Drug-resistant Human Pathogens Research Articles

Phytochemical Analysis and Antibacterial Studies of Some Yemeni Medicinal Plants against Selected Common Human Pathogenic Bacteria

In traditional medicine, medicinal plants are often used to treat a wide range of infectious diseases in humans. Objective: The aim of this study was to identify the phytochemicals contained in thirteen parts of six Yemeni medicinal plants: Artemisia Judaica, Ficus carica L., Nerium oleander L., Olea europaea, Santolina chamaecyparissus L. and Withania somnifera and to investigate the antimicrobial activity of different concentrations of methanol extracts from the aerial part of the selected plants against S. saprophyticus, Salmonella and E. coli in vitro. Methods: Phytochemical screening was carried out using standard procedures and the antibacterial activity of different extracts of each plant was studied by agar well diffusion method. Results: Phytochemical analysis of the plant extracts revealed the presence of phenols, saponins, essential oils, flavonoids, steroids, tannins, cardiac glycosides and alkaloids. The occurrence of phytochemicals varied from plant to plant. Tannins and phenols were found in all samples, while all other test samples contained at least five of the phytochemicals tested. Almost all extracts were able to inhibit the growth of the bacterial strains, with the exception of the species S. saprophyticus, which was resistant to the methanolic extracts of A. judaica and F. carica L. However, the methanol extract (0.1 g/ml) of S. chamaecyparissus L. and O. europaea showed the largest zone of inhibition (35 mm and 20 mm, respectively) against S. saprophyticus. This is the first report on the antibacterial activity of S. chamaecyparissus L. species against S. saprophyticus. Conclusions: The present screening result shows that the methanol extract of the tested traditional Yemeni medicinal plants exhibits potent antibacterial activity, and the studied plants may represent a new source for the discovery of novel antibacterial compounds for the treatment of drug-resistant human pathogens.

ANTIFUNGAL RESISTANCE: A GROWING CONCERN

Globally, the increasing number of drug-resistant human pathogens represents a major threat to public health. Among these pathogens, fungi that have acquired resistance to the already scarce arsenal of antifungals are of particular significance, as they present therapeutic challenges that increase morbidity and mortality rates. Particularly, most mycoses are opportunistic since they mainly affect hosts with a weakened immune system, including patients with cancer, hematological malignancies, prolonged neutropenia, solid organ transplants, HIV/AIDS, patients in intensive care units, using central venous catheters or on dialysis, using corticosteroids, among others. In most cases, fungal infections have a significant medical and economic burden that outweighs the burden of the underlying disease alone and changes the outcome. In addition, the treatment for mycoses, which consists of four classes of antifungals described several decades ago, polyenes, flucytosine, azoles, and echinocandins, continues to be a major challenge. With the increase in patients at risk, the incidence of mycoses is therefore a growing concern. Considering as well, the scarcity of drugs, together with toxicity, the high price of some formulations, the low availability in low-resource countries, and the development of resistance, there is an urgent need to discover new antifungals or therapeutic strategies or to modify the existing molecules with antifungal activity. This reflection article reveals that various of the most common human fungal pathogens have had the ability to acquire antifungal resistance as antifungal drugs are developed.

Antibacterial Activity of Moringa oleifera Plant Extracts in Comparison with Ciprofloxacin Antibiotic Against Staphylococcus aureus

