Legionella pneumophila sg1-sensing signal enhancement using a novel electrochemical immunosensor in dynamic detection mode

International audienc

Control of Multidrug-Resistant Pathogenic Staphylococci Associated with Vaginal Infection Using Biosurfactants Derived from Potential Probiotic Bacillus Strain

Biosurfactants exhibit antioxidant, antibacterial, antifungal, and antiviral activities. They can be used as therapeutic agents and in the fight against infectious diseases. Moreover, the anti-adhesive properties against several pathogens point to the possibility that they might serve as an anti-adhesive coating agent for medical inserts and prevent nosocomial infections, without using synthetic substances. In this study, the antimicrobial, antibiofilm, cell surface hydrophobicity, and antioxidative activities of biosurfactant extracted from Bacillus sp., against four pathogenic strains of Staphylococcus spp. associated with vaginal infection, were studied. Our results have shown that the tested biosurfactant possesses a promising antioxidant potential, and an antibacterial potency against multidrug clinical isolates of Staphylococcus, with an inhibitory diameter ranging between 27 and 37 mm, and a bacterial growth inhibition at an MIC of 1 mg/ mL, obtained. The BioSa3 was highly effective on the biofilm formation of different tested pathogenic strains. Following their treatment by BioSa3, a significant decrease in bacterial attachment (p < 0.05) was justified by the reduction in the optical (from 0.709 to 0.111) following their treatment by BioSa3. The antibiofilm effect can be attributed to its ability to alter the membrane physiology of the tested pathogens to cause a significant decrease (p < 0.05) of over 50% of the surface hydrophobicity. Based on the obtained result of the bioactivities in the current study, BioSa3 is a good candidate in new therapeutics to better control multidrug-resistant bacteria and overcome bacterial biofilm-associated infections by protecting surfaces from microbial contamination

Nosocomial Outbreak Caused by Salmonella enterica Serotype Livingstone Producing CTX-M-27 Extended-Spectrum β-Lactamase in a Neonatal Unit in Sousse, Tunisia

In this study, we report an outbreak of Salmonella enterica serotype Livingstone resistant to extended-spectrum cephalosporins that occurred in a neonatal ward of the maternity department of Farhat Hached Hospital, Sousse, Tunisia, in 2002. A total of 16 isolates were recovered from 16 babies hospitalized in the ward during the period 1 to 16 July. All these babies developed diarrhea, and three of them developed septicemia. All the isolates demonstrated resistance to ceftriaxone and ceftazidime due to the production of an extended-spectrum β-lactamase (ESBL). The isolates were also resistant to aminoglycosides (kanamycin, tobramycin, netilmicin, gentamicin, and amikacin) and sulfamethoxazole-trimethoprim. DNA profiles were determined by pulsed-field gel electrophoresis using the XbaI and SpeI endonucleases and by ribotyping with PstI digestion. They yielded the same patterns, showing that the outbreak was caused by a single clone. The ESBL was identified as CTX-M-27 by sequencing of PCR products and by isoelectric focusing. The ESBL resistance was transferred by a 40-kb conjugative plasmid. The mobile insertion sequence ISEcp1 was found to be located upstream of bla(CTX-M-27) in the same position as that known for a bla(CTX-M-14) sequence. A new gene named dfrA21, encoding resistance to trimethoprim and carried by a 90-kb plasmid, was characterized. The dfrA21 gene was inserted as a single resistance cassette in a class I integron. The babies were treated with colistin, and all except two recovered. The outbreak came to an end when appropriate actions were taken: patient isolation, hand washing, and disinfection of the ward

Microbial diversity and pathogenic properties of microbiota associated with aerobic vaginitis in women with recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a major reproductive problem that affects approximately 5% of couples. The objective of this study was to assess vaginal flora dysbiosis in women suffering from unexplained RPL and to investigate the pathogenic properties of the microbiota associated with aerobic vaginitis (AV). The study included one hundred fifteen women, 65 with RPL and 50 controls. The diversity of vaginal microbiota isolated was evaluated by molecular sequencing. Then, pathogenic factors, such as acid-resistance, antibiotics susceptibility, and biofilm formation were evaluated. The prevalence of AV was five-fold higher in the RPL group than in the controls (64.6% vs. 12.0%). The most prevalent isolates in the case group were Enterococcus spp. (52%) and Staphylococcus spp. (26%). All bacterial strains tolerate low pH. The prevalence of multidrug resistance (MDR) among all bacteria was 47.7%. Of all strains, 91.0% were biofilm producers. The presence of MDR was found to be related to biofilm formation. The results provide evidence supporting an increased presence of dysbiosis of the vaginal flora, especially AV, in women with RPL in Tunisia. The viability of the AV-associated bacteria and their persistence in the genitals may be due to their ability to resist low pH and to produce a biofilm

