Prevalence of Class 1 Integrons and Extended Spectrum Beta Lactamases among Multi-Drug Resistant Escherichia coli Isolates from North of Iran

Background:

Extended spectrum beta lactamases (ESBLs) are an important cause of transferable multidrug resistance (MDR) in gram-negative bacteria. The most described ESBL genes are generally found within integron-like structures as mobile genetic elements. The aim of this study was to identify the accompanying of class 1 integrons and ESBLs in the MDR E. coli isolates.

Methods:

Susceptibility to antimicrobial agents was determined for 33 E. coli strains by the disk diffusion method. Double-disk synergy test was applied for screening ESBL. To identify the strains carrying integrons, the conserved regions of integron-encoded integrase gene intI1 were amplified. For detection of gene cassettes, 5′CS and 3′CS primers were used.

Results:

All E. coli isolates were identified as multi-drug resistant. More than 50% of the isolates were resistant to tetracycline, cephalothin, cefuroxime, amoxicillin-clavulanic acid, and third generation cephalosporines. Nearly all of the isolates displayed sensitivity to piperacillin. There was a significant correlation between production of ESBL and resistance to all antibiotics except for ciprofloxacin and piperacillin (P < 0.01). Thirty two MDR strains (97%) included class 1 integron, and some isolates that included integrons were similar in the size of gene cassettes. The isolates were different in the resistance profiles; however, some others had similar resistance profiles. Of eight ESBL positive isolates, seven (87.5%) carried class 1 integrons.

Conclusion:

Class 1 integrons were frequent in MDR and also ESBL-producing E. coli isolates. High prevalence of class 1 integrons confirms that integron-mediated antimicrobial gene cassettes are important in E. coli resistance profile. Key Words: Antibiotic, Integrons, Escherichia coli     

A PCR-based assay for differentiating A- and A*-type strains of Xanthomonas citri subsp. citri, the causal agent of Asiatic citrus canker

By applying A- and A*-type strains of Xanthomonas citri subsp. citri (Xcc) in a repetitive sequence-based polymerase chain reaction (rep-PCR), two DNA amplicons, one unique to each strain, were evaluated as a probe against the DNA of Xcc strains. Two pairs of primers derived from these amplicons were tested in a PCR analysis. The results confirmed that primers Ms⁺/Ms^? are useful for differentiating A-type from A*-type strains of Xcc. Also, a multiplex PCR with both set of primers can be used to distinguish three groups in Xcc populations: A-type strains and two subgroups of A* strains including Iranian and Thai A* strains.     

Serum biochemical and non-specific immune responses of rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) to dietary nucleotide and chronic stress

The aim of the present study was to investigate whether supplementary nucleotide “Optimun” mitigates the adverse effects of chronic overcrowding in Oncorhynchus mykiss. Two experimental diets [control and nucleotide-supplemented (0.2 %)] and two rearing densities (10 and 30 kg m^?3) were combined to have four experimental treatments. The fish were reared for 45 days under different densities using different diets. At the end of the trial, FCR of the fish in higher density was significantly higher than those of the lower density. Nucleotide had no significant effects on growth performance and survival rate. Supplemented nucleotide significantly increased blood hematocrit, whereas it decreased serum total protein, total immunoglobulin (Ig) and creatinine. Overcrowding significantly increased serum glucose and total protein level and decreased serum lysozyme activity, but supplemented nucleotide produced no improvement in these items. No significant effect of overcrowding and dietary nucleotide was observed on serum cortisol. Supplemented nucleotide significantly increased serum urea under low stocking density. Overall, the results showed that 0.2 % “Optimun” had no positive effects on rainbow trout and also caused some immunological and metabolic problems. These findings are not in accordance with those obtained in the same species, with same nucleotide source and level, but acute stress; thus, further studies are encouraged on this topic.     

Effect of β-aminobutyric acid on resistance of tomato against Pectobacterium carotovorum subsp. carotovorum

Journal of Plant Diseases and Protection - Stem rot of tomato caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) results in economic yield loss worldwide. Previous studies have...     

Investigation on the Biodegradability and Antibacterial Properties of Nanohybrid Suture Based on Silver Incorporated PGA-PLGA Nanofibers

Polyglycolic acid-poly lactic glycolic acid (PGA-PLGA) electrospun nanofibers containing silver nanoparticles have been produced and twisted into the nanofibrous yarn. The morphology of nanofibers and produced yarns, as well as the mechanical properties of the yarns, were investigated. Furthermore, in vitro antibacterial properties and in vitro degradation behavior of yarns containing various silver nanoparticles were studied. SEM images confirmed that the addition of the silver nanoparticles into the polymer solution increases the fiber diameters. The result of the mechanical test of the yarns alone and used in two different forms of the knots was measured and results showed that the strength of the yarns without the knot was significantly more than that of others. The biodegradability test showed that the mechanical properties and the weight of the yarns were quickly reduced after subjecting to in vitro condition. The result of the antibacterial test indicated that the nanofiber yarns containing %3 silver nanoparticles were the most appropriate sample with a considerably antibacterial activity against both gram-positive bacterium Staphylococcus aureus and gram-negative bacterium Escherichia Coli with inhibition zones of 8.1 and 9.5 mm, respectively; which demonstrated that silver nanoparticles retained their effectiveness after the electrospinning process. Therefore the nanofibrous yarns containing silver nanoparticles could be successfully produced by the electrospinning process with the proper antibacterial property as a candidate for the surgical sutures.     