The current drug resistance in human pathogens is a result of the abuse of antibacterial drugs commonly used to treat diseases. Early human civilizations used Moringa oleifera extracts to treat illnesses and infections caused by food-borne bacteria such as Staphylococcus aureus. In order to calculate the antibacterial effect of Moringa oleifera against Staphylococcus aureus, methanolic extracts from its three parts were prepared. A photochemical analysis of the methanolic leaves, seeds, and roots extracts was performed when the extracts were ready for testing. We used well-diffusion methods to add the three extracts, and the ciprofloxacin antibiotic was used as the standard. From the stock solution, serial dilutions were made in order to calculate the minimum inhibitory concentration (MIC). In the phytochemical screening test, steroids, terpenoids, tannins, phenolic compounds, saponins, and flavonoids were most abundant in leaves extract, followed by seeds then roots extracts. Moringa oleifera seeds have the highest inhibition zone, which is about 10mm, followed by Moringa oleifera roots at 9mm, and Moringa oleifera leaves at 7mm. In comparison to the other two extracts, the MIC of methanolic extract from Moringa oleifera leaves was 250 mm, the highest concentration, with a MIC of 125 mm for roots and 62.50 mm for seeds. Methanolic extracts of Moringa seeds demonstrated antibacterial activity against Staphylococcus aureus in the present study. For further studies, it is suggested a deeper investigation to study the antibacterial agent dosages of these plant parts, which may be used by the pharmaceutical industry.

Antimicrobial Activity of the Nanoparticle Form of Greens (Lemon, Black Seeds or Flax) with Silver on Drug-resistant Human Pathogens.

Synthesizing a green source that has antimicrobial activity in nanoparticles is a novel and exciting approach to pharmaceutical science with promising results. Green-silver nanoparticles (G-AgNPs) were evaluated for their antimicrobial action on drugresistant pathogens. Lemon, black seeds, and flax were selected as green sources to synthesize nanoparticles formed with silver. Physical and chemical characteristics of these preparations were identified. The antimicrobial activities of the prepared compounds against drug-resistant clinical isolates of seven bacteria and five fungi were identified by disk diffusion and dilution methods. The nanoparticle characteristics were confirmed by physical and chemical measurements. Lemon extract with silver nanoparticles (L-AgNP) showed more antimicrobial action, particularly on Gram-positive bacteria and Candida albicans. Silver nanoparticles with black seeds (B-AgNP) and flax (F-AgNP) had only antibacterial effects on a single bacterium (Enterobacter cloacae). Escherichia coli, Staphylococcus aureus, and two fungi, Candida glabrata and Candida utilis, showed resistance to all nanoparticles from plants. Lemon with silver nanoparticle is an effective plant product for use against various drugresistant species of human pathogens. Further pharmaceutical studies are required to verify the suitability of this form of the drug for human use. Another plant is recommended for testing against the most resistant strains of pathogens.

Discovery and biosynthetic assessment of 'Streptomyces ortus' sp. nov. isolated from a deep-sea sponge.

The deep sea is known to host novel bacteria with the potential to produce a diverse array of undiscovered natural products. Thus, understanding these bacteria is of broad interest in ecology and could also underpin applied drug discovery, specifically in the area of antimicrobials. Here, we isolate a new strain of Streptomyces from the tissue of the deep-sea sponge Polymastia corticata collected at a depth of 1869 m from the Gramberg Seamount in the Atlantic Ocean. This strain, which was given the initial designation A15ISP2-DRY2T, has a genome size of 9.29 Mb with a G+C content of 70.83 mol%. Phylogenomics determined that A15ISP2-DRY2T represents a novel species within the genus Streptomyces as part of the Streptomyces aurantiacus clade. The biosynthetic potential of A15ISP2-DRY2T was assessed relative to other members of the S. aurantiacus clade via comparative gene cluster family (GCF) analysis. This revealed a clear congruent relationship between phylogeny and GCF content. A15ISP2-DRY2T contains six unique GCFs absent elsewhere in the clade. Culture-based assays were used to demonstrate the antibacterial activity of A15ISP2-DRY2T against two drug-resistant human pathogens. Thus, we determine A15ISP2-DRY2T to be a novel bacterial species with considerable biosynthetic potential and propose the systematic name 'Streptomyces ortus' sp. nov.

Characterization of a Bacteriophage GEC_vB_Bfr_UZM3 Active against Bacteroides fragilis.

