Advances in Phage Therapy: Targeting the Burkholderia cepacia Complex.

The increasing prevalence and worldwide distribution of multidrug-resistant bacterial pathogens is an imminent danger to public health and threatens virtually all aspects of modern medicine. Particularly concerning, yet insufficiently addressed, are the members of the Burkholderia cepacia complex (Bcc), a group of at least twenty opportunistic, hospital-transmitted, and notoriously drug-resistant species, which infect and cause morbidity in patients who are immunocompromised and those afflicted with chronic illnesses, including cystic fibrosis (CF) and chronic granulomatous disease (CGD). One potential solution to the antimicrobial resistance crisis is phage therapy-the use of phages for the treatment of bacterial infections. Although phage therapy has a long and somewhat checkered history, an impressive volume of modern research has been amassed in the past decades to show that when applied through specific, scientifically supported treatment strategies, phage therapy is highly efficacious and is a promising avenue against drug-resistant and difficult-to-treat pathogens, such as the Bcc. In this review, we discuss the clinical significance of the Bcc, the advantages of phage therapy, and the theoretical and clinical advancements made in phage therapy in general over the past decades, and apply these concepts specifically to the nascent, but growing and rapidly developing, field of Bcc phage therapy.

Of onions and men: Report of cavitary community acquired pneumonia due to Burkholderia cepacia complex in an immunocompetent patient and review of the literature.

Burkholderia cepacia complex consists of highly antibiotic resistant gram negative bacilli that are plant symbionts and also potential agents of human infection.  This bacterial family's claim to fame in clinical medicine is as the scourge of cystic fibrosis patients, in whom it is a notorious respiratory pathogen.  Outside of cystic fibrosis, it rarely comes to mind as an etiology of community acquired pneumonia with or without lung cavitation in immunocompetent hosts.  We describe a case of an otherwise healthy, community-dwelling man who presented with subacute cavitary lung disease, the causative organism of which turned out to be Burkholderia cepacia complex.  Our report is accompanied by a review of the literature, which identified an additional eleven cases in the same category.  We analyze all of the available cases for the emergence of any identifiable patterns or peculiarities.

Major Aspects of Burkholderia gladioli and Burkholderia cepacia Infections in Children.

BACKGROUND: Burkholderia cepacia complex is an aerobic, non-spore-forming, catalase-positive, nonfermentative, Gram-negative bacterium common in environment. It is a serious pathogen especially for patients with cystic fibrosis (CF). But pathogenicity of Burkholderia is not limited to patients with CF. Herein, we aimed to reveal clinical patterns and outcomes of Burkholderia infections in pediatric patients in our hospital and also antimicrobial susceptibility of the isolated strain. METHODS: This retrospective study was conducted in Ankara Hematology Oncology Children's Training and Research Hospital. Patients with isolates of Burkholderia spp. between January 6, 2013, and January 12, 2018, were included in the study. RESULTS: Burkholderia spp. was isolated from 55 patients. 94.6% of these patients had underlying diseases and had prior hospitalization within a year. Burkholderia gladioli grew in 15 patients' samples (27.3%); 38 patients grew B. cepacia (69.1%). None of the patients that B. gladioli was isolated was diagnosed as CF;. all had nosocomial infections. B. gladioli seemed to be more susceptible to aminoglycosides, piperacillin-tazobactam, carbapenems and ciprofloxacin than B. cepacia (P = 0.00), whereas B. cepacia seemed to be more susceptible to ceftazidime than B. gladioli (P = 0.032). In addition, B. cepacia was more susceptible to trimethoprim-sulfamethoxazole and levofloxacin than B. gladioli, but this difference was not statistically significant (P = 0.76). CONCLUSIONS: The incidence of nosocomial infections caused by Burkholderia spp. is rare especially in pediatric literature. In our study, nosocomial Burkholderia infections occurred mostly in intensive care unit patients. The surveillance of Burkholderia infections is still very important, and the clinicians should be aware of changing epidemiology and increasing resistance of the microorganism. Besides, there are no internationally agreed minimal inhibitory concentration breakpoints and disk-diffusion test thresholds for susceptibility testing for Burkholderia. Thus, the methods which were used for antibiotic susceptibility testing in our center might cause uncertainty about the results and internationally agreed minimal inhibitory concentration breakpoints and disk-diffusion test thresholds for susceptibility testing for Burkholderia is still a gap to fill for the current literature.

Intracellular survival and innate immune evasion of Burkholderia cepacia: Improved understanding of quorum sensing-controlled virulence factors, biofilm, and inhibitors.

