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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. [ABSTRACT FROM AUTHOR]

Multidrug resistance prompts the search for new sources of antibiotics with new targets at bacteria cell. To investigate the antibacterial activity of Cinnamomum cassia L. essential oil (CCeo) alone and in combination with antibiotics against carbapenemase-producing Klebsiella pneumoniae and Serratia marcescens. The antimicrobial susceptibility of the strains was determined by Vitek® 2 and confirmed by MALDI-TOF/TOF. The antibacterial activity of CCeo and its synergism with antibiotics was determined using agar disk diffusion, broth microdilution, time-kill, and checkboard methods. The integrity of the bacterial cell membrane in S. marcescens was monitored by protein leakage assay. CCeo exhibited inhibitory effects with MIC = 281.25 μg.mL-1. The association between CCeo and polymyxin B showed a decrease in terms of viable cell counts on survival curves over time after a 4 hour-treatment with a FIC index value of 0.006. Protein leakage was observed with increasing concentrations for CCeo and CCeo + polymyxin B treatments. CCeo showed antibacterial activity against the studied strains. When associated with polymyxin B, a synergistic effect was able to inhibit bacterial growth rapidly and consistently, making it a potential candidate for the development of an alternative treatment and drug delivery system for carbapenemase-producing strains. [ABSTRACT FROM AUTHOR]

Multidrug-resistant Acinetobacter baumannii has emerged as a problematic hospital-acquired pathogen. It is vital to search for new sources of antibiotics. Natural plant essential oils have several biological properties, including antimicrobial activity and may be valuable for new drug development. Chemical composition of the essential oil of Nectandra megapotamica flowers was assessed by Gas Chromatography/Flame Ionization Detector and Gas Chromatography/Mass Spectrometry analysis. Antibacterial activity against OXA-23-producing A. baumannii and synergism with antibiotics were performed by broth microdilution, time kill, and checkerboard methods. The essential oil of Nectandra megapotamica flowers showed a predominance of oxygenated sesquiterpenes and caryophyllene oxide was the main component. Survival curves showed a linear decrease in viable OXA-23-producing A. baumannii cell counts over time for the association between the essential oil of Nectandra megapotamica flowers and imipenem. Checkerboard assay with imipenem presented Fractional Inhibitory Concentration Index of 0.156, suggesting synergism. The synergistic effect of essential oil of Nectandra megapotamica flowers with imipenem could be a potential approach to combat multiresistant OXA-23-producing A. baumannii strains, and could be used as a drug delivery system, as an excipient for imipenem, reducing its dosage. [ABSTRACT FROM AUTHOR]

The global spread of carbapenem-resistant Acinetobacter baumannii (A. baumannii) strains has restricted the therapeutic options available to treat infections due to this pathogen. Understanding the prevalence of such infections and the underlying genetic mechanisms of resistance may help in the implementation of adequate measures to control and prevent acquisition of nosocomial infections, especially in an intensive care unit setting. This study describes the molecular characteristics and risk factors associated with OXA-23-producing A. baumannii infections. A case-control study was undertaken from September/2013 to April/2015. Acquisition of OXA-23-producing A. baumannii was found to be associated with the use of nasogastric tubes, haemodialysis, and the use of cephalosporins. These isolates were only susceptible to amikacin, gentamicin, tigecycline, and colistin, and contained the ISAba1 insertion sequence upstream ofblaOXA-23 and blaOXA-51 genes. Twenty-six OXA-23-producing A. baumannii strains belonged to the ST79 (CC79) clonal group,and patients infected or colonised by these isolates had a higher mortality rate (34.6%). In conclusion, this study showed a dissemination of OXA-23-producing A. baumannii strains that was associated with several healthcare-related risk factors and high mortality rates among intensive care unit patients. [ABSTRACT FROM AUTHOR]

An abstract of the article "Identification of carbapenemase genes in Serratia spp" by Peceu Magyve Ragagnin De Oliveira and colleagues is presented.