Bacteroides fragilis is a commensal gut bacterium that is associated with a number of blood and tissue infections. It has not yet been recognized as one of the drug-resistant human pathogens, but cases of the refractory infections, caused by strains that are not susceptible to the common antibiotic regimes established for B. fragilis, have been more frequently reported. Bacteriophages (phages) were found to be a successful antibacterial alternative to antibiotic therapy in many cases of multidrug-resistant (MDR) bacterial infections. We have characterized the bacteriophage GEC_vB_Bfr_UZM3 (UZM3), which was used for the treatment of a patient with a chronic osteomyelitis caused by a B. fragilis mixed infection. Studied biological and morphological properties of UZM3 showed that it seems to represent a strictly lytic phage belonging to a siphovirus morphotype. It is characterized by high stability at body temperature and in pH environments for about 6 h. Whole genome sequencing analysis of the phage UZM3 showed that it does not harbor any known virulence genes and can be considered as a potential therapeutic phage to be used against B. fragilis infections.

Mass trends of parabens, triclocarban and triclosan in Arizona wastewater collected after the 2017 FDA ban on antimicrobials and during the COVID-19 pandemic

Antimicrobials like parabens, triclosan (TCS), and triclocarban (TCC) are of public health concern worldwide due to their endocrine-disrupting properties and ability to promote antimicrobial drug resistance in human pathogens. The overall use of antimicrobials presumably has increased during the COVID-19 pandemic, whereas TCS and TCC may have experienced reductions in use due to their recent ban from thousands of over-the-counter (OTC) personal care products by the U.S. Food and Drug Administration (FDA). No quantitative data are available on the use of parabens or the impact the FDA ban had on TCC and TCS. Here, we use wastewater samples (n = 1514) from 10 different communities in Arizona to measure the presence of the six different antimicrobial products (TCS, TCC, and four alkylated parabens [methylparaben (MePb), ethylparaben (EtPb), propylparaben (PrPb), butylparaben (BuPb)]) collected before and during the COVID-19 pandemic using a combination of solid-phase extraction, liquid chromatography/tandem mass spectrometry (LC-MS/MS), and isotope dilution for absolute quantitation. The average mass loadings of all antimicrobials combined (1,431 ± 22 mg/day per 1,000 people) after the onset of the local epidemic (March 2020 - October 2020) were significantly higher (945 ± 62 mg/day per 1,000 people; p < 0.05) than before the pandemic (January 2019 - February 2020). Overall, parabens (∑Pbs = 999 ± 16 mg/day per 1,000 people) were the most used antimicrobials, followed by TCS (117 ± 14 mg/day per 1,000 people) and TCC (117 ± 14 mg/day per 1,000 people). After the 2017 U.S. FDA ban, we found a statistically significant (p < 0.05) reduction in the mass loadings of TCS (-89%) and TCC (-80%) but a rise in paraben use (+72%). Mass flows of 3 of a total of 4 parabens (MePb, EtPb, and PrPb) in wastewater were significantly higher upon the onset of the epidemic locally (p < 0.05). This is the first longitudinal study investigating the use of antimicrobials during the COVID-19 pandemic by employing wastewater-based epidemiology. Whereas an overall increase in the use of antimicrobials was evident from analyzing Arizona wastewater, a notable reduction in the use of TCS and TCC was evident during the pandemic, triggered by the U.S. FDA ban.

Characterization and Genome Analysis of Arthrobacter bangladeshi sp. nov., Applied for the Green Synthesis of Silver Nanoparticles and Their Antibacterial Efficacy against Drug-Resistant Human Pathogens.

