Detection of some virulence factors in staphylococcus aureus isolated from shahid beheshti hospital of hamedan in the years 2014-2015

Background and Objectives: Staphylococcus aureus is one of the most important nosocomial pathogens. Pathogenicity of this organism is attributed to various virulence factors such as surface adhesion proteins, the ability to produce toxins and enzymes, rapid development of drug resistance and biofilm formation. The present study was conducted to investigate some of the virulence factors of S. aureus isolates

Materials and Methods: A total of 30 isolates of S. aureus were collected from clinical samples of patients hospitalized in Shahid Beheshti hospital of Hamedan. Identification of bacteria was done using biochemical [catalase, coagulase and DNase] and molecular [PCR] tests. Thereafter, antibiotic susceptibility of the isolates and their ability to produce hemolysin, beta-lactamase and biofilm were assessed using disk diffusion, blood agar medium, acidimetric and microtiter-plate tests, respectively

Results: Hemolysis activities of the isolates on sheep blood agar showed that 8 [26.66%], 14 [46.66%] and 15 [50%] out of 30 isolates, produced a-, 3- and p-hemolysins, respectively. While, using human blood agar media, the prevalence of these toxins were 40%, 53.33% and 13.33%, respectively. Twenty one isolates [70%] were found to be beta-lactamase producer using the acidimetric test. Meanwhile, the results of antibiotic susceptibility test indicated that penicillin was the less effective antibiotic [90% resistance]. However, none of the isolates was resistant to vancomycin. Moreover, regarding to biofilm formation, 14 [46.66%] isolates strongly produced biofilms

Conclusions: The results of this study revealed high frequencies of the virulence factors among the examined 5. aureus isolates, specially the ability of biofilm formation and antibiotic resistance

Generation of a uracil auxotroph strain of the probiotic yeast Saccharomyces boulardii as a host for the recombinant protein production

Saccharomyces boulardii [S. boulardii] is the best known probiotic yeast. The genetic engineering of this probiotic strain requires the availability of appropriate mutants to accept various gene constructs carrying different selection markers. As the auxotrophy selection markers are under focus, we have generated a ura3 auxotroph mutant of S. boulardii for use in further genetic manipulations. Classical UV mutagenesis was used for the generation of auxotroph mutants. The mutants were selected in the presence of 5-FOA [5-Fluoroorotic acid], uracil and uridine. Uracil auxotrophy phenotype was confirmed by the ability of mutants to grow in the presence of uracil and the lack of growth in the absence of this compound. To test whether the uracil auxotrophy phenotype is due to the inactivation of URA3, the mutants were transformed with a plasmid carrying the gene. An in vitro assay was used for the analysis of acid and bile resistance capacity of these mutants. Three mutants were found to be ura3 auxotroph as they were able to grow only in the presence of uracil. When the URA3 gene was added, these mutants were able to grow normally in the absence of uracil. Further in vitro analysis showed that the acid and bile resistance capacity of one of these mutants is intact and similar to the wild type. A uracil auxotroph mutant of the probiotic yeast, S. boulardii, was generated and characterized. This auxotroph strain may have potential applications in the production and delivery of the recombinant pharmaceutics into the intestinal lumen

Molecular characterization of a Salmonella typhimurium isolate from Caspian pony

Typhoid disease or salmonellosis is a common sickness in horses. In several epidemiological studies in hospitalized horses, several serotypes of Salmonella often are predominant in nosocomial infections. Transportation, overcrowding, dehydration, oral antimicrobial therapy and infections are the risk factors which may activate latent or subclinical salmonellosis. In this study, the occurrence of typhoid due to Salmonella serogroup B was considered in a Caspian ponies flock kept in a husbandry center of ponies around Tehran. During transportation of 19 ponies, two pregnant ponies aborted and four cases died because of acute septicemia. Pathological and bacteriological follow up showed salmonellosis. A multiplex poly-merase chain reaction [m-PCR] assay was used for detection and identification of Salmonella to confirm pathological and bacteriological studies. Salmonella typhimurium was isolated from bone marrow, mesenteric lymph nodes, liver and intestinal contents of died pony. Salmonella was not isolated from stools of other ponies. Pulsed Field Gel Electrophoresis [PFGE] and antibiotic susceptibility test were also performed. PFGE pattern was similar to the other collected isolates which have existed since more than 30 years ago in Iran. Because of importance of salmonellosis in ponies, using rapid methods are recommended to confirm the presence of Salmonella. Results showed that m-PCR permit to evaluate samples more rapidly than other methods and also can detect multiple genes simultaneously like virulence factors which declare virulence of the isolates and have surveillance significances