Gram-negative bacilli carrying mcr gene in Brazil: a pathogen on the rise.

The incidence of infections caused by resistant Gram-negative pathogens has become a critical factor in public health due to the limitation of therapeutic options for the control of infections caused, especially, by Enterobacteriaceae (Escherichia coli and Klebsiella pneumoniae), Pseudomonas spp., and Acinetobacter spp. Thus, given the increase in resistant pathogens and the reduction of therapeutic options, polymyxins were reintroduced into the clinic. As the last treatment option, polymyxins were regarded as the therapeutic key, since they were one of the few classes of antimicrobials that had activity against multidrug-resistant Gram-negative bacilli. Nonetheless, over the years, the frequent use of this antimicrobial has led to reports of resistance cases. In 2015, mcr (mobile colistin resistance), a colistin resistance gene, was described in China. Due to its location on carrier plasmids, this gene is characterized by rapid spread through conjugation. It has thus been classified as a rising threat to public health worldwide. In conclusion, based on several reports that show the emergence of mcr in different regional and climatic contexts and species of isolates, this work aims to review the literature on the incidence of the mcr gene in Brazil in different regions, types of samples identified, species of isolates, and type of carrier plasmid.

Chemical composition and evaluation of the antinociceptive, antioxidant and antimicrobial effects of essential oil from Hymenaea cangaceira (Pinto, Mansano & Azevedo) native to Brazil: A natural medicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Hymenaea cangaceira Pinto, Mansano & Azevedo (Fabaceae) is a Brazilian medicinal plant widely known as "Jatobá". In folk medicine, it is used to treat infections, respiratory problems, rheumatism, antitumoral, inflammation and pain, however, no activity has been scientifically validated. AIM OF THE STUDY: This study investigated chemical composition of essential oil from Hymenaea cangaceira (EOHc), antimicrobial, antinociceptive and antioxidant activities besides protection against DNA damage and hemolysis. MATERIAL AND METHODS: The essential oil was obtained by hydrodistillation, and characterized by GC-MS and GC-FID. The evaluation of antimicrobial activity was performed by microdilution method. The evaluation of the antioxidant activity was performed using the radicals DPPH, ABTS, O2- and OH-, and the protection of DNA damage using plasmid pBR322. Different experimental models were used to evaluate the antinociceptive effect (acetic acid and formalin), and evaluate the mechanisms of action involved with pharmacological antagonists (naloxone, atropine and gibenclamide) in mice. The essential oil was evaluated for hemolysis on human erythrocytes. RESULTS: The extraction of EOHc showed a yield of 0.18% on a dry basis, presenting high content of hydrocarbon sesquiterpenes (79.04%), high antioxidant activity and protect DNA from damage, besides presenting antifungal and antibacterial activity against Gram-positive and Gram-negative bacteria in vitro. It was found that the essential oil had no acute toxicity in mice up to 5000 mg/kg oral administration (o.a.), in addition to no hemolysis on human erythrocytes. The reduction of antinociceptive activity was 75%, with the opioid system as the mechanism of action. CONCLUSION: Our results validate the main activities by the traditional use attributed to H. cangaceira for antimicrobial and analgesic activity. In addition, the oil has a potent antioxidant activity, protecting the body against oxidative stress damage, adding new value to an endemic species not known to the industry.