The occurrence and resistance of Shigella flexneri CECT4804 to acid stress in vitro and in vivo.

The ability to maintain intra­cellular pH is crucial for many microbes mainly the enterobacteria to survive in diverse environments, particularly those that undergo fluctuations in pH. In this context, the growth and survival of Shigella flexneri at different acid pH values were evaluated to explain the response strategies involved in the adaptation of S. flexneri CECT4804 in acid stress conditions. Furthermore, the capacity of this strain to produce slime on Congo Red Agar, biofilm formation on polystyrene plate and hydrophobicity are reported. In addition, the modification of the membrane fatty acids profiles has been studied. Moreover, an infection with the stressed strain was realized on rats in rates and examined for their toxicity in intestine tissue. The obtained results show that the strain survival is strongly influenced by acidity. Indeed, the stressed and unstressed strains became biofilm positive after acid stress. A significant increase in the hydrophobicity percentage compared to the values found under normal conditions, is also noticed. For the membrane fatty acids analysis, the acidity induces several modifications in the membrane composition. After the infection, the gravest lesion was registered in the intestine of rats administered with the bacteria stressed at the lowest pH.

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.

Modeling and optimization of biodegradation of methylene blue by Staphylococcus aureus through a statistical optimization process: a sustainable approach for waste management.

Bacterial species for metabolizing dye molecules were isolated from textile wastewater. The best microbial species for such an application was selected amongst the isolated bacterial populations by conducting methylene blue (MB) batch degradation studies with the bacterial strains. The most suitable bacterial species was Staphylococcus aureus (S. aureus). Process parameters were optimized using Full Factorial Design (FFD) and under the optimum conditions (pH of 5, temperature of 35 °C, 150 ppm, and time of 8 h). Response Surface Methodology (RSM) modeling technique was applied to model the process and their performance and predictive capabilities of the response (removal efficiency) was also examined. When tested with 20 ppm dye using batch reactors, the maximum COD and color removal efficiencies, were found to be 88% and 98%, respectively. Our results showed that Staphylococcus aureus had a high decolorization capacity. UV-Visible and Fourier-transform infrared (FTIR) spectroscopy analysis confirmed the biodegradation of MB. Using phytotoxicity and mutagenicity endpoints, toxicological studies of MB before and after biodegradation were studied. Toxicity assay signaled that biodegradation led to the detoxification of MB dye.

Control of Staphylococcus aureus methicillin resistant isolated from auricular infections using aqueous and methanolic extracts of Ephedra alata.

In the current study the potential use of aqueous and methanolic extracts of Ephedra alata aerial parts as biological control agent against pathogenic bacteria and especially Staphylococcus aureus methicillin resistant isolated from auricular infections was evaluated. Chemical tests and spectrophotometric methods were used for screening and quantification of phytochemicals. The assessment of the antioxidant activity was accomplished by DPPH and ABTS radicals scavenging assays. Extracts were evaluated for their antibacterial efficacy by diffusion and microdilution methods. Biofilm inhibition was tested using XTT assay and the cytotoxicity of extracts was carried out on Vero cell line. The GC-FID analysis revealed that E. alata was rich in unsatured fatty acids. In addition, the aqueous extract had the highest flavonoid and protein contents (30.82 mg QE /g dry extract and 98.92 mg BSAE/g dry extract respectively). However, the methanolic extract had the highest phenolic, sugars and tannins. The antioxidant activity demonstrated that the aqueous extract exhibited the strong potency (IC50 ranged between 0.001 and 0.002 mg/mL). Both extracts displayed antimicrobial activity on Gram negative and positive strains. They were effective against S. aureus isolated from auricular infections. The tested extracts were able to inhibit biofilm formation with concentration-dependent manner. Moreover, no cytotoxic effect on Vero cells line was demonstrated for the extracts. Overall, our findings highlight the potential use of E. alata extract as a novel source of bioactive molecules with antioxidant, antibacterial and antiobiofilm effects for the control of infectious disease especially those associated to S. aureus methicillin resistant.