First detection of mobilized colistin resistance mcr-1 gene in Escherichia coli isolated from livestock and sewage in Iran

Currently, few studies have investigated the mechanisms of resistance to colistin in Iran. The aim of this study was to investigate mcr-harbouring Escherichia coli dissemination in livestock and sewage in Iran. A total of 115 samples from cows (n = 38), chickens (n = 47) and urban sewage samples (n = 30) were collected. The presence of genes including mcr1–6 and ampC β-lactamase (bla_MOX, bla_CIT, bla_DHA, bla_ACC, bla_EBC, bla_FOX) for colistin-resistant isolates was investigated by multiplex PCR method. Genetic association of colistin-resistant strains was also evaluated by ERIC PCR. Sixty-five isolates were identified as E. coli. Meaningless were resistant to colistin. The highest (26.1%) and lowest (3.07%) resistance were shown to ampicillin and meropenem respectively. Among the three colistin-resistant isolates, 2 (66%) were multidrug resistant, with one of them being mcr-1 positive and the other one positive for DHA ampC β-lactamase gene. No mcr2–6 genes were found. Minimum inhibitory concentration of mcr-producing isolate was 4 mg/L by microbroth dilution. This study reports, first the detection of mcr-1 in E. coli from farm animals in Iran, a finding that is indicative of a global distribution of this plasmidic element and threatning the use of colistin as a last resort antibiotic. No clonal relationship was observed between the colistin-resistant E. coli isolates by ERIC-PCR. Monitoring the presence of these strains in animal sources help as to controlling the spread of resistance genes from animal to human is vital.

Preparation of multiwall carbon nanotube/urea-formaldehyde nanocomposite as a new sorbent in solid-phase extraction and its combination with deep eutectic solvent-based dispersive liquid-liquid microextraction for extraction of antibiotic residues in honey

A solid-phase extraction method combined with deep eutectic solvent-based dispersive liquid-liquid microextraction has been developed for the extraction of three antibiotics in honey samples prior to their determination by ion mobility spectrometry. In this method, first, a multiwall carbon nanotube/urea-formaldehyde nanocomposite was synthesized using co-precipitation polymerization method and then it was used as a sorbent for the analytes extraction from the samples. After that the adsorbed analytes were eluted from the sorbent using a water-miscible organic solvent. The collected elution solvent was mixed with tetrabutylammonium chloride:butanol deep eutectic solvent and the mixture was applied in the following microextraction method. The method provided low limits of detection and quantification in the ranges of 0.32-0.86 and 1.1-2.9 ng/g, respectively. The method had a proper repeatability expressed as relative standard deviation less than or equal to 9.1%. The validated method was successfully performed on different honey samples obtained from different producers.

Astaxanthin–garlic oil nanoemulsions preparation using spontaneous microemulsification technique: optimization and their physico–chemical properties

Garlic oil in water nanoemulsion was resulted through subcritical water method (temperature of 120 °C and pressure of 1.5 bar, for 2 h), using aponin, as emulsifier. Based on the prepared garlic oil nanoemulsion, astaxanthin–garlic oil nanoemulsions were prepared using spontaneous microemulsification technique. Response surface methodology was employed to evaluate the effects of independent variables namely, amount of garlic oil nanoemulsion (1–9 mL) and amount of provided astaxanthin powder (1–9 g) on particle size and polydispersity index (PDI) of the resulted nanoemulsions. Results of optimization indicated that well dispersed and spherical nanodroplets were formed in the nanoemulsions with minimum particle size (76 nm) and polydispersity index (PDI, 0.358) and maximum zeta potential value (−8.01 mV), using garlic oil nanoemulsion amount of 8.27 mL and 4.15 g of astaxanthin powder. Strong antioxidant activity (>100%) of the prepared astaxanthin–garlic oil nanoemulsion, using obtained optimum amounts of the components, could be related to the highest antioxidant activity of the colloidal astaxanthin (>100%) as compared to that of the garlic oil nanoemulsion (16.4%). However, higher bactericidal activity of the resulted nanoemulsion against Escherichia coli and Staphylococcus aureus, were related to the main sulfur bioactive components of the garlic oil in which their main functional groups were detected by Fourier transform-infrared spectroscopy.

