Complete Genetic Analysis of Plasmids Carried by Two Nonclonal bla NDM-5 - and mcr-1 -Bearing Escherichia coli Strains: Insight into Plasmid Transmission among Foodborne Bacteria

Carbapenem and colistin are last-resort antibiotics used to treat serious clinical infections caused by multidrug-resistant (MDR) bacterial pathogens. Plasmids encoding resistance to carbapenems and colistin have been reported in clinical pathogens in recent years, and yet few studies reported cocarriage of mcr and bla NDM genes in Escherichia coli strains of food origin.

A transposon-associated CRISPR/Cas9 system specifically eliminates both chromosomal and plasmid-borne mcr-1 in Escherichia coli

The global spread of antimicrobial-resistant bacteria has been one of the most severe threat to public health. The emergence of mcr-1 gene has posed a considerable threat to antimicrobial medication since it deactivates one last-resort antibiotic, colistin. There have been reports regarding the mobilization of the mcr-1 gene facilitated by IS Apl1- formed transposon Tn 6330 and mediated rapid dispersion among Enterobacteriaceae species. Here we developed a CRISPR-Cas9 system flanked by IS Apl1 in a suicide plasmid capable of exerting the sequence-specific curing against mcr-1 bearing plasmid and killing the strain with chromosomal-borne mcr-1 . The constructed IS Apl1 -carried CRISPR-Cas9 system either restored the sensitivity to colistin of strains with plasmid-borne mcr-1 or directly eradicated the bacteria harbored the chromosomal-borne mcr-1 by introducing an exogenous CRISPR/Cas9 targeting mcr-1 gene. This method is highly efficient in removing mcr-1 gene from Escherichia coli and thereby resensitizing these strains to colistin. The further results demonstrated that it conferred the recipient bacteria with the immunity against the acquisition of the exogenous mcr-1- containing the plasmid. The data from the current study highlighted the potential of the transposon-associated CRISPR/Cas9 system to serve as a therapeutic approach to control the dissemination of mcr-1 resistance among clinical pathogens.

S. aureus and MRSA Nasal Carriage in Dental Students: A Comprehensive Approach

Staphylococcus aureus and MRSA are important clinical pathogens representing a serious public health problem. This study aimed to determine the prevalence of S. aureus and methicillin-resistant S. aureus (MRSA) nasal carriage among dental students, identify the factors that influence this carriage, and characterize MRSA. A prevalence of S. aureus and MRSA carriage of 25.2% and 0.86% was estimated, respectively, and SCCmec Type VI, was identified in all isolated MRSA. The low MRSA colonization rate can reflect good infection control practices followed by students.

Antibacterial and Antioxidant Activity of Metabolites From Bioconverted Docosahexaenoic Acid Using Gut Bacteria

Docosahexaenoic acid (DHA) is an essential fatty acid necessary for brain development in both infants and adults. However, the role of gut microbiome and their metabolites produced from DHA remain unclear. In present study, the bacterial isolates Lactobacillus spp. Clostridium spp. Escherichia coli; Staphylococcus spp. Enterococcus spp. were used to convert the metabolites from DHA with SM medium supplemented with 200mg of DHA as substrate. The metabolites were extracted after 24 hours of incubation at 37°C and analyzed by GC/MS. The antimicrobial activity of these metabolites confirmed their effectiveness against clinical pathogens such as Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Staphylococcus aureus.

Identification of floR Variants Associated With a Novel Tn4371-Like Integrative and Conjugative Element in Clinical Pseudomonas aeruginosa Isolates

Florfenicol is widely used to control respiratory diseases and intestinal infections in food animals. However, there are increasing reports about florfenicol resistance of various clinical pathogens. floR is a key resistance gene that mediates resistance to florfenicol and could spread among different bacteria. Here, we investigated the prevalence of floR in 430 Pseudomonas aeruginosa isolates from human clinical samples and identified three types of floR genes (designated floR, floR-T1 and floR-T2) in these isolates, with floR-T1 the most prevalent (5.3%, 23/430). FloR-T2 was a novel floR variant identified in this study, and exhibited less identity with other FloR proteins than FloRv. Moreover, floR-T1 and floR-T2 identified in P. aeruginosa strain TL1285 were functionally active and located on multi-drug resistance region of a novel incomplete Tn4371-like integrative and conjugative elements (ICE) in the chromosome. The expression of the two floR variants could be induced by florfenicol or chloramphenicol. These results indicated that the two floR variants played an essential role in the host’s resistance to amphenicol and the spreading of these floR variants might be related with the Tn4371 family ICE.

Recipe for Success: Suggestions and Recommendations for the Isolation and Characterisation of Bacteriocins

Bacteriocins are bacterially produced antimicrobial peptides. Although only two peptides have been approved for use as natural preservatives foods, current research is focusing on expanding their application as potential therapeutics against clinical pathogens. Our laboratory group has been working on bacteriocins for over 25 years, and during that time, we have isolated bacteriocin-producing microorganisms from a variety of sources including human skin, human faeces, and various foods. These bacteriocins were purified and characterised, and their potential applications were examined. We have also identified bioengineered derivatives of the prototype lantibiotic nisin which possess more desirable properties than the wild-type, such as enhanced antimicrobial activity. In the current communication, we discuss the main methods that were employed to identify such peptides. Furthermore, we provide a step-by-step guide to carrying out these methods that include accompanying diagrams. We hope that our recommendations and advice will be of use to others in their search for, and subsequent analysis of, novel bacteriocins, and derivatives thereof.

Biogenic Synthesis of ZnO Nanoparticles Mediated From Borassus Flabellifer (Linn): Antioxidant, Antimicrobial Activity Against Clinical Pathogens, And Photocatalytic Degradation Activity With Molecular Modeling.

Borassus flabellifer leaf extract has been used for rapid biogenic-synthesis of Zinc-Oxide nanoparticles (ZnO-NPs) due to rich source of bioactive compounds. The synthesized ZnO-NPs were preliminarily confirmed by UV-Visible spectroscopy adsorption peak range at 365nm. The XRD (X-ray diffraction) confirm purity of ZnO-NPs that were crystalline in nature. The analysis of FT-IR (Fourier-transform infrared spectroscopy) confirm the presence of following functional group such as alcohol, phenols, carboxylic acids, primary amides, secondary amides, alkyl halide. FE-SEM analysis indicated that ZnO-NPs were in spherical shape, followed by EDX analysis which confirmed the presence of Zn-element. Antimicrobial effect of ZnO-NPs was investigated using different clinical pathogens like bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella Pneumonia, Pseudomonas aeruginosa and fungi Aspergillus flavus, Candida albicans and Penicillium expansum and which confirmed ZnO-NPs efficiency as an antimicrobial agent. Antioxidant activity were ascertained to used for several biomedical applications. The ZnO-NPs was efficiently degraded the environmental toxic dyes (methylene blue and crystal violet) under sunlight. In support of photolight-degradation, the study was progressed to understand the ZnO-dye interaction stability using molecular mechanism and it was showing efficient bonding features in the NPs environment. Overall, this investigation have great potential for being an effective and eco-friendly materials was used in environmental applications.