Control of Multidrug-Resistant Pathogenic Staphylococci Associated with Vaginal Infection Using Biosurfactants Derived from Potential Probiotic <i>Bacillus</i> Strain

Biosurfactants exhibit antioxidant, antibacterial, antifungal, and antiviral activities. They can be used as therapeutic agents and in the fight against infectious diseases. Moreover, the anti-adhesive properties against several pathogens point to the possibility that they might serve as an anti-adhesive coating agent for medical inserts and prevent nosocomial infections, without using synthetic substances. In this study, the antimicrobial, antibiofilm, cell surface hydrophobicity, and antioxidative activities of biosurfactant extracted from Bacillus sp., against four pathogenic strains of Staphylococcus spp. associated with vaginal infection, were studied. Our results have shown that the tested biosurfactant possesses a promising antioxidant potential, and an antibacterial potency against multidrug clinical isolates of Staphylococcus, with an inhibitory diameter ranging between 27 and 37 mm, and a bacterial growth inhibition at an MIC of 1 mg/ mL, obtained. The BioSa3 was highly effective on the biofilm formation of different tested pathogenic strains. Following their treatment by BioSa3, a significant decrease in bacterial attachment (p p < 0.05) of over 50% of the surface hydrophobicity. Based on the obtained result of the bioactivities in the current study, BioSa3 is a good candidate in new therapeutics to better control multidrug-resistant bacteria and overcome bacterial biofilm-associated infections by protecting surfaces from microbial contamination

Isolation, characterization and identification of a new lysinibacillus fusiformis strain zc from metlaoui phosphate laundries wastewater: Bio-treatment assays

The aim of the present study is to isolate, characterize and identify a novel strain ZC from the Metlaoui phosphate laundries wastewater (MPLW). The chemical characterization of this phosphate rich effluent showed an alkaline pH and is saline, highly turbid and rich in suspended matter and total solids. The MPLW samples were loaded with potentially toxic metals, presented in decreasing order as follows: magnesium (5655 mg L), potassium (45 mg L), lead (1 mg L), iron (0.7 mg L), cadmium (0.5 mg L), copper (0.3 mg L) and zinc (0.1 mg L). Due to the high COD/BOD ratio, a poorly biodegradable organic load is underlining. The newly isolated strain was identified as Lysinibacillus fusiformis using 16S rDNA sequencing analysis. The viability of this new strain was tested in presence of the zinc, lead, cadmium, manganese and copper at 1, 10 and 100 mM. The L. fusiformis survival, under metallic stress, was inversely proportional to metal ion concentrations, while lead and zinc were the most toxic ones using MTT assay. Then, the newly isolated strain was characterized in terms of enzyme production, proteomic alteration and antibiotic resistance. The strain ZC revealed some modifications in the biochemical and enzymatic profiles by either the appearance or/and the disappearance of some activities. In addition, the increase in metal ions stress and concentrations was proportional to the adherence and to the hydrophobicity. The presence of the metal ions suggested the change of sensitivity to the resistance of this strain towards tobramycin, kanamycin, neomycin, netilmicin and cefoxitin, showing an increase in the MAR. The strain ZC, used as a biological tool for MPLW treatment, showed a reduction in the metal ion contents. This reduction was due to accumulation and/or adsorption, showing a bioprocessing performance of the newly isolated L. fusiformis

Characterisation of electrochemical immunosensor for detection of viable not-culturable forms of Legionellla pneumophila in water samples

International audienceLegionella pneumophila may cause a fatal pneumonia in humans known as Legionnaires’ disease (LD). The strategies of L. pneumophila to adapt to and resist stressful environmental conditions include the ability to enter into a VBNC (viable but not culturable) state. The detection of L. pneumophila in environmental samples benefits from the use of standardised methods: for detection and enumeration following membrane filtration (AFNOR T90-431, ISO 11731) and detection and quantification by polymerase chain reaction PCR (AFNOR T90-471, ISO 12869). Culture is hampered by its inability to detect VBNC forms and PCR is unable to discriminate between live and dead bacteria. The present immunosensor was obtained by the immobilisation of a monoclonal anti-L. pneumophila antibody (MAb) on an indium-tin oxide (ITO) electrode by the self-assembled monolayers (SAMs) method using an aminosilane. The immunosensor was characterised by wettability (contact angle measurement), atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM), and electrochemical impedance spectroscopy (EIS). A limit of detection of 10 bacteria per mL was observed on artificial samples