Bioprospecting the potential of metabolites from a Saharan saline soil strain Nocardiopsis dassonvillei GSBS4

Saharan soil samples collected in El-Oued province have been investigated for actinobacteria as a valuable source for the production of bioactive metabolites. A total of 273 isolates were obtained and subjected to antagonistic activity tests against human pathogenic germs. A strain with a broad-spectrum antimicrobial activity was selected and identified as Nocardiopsis dassonvillei GSBS4, with high sequence similarities to N. dassonvillei subsp. dassonvilleiT X97886.1 (99%) based on polyphasic taxonomy approach and 16S ribosomal ribonucleic acid gene sequence analysis. The GSBS4 ethyl acetate crude extract showed strong antibacterial activity towards pathogenic bacteria and Candida albicans. It inhibited biofilm formation by Staphylococcus aureus and methicillin-resistant S. aureus with minimum inhibitory concentrations estimated at 0.144 and 1.15 mg·mL-1 , respectively. A 44% biofilm reduction was obtained for S. aureus and 61% for Pseudomonas aeruginosa. Furthermore, phenols composition of the crude extract showed a significant dose-dependent antioxidant activity by α-diphenyl-β-picrylhydrazyl (57.21%) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (64.29%) radicals scavenging assays. Although no inhibition was obtained on human coronavirus human coronavirus (HCoV) 229E and on model enterovirus (poliovirus 1) infection, a dose-dependent increase in cell viability of HCoV 229E-infected cells was noticed as the viability increased from 21% to 37%. Bioassay-guided fractionation of the crude extract gave a fraction showing antibacterial activity, which was analyzed by liquid chromatography-electrospray mass spectrometric technique, providing structural features on a major purple metabolite.

Alkaloids Extract from Linum usitatissimum Attenuates 12-OTetradecanoylphorbol- 13-Acetate (TPA)-induced Inflammation and Oxidative Stress in Mouse Skin

BACKGROUND

In traditional medicine, Linum usitatissimum treats inflammatory, gastrointestinal, and cardiovascular diseases.

OBJECTIVES

The present study aims to assess the anti-inflammatory and anti-oxidant effects of total alkaloid extract from Linum usitatissimum seeds (ALU) on the ear histological integrity and oxidant- antioxidant status in a mice model of a sub-chronic inflammation induced by multiapplication of TPA.

METHODS

Topical TPA treatment induced various inflammatory changes, including edema formation, epidermal thickness, and the excess production of reactive oxygen species. Tissue samples were used for the measurement of reduced glutathione (GSH) and nitric oxide (NO) levels and Myeloperoxidase (MPO) and Catalase (CAT) activities.

RESULTS

Oral administration of ALU (50, 100, and 200 mg/kg) produced anti-inflammatory and anti-oxidant effects. Also, ALU significantly reduced ear edema and inflammatory cell infiltration and restored the integrity of the ear.

CONCLUSION

These findings suggest that the total alkaloid extract from Linum usitatissimum seeds presents significant anti-inflammatory and anti-oxidant effects on TPA-induced sub-chronic inflammation model in NMRI mice and can be used as an anti-inflammatory and anti-oxidant agent for the therapeutic management of inflammatory disorders.

Occurrence of the Plasmid-Mediated Fluoroquinolone Resistance qepA1 Gene in Two Clonal Clinical Isolates of CTX-M-15-Producing Escherichia coli from Algeria

QepA is a plasmid-mediated quinolone resistance determinant of low prevalence described worldwide, mainly in Enterobacteriaceae. This study describes, for the first time in Algeria, two clonally related, QepA-producing Escherichia coli clinical isolates positive for CTX-M-15. The clonal spread of these multidrug-resistant isolates is a major public health concern.

Characterization of Plasmid-Mediated Quinolone Resistance Determinants in High-Level Quinolone-Resistant Enterobacteriaceae Isolates from the Community: First Report of qnrD Gene in Algeria

OBJECTIVE

The objective was to assess the prevalence of plasmid-mediated quinolone resistance (PMQR)-producing isolates in a collection of quinolone-resistant Enterobacteriaceae of community origin isolated in Bejaia, Algeria.

METHODS

A total of 141 nalidixic acid-resistant Enterobacteriaceae community isolates were collected in Bejaia (Northern Algeria) and screened for PMQR genes using polymerase chain reaction (PCR). For PMQR-positive strains, antimicrobial susceptibility testing was performed by broth microdilution and disk diffusion. Mutations in the quinolone resistance-determining regions of the target genes, gyrA and parC, were detected with a PCR-based method and sequencing. Southern blotting, conjugation and transformation assays and molecular typing by pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing were also performed.

RESULTS

The prevalence of PMQR-producing Enterobacteriaceae isolates was 13.5% (19/141); 11 of these isolates produced Aac(6')-Ib-cr and 8 were qnr-positive (4 qnrB1-like, 2 qnrS1-like, and 2 qnrD1-like), including the association with aac(6')-Ib-cr gene in three cases. PMQR gene transfer by conjugation was successful in 6 of 19 isolates tested. PFGE revealed that most of the PMQR-positive Escherichia coli isolates were unrelated, except for two groups comprising two and four isolates, respectively, including the virulent multidrug-resistant clone E. coli ST131 that were clonally related.

CONCLUSION

Our findings indicate that PMQR determinants are prevalent in Enterobacteriaceae isolates from the community studied. We describe the first report of the qnrD gene in Algeria.