The cis -2-dodecenoic acid (BDSF) quorum sensing system in Burkholderia cenocepacia

It has been demonstrated that quorum sensing (QS) is widely employed by bacterial cells to coordinately regulate various group behaviors. Diffusible signal factor (DSF)-type signals have emerged as a growing family of conserved cell-cell communication signals. In addition to the DSF signal initially identified in Xanthomonas campestris pv. campestris, B urkholderia d iffusible s ignal f actor (BDSF, cis -2-dodecenoic acid) has been recognized as a conserved DSF-type signal with specific characteristics in both signal perception and transduction from DSF signals. Here, we review the history and current progress of the research of this type of signal, especially focusing on its biosynthesis, signaling pathways, and biological functions. We also discuss and explore the huge potential of targeting this kind of QS system as a new therapeutic strategy to control bacterial infections and diseases.

Human Milk Oligosaccharides Exhibit Biofilm Eradication Activity Against Matured Biofilms Formed by Different Pathogen Species

Human milk oligosaccharides (HMOs) have been shown to exhibit plenty of benefits for infants, such as prebiotic activity shaping the gut microbiota and immunomodulatory and anti-inflammatory activity. For some pathogenic bacteria, antimicrobial activity has been proved, but most studies focus on group B streptococci. In the present study, we investigated the antimicrobial and antibiofilm activities of the total and fractionated HMOs from pooled human milk against four common human pathogenic Gram-negative species (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Burkholderia cenocepacia) and three Gram-positive species (Staphylococcus aureus, Enterococcus faecium, and Enterococcus faecalis). The activity of HMOs against enterococci and B. cenocepacia are addressed here for the first time. We showed that HMOs exhibit a predominant activity against the Gram-positive species, with E. faecalis being the most sensitive to the HMOs, both in planktonic bacteria and in biofilms. In further tests, we could exclude fucosyllactose as the antibacterial component. The biological significance of these findings may lie in the prevention of skin infections of the mother’s breast as a consequence of breastfeeding-induced skin laceration and/or protection of the infants’ nasopharynx and lung from respiratory pathogens such as staphylococci.

Fourier Transform Infrared Spectroscopy for Typing Burkholderia cenocepacia ET12 Isolates

Respiratory infections due to Burkholderia cenocepacia , particularly the ET12 epidemic strain, are considered sentinel events for persons with cystic fibrosis, as they are often associated with person-to-person transmission and accelerated decline in lung function and early mortality. Current typing methods are generally only available at reference centers, with long turn-around-times, which can affect the identification of outbreaks and critical patient triage.

A Polyclonal Antibody Raised against the Burkholderia cenocepacia OmpA-like Protein BCAL2645 Impairs the Bacterium Adhesion and Invasion of Human Epithelial Cells In Vitro

Respiratory infections by bacteria of the Burkholderia cepacia complex (Bcc) remain a life threat to cystic fibrosis (CF) patients, due to the faster lung function decline and the absence of effective eradication strategies. Immunotherapies are regarded as an attractive alternative to control and reduce the damages caused by these infections. In this work, we report the cloning and functional characterization of the OmpA-like BCAL2645 protein, previously identified and found to be immunoreactive against sera from CF patients with a record of Bcc infections. The BCAL2645 protein is shown to play a role in biofilm formation, adherence to mucins and invasion of human lung epithelial cells. The expression of the BCAL2645 protein was found to be increased in culture medium, mimicking the lungs of CF patients and microaerophilic conditions characteristic of the CF lung. Moreover, a polyclonal antibody raised against BCAL2645 was found to inhibit, by about 75 and 85%, the ability of B. cenocepacia K56-2 to bind and invade in vitro CFBE41o- human bronchial epithelial cells. These results highlight the potential of anti-BCAL2645 antibodies for the development of passive immunization therapies to protect CF patients against Bcc infections.

