Copper as an antibacterial agent for human pathogenic multidrug resistant Burkholderia cepacia complex bacteria.

The Burkholderia cepacia complex (Bcc) consists of 17 closely related multidrug resistant bacterial species that are difficult to eradicate. Copper has recently gained attention as an antimicrobial agent because of its inhibitory effects on bacteria, yeast, and viruses. The objective of this study was to evaluate the antibacterial activity of copper surfaces and copper powder against members of the B. cepacia complex. The antibacterial activity of different copper surfaces was evaluated by incubating them with Bcc strain suspensions (5×10(7)cfu/ml). The bacterial survival counts were calculated and the data for various copper surfaces were compared to the data for stainless steel and polyvinylchloride, which were used as control surfaces. The antibacterial activity of copper powder was determined with the diffusimetrical technique and the zone of inhibition was evaluated with paper disks. A single cell gel electrophoresis assay, staining assays, and inductively coupled plasma mass spectroscopy were performed to determine the mechanism responsible for the bactericidal activity. The results showed a significant decrease in the viable bacterial count after exposure to copper surfaces. Moreover, the copper powder produced a large zone of inhibition and there was a significantly higher influx of copper ions into the bacterial cells that were exposed to copper surfaces compared to the controls. The present study demonstrates that metallic copper has an antibacterial effect against Bcc bacteria and that copper adversely affects the bacterial cellular structure, thus resulting in cell death. These findings suggest that copper could be utilized in health care facilities to reduce the bioburden of Bcc species, which may protect susceptible members of the community from bacterial infection.

Matrix-assisted laser desorption ionisation-time-of of-flight mass spectrometry of intact cells allows rapid identification of Burkholderia cepacia complex.

The present study examined the potential of intact-cell matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS) for a rapid identification of Burkholderia cepacia complex (Bcc) bacteria using an Applied Biosystems 4700 Proteomics Analyser. Two software packages were used to analyse mass profiles based on densitometric curves and peak positions. The 75 strains examined, represented the nine established Bcc species and some commonly misidentified species, closely related or biochemically similar to Bcc and relevant in the context of cystic fibrosis microbiology. All Bcc strains clustered together, separated from non-Bcc strains. Within Bcc, most Bcc strains grouped in species specific clusters, except for Burkholderia anthina and Burkholderia pyrrocinia strains which constituted a single cluster. The present study demonstrates that MALDI-TOF MS is a powerful approach for the rapid identification of Bcc bacteria.

A putative gene cluster for aminoarabinose biosynthesis is essential for Burkholderia cenocepacia viability.

Using a conditional mutagenesis strategy we demonstrate here that a gene cluster encoding putative aminoarabinose (Ara4N) biosynthesis enzymes is essential for the viability of Burkholderia cenocepacia. Loss of viability is associated with dramatic changes in bacterial cell morphology and ultrastructure, increased permeability to propidium iodide, and sensitivity to sodium dodecyl sulfate, suggesting a general cell envelope defect caused by the lack of Ara4N.

Burkholderia cepacia complex isolates survive intracellularly without replication within acidic vacuoles of Acanthamoeba polyphaga.

We have previously demonstrated that isolates of the Burkholderia cepacia complex can survive intracellularly in murine macrophages and in free-living Acanthamoeba. In this work, we show that the clinical isolates B. vietnamiensis strain CEP040 and B. cenocepacia H111 survived but did not replicate within vacuoles of A. polyphaga. B. cepacia-containing vacuoles accumulated the fluid phase marker Lysosensor Blue and displayed strong blue fluorescence, indicating that they had low pH. In contrast, the majority of intracellular bacteria within amoebae treated with the V-ATPse inhibitor bafilomycin A1 localized in vacuoles that did not fluoresce with Lysosensor Blue. Experiments using bacteria fluorescently labelled with chloromethylfluorescein diacetate demonstrated that intracellular bacteria remained viable for at least 24 h. In contrast, Escherichia coli did not survive within amoebae after 2 h post infection. Furthermore, intracellular B. vietnamiensis CEP040 retained green fluorescent protein within the bacterial cytoplasm, while this protein rapidly escaped from the cytosol of phagocytized heat-killed bacteria into the vacuolar lumen. Transmission electron microscopy analysis confirmed that intracellular Burkholderia cells were structurally intact. In addition, both Legionella pneumophila- and B. vietnamiensis-containing vacuoles did not accumulate cationized ferritin, a compound that localizes within the lysosome. Thus, our observations support the notion that B. cepacia complex isolates can use amoebae as a reservoir in the environment by surviving without intracellular replication within an acidic vacuole that is distinct from the lysosomal compartment.