Burkholderia cepacia complex (Bcc) are opportunistic pathogens implicated with nosocomial infections, and high rates of morbidity and mortality, especially in individuals with cystic fibrosis (CF). B. cepacia are naturally resistant to different classes of antibiotics, and can subvert the host innate immune responses by producing quorum sensing (QS) controlled virulence factors and biofilms. It still remains a conundrum as to how exactly the bacterium survives the intracellular environment within the host cells of CF patients and immunocompromised individuals although the bacterium can invade human lung epithelial cells, neutrophils, and murine macrophages. The mechanisms associated with intracellular survival in the airway epithelial cells and the role of QS and virulence factors in B. cepacia infections in cystic fibrosis remain largely unclear. The current review focuses on understanding the role of QS-controlled virulence factors and biofilms, and provides additional impetus to understanding the potentials of QS-inhibitory strategies against B. cepacia.

Potent modulation of the CepR quorum sensing receptor and virulence in a Burkholderia cepacia complex member using non-native lactone ligands.

The Burkholderia cepacia complex (Bcc) is a family of closely related bacterial pathogens that are the causative agent of deadly human infections. Virulence in Bcc species has been shown to be controlled by the CepI/CepR quorum sensing (QS) system, which is mediated by an N-acyl L-homoserine lactone (AHL) signal (C8-AHL) and its cognate LuxR-type receptor (CepR). Chemical strategies to block QS in Bcc members would represent an approach to intercept this bacterial communication process and further delineate its role in infection. In the current study, we sought to identify non-native AHLs capable of agonizing or antagonizing CepR, and thereby QS, in a Bcc member. We screened a library of AHL analogs in cell-based reporters for CepR, and identified numerous highly potent CepR agonists and antagonists. These compounds remain active in a Bcc member, B. multivorans, with one agonist 250-fold more potent than the native ligand C8-AHL, and can affect QS-controlled motility. Further, the CepR antagonists prolong C. elegans survival in an infection model. These AHL analogs are the first reported non-native molecules that both directly modulate CepR and impact QS-controlled phenotypes in a Bcc member, and represent valuable chemical tools to assess the role of QS in Bcc infections.

El controvertido complejo Burkholderia cepacia, un grupo de especies promotoras del crecimiento vegetal y patógenas de plantas, animales y humanos / The controversial Burkholderia cepacia complex, a group of plant growth promoting species and plant, animals and human pathogens

El complejo Burkholderia cepacia está formado por 22 especies conocidas como patógenos oportunistas en personas inmunocomprometidas, especialmente en aquellas con fibrosis quística. También se aíslan de infecciones nosocomiales y son difíciles de erradicar debido a su capacidad intrínseca para resistir una gran variedad de antibióticos. En general, estas especies presentan genomas de gran tamaño (hasta 9 Mpb) divididos en 2-5 replicones. Esta característica aporta una gran versatilidad metabólica, que se considera importante para habitar el suelo, el agua, las plantas, incluso los nódulos en leguminosas. Algunas especies del complejo B. cepacia exhiben actividades benéficas, como biorremediación, biocontrol y promoción del crecimiento vegetal. No obstante, debido a su papel en infecciones de humanos, su uso en la agricultura está restringido. El complejo B. cepacia es un tema constante de estudio debido a su impacto en el sector salud y su potencial en la agricultura. En este trabajo se examina la historia del complejo B. cepacia y se revisa la información reciente relacionada con este grupo de bacterias.

The Burkholderia cepacia complex is a group of 22 species, which are known as opportunistic pathogens in immunocompromised people, especially those suffering from cystic fibrosis. It is also found in nosocomial infections and is difficult to eradicate due to intrinsic resistance to several antibiotics. The species have large genomes (up to 9 Mbp), distributed into 2-5 replicons. These features significantly contribute to genome plasticity, which makes them thrive in different environments like soil, water, plants or even producing nodules in legume plants. Some B. cepacia complex species are beneficial in bioremediation, biocontrol and plant-growth promotion. However, because the B. cepacia complex is involved in human infection, its use in agriculture is restricted. B. cepacia complex is being constantly studied due to the health problems that it causes and because of its agricultural potential. In this review, the history of B. cepacia complex and the most recently published information related to this complex are revised.

Accurate identification and epidemiological characterization of Burkholderia cepacia complex: an update.