Development of homogeneous liquid-liquid extraction combined with dispersive liquid-liquid microextraction based on solidification of floating droplets of a ternary component deep eutectic solvent for the analysis of antibiotic residues in sausage samples prior to ion mobility spectrometry

In this study, a combination of homogeneous liquid-liquid extraction and dispersive liquid-liquid microextraction based on solidification of a deep eutectic solvent has been utilized as an efficient method for the extraction of three widely used antibiotics (oxytetracycline, penicillin G, and tilmicosin) from sausage samples. In this method, initially the antibiotics are extracted from the powdered sausage sample into acetonitrile and then, to concentrate the analytes and achieve a high sensitivity, the obtained acetonitrile is mixed with an extraction solvent (a newly synthesized water-immiscible deep eutectic solvent with a melting point near room temperature), and the obtained mixture is rapidly injected into deionized water. In the next step, the mixture is transferred into an ice bath and the solidified extraction solvent containing the analytes is removed and dissolved in ACN. For quantitative analysis, this phase is taken and injected into an ion mobility spectrometer which operated in the positive mode and is equipped with a continuous corona discharge ionizer. This instrumental technique characterizes molecules based on the gaseous phase mobility of their ions formed at ambient pressure and under an electric field. Under the optimum conditions, limits of detection and quantification were achieved in the ranges of 1.52-2.73 and 5.1-9.1 ng g^-1, respectively. The relative standard deviations were less than 8% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 20 ng g^-1 of each analyte. Finally, the proposed method was applied to the analysis of the studied antibiotics in fifteen different sausage samples marketed in Tabriz, Iran. Oxytetracycline was determined in three of the studied sausage samples.

Photo-bioconvection: towards light control of flows in active suspensions

The persistent motility of individual constituents in microbial suspensions represents a prime example of the so-called active matter systems. Cells consume energy, exert forces and move, overall releasing the constraints of equilibrium statistical mechanics of passive elements and allowing for complex spatio-temporal patterns to emerge. Moreover, when subject to physico-chemical stimuli their collective behaviour often drives large-scale instabilities of a hydrodynamic nature, with implications for biomixing in natural environments and incipient industrial applications. In turn, our ability to exert external control of these driving stimuli could be used to govern the emerging patterns. Light, being easily manipulable and, at the same time, an important stimulus for a wide variety of microorganisms, is particularly well suited to this end. In this paper, we will discuss the current state, developments and some of the emerging advances in the fundamentals and applications of light-induced bioconvection with a focus on recent experimental realizations and modelling efforts. This article is part of the theme issue 'Stokes at 200 (part 2)'.

Hydrothermally extraction of saponin from Acanthophyllum glandulosum root - Physico-chemical characteristics and antibacterial activity evaluation

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Saponin extraction was performed hydrothermally (121 °C and 1.5 atm for 15 min).

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Optimum extraction conditions: 10 g of the root powder and pH of 4.

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Optimum results: foam height (4.66 cm), concentration (0.080 ppm) and antioxidant activity (90.6 %).

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Demonstration of appropriateness of resulted models by RSM.

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Extracted saponin from A. glandulosum root had bactericidal effect.

Saponin was extracted from Acanthophyllum glandulosum root under subcritical water conditions, and effects of root powder and pH of the solution were evaluated on the concentration of the saponin as manifested in its foamability and antioxidant activity using RSM. FT-IR analysis indicated that A. glandulosum root extract had 2 main functional groups (hydroxyl and amide I groups). Saponin with the highest foam height (4.66 cm), concentration (0.080 ppm) and antioxidant activity (90.6 %) was extracted using 10 g of the root powder and pH value of 4. Non-significant differences were observed between the predicted and experimental values of the extraction response variables. The study demonstrated good appropriateness of resulted models by Response Surface Methodology. Furthermore, higher values of R² was attained for the foamability (>0.81) and antioxidant activity (>0.97), as well as large p-values (p > 0.05) indication of their lack-of-fit response verified the acceptable fitness of the provided models. The extracted saponin also showed bactericidal effect, which shows potential as a natural antibacterial compound.

New view of the adsorption of surfactants at water/alkane interfaces - Competitive and cooperative effects of surfactant and alkane molecules

The theoretical description of the adsorption of surfactants at interfaces between aqueous solutions and oil was based over a very long time on models derived for the solution/air interface. Thus, most of the experimentally observed peculiarities could not be specifically considered but were merely interpreted in terms of a penetration of oil molecules into the alkyl chain layer of the adsorbed surfactant molecules. These penetrating oil molecules enhance the surfactant adsorption as compared to the water/air interface. Later on, for the special situations at water/oil interfaces a competitive adsorption of surfactant and oil molecules was postulated, allowing a much better description of experimental data. This picture, however, was unable to explain why the interfacial tension of the water/oil interface decreases very quickly when extremely small amounts of surfactants are added to the water. This effect cannot be of competitive nature, but a cooperativity of surfactant and oil molecules forming a mixed adsorption layer is required instead. This cooperative effect means that already few surfactant molecules adsorbed at the interface can induce a significant ordering of oil molecules in the interfacial layer. This new interfacial structure, in turn, attracts further surfactant molecules to adsorb. Improving the theoretical description of experimental data was finally achieved by applying suitable adsorption models for the two adsorbing compounds, i.e. a Frumkin adsorption model for the oil molecules and a Langmuir, Frumkin, or reorientation model for the adsorbing surfactant molecules. Here, the progress in modelling surfactant adsorption at water/oil interfaces is discussed mainly for the homologous series of the cationic surfactants C_nTAB, of the anionic surfactant SDS, and members of the homologous series of the non-ionic surfactants C_nDMPO at water/alkane interfaces.

