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.

Effect of fungicide on Fusarium verticillioides mycelial morphology and fumonisin B1 production.

The effect of fludioxonil + metalaxyl-M on the mycelial morphology, sporulation and fumonisin B 1 production by Fusarium verticillioides 103 F was evaluated. Scanning electron microscopy analysis showed that the fungicide caused inhibition of hyphal growth and defects on hyphae morphology such as cell wall disruption, withered hyphae, and excessive septation. In addition, extracellular material around the hyphae was rarely observed in the presence of fludioxonil + metalaxyl-M. While promoting the reduction of mycelial growth, the fungicide increased sporulation of F. verticillioides compared to the control, and the highest production occurred on the 14 (th) day in the treatments and on the 10 (th) day in the control cultures. Fumonisin B 1 production in the culture media containing the fungicide (treatment) was detected from the 7 (th) day incubation, whereas in cultures without fungicide (control) it was detected on the 10 (th) day. The highest fumonisin B 1 production occurred on the 14 (th) day, both for the control and for the treatment. Fludioxonil + metalaxyl - M can interfere in F. verticillioides mycelial morphology and sporulation and increase fumonisin B 1 levels. These data indicate the importance of understanding the effects of fungicide to minimize the occurrence of toxigenic fungi and fumonisins.

Effect of fungicide on Fusarium verticillioides mycelial morphology and fumonisin B1 production

The effect of fludioxonil + metalaxyl-M on the mycelial morphology, sporulation and fumonisin B1 production by Fusarium verticillioides 103 F was evaluated. Scanning electron microscopy analysis showed that the fungicide caused inhibition of hyphal growth and defects on hyphae morphology such as cell wall disruption, withered hyphae, and excessive septation. In addition, extracellular material around the hyphae was rarely observed in the presence of fludioxonil + metalaxyl-M. While promoting the reduction of mycelial growth, the fungicide increased sporulation of F. verticillioides compared to the control, and the highest production occurred on the 14th day in the treatments and on the 10th day in the control cultures. Fumonisin B1 production in the culture media containing the fungicide (treatment) was detected from the 7th day incubation, whereas in cultures without fungicide (control) it was detected on the 10th day. The highest fumonisin B1 production occurred on the 14th day, both for the control and for the treatment. Fludioxonil + metalaxyl - M can interfere in F. verticillioides mycelial morphology and sporulation and increase fumonisin B1 levels. These data indicate the importance of understanding the effects of fungicide to minimize the occurrence of toxigenic fungi and fumonisins.