This study shows that rhamnolipid mixtures of MR01 and MASH1 have antimicrobial efficacy against Gram positive bacteria and may be evaluated as antimicrobial agent against multidrugresistant clinical pathogenic isolates. Background:In recent decades, biological properties of biosurfactants, particularly glycolipids, including antimicrobial, antifungal, and anti-cellular effects have been projected in many research studies. The unique advantages of these compounds in terms of production and environment made them important as antimicrobial agents. Objectives: This study aims to evaluate probable antibacterial and antifungal properties of MR01 and MASH1 biosurfactants against several specified microorganisms. Materials and Methods:In this article antibacterial activities of two rhamnolipid mixtures of MR01 and MASH1 were studied. MR01 and MASH1 are glycolipid-type biosurfactants that are being produced by two strains of Pseudomonas aeruginosa MR01 and MASH1, respectively. Antibacterial effects of two biosurfactants were assessed by disc diffusion test method and determination of minimum inhibitory concentration (MIC). Results: They exhibit not only excellent surface activity but also remarkable inhibitory effect against Gram-positive bacteria. According to results, although none of two biosurfactants showed significant effects on Gram negative bacteria growth inhibition, both assessing methods confirmed the growth inhibition of Gram-positive bacteria by MR01 and MASH1 biosurfactants. Conclusions: According to results of this study, MR01 and MASH1 biosurfactants had antimicrobial efficacy against Gram positive bacterial groups. This effect is comparable to antibiotics and therefore the future use of these biosurfactants as broad spectrum antibiotics is highly promising. These features of biosurfactants (BS) should broaden its applications in new advanced technologies. Future studies will be performed on characterization and isolation of biologically active fraction of the rhamnolipid biosurfactant produced by P. aeruginosa strains. This bioactive compound may be evaluated as a potent antimicrobial agent to be applied against a panel of pathogenic micro-organisms including a few multidrug-resistant (MDR) clinical pathogenic isolates such as methicillin-resistant Staphylococcus aureus (MRSA) and other MDR pathogenic strains.

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Objectives. The increasing prevalence of antibiotic-resistant Staphylococcus aureus, besides the inadequate numbers of effective antibiotics, emphasises the need to find new therapeutic agents against this lethal pathogen. Methods. In this study, to obtain antibody fragments against S. aureus, a human single-chain fragment variable (scFv) library was enriched against living methicillin-resistant S. aureus (MRSA) cells, grown in three different conditions, that is human peripheral blood mononuclear cells with plasma, whole blood and biofilm. The antibacterial activity of scFvs was evaluated by the growth inhibition assay in vitro. Furthermore, the therapeutic efficacy of anti-S. aureus scFvs was appraised in a mouse model of bacteraemia. Results. Three scFv antibodies, that is MEH63, MEH158 and MEH183, with unique sequences, were found, which exhibited significant binding to S. aureus and reduced the viability of S. aureus in in vitro inhibition assays. Based on the results, MEH63, MEH158 and MEH183, in addition to their combination, could prolong the survival rate, reduce the bacterial burden in the blood and prevent inflammation and tissue destruction in the kidneys and spleen of mice with MRSA bacteraemia compared with the vehicle group (treated with normal saline). Conclusion. The combination therapy with anti-S. aureus scFvs and conventional antibiotics might shed light on the treatment of patients with S. aureus infections.

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Background:Whooping cough was considered as one of the major causes of childhood morbidity and mortality worldwide. Resistant isolates of Bordetella pertussis to macrolides in some countries have been recently reported.Objectives:Recent reports on macrolide-resistant B. pertussis isolates and lack of evidence for such resistance in clinical isolates of the Iranian patients led the authors of the current study to study antibiotic susceptibility of the collected isolates in the country. Susceptibility of the B. pertussis isolates to three antibiotics was studied. Relatedness of the strains recovered in this research was also examined.Materials and Methods:The antibacterial activities of erythromycin, azithromycin, and clarithromycin antibiotics against the recovered isolates of 779 nasopharyngeal swabs were examined using MIC (Minimum Inhibitory Concentration) method. Relationship of the strains was characterized by Pulsed-field Gel Electrophoresis (PFGE).Results:Among the specimens, 11 cases (1.4%) were culture-positive. Among these isolates, only two isolates had high MIC values for erythromycin and clarithromycin. Pulsed-field gel electrophoresis analysis of the isolates revealed 6 PFGE profiles (A-F) among which three and two isolates had the same patterns in profiles A and B, respectively.Conclusions:Azithromycin can be a good drug of choice to treat patients infected by B. pertussis in Iran. Clonal relationship of the isolates showed that the same B. pertussis strains were isolated from different patients in Iran.