Bacteria belonging to the Burkholderia cepacia complex (Bcc) are among the most important pathogens isolated from cystic fibrosis (CF) patients and in hospital acquired infections (HAI). Accurate identification of Bcc is questionable by conventional biochemical methods. Clonal typing of Burkholderia is also limited due to the problem with identification. Phenotypic identification methods such as VITEK2, protein signature identification methods like VITEK MS, Bruker Biotyper, and molecular targets such as 16S rRNA, recA, hisA and rpsU were reported with varying level of discrimination to identify Bcc. rpsU and/or 16S rRNA sequencing, VITEK2, VITEK MS and Bruker Biotyper could discriminate between Burkholderia spp. and non-Burkholderia spp. Whereas, Bcc complex level identification can be given by VITEK MS, Bruker Biotyper, and 16S rRNA/rpsU/recA/hisA sequencing. For species level identification within Bcc hisA or recA sequencing are reliable. Identification of Bcc is indispensable in CF patients and HAI to ensure appropriate antimicrobial therapy.

[The controversial Burkholderia cepacia complex, a group of plant growth promoting species and plant, animals and human pathogens]. / El controvertido complejo Burkholderia cepacia, un grupo de especies promotoras del crecimiento vegetal y patógenas de plantas, animales y humanos.

The Burkholderia cepacia complex is a group of 22 species, which are known as opportunistic pathogens in immunocompromised people, especially those suffering from cystic fibrosis. It is also found in nosocomial infections and is difficult to eradicate due to intrinsic resistance to several antibiotics. The species have large genomes (up to 9 Mbp), distributed into 2-5 replicons. These features significantly contribute to genome plasticity, which makes them thrive in different environments like soil, water, plants or even producing nodules in legume plants. Some B. cepacia complex species are beneficial in bioremediation, biocontrol and plant-growth promotion. However, because the B. cepacia complex is involved in human infection, its use in agriculture is restricted. B. cepacia complex is being constantly studied due to the health problems that it causes and because of its agricultural potential. In this review, the history of B. cepacia complex and the most recently published information related to this complex are revised.

Burkholderia multivorans septicemia in a pediatric liver transplant patient.

"Cepacia syndrome", caused by Burkholderia cepacia complex and often associated with cystic fibrosis, carries a high mortality rate. It is rare for Burkholderia multivorans, a species within the B. cepacia complex, to cause cepacia syndrome even among patients with cystic fibrosis. This is the first reported fatal case of cepacia syndrome caused by B. multivorans occurring in a pediatric liver transplant recipient who does not have cystic fibrosis. We describe the unique characteristics of this pathogen among the non-cystic fibrosis population and the importance of early recognition and treatment.

Small Noncoding Regulatory RNAs from Pseudomonas aeruginosa and Burkholderia cepacia Complex.

Cystic fibrosis (CF) is the most life-limiting autosomal recessive disorder in Caucasians. CF is characterized by abnormal viscous secretions that impair the function of several tissues, with chronic bacterial airway infections representing the major cause of early decease of these patients. Pseudomonas aeruginosa and bacteria from the Burkholderia cepacia complex (Bcc) are the leading pathogens of CF patients' airways. A wide array of virulence factors is responsible for the success of infections caused by these bacteria, which have tightly regulated responses to the host environment. Small noncoding RNAs (sRNAs) are major regulatory molecules in these bacteria. Several approaches have been developed to study P. aeruginosa sRNAs, many of which were characterized as being involved in the virulence. On the other hand, the knowledge on Bcc sRNAs remains far behind. The purpose of this review is to update the knowledge on characterized sRNAs involved in P. aeruginosa virulence, as well as to compile data so far achieved on sRNAs from the Bcc and their possible roles on bacteria virulence.

Three Distinct Contact-Dependent Growth Inhibition Systems Mediate Interbacterial Competition by the Cystic Fibrosis Pathogen Burkholderia dolosa.