The present study describes the isolation and characterization of novel bacterial species Arthrobacter bangladeshi sp. nov., applied for the green synthesis of AgNPs, and investigates its antibacterial efficacy against drug-resistant pathogenic Salmonella Typhimurium and Yersinia enterocolitica. Novel strain MAHUQ-56T is Gram-positive, aerobic, non-motile, and rod-shaped. Colonies were spherical and milky white. The strain showed positive activity for catalase and nitrate reductase, and the hydrolysis of starch, L-tyrosine, casein, and Tween 20. On the basis of the 16S rRNA gene sequence, strain MAHUQ-56T belongs to the Arthrobacter genus and is most closely related to Arthrobacter pokkalii P3B162T (98.6%). Arthrobacter bangladeshi MAHUQ-56T has a genome 4,566,112 bp long (26 contigs) with 4125 protein-coding genes, 51 tRNA and 6 rRNA genes. The culture supernatant of Arthrobacter bangladeshi MAHUQ-56T was used for the easy and green synthesis of AgNPs. Synthesized AgNPs were characterized by UV–vis spectroscopy, FE-TEM, XRD, DLS, and FT-IR. Synthesized AgNPs were spherical and 12–50 nm in size. FT-IR analysis revealed various biomolecules that may be involved in the synthesis process. Synthesized AgNPs showed strong antibacterial activity against multidrug-resistant pathogenic S. typhimurium and Y. enterocolitica. MIC values of the synthesized AgNPs against S. typhimurium and Y. enterocolitica were 6.2 and 3.1 ug/mL, respectively. The MBC of synthesized AgNPs for both pathogens was 12.5 ug/mL. FE-SEM analysis revealed the morphological and structural alterations, and damage of pathogens treated by AgNPs. These changes might disturb normal cellular functions, which ultimately leads to the death of cells.

Ribosome-binding and anti-microbial studies of the mycinamicins, 16-membered macrolide antibiotics from Micromonospora griseorubida.

Macrolides have been effective clinical antibiotics for over 70 years. They inhibit protein biosynthesis in bacterial pathogens by narrowing the nascent protein exit tunnel in the ribosome. The macrolide class of natural products consist of a macrolactone ring linked to one or more sugar molecules. Most of the macrolides used currently are semi-synthetic erythromycin derivatives, composed of a 14- or 15-membered macrolactone ring. Rapidly emerging resistance in bacterial pathogens is among the most urgent global health challenges, which render many antibiotics ineffective, including next-generation macrolides. To address this threat and advance a longer-term plan for developing new antibiotics, we demonstrate how 16-membered macrolides overcome erythromycin resistance in clinically isolated Staphylococcus aureus strains. By determining the structures of complexes of the large ribosomal subunit of Deinococcus radiodurans (D50S) with these 16-membered selected macrolides, and performing anti-microbial studies, we identified resistance mechanisms they may overcome. This new information provides important insights toward the rational design of therapeutics that are effective against drug resistant human pathogens.

Preparation and evaluation of antibacterial properties of Pexiganan, a Magainin analogue with Broadly-Spectrum Antimicrobial Activity

Introduction: Pexiganan is one of the most popular Maganin-2 analogues, which has broadly- spectrum bactericidal effects against both gram-positive and gram-negative bacteria. In this study, the effects of temperature, pH, and in vitro resistant analysis were evaluated on the antibacterial activity of this peptide. Materials and Methods: Pexiganan recombinant was expressed in P. pastoris GS115, and after its characterization, the cell cytotoxicity characteristics, effects of temperature on antibacterial activity, as well as the emergence of resistance to pexiganan in continuous sub-cultures and MIC of this peptide were investigated against 12 bacterial pathogens. Results: Pexiganan was not cytotoxic to HeLa cell lines. Increasing the temperature had no effect on the zone of inhibition, but increasing the pH caused a significant increase in MIC against S. aureus ATCC 29213 strain. In addition, Pexiganan had inhibitory properties against all the 12 human pathogens (MIC range: 1-32 /g / ml), and no resistance was observed even after 28 sub- cultures. Conclusion: Pexiganan is an AMP with antimicrobial properties against a wide range of susceptible and drug-resistant human pathogens with a very low rate of resistance compared to available antibiotics and is a reliable candidate for further investigation on therapeutic applications. Keywords: Pexiganan; Antimicrobial Peptides; Resistance; Minimum Inhibitory Concentration

Isolation and Characterization of Multiple Drug Resistant Human Enteric Pathogens from Sewage Water of Delhi

Isolation and Characterization of Multiple Drug Resistant Human Enteric Pathogens from Sewage Water of Delhi

Exploring an Indian Herb Sphaeranthus indicus for Antimicrobial Efficacy against Helicobacter pylori and Effect of Combination Therapy against Drug Resistant Human Pathogens

Exploring an Indian Herb Sphaeranthus indicus for Antimicrobial Efficacy against Helicobacter pylori and Effect of Combination Therapy against Drug Resistant Human Pathogens

Carrier-Mediated Drug Uptake in Fungal Pathogens.

Candida, Aspergillus, and Cryptococcus species are the most frequent cause of severe human fungal infections. Clinically relevant antifungal drugs are scarce, and their effectiveness are hampered by the ability of fungal cells to develop drug resistance mechanisms. Drug effectiveness and drug resistance in human pathogens is very often affected by their “transportome”. Many studies have covered a panoply of drug resistance mechanisms that depend on drug efflux pumps belonging to the ATP-Binding Cassette and Major Facilitator Superfamily. However, the study of drug uptake mechanisms has been, to some extent, overlooked in pathogenic fungi. This review focuses on discussing current knowledge on drug uptake systems in fungal pathogens, highlighting the need for further studies on this topic of great importance. The following subjects are covered: (i) drugs imported by known transporter(s) in pathogenic fungi; and (ii) drugs imported by known transporter(s) in the model yeast Saccharomyces cerevisiae or in human parasites, aimed at the identification of their homologs in pathogenic fungi. Besides its contribution to increase the understanding of drug-pathogen interactions, the practical implications of identifying drug importers in human pathogens are discussed, particularly focusing on drug development strategies.

Vaccines Against Antimicrobial Resistance.

In the last century, life expectancy has increased considerably, thanks to the introduction of antibiotics, hygiene and vaccines that have contributed to the cure and prevention of many infectious diseases. The era of antimicrobial therapy started in the nineteenth century with the identification of chemical compounds with antimicrobial properties. However, immediately after the introduction of these novel drugs, microorganisms started to become resistant through different strategies. Although resistance mechanisms were already present before antibiotic introduction, their large-scale use and mis-use have increased the number of resistant microorganisms. Rapid spreading of mobile elements by horizontal gene transfer such as plasmids and integrative conjugative elements (ICE) carrying multiple resistance genes has dramatically increased the worldwide prevalence of relevant multi drug-resistant human pathogens such as Staphylococcus aureus, Neisseria gonorrhoeae, and Enterobacteriaceae. Today, antimicrobial resistance (AMR) remains one of the major global concerns to be addressed and only global efforts could help in finding a solution. In terms of magnitude the economic impact of AMR is estimated to be comparable to that of climate global change in 2030. Although antibiotics continue to be essential to treat such infections, non-antibiotic therapies will play an important role in limiting the increase of antibiotic resistant microorganisms. Among non-antibiotic strategies, vaccines and therapeutic monoclonal antibodies (mAbs) play a strategic role. In this review, we will summarize the evolution and the mechanisms of antibiotic resistance, and the impact of AMR on life expectancy and economics.

The effect of black and green tea extracts on some bacteria-infected burns skin in rats

Herbal teas are the most common natural alternatives for the treatment of infectious diseases due to increasing antibiotic resistance, and are increasingly gaining more popularity and are known for their activity of antibacterial to many pathogenic micro-organisms. This research was necessitated by the need to counter the rapid emergence of drug-resistant human pathogens, which is becoming a regular phenomenon in the world making life-threatening illnesses easily curable infections. The study was done to determine the antimicrobial activities by agar diffusion inhibition assay of black and green tea Extract (cold and hot) against Pseudomonas aeruginosa and Staphylococcus aureus antibiotic resistance after injuring the skin of rats for burning, also to screen the effect of both types of tea on rat skin healing. Minimum inhibitory concentration was performed by broth micro-dilution assays, and Antibiotic Sensitivity was done for both types of bacteria. Our findings are in accordance that hot watery green and black tea extracts are more effective against both bacterial types than cold once based on an assessment of inhibition zones, green tea extract could be used for wound healing and burned skin of rats when treated with green and black tea showed reductions in the number of inflammatory cells and also arranged collagen bands. We concluded that green tea has a greater activity which is indicated by a higher anti-inflammatory effect compared to black tea.