Surveillance for enterotoxigenic & enteropathogenic Escherichia coli isolates from animal source foods in Northwest Iran

Background & objectives:

Diarrhoeagenic Escherichia coli strains are common agents of diarrhoea particularly in developing countries. Food products of animal origin are considered as common carriers of E. coli. This study was undertaken to identify enterotoxigenic Escherichia coli (ETEC) and enteropathogenic E. coli (EPEC) pathotypes in animal-source foods (ASF).

Methods:

A total of 222 ASF samples were investigated. Based on the culture and biochemical tests, 109 E. coli isolates were identified. Duplex-polymerase chain reaction assay was used to detect ETEC and EPEC. The target genes selected for each category were the lt and st for the ETEC, and eae and bfp for the EPEC isolates.

Results:

The occurrence of E. coli in dairy and meat products was 45 and 52.5 per cent, respectively. Among the E. coli isolates, two ETEC, one typical EPEC and three atypical EPEC were detected in meat samples, whereas only one typical EPEC and one atypical EPEC were detected in dairy samples.

Interpretation & conclusions:

Our results showed presence of ETEC and EPEC strains in ASFs. The milk without pasteurization and traditional dairy products produced in unhygienic conditions are most likely the main sources of E. coli pathotypes and other zoonotic pathogens and thus can be considered a potential hazard to the health of the community.

Quality properties of sausage incorporated with flaxseed and tomato powders

The present study investigates the chemical properties and sensory attributes of beef sausages which have been incorporated with three tomato powder levels (0, 1.5 and 3%) and three flaxseed powder levels (0, 3 and 6%). All samples were stored at 4 °C for 42 days. The addition of tomato and flaxseed powders decreased (P < .001) L* values, pH, residual nitrite and moisture contents and increased b* value (P < .001), protein, carbohydrate, ash, fiber and total calories contents. The nitrite content decreased during the storage time. Linolenic acid increased with the addition of flaxseed powder. Generally, adding tomato and flaxseed powders up to 3% had no effect (P > .05) on the sensory evaluation parameters on cooked and fried sausages. Based on the obtained results, it is possible to produce sausages incorporated with tomato and flaxseed powders and introduce to the market as a new processed meat product.

Determination of Enrofloxacin and Ciprofloxacin Residues in Five Different Kinds of Chicken Tissues by Dispersive Liquid-Liquid Microextraction Coupled with HPLC

Contamination of food producing animals by veterinary drug residues, particularly quinolones, is an essential issue in food safety that causes increasing concern in consumers. The aim of this study was to investigate the occurrence of enrofloxacin and its main metabolite, ciprofloxacin, in chicken tissue samples slaughtered in Tabriz, Iran. Totally 250 samples including liver, muscle, gizzard, heart, and skin were studied. Dispersive liquid-liquid microextraction technique (DLLME) was used as a simple, high performance, low-cost, and fast sample pre-treatment method followed by a high-performance liquid chromatography with UV detection for quantitative analysis. The residues of enrofloxacin were detected and quantified in 26 liver (52%) and 10 skin (20%) samples and ciprofloxacin residues were detected in 3 skin (6%) samples and accurately determined in 15 liver (30%) samples; however they were not detected in gizzard, heart, and muscle samples. The results showed the accumulation of enrofloxacin and ciprofloxacin residues in chicken liver and skin.

Effect of commercial probiotic (Protexin®) on growth, survival and microbial quality of shrimp (Litopenaeus vannamei)

Purpose

The purpose of this study was to investigate the effect of a dietary probiotic on the growth performance and survival rate of Litopenaeus vannamei shrimp. Furthermore, the microbial quality of shrimp was evaluated.

Design/methodology/approach

Shrimp were divided into treatment and control groups (each group containing 45 shrimp). They were fed for four weeks with a control diet alone or supplemented with a commercial probiotic (Protexin®). At the end of the trial, they were assessed for survival rate, weight gain, average daily gain and specific growth rate. Samples of tail meat were also provided aseptically from peeled shrimp for bacteriological analysis including the count of Staphylococcus aureus, enterococci, Clostridium perfringens, fecal coliform, Salmonella, Escherichia coli, Listeria monocytogenes and total bacterial count.