The respiratory tracts of individuals afflicted with cystic fibrosis (CF) harbor complex polymicrobial communities. By an unknown mechanism, species of the Gram-negative Burkholderia cepacia complex, such as Burkholderia dolosa, can displace other bacteria in the CF lung, causing cepacia syndrome, which has a poor prognosis. The genome of Bdolosa strain AU0158 (BdAU0158) contains three loci that are predicted to encode contact-dependent growth inhibition (CDI) systems. CDI systems function by translocating the toxic C terminus of a large exoprotein directly into target cells, resulting in growth inhibition or death unless the target cells produce a cognate immunity protein. We demonstrate here that each of the three bcpAIOB loci in BdAU0158 encodes a distinct CDI system that mediates interbacterial competition in an allele-specific manner. While only two of the three bcpAIOB loci were expressed under the in vitro conditions tested, the third conferred immunity under these conditions due to the presence of an internal promoter driving expression of the bcpI gene. One BdAU0158 bcpAIOB allele is highly similar to bcpAIOB in Burkholderia thailandensis strain E264 (BtE264), and we showed that their BcpI proteins are functionally interchangeable, but contact-dependent signaling (CDS) phenotypes were not observed in BdAU0158. Our findings suggest that the CDI systems of BdAU0158 may provide this pathogen an ecological advantage during polymicrobial infections of the CF respiratory tract.IMPORTANCE Human-associated polymicrobial communities can promote health and disease, and interbacterial interactions influence the microbial ecology of such communities. Polymicrobial infections of the cystic fibrosis respiratory tract impair lung function and lead to the death of individuals suffering from this disorder; therefore, a greater understanding of these microbial communities is necessary for improving treatment strategies. Bacteria utilize contact-dependent growth inhibition systems to kill neighboring competitors and maintain their niche within multicellular communities. Several cystic fibrosis pathogens have the potential to gain an ecological advantage during infection via contact-dependent growth inhibition systems, including Burkholderia dolosa Our research is significant, as it has identified three functional contact-dependent growth inhibition systems in Bdolosa that may provide this pathogen a competitive advantage during polymicrobial infections.

Targeting the Bacterial Cytoskeleton of the Burkholderia cepacia Complex for Antimicrobial Development: A Cautionary Tale.

Burkholderia cepacia complex (BCC) bacteria are a group of opportunistic pathogens that cause severe lung infections in cystic fibrosis (CF). Treatment of BCC infections is difficult, due to the inherent and acquired multidrug resistance of BCC. There is a pressing need to find new bacterial targets for antimicrobials. Here, we demonstrate that the novel compound Q22, which is related to the bacterial cytoskeleton destabilising compound A22, can reduce the growth rate and inhibit growth of BCC bacteria. We further analysed the phenotypic effects of Q22 treatment on BCC virulence traits, to assess its feasibility as an antimicrobial. BCC bacteria were grown in the presence of Q22 with a broad phenotypic analysis, including resistance to H2O2-induced oxidative stress, changes in the inflammatory potential of cell surface components, and in-vivo drug toxicity studies. The influence of the Q22 treatment on inflammatory potential was measured by monitoring the cytokine responses of BCC whole cell lysates, purified lipopolysaccharide, and purified peptidoglycan extracted from bacterial cultures grown in the presence or absence of Q22 in differentiated THP-1 cells. BCC bacteria grown in the presence of Q22 displayed varying levels of resistance to H2O2-induced oxidative stress, with some strains showing increased resistance after treatment. There was strain-to-strain variation in the pro-inflammatory ability of bacterial lysates to elicit TNFα and IL-1ß from human myeloid cells. Despite minimal toxicity previously shown in vitro with primary CF cell lines, in-vivo studies demonstrated Q22 toxicity in both zebrafish and mouse infection models. In summary, destabilisation of the bacterial cytoskeleton in BCC, using compounds such as Q22, led to increased virulence-related traits in vitro. These changes appear to vary depending on strain and BCC species. Future development of antimicrobials targeting the BCC bacterial cytoskeleton may be hampered if such effects translate into the in-vivo environment of the CF infection.

The OmpR Regulator of Burkholderia multivorans Controls Mucoid-to-Nonmucoid Transition and Other Cell Envelope Properties Associated with Persistence in the Cystic Fibrosis Lung.

Bacteria from the Burkholderia cepacia complex grow in different natural and man-made environments and are feared opportunistic pathogens that cause chronic respiratory infections in cystic fibrosis patients. Previous studies showed that Burkholderia mucoid clinical isolates grown under stress conditions give rise to nonmucoid variants devoid of the exopolysaccharide cepacian. Here, we determined that a major cause of the nonmucoid morphotype involves nonsynonymous mutations and small indels in the ompR gene encoding a response regulator of a two-component regulatory system. In trans complementation of nonmucoid variants (NMVs) with the native gene restored exopolysaccharide production. The loss of functional Burkholderia multivorans OmpR had positive effects on growth, adhesion to lung epithelial cells, and biofilm formation in high-osmolarity medium, as well as an increase in swimming and swarming motilities. In contrast, phenotypes such as antibiotic resistance, biofilm formation at low osmolarity, and virulence in Galleria mellonella were compromised by the absence of functional OmpR. Transcriptomic studies indicated that loss of the ompR gene affects the expression of 701 genes, many associated with outer membrane composition, motility, stress response, iron acquisition, and the uptake of nutrients, consistent with starvation tolerance. Since the stresses here imposed on B. multivorans may strongly resemble the ones found in the cystic fibrosis (CF) airways and mutations in the ompR gene from longitudinally collