From the environment to the hospital: How plants can help to fight bacteria biofilm.

The emergence of resistance to antibiotics has become a global challenge as far as the control and treatment of nosocomial infections are concerned. Compared to the planktonic state, biofilms generally confer more resistance to antibiotics and may become a potential source of infection. Researchers are thus focused on developing novel drugs not as vulnerable as the current ones to bacterial resistance mechanisms and also able to target bacteria in biofilms. Natural products, especially those derived from plant sources, have substantiated significant medicinal activity with unique properties, making them perfect candidates for these much-needed therapeutics. Despite being a vast resource of antimicrobial molecules, limitations, including the low concentration of the extracted active compound and bioavailability, challenge the clinical application of medicinal plants to combat these infections. Nanotechnology through green synthesis is one of the strategies to explore the medicinal potential of plants. Research has established the promising outcome of this method in antibiofilm activity, in addition to improved drug delivery, targeting, and pharmacokinetic profiles. This review summarized the current knowledge on the potentialities of plant products as antibiotic adjuvants to restore the therapeutic activity of drugs. We also discussed biotechnological advances in medicinal plants to fight and eradicate biofilm-forming microorganisms.

Antibacterial activity of gallium nitrate against polymyxin-resistant Klebsiella pneumoniae strains.

Iron uptake and metabolism have become attractive targets for the development of new antibacterial drugs. In this scenario, the FDA-approved iron mimetic metal gallium [Ga (III)] has been successfully researched as an antimicrobial drug. Ga (III) inhibits microbial growth by disrupting ferric iron-dependent metabolic pathways. In this study, we revealed that gallium nitrate III (GaN) inhibits the growth of a collection of twenty polymyxin-resistant Klebsiella pneumoniae strains at concentrations ranging from 2 to 16µg/mL, using a medium, on which the low iron content and the presence of human serum better mimic the in vivo environment. GaN was also successful in protecting Caenorhabditis elegans from polymyxin-resistant K. pneumoniae strains lethal infection, with survival rates of >75%. GaN also exhibited synergism with polymyxin B, suggesting that a polymyxin B-GaN combination holds promise like as one alternative therapy for infections caused by resistant polymyxin B K. pneumoniae strains.

Antibacterial activity of Cinnamomum cassia L. essential oil in a carbapenem- and polymyxin-resistant Klebsiella aerogenes strain.

INTRODUCTION: Essential oils can serve as novel sources of antibiotics for multidrug-resistant bacteria. METHODS: The multidrug-resistance profile of a Klebsiella aerogenes strain was assessed by PCR and sequencing. The antibacterial activity of Cinnamomum cassia essential oil (CCeo) against K. aerogenes was assessed by broth microdilution and time-kill methods. RESULTS: K. aerogenes showed high antibiotic resistance. The genes bla KPC-2, ampC, bla CTX-M-15, bla OXA-1, and bla TEM were present. CCeo exhibited an inhibitory effect with a minimum inhibitory concentration of 17.57 µg/mL. CONCLUSIONS: The antibacterial activity of CCeo makes it a potential candidate for treating carbapenem- and polymyxin-resistant K. aerogenes strains.

Antimicrobial activity of plant extracts against carbapenem-producing Klebsiella pneumoniae and in vivo toxicological assessment.

The global spread of multidrug-resistant strains has prompted the scientific community to explore novel sources of chemicals with antimicrobial activity. The aim of the study was to examine the antimicrobial activity in vitro of 28 extracts against carbapenem-producing Klebsiella pneumoniae, individually and in combination with antibiotics and in vivo toxicological assessment of the most active product. The multi-resistant K. pneumoniae strain was submitted for phenotypic and molecular characterization. The antibacterial activity of 28 plant extracts was evaluated alone and in combination with antibiotics against this strain through the agar disk diffusion. Of these, 16 extracts showed synergism against carbapenem-producing K. pneumoniae, being that B. crassifolia extract exhibited synergism with three antibiotics. Based on this assessment, B. crassifolia-extract-induced toxicity on Swiss male mice was evaluated by administering this extract and subsequently determining apoptosis and splenic phagocytosis using the comet and micronucleus assays. The results of this study showed that B. crassifolia extract had synergistic activity promising and groups treated with B. crassifolia exhibited no genotoxic or mutagenic activity, indicating that B. crassifolia extract exerted beneficial effects and appeared safe to use at the studied concentrations.

Antibacterial activity of Cinnamomum cassia L. essential oil in a carbapenem- and polymyxin-resistant Klebsiella aerogenes strain

Abstract INTRODUCTION: Essential oils can serve as novel sources of antibiotics for multidrug-resistant bacteria. METHODS: The multidrug-resistance profile of a Klebsiella aerogenes strain was assessed by PCR and sequencing. The antibacterial activity of Cinnamomum cassia essential oil (CCeo) against K. aerogenes was assessed by broth microdilution and time-kill methods. RESULTS: K. aerogenes showed high antibiotic resistance. The genes bla KPC-2, ampC, bla CTX-M-15, bla OXA-1, and bla TEM were present. CCeo exhibited an inhibitory effect with a minimum inhibitory concentration of 17.57 μg/mL. CONCLUSIONS: The antibacterial activity of CCeo makes it a potential candidate for treating carbapenem- and polymyxin-resistant K. aerogenes strains.