Findings

The growth performance of the probiotic-treated group significantly (p < 0.05) increased at the end of the experimental period. However, no significant differences were observed for the survival rate between the groups (p > 0.05). The count of C. perfringens and the total bacterial count in shrimp supplemented with the probiotic were significantly lower than those of controls (p < 0.05). The count of coliforms and S. aureus was not significantly different between the groups (p > 0.05).

Originality/value

It could be concluded that the probiotic bacteria have the potential to stimulate the growth performance of L. vannamei. They can also be used for biological control of food-borne pathogens and improve the microbial quality and safety of shrimp at the farm level.

Comparison of serum PCR assay and histopathology for the diagnosis of invasive aspergillosis and mucormycosis in immunocompromised patients with sinus involvement

BACKGROUND AND PURPOSE

Invasive fungal infections cause morbidity and mortality in patients with hematologic malignancies and immunosuppression. Although these infections are commonly caused by Candida and Aspergillus species, infections caused by Mucoralean fungi are also on a growing trend. The definitive diagnosis of mucormycosis includes visualization of non-septate hyphae on pathology or growth of Mucoralean fungi culture. Polymerase chain reaction (PCR) is used to diagnose mucormycosis from paraffin blocks; however, it yields discrepant results in diagnosis of mucormycosis from blood samples. In the current study, we sought to examine the efficiency of PCR test for the diagnosis of mucormycosis and aspergillosis.

MATERIALS AND METHODS

Thirty-one patients with suspected fungal sinus infection were recruited from the Hematology-Oncology unit in Taleghani Hospital, Tehran, Iran. DNA was extracted and semi-nested PCR was performed.

RESULTS

PCR was reported negative for all the 31 serum samples. Our assay had a sensitivity of 1.3 ng and 12 pg for Mucoralean and Aspergillus species, respectively.

CONCLUSION

Using serum PCR, we detected Aspergillus and Mucoralean species in patients with suspected fungal sinus infection. While this test may have utility in diagnosis directly from biopsy site, it appears unreliable for use as a noninvasive blood test.

Dynamics of drops – Formation, growth, oscillation, detachment, and coalescence

Single drops or bubbles are frequently used for the characterization of liquid-fluid interfaces. Their advantage is the small volume and the various protocols of their formation. Thus, several important methods are based on single drops and bubbles, such as capillary pressure and profile analysis tensiometry. However, these methods are often applied under dynamic conditions, although their principles are defined under equilibrium conditions. Thus, specific attention has to be paid when these methods are used beyond certain limits. In many cases, computational fluid dynamics (CFD) simulations have allowed researchers, to extend these limits and to gain important information on the interfacial dynamics. Examples discussed here are the capillary pressure tensiometry used for short time and profile analysis tensiometry for long time dynamic interfacial tension measurements, the oscillating drop methods for measuring dilational visco-elasticity. For measuring the coalescence of two drops the liquid dynamics of the subsequently formed liquid bridges have to be considered. In this paper, a thorough review of important experimental and computational findings, related to the dynamics of drops, including its formation, growth, oscillation, detachment, and coalescence is presented. Emphasis is however on some selected important developments. In addition, the paper tries to predict the main directions of advancement in interfacial research for the near future.

Adsorption of proteins at the solution/air interface influenced by added nonionic surfactants at very low concentrations for both components. 2. Effect of different surfactants and theoretical model

The influence of the addition of the nonionic surfactants dodecyl dimethyl phosphine oxide (C12DMPO), tetradecyl dimethyl phosphine oxide (C14DMPO), decyl alcohol (C10OH), and C10EO5 at concentrations between 10(-5) and 10(-1) mmol/L to solutions of β-casein (BCS) and β-lactoglobulin (BLG) at a fixed concentration of 10(-5) mmol/L on the surface tension is studied. It is shown that a significant decrease of the water/air surface tension occurs for all the surfactants studied at very low concentrations (10(-5)-10(-3) mmol/L). All measurements were performed with the buoyant bubble profile method. The dynamics of the surface tension was simulated using the Fick and Ward-Tordai equations. The calculation results agree well with the experimental data, indicating that the equilibration times in the system studied do not exceed 30 000 s, while the time required to attain the equilibrium on a plane surface is by one order of magnitude higher. To achieve agreement between theory and experiment for the mixtures, a supposition was made about the influence of the concentration of nonionic surfactant on the adsorption activity of the protein. The adsorption isotherm equation of the protein was modified accordingly, and this corrected model agrees well with all experimental data.