Interactive Effect of Fluorescent Pseudomonads Rhizobacteria and Zn on the Growth,Chemical Composition,and Water Relations of Pistachio (Pistacia vera L.) Seedlings under NaCl Stress

The role of fluorescent pseudomonads isolates (pf₀, pf₁, pf₂, and pf₃) and zinc (Zn) (0 and 5 mg kg^?1 soil) interactions in alleviating salinity in pistachio seedlings were investigated. The experiment was conducted following completely randomized design with three replicates. The results revealed that salinity decreased the growth parameters, while application of PGPR (plant growth-promoting rhizobacteria) and Zn increased these parameters. Application of PGPR significantly enhanced phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), Zn, Ca/sodium (Na), and K/Na contents, while decreased the accumulation of Na and chloride (Cl). Application of PGPR and Zn increased the phenolic compounds, sucrose, membrane stability index (MSI), and relative water content (RWC) but reduced the malondialdehyde (MDA) amount. A positive correlation was observed between Zn concentrations with seedling dry weights, phenolic compounds, MSI, and RWC contents. These results indicated that the combined application of PGPR and Zn could be a simple treatment for growth and establishment of pistachio seedlings under Zn deficiency and soil salinity.     

Surveying the relations among traits affecting seed yield in sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.)

To determine the most important traits influencing seed yield of sesame, 18 lines were evaluated in a randomized block design with three replicates in two years during the 2013 and 2014 growing seasons. Following a combined analysis of variance, multivariate statistical analyses such as simple correlation coefficients, factor analysis, stepwise analysis, path analysis, and cluster analysis were administered on combined means. The correlation coefficient analysis showed a significant negative correlation between seed yield and number of capsules per plant and number of seeds per capsule. Correlation between germination period and seed yield was positive and significant at 5% probability level. Factor analysis divided the 14 measured variables into five factors. In the stepwise regression analysis for seed yield as the independent variable, four traits including number of capsules per plant, first capsule height, number of seeds per capsule, and stem length to first capsule were entered into the regression model in four steps with r² =0.72. The regression coefficient of number of capsules per plant, number of seeds per capsule, and stem length to first capsule were negative and the regression coefficient of the first capsule height was positive and significant at the 5% probability level. The path coefficient analysis based on seed yield as a dependent variable implicated that the number of seeds per capsule had the highest negative direct effect on seed yield. The highest negative indirect effect on seed yield was related to the number of capsules per plant through the number of seeds per capsule. Cluster analysis using Ward’s method divided 18 investigated lines into five clusters.     

Incorporating Roasted Coffee Bean into Nile Tilapia Diets Does Not Improve Growth Performance

This study was conducted to use ground roasted coffee bean (GRC; Coffee arabia) as a feed supplement in diets for Nile tilapia, Oreochromis niloticus. Fish (1.9 ± 0.03 g) were fed diets containing 0.0, 0.5, 1.0, 2.0, or 5.0 g GRC/kg in triplicate for 10 weeks. Final fish weight, weight gain, and specific growth rate were not significantly (P < 0.05) affected by GRC incorporation up to 1.0 g/kg, after which growth declined. Fish fed diets containing 2.0 and 5.0 g GRC/kg consumed less than the other treatments, giving the highest FCR (1.4 and 1.5, respectively). No significant differences were observed in fat efficiency ratio, protein efficiency ratio, and energy utilization for the 0.0–1.0 GRC/kg diets; lowest values of these parameters were obtained with the 2.0 and 5.0 g GRC/kg diets. Supplementation of GRC significantly reduced fish whole-body protein content and increased lipid and ash.     

The Use of American Ginseng (Panax quinquefolium) in Practical Diets for Nile Tilapia (Oreochromis niloticus): Growth Performance and Challenge with Aeromonas hydrophila

This study was carried out to evaluate the effect of American ginseng (AG), Panax quinquefolium, on growth and resistance to Aeromonas hydrophila in Nile tilapia, Oreochromis niloticus. Ginseng was included in practical test diets at rates of 0.0 (control), 0.50, 1.0, 2.0, or 5.0 g/kg diet. Fish (9.1 ± 0.3 g) were distributed into quadricated 100-L aquaria at a density of 20 fish per aquarium. Fish in all treatments were fed up to satiation twice daily for 8 weeks. After the feeding trial, fish of each treatment were intraperitoneally injected with pathogenic A. hydrophila and kept under observation for 10 days. Highest growth was obtained at 1.0 – 5.0 g AG/kg diet. The survival of fish challenged by A. hydrophila increased with increasing AG levels in fish diets. Cost-benefit analysis indicated that ginseng supplementation could reduce per kg costs by 15% with an optimum inclusion level of 2.0 g/kg.     

Influence of the Dietary Addition of Butylated-Hydroxytoluene and Lipid Level on the Flesh Lipid Quality of Beluga Sturgeon (Huso huso) During Frozen Storage

The main aim of the present work was to evaluate the effect of dietary butylated-hydroxytoulene (BHT as an antioxidant) and dietary lipid level on flesh lipid quality of Beluga sturgeon during frozen storage. An initial 135-day feeding trial evaluated practical-type diets containing 0 or 250 mg BHT kg^?1 with two lipid levels (12 and 24% diet on dry matter basis) in a factorial arrangement. Fillet samples were analyzed fresh or after storage at ?18 ± 1°C for 12 months. Dietary antioxidant supplementation had no significant effect on fat content and fatty acid composition in the studied fish muscle, but increasing the lipid concentration in the feed increased muscle lipid concentration. Lipid oxidation in fish muscle is related to increasing lipid concentration in the feed. In addition, oxidation was reduced for fish fed BHT. Results showed that dietary BHT supplementation can slow down the level of lipid oxidation in Beluga sturgeon muscles during frozen storage, but it had a direct relationship with dietary lipid level.