Helicobacter pylori.

PURPOSE

An existing survey was accompanied to assess phenotypic and genotypic profiles of antibiotic resistance and genotyping of vacA, cagA, cagE, iceA, oipA, and babA2 alleles amongst the H. pylori bacteria recovered from raw meat.

METHODS

Six-hundred raw meat samples were collected and cultured. H. pylori isolates were tested using disk diffusion and PCR identification of antibiotic resistance genes and genotyping.

RESULTS

Fifty-two out of 600 (8.66%) raw meat samples were contaminated with H. pylori. Raw ovine meat (13.07%) had the uppermost contamination. H. pylori bacteria displayed the uppermost incidence of resistance toward tetracycline (82.69%), erythromycin (80.76%), trimethoprim (65.38%), levofloxacin (63.46%), and amoxicillin (63.46%). All H. pylori bacteria had at least resistance toward one antibiotic, even though incidence of resistance toward more than eight antibiotics was 28.84%. Total distribution of rdxA, pbp1A, gyrA, and cla antibiotic resistance genes were 59.61%, 51.92%, 69.23%, and 65.38%, respectively. VacA s1a (84.61%), s2 (76.92%), m1a (50%), m2 (39.13%), iceA1 (38.46%), and cagA (55.76%) were the most generally perceived alleles. S1am1a (63.46%), s2m1a (53.84%), s1am2 (51.92%), and s2m2 (42.30%) were the most generally perceived genotyping patterns. Frequency of cagA-, oipA-, and babA2- genotypes were 44.23%, 73.07%, and 80.76%, respectively. A total of 196 combined genotyping patterns were also perceived.

CONCLUSION

The role of raw meat, particularly ovine meat, in transmission of virulent and resistant H. pylori bacteria was determined. VacA and cagA genotypes had the higher incidence. CagE-, babA2-, and oipA- H. pylori bacteria had the higher distribution. Supplementary surveys are compulsory to originate momentous relations between distribution of genotypes, antibiotic resistance, and antibiotic resistance genes.

Prevalence of Staphylococcal Cassette Chromosome mec and Panton-Valentine Leukocidin Gene Amongst the Methicillin-resistant Staphylococcus aureus Strains Isolated From Fowl Meat

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is considered to be one of the most important causes of foodborne diseases. Objective: The current examination was performed to examine the distribution of staphylococcal cassette chromosome mec (SCCmec) and Panton-Valentine leukocidin (PVL) gene amongst the MRSA strains isolated from raw fowl meat samples. Materials and Methods: A total of 240 fowl meat samples were collected and cultured. MRSA strains were identified using cefoxitin and oxacillin susceptibility tests. DNA samples extracted from the MRSA strains were subjected to polymerase chain reaction (PCR) for detection of SCCmec and PVL gene. Results: Twenty-two out of 240 (9.16%) raw fowl meat samples were positive for S. aureus strains. Twelve out of 22 S. aureus strains (54.54%) were determined as MRSA strains. The incidence of MRSA strains in raw chicken, turkey, quail, and ostrich meat samples was 66.66%, 50%, 50%, and 33.33%, respectively. The incidence of SCCmec IVa, SCCmec IVd, and SCCmec V was 50%, 8.33% and 41.66%, respectively. The applied method failed to detect SCCmec types I, II, III, IVb, and IVc. The incidence of the PVL gene amongst the MRSA strains was 75%. Conclusion: The presence of SCCmec IV and SCCmec V and PVL gene revealed occurrence of community-associated MRSA (CA-MRSA) in fowl meat samples. Further studies are required to find additional epidemiological aspects of the MRSA strains in fowl meat samples.

Phenotypic and genotypic characterization of antibiotic resistance in the methicillin-resistant Staphylococcus aureus strains isolated from hospital cockroaches

Background

Cockroaches are one of the most important and frequent insects responsible for harboring, transmission and dissemination of human pathogens in the hospital environment. The present research was done to study the phenotypic and genotypic characterization of antibiotic resistance in the Methicillin-resistant Staphylococcus aureus strains isolated from hospital cockroaches.

Methods

Five-hundred and thirty Periplanets americana and Blattella germanica cockroaches were collected and their gut content and external washing samples were subjected to bacterial isolation. MRSA strains were subjected to disk diffusion and PCR amplification of antibiotic resistance genes.

Results

Prevalence of MRSA strains in P. americana and B. germanica cockroaches were 52.77 and 43.33%, respectively. External washing samples of P. americana cockroaches had the highest prevalence of MRSA strains (59.57%). MRSA isolates of external washing samples harbored the highest prevalence of resistance against penicillin (100%), ceftaroline (100%), tetracycline (100%), gentamicin (83.33%) and trimethoprim-sulfamethoxazole (80.55%). MRSA strains isolated from gut content samples harbored the highest prevalence of resistance against penicillin (100%), ceftaroline (100%), tetracycline (100%), trimethoprim-sulfamethoxazole (80%) and gentamicin (73.33%). BlaZ, aacA-D, tetK, msrA, dfrA, ermA, gyrA, grlA and rpoB were the most commonly detected antibiotic resistance genes amongst the MRSA strains.

Conclusions

The present investigation is the first report of the phenotypic and genotypic evaluation of antibiotic resistance in the MRSA strains isolated from P. americana and B. germanica hospital cockroaches. Hospital cockroaches are considered as a potential mechanical vector for MRSA strains.

