Evaluation of Three Culture Media for Isolation of Burkholderia cepacia Complex from Respiratory Samples of Patients with Cystic Fibrosis

Burkholderia cepacia complex (BCC) is a significant pathogen causing respiratory disease in individuals with cystic fibrosis (CF). Diagnosis is typically achieved by isolation of BCC on selective culture media following culture of sputum or other respiratory samples. The aim of this study was to compare the efficacy of three commercially available selective media for the isolation of BCC. The three media comprised Burkholderia cepacia selective agar (BCSA; bioMérieux), BD Cepacia medium (BD: Becton–Dickinson) and MAST Cepacia medium (MAST laboratories). Each medium was challenged with 270 respiratory samples from individuals with CF as well as an international collection of BCC (n = 26) and 14 other isolates of Burkholderia species at a range of inocula. The international collection was also used to artificially “spike” 26 respiratory samples. From a total of 34 respiratory samples containing BCC, 97% were recovered on BD and 94% were detected on MAST and BCSA. All three media were effective for isolation of BCC. BCSA was much more selective than the other two media (p < 0.0001) meaning that fewer isolates required processing to exclude the presence of BCC.

Burkholderia species in human infections in Mexico: Identification of B. cepacia, B. contaminans, B. multivorans, B. vietnamiensis,B. pseudomallei and a new Burkholderia species

Background Burkholderia sensu stricto is comprised mainly of opportunistic pathogens. This group is widely distributed in the environment but is especially important in clinical settings. In Mexico, few species have been correctly identified among patients, most often B. cepacia is described. Methodology/Principal findings In this study, approximately 90 strains identified as B. cepacia with the VITEK2 system were isolated from two medical centers in Mexico City and analyzed by MLSA, BOX-PCR and genome analysis. The initial identification of B. cepacia was confirmed for many strains, but B. contaminans, B. multivorans and B. vietnamiensis were also identified among clinical strains for the first time in hospitals in Mexico. Additionally, the presence of B. pseudomallei was confirmed, and a novel species within the B. cepacia complex was documented. Several strains misidentified as B. cepacia actually belong to the genera Pseudomonas, Stenotrophomonas and Providencia. Conclusions/Significance The presence of different Burkholderia species in Mexico was confirmed. Correct identification of Burkholderia species is important to provide accurate treatment for immunosuppressed patients.

The In Vitro and In Planta Interspecies Interactions Among Rice-Pathogenic Burkholderia Species

Burkholderia glumae, B. plantarii, and B. gladioli are responsible for serious diseases in rice crops and co-occurrence among them has been reported. In this study, in vitro assays revealed antagonistic activity among these organisms, with B. gladioli demonstrating strong inhibition of B. glumae and B. plantarii. Strains of B. glumae and B. plantarii that express green fluorescent protein were constructed and used for cocultivation assays with B. gladioli, which confirmed the strong inhibitory activity of B. gladioli. Cell-free supernatants from each species were tested against cultures of counterpart species to evaluate the potential to inhibit bacterial growth. To investigate the inhibitory activity of B. gladioli on B. glumae and B. plantarii in rice, rice plant assays were performed and quantitative PCR (qPCR) assays were developed for in planta bacterial quantification. The results indicated that coinoculation with B. gladioli leads to significantly reduced disease severity and colonization of rice tissues compared with single inoculation with B. glumae or B. plantarii. This study demonstrates the interactions among three rice-pathogenic Burkholderia species and strong antagonistic activity of B. gladioli in vitro and in planta. The qPCR assays developed here could be applied for accurate quantification of these organisms from in planta samples in future studies.

Inhibiting quinolone biosynthesis of Burkholderia

2-Alkylquinolones are important signalling molecules of Burkholderia species. We developed a substrate-based chemical probe against the central quinolone biosynthesis enzyme HmqD and applied it in competitive profiling experiments to discover...

Burkholderia gladioli CGB10: A Novel Strain Biocontrolling the Sugarcane Smut Disease

In this study, we isolated an endophytic Burkholderia gladioli strain, named CGB10, from sugarcane leaves. B. gladioli CGB10 displayed strong inhibitory activity against filamentous growth of fungal pathogens, one of which is Sporisorium scitamineum that causes sugarcane smut, a major disease affecting the quality and production of sugarcane in tropical and subtropical regions. CGB10 could effectively suppress sugarcane smut under field conditions, without itself causing any obvious damage or disease, thus underscoring a great potential as a biocontrol agent (BCA) for the management of sugarcane smut. A toxoflavin biosynthesis and transport gene cluster potentially responsible for such antifungal activity was identified in the CGB10 genome. Additionally, a quorum-sensing gene cluster was identified too and compared with two close Burkholderia species, thus supporting an overall connection to the regulation of toxoflavin synthesis therein. Overall, this work describes the in vitro and field Sporisorium scitamineum biocontrol by a new B. gladioli strain, and reports genes and molecular mechanisms potentially involved.

What are we missing by using hydrophilic enrichment? Improving bacterial glycoproteome coverage using total proteome and FAIMS analysis

ABSTRACTHydrophilic Interaction Liquid Chromatography (HILIC) glycopeptide enrichment is an indispensable tool for the high-throughput characterisation of glycoproteomes. Despite its utility, HILIC enrichment is associated with a number of short comings including requiring large amounts of starting material, potentially introducing chemical artefacts such as formylation, and biasing/under-sampling specific classes of glycopeptides. Here we investigate HILIC enrichment independent approaches for the study of bacterial glycoproteomes. Using three Burkholderia species (B. cenocepacia, B. dolosa and B. ubonensis) we demonstrate that short aliphatic O-linked glycopeptides are typically absent from HILIC enrichments yet are readily identified in whole proteome samples. Using Field Asymmetric Waveform IMS (FAIMS) fractionation we show that at low compensation voltages (CVs) short aliphatic glycopeptides can be enriched from complex samples providing an alternative means to identify glycopeptides recalcitrant to hydrophilic based enrichment. Combining whole proteome and FAIMS analysis we show that the observable glycoproteome of these Burkholderia species is at least 30% larger than initially thought. Excitingly, the ability to enrich glycopeptides using FAIMS appears generally applicable, with the N-linked glycopeptides of Campylobacter fetus subsp. fetus also enrichable at low FAIMS CVs. Taken together, these results demonstrate that FAIMS provides an alternative means to access glycopeptides and is a valuable tool for glycoproteomic analysis.