Antibacterial Combination of Oleoresin from Copaifera multijuga Hayne and Biogenic Silver Nanoparticles Towards Streptococcus agalactiae.

BACKGROUND: Streptococcus agalactiae (group B Streptococcus - GBS) remains a leading cause of neonatal infections and an important cause of invasive infections in adults with underlying conditions. METHODS: This study evaluated for the first time the effect of an oleoresin collected from Copaifera multijuga Hayne (copaiba oil) alone or in combination with silver nanoparticles produced by green synthesis using Fusarium oxysporum (AgNPbio) against planktonic and sessile cells of GBS isolated from colonized women. RESULTS: Copaiba oil showed a dose-dependent bactericidal activity against planktonic GBS strains, including those resistant to erythromycin and/or clindamycin. Scanning and transmission electron microscopy of GBS treated with copaiba oil revealed morphological and ultrastructural alterations, displaying disruption of the cell wall and decreased electron density due to leakage of cytoplasmic content. Copaiba oil also exhibited antibacterial activity against biofilms of GBS strains, inhibiting their formation as well as the viability of mature biofilms. In addition, the combination of copaiba oil with AgNPbio resulted in a synergistic effect against planktonic cells and biofilm formation, reducing the minimal inhibitory concentration values of both compounds. No hemolytic activity was detected for both compounds. CONCLUSION: These results indicate the potential of copaiba oil, alone or in combination with AgNPbio, for the development of new alternative strategies for controlling GBS infections.

Effect of a Metalloantibiotic Produced by Pseudomonas aeruginosa on Klebsiella pneumoniae Carbapenemase (KPC)-producing K. pneumoniae.

Multidrug-resistant organisms (MDRO) are a great problem in hospitals, where thousands of people are infected daily, with the occurrence of high mortality rates, especially in infections caused by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-producing Kpn). The challenge is to find new compounds that can control KPC producing-Kpn infections. The aim of this study was to evaluate the antibiotic activity of the F3d fraction produced by the Pseudomonas aeruginosa LV strain against clinical isolates of KPC-producing Kpn. The results showed that the minimum inhibitory concentration of F3d (62.5 µg mL(-1)), containing an organic metallic compound, killed planktonic cells of KPC-producing Kpn strains after 30 min of incubation. At the same concentration, this fraction also showed an inhibitory effect against biofilm of these bacteria after 24 h of incubation. Treatment with the F3d fraction caused pronounced morphological alterations in both planktonic and biofilm cells of the bacteria. The inhibitory effect of the F3d fraction seems to be more selective for the bacteria than the host cells, indicating its potential in the development of new drugs for the treatment of infections caused by KPC-producing Kpn and other MDRO.

Antifungal Activity of Condensed Tannins from Stryphnodendron adstringens: Effect on Candida tropicalis Growth and Adhesion Properties.

Candida species are some of the most common causes of fungal infection worldwide. The limited efficacy of clinically available antifungals warrants the search for new compounds for treating candidiasis. This study evaluated the effect of condensed tannin-rich fraction (F2 fraction) of Stryphnodendron adstringens on in vitro and in vivo growth of Candida tropicalis, and on yeast adhesion properties. F2 exhibited a fungistatic effect with the minimum inhibitory concentration ranging from 0.5 to 8.0 µg/mL. A significant reduction in biofilm mass was observed after either pretreatment of planktonic cells for 2 h (mean reduction of 46.31±8.17%) or incubation during biofilm formation (mean reduction of 28.44±13.38%) with 4x MIC of F2. Prior exposure of planktonic cells to this F2 concentration also significantly decreased yeast adherence on HEp-2 cells (mean reduction of 43.13±14.29%), cell surface hydrophobicity (mean reduction of 25.89±10.49%) and mRNA levels of the genes ALST1-3 (2.9-, 1.8- and 1.8-fold decrease, respectively). Tenebrio molitor larvae, which are susceptible to C. tropicalis infection, were used for in vivo testing. Treatment with 128 and 256 µg/mL F2 significantly increased the survival of infected larvae. These results indicate a combined effect of F2 on inhibition of yeast growth and interference in yeast adhesion, which may contribute to the suppression of infection caused by C. tropicalis, thus reinforcing the potential of the condensed tannins from S. adstringens for the development of novel antifungal agents.