One-year prevalence of antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus recovered from raw meat

Food with animal origins and especially meat may play an important role in transmission of methicillin-resistant strains of Staphylococcus aureus to humans. The present investigation was carried out to determine the prevalence of MRSA in various types of Iranian meat samples as well as study their antimicrobial resistance properties. Nine-hundred raw meat samples were collected during various months of the year. Samples were cultured and those that were MRSA-positive were subjected to the disk diffusion method to study the antibiotic resistance pattern. One-hundred and sixty out of 900 raw meat samples (17.7%) were positive for MRSA. Raw sheep meat samples had the highest (24.0%), while raw camel meat samples had the lowest (10%) prevalence of MRSA. Samples which were collected in June, July, August, September and June months had the highest prevalence of MRSA. Bacterial strains were also resistant to ampicillin (100%), penicillin G (100%), gatifloxacin (96.8%), ceftriaxone (80%) and oxacillin (76.2%) antibiotics. We found that only one isolate was resistant to all tested antimicrobial agents. Contaminated meat samples are potential risk factor for transmission of MRSA. Thoughtful antibiotics prescription, control the hygienic quality of meat inspections and increase the hygienic status of butchers and slaughterhouses can decrease the prevalence of MRSA in meat.

Assessment of AflatoxinM1 Contamination in UHT Flavored Milk Samples in Karaj, Iran

This study was carried out to detect the presence of aflatoxin M1 (AFM1) in 30 UHT flavored milk samples in Karaj, Alborz province, Iran. High-performance liquid chromatography (HPLC) was applied to analyze AFM1 in the samples. The results showed that aflatoxin M1 was detected in all the UHT flavored milk samples, the AFM1 concentration ranged from 0.015 to 0.14 µg/L. Also, 10 samples (33.3%) were contaminated with more than 0.05 µg/L of European Union regulations for aflatoxin M1. Wherease, according to the proposed Iranian national standard and FDA (0.5 µg/L), none of the samples has not been contaminated more than the maximum AFM1 concentrations threshold. This is the first report discovering the fact that UHT flavored milk is an important contributor to the dietary intake of AFM1 in Iran.

Prevalence and antimicrobial resistance of Salmonella serotypes isolated from retail chicken meat and giblets in Iran

INTRODUCTION

Salmonella is one of the major foodborne pathogens responsible for outbreaks of foodborne illness in humans worldwide.

METHODOLOGY

A total of 560 samples of chicken meat and giblets were collected from retail markets for Salmonella identification, serotyping, and antimicrobial resistance testing.

RESULTS

Salmonella was detected in 19.8% of samples. Among the five serotypes identified, S. Thompson was the predominant type (48.7%). High antimicrobial resistance rates were observed to nalidixic acid (92.8%), tetracycline (81%), trimethoprim (68.4%), sulfamethoxazole / trimethoprim (61.2%), streptomycin (56.7%), and kanamycin (36.9%). Although resistance to chloramphenicol (3.6%), amoxicillin-clavulanic acid (5.4%), and ampicillin (11.7%) was detected, none of the isolates were resistant to ceftazidime, ceftriaxone, cefotaxime, ciprofloxacin, colistin, gentamicin, nor imipenem.

CONCLUSIONS

Restrictions on the irrational use of antibiotics in humans and animals are suggested for the reduction of resistant strains.

Antimicrobial Activities of the Combined Use of Cuminum Cyminum L. Essential Oil, Nisin and Storage Temperature Against Salmonella typhimurium and Staphylococcus aureus In Vitro

Background:

Foodborne diseases are considered as major health problems in different countries. Concerns over the safety of some chemical preservatives and negative consumer reactions to them have prompted interest in natural alternatives for the maintenance or extension of food shelf life. In this respect, the combination of a plant essential oil and nisin has used for controlling the growth of foodborne pathogens as natural food preservative using the mathematical model.

Objectives:

The purpose of this study was to determine the effect of different concentrations of Cuminum cyminum L. essential oil (0, 15, 30 and 45 µL/100 mL) and nisin (0, 0.5 and 1.5 µg/mL) combination at different temperatures (10, 25 and 35°C) on growth of Salmonella typhimurium and Staphylococcus aureus in the Brain-Heart Infusion (BHI) broth model. The concentrations of 0 µL/100 mL for essential oil and 0 µg/mL for nisin imply the negative control.

Materials and Methods:

A multivariate variance experiment was performed. To assess the effect of essential oil, nisin and the incubation temperature on growth probability (log P%) of S. typhimurium and S. aureus, four concentrations of C. cyminum L. essential oil (0, 15, 30 and 45 µL/100 mL), three concentrations of nisin (0, 0.5 and 1.5 µg/mL) and three storage temperatures (10, 25 and 35°C) were considered.

Results:

The growth of S. typhimurium was significantly decreased by the concentration of essential oil ≥ 30 µL/100 mL in combination with nisin ≥ 0.5 µg/mL at temperature = 10°C (P < 0.05). Also, in combination of the essential oil ≥ 15 µL/100 mL and nisin ≥ 0.5 µg/mL at temperature ≤ 25°C, the growth of S. aureus was significantly reduced (P < 0.05).

Conclusions:

These results indicate that the combination of essential oil and nisin inhibits the growth of S. typhimurium and S. aureus bacteria and there is the possibility of using them as substitutes for chemical food preservatives. Moreover, the model (log P%) in this study can be a good tool for the reduction of microbiological hazards in food industry.