211. Burkholderia Cenocepacia Infections at Sites Other Than the Respiratory Tract, a Large Case Series from a Tertiary Referral Hospital in Lebanon

Background Burkholderia cenocepacia has been described to cause mainly respiratory tract infections. We noticed an increased number of skin and soft tissue infections (SSTIs), bloodstream infections (BSIs) and osteomyelitis over the past years at our medical center. Methods This is a retrospective chart review of 44 patients with documented B. cenocepacia infection at sites other than the respiratory tract diagnosed between 2005 and 2020 at the American University of Beirut Medical Center, a tertiary referral hospital for the Middle East region. Results The nationalities of our patients were Iraqi (40.9%), Lebanese (34.1%), and Syrian (20.5%). Twenty six of the infections (59.1%) were hospital-acquired infections (HAIs). The most common infections were BSIs (17/44, 38.6%), then SSTIs as well as deep seated cysts and abscesses (16/44, 36.4%) and vertebral osteomyelitis (8/44, 18.2%). Half of the vertebral osteomyelitis were located in the lumbar, and 3 in the cervical region; 5 of these cases were native osteomyelitis. Sixteen patients (36.4%) had prior antibiotic intake within 30 days with ceftazidime, carbapenems and quinolones being the most common. All the patients received directed therapy for an average duration of 23.48 (+/- 37.779) days, and for 60 days for those with osteomyelitis. Combination regimens of 2 antibiotics (ceftazidime, quinolones, carbapenems, trimethoprim-sulfamethoxazole (TMP-SMX)) were used in 10 patients, whereas 24 received a single antibiotic. Thirty three patients (75%) were admitted to the hospital, 20 (45.5%) of which had an indwelling catheter and 12 (27.3%) were in the intensive care unit. Thirty two patients (96.9%) were discharged home. Susceptibility testing revealed 84.1%, 54.5%, 63.2%, and 65.9% susceptibility to ceftazidime, tetracycline, TMP-SMX, and carbapenems respectively. Characteristics of patients Conclusion B. cenocepacia BSIs, SSTIs, abscesses, and osteomyelitis were noted to be more common at our medical center as HAIs particularly in Iraqi and Syrian patients, raising the concern that countries at war might be at increased risk for such infections. Our susceptibilities results were consistent with the literature. Although B. cenocepacia is a resistant bacteria, the majority of our patients were successfully treated. Disclosures All Authors: No reported disclosures

Metabolomic profiling of Burkholderia cenocepacia in synthetic cystic fibrosis sputum medium reveals nutrient environment-specific production of virulence factors

Infections by Burkholderia cenocepacia lead to life-threatening disease in immunocompromised individuals, including those living with cystic fibrosis (CF). While genetic variation in various B. cenocepacia strains has been reported, it remains unclear how the chemical environment of CF lung influences the production of small molecule virulence factors by these strains. Here we compare metabolomes of three clinical B. cenocepacia strains in synthetic CF sputum medium (SCFM2) and in a routine laboratory medium (LB), in the presence and absence of the antibiotic trimethoprim. Using a mass spectrometry-based untargeted metabolomics approach, we identify several compound classes which are differentially produced in SCFM2 compared to LB media, including siderophores, antimicrobials, quorum sensing signals, and various lipids. Furthermore, we describe that specific metabolites are induced in the presence of the antibiotic trimethoprim only in SCFM2 when compared to LB. Herein, C13-acyl-homoserine lactone, a quorum sensing signal previously not known to be produced by B. cenocepacia as well as pyochelin-type siderophores were exclusively detected during growth in SCFM2 in the presence of trimethoprim. The comparative metabolomics approach described in this study provides insight into environment-dependent production of secondary metabolites by B. cenocepacia strains and suggests future work which could identify personalized strain-specific regulatory mechanisms involved in production of secondary metabolites. Investigations into whether antibiotics with different mechanisms of action induce similar metabolic alterations will inform development of combination treatments aimed at effective clearance of Burkholderia spp. pathogens.