[Isolation of actinomycetes producing antibacterial against methicillin-resistant staphylococcus aureus from soils of Astara region, Iran]

Staphylococcus aureus is one of the important causes of severe infections in hospital and community, and the methicillin-resistant strains [MRSA] of the bacterium have high prevalence and mortality. This study aimed to isolate Actinomycete strains producing antibacterial agents for antibiotic therapy and control of infection spread. After sampling from the soils of different regions of Astara city, Starch Casein Agar [SCA] medium was used for isolation and purification of Actinomyces spp. In the next step, investigation of antimicrobial characteristics was done by primary screening via spot inoculation method on 96 isolates. Then, the ISP-2 medium was used for the isolation of Streptomyces at the secondary screening stage, and by determination of the antimicrobial activity against MRSA, the strong isolates in terms of producing antimicrobial agents were selected by well diffusion method and based on the diameter of inhibition zone. In the final step, various biochemical tests, such as sugar tests, urease, citrate consumption, etc. were used to identify the active isolates. 96 Actinomycetes isolates were isolated from 51 soil samples of different areas of Astara. In primary screening, 9 isolates showed anti-MRSA activity, of which, 3 isolates of AS22, FS38, and AS13 were active in the secondary screening, and showed inhibition zones with the diameters of 28, 17, and 15 mm, respectively. The results of this research indicated that soils of Astara are rich in active isolates producing antibacterial agents, which needs further investigations

[Evaluation of the level of contamination with salmonella spp. in red meat, chicken, and domestic and industrial eggs produced in Talesh city and assessment of their antibiotic resistance pattern, Iran]

Red meat, chicken meat and egg play a crucial role in supplying human dietary protein. Bacteria of enterobacteriaceae family, particularly Salmonella spp. Are one of the factors that endanger the health of protein food product. This study was undertaken aimed at determining the contamination level of these foodstuffs with Salmonella spp. and then evaluating their antibiotic resistance pattern. In this descriptive-cross sectional study, chicken, domestic eggs, and industrial eggs, each of them 100 samples, and 150 samples of red meats [beef and lamb] were collected through random sampling in Talesh city, and were assessed for contamination with Salmonella. For a definitive identification, biochemical assays as well as agglutination tests with related antisera were used. Data were analyzed using chi-square test. The significance level of differences was considered p<0.05. No bacteria were observed in the inner content of the domestic and industrial eggs. However 19 [19%] Salmonella isolates were obtained from the outer surface of industrial eggs shell, 4 [4%] from domestic eggs, 21 [21%] from industrial chicken, 5 [5%] from domestic chicken, and 5 [3.3%] from red meat. In terms of antibiotic resistance in isolated bacteria, the highest resistance was seen against erythromycin, nalidixic acid, and sulfamethoxazole, and the most susceptibility was for ciprofloxacin, cephalexin, and gentamicin. Based on the obtained results, attention to healthiness of foodstuffs is of particular importance for prevention of food-borne infections. Also, in order to prevent the appearance of resistant strains, indiscriminate use of antibiotics should be avoided in poultry and livestock industries

Extraction, purification and characterization of lipopolysaccharide from Escherichia coli and Salmonella typhi

Lipopolysaccharide [LPS] is an important structural component of the outer cell membrane complex of gram negative microorganisms. Its causative role in gram negative bacteria-induced diseases and broad applications in different kinds of cell stimulation experiments provided a conceptual basis for studies directed at the isolation, purification, and detailed chemical characterization of LPS. The main problem with LPS purification protocols is the contamination of the end product with nucleic acids and proteins in variable proportions which could potentially interfere with downstream applications. In this study, a simple procedure for purification of LPS from Escherichia coli [E.coli] and Salmonella typhi [S.typhi] with high purity and very low contaminating nucleic acids and proteins based on the hot phenol-water extraction protocol has been introduced. The purity of extracted LPS was evaluated by silver and coomassie blue staining of SDS-PAGE gels and HPLC analysis. Limulus Amebocyte Lysate [LAL] coagulation activity and rabbit pyrogen assay were exploited to monitor the functionality of purified LPS. The results showed that DNase and RNase treatment of the sample is essential after the sonication step to eliminate nucleic acid contamination in the LPS fraction. Silver staining demonstrated ladder pattern which is characteristic of LPS. No contaminating protein was found as assessed by coomassie blue staining. HPLC fractionation revealed high degree of purity comparable with commercial LPS. Parenteral administration of purified LPS resulted in substantial increase of rabbits' body temperature [mean: 1.45°C]. LAL coagulation assay confirmed the functional activity of the purified LPS. In conclusion, the protocol presented here could be employed for isolation of LPS with high purity and functional activity