Green Synthesis of Silver Nanoparticles Using Pseudoduganella eburnea MAHUQ-39 and Their Antimicrobial Mechanisms Investigation against Drug Resistant Human Pathogens.

Silver nanoparticles (AgNPs) have shown great promise in biomedical applications. The exact mechanism and mode of action of AgNPs regarding antimicrobial activity are still not well known. Moreover, synthesis of nanoparticles by physical and chemical methods is expensive and not ecofriendly. This study highlights the green, rapid, facile, cost-effective and ecofriendly synthesis of AgNPs using Pseudoduganella eburnea MAHUQ-39 and also investigates their antibacterial mechanisms. The transmission electron microscopy (TEM) image revealed a spherical shape of the AgNPs. The size of the synthesized AgNPs was 8 to 24 nm. The elemental mapping and selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns revealed the crystalline structure of AgNPs. Fourier-transform infrared spectroscopy (FTIR) analysis identified the functional groups that are involved in the reduction of silver ion to AgNPs. The green synthesized AgNPs exhibited strong antimicrobial activity against multidrug-resistant pathogenic microbes. Minimal inhibitory concentrations (MICs) of Staphylococcus aureus and Pseudomonas aeruginosa were 100 μg/mL and 6.25 μg/mL, respectively, and the minimum bactericidal concentrations (MBCs) of S. aureus and P. aeruginosa were 200 μg/mL and 50 μg/mL, respectively. Our data demonstrated that synthesized AgNPs created structural changes of cells and destroyed the membrane integrity of strains S. aureus and P. aeruginosa. Therefore, AgNPs synthesized by strain MAHUQ-39 can be used as a powerful antimicrobial agent for various therapeutic applications.

Chicken Meat-Associated Enterococci: Influence of Agricultural Antibiotic Use and Connection to the Clinic.

Industrial farms are unique, human-created ecosystems that provide the perfect setting for the development and dissemination of antibiotic resistance. Agricultural antibiotic use amplifies naturally occurring resistance mechanisms from soil ecologies, promoting their spread and sharing with other bacteria, including those poised to become endemic within hospital environments. To better understand the role of enterococci in the movement of antibiotic resistance from farm to table to clinic, we characterized over 300 isolates of Enterococcus cultured from raw chicken meat purchased at U.S. supermarkets by the Consumers Union in 2013. Enterococcus faecalis and Enterococcus faecium were the predominant species found, and antimicrobial susceptibility testing uncovered striking levels of resistance to medically important antibiotic classes, particularly from classes approved by the FDA for use in animal production. While nearly all isolates were resistant to at least one drug, bacteria from meat labeled as raised without antibiotics had fewer resistances, particularly for E. faecium Whole-genome sequencing of 92 isolates revealed that both commensal- and clinical-isolate-like enterococcal strains were associated with chicken meat, including isolates bearing important resistance-conferring elements and virulence factors. The ability of enterococci to persist in the food system positions them as vehicles to move resistance genes from the industrial farm ecosystem into more human-proximal ecologies.IMPORTANCE Bacteria that contaminate food can serve as a conduit for moving drug resistance genes from farm to table to clinic. Our results show that chicken meat-associated isolates of Enterococcus are often multidrug resistant, closely related to pathogenic lineages, and harbor worrisome virulence factors. These drug-resistant agricultural isolates could thus represent important stepping stones in the evolution of enterococci into drug-resistant human pathogens. Although significant efforts have been made over the past few years to reduce the agricultural use of antibiotics, continued assessment of agricultural practices, including the roles of processing plants, shared breeding flocks, and probiotics as sources for resistance spread, is needed in order to slow the evolution of antibiotic resistance. Because antibiotic resistance is a global problem, global policies are needed to address this threat. Additional measures must be taken to mitigate the development and spread of antibiotic resistance elements from farms to clinics throughout the world.

A review on anti-tuberculosis peptides: Impact of peptide structure on anti-tuberculosis activity.

Antibiotic resistance is a major public health problem globally. Particularly concerning amongst drug-resistant human pathogens is Mycobacterium tuberculosis that causes the deadly infectious tuberculosis (TB) disease. Significant issues associated with current treatment options for drug-resistant TB and the high rate of mortality from the disease makes the development of novel treatment options against this pathogen an urgent need. Antimicrobial peptides are part of innate immunity in all forms of life and could provide a potential solution against drug-resistant TB. This review is a critical analysis of antimicrobial peptides that are reported to be active against the M tuberculosis complex exclusively. However, activity on non-TB strains such as Mycobacterium avium and Mycobacterium intracellulare, whenever available, have been included at appropriate sections for these anti-TB peptides. Natural and synthetic antimicrobial peptides of diverse sequences, along with their chemical structures, are presented, discussed, and correlated to their observed antimycobacterial activities. Critical analyses of the structure allied to the anti-mycobacterial activity have allowed us to draw important conclusions and ideas for research and development on these promising molecules to realise their full potential. Even though the review is focussed on peptides, we have briefly summarised the structures and potency of the various small molecule drugs that are available and under development, for TB treatment.

Microplastics in ballast water as an emerging source and vector for harmful chemicals, antibiotics, metals, bacterial pathogens and HAB species: A potential risk to the marine environment and human health.

Microplastic pollution in marine waters around the globe is increasing exponentially. This is the first comprehensive review which focuses on microplastics as a source and vector for metals, antibiotics, toxic chemicals, pathogenic bacteria (Vibrio cholerae), and Harmful Algal Bloom (HAB)-forming dinoflagellates across the continents through ballast water. Microplastics in ballast waters serve as 'hotspots' for the development and spread of multiple drug-resistant human pathogens through co-selection mechanisms. Microplastic inoculation at distant countries through ballast water may pose a serious threat to human health due to higher incidences of bacterial disease outbreaks and HABs. The 2017 ballast water management convention lacks a provision for on-board treatment of microplastic-contaminated ballast water. We conclude that there is a pressing need to include microplastics in the ballast water management convention as a hazardous material. Efficient on-board ballast water treatment strategies and effective limits for microplastics in ballast waters need to be developed.

Biofunctionalization of mycosynthesized silver nanoparticles on selected drug resistant human pathogens

Nanotechnology has been a boon to mankind as its significance paved the way for several applications in therapeutics. Silver nanoparticles are powerful nano-weapons in the destruction of multiple drug resistant pathogens. The process of biosynthesis of silver nanoparticles is a simple, cost effective and eco-friendly approach. In the present study, aqueous extract of edible mushroom Pleurotus florida is used for the synthesis of biofunctionalized silver nanoparticles. The biosynthesis parameters such as pH, silver nitrate concentration, silver nitrate to mushroom extract ratio, temperature, incubation condition and duration of synthesis were optimized to maximize the yield of silver nanoparticles. Its formation was confirmed using UV–visible spectroscopy and characterized by Scanning Electron Microscopy (SEM), Energy Dispersive x-ray Spectroscopy (EDX) and Fourier Transform Infrared Spectroscopy (FTIR). FTIR spectrum revealed the possible biomolecules responsible for capping and efficient stabilization of the nanoparticles. Further, biological evaluation of these silver nanoparticles showed potential antimicrobial action against seven bacterial and two fungal pathogens by agar well diffusion method. The microbicidal property of the biosynthesized nanosilver showed significant positive correlations associated with the dose- dependent effect and thus it might have high potential medical applications in controlling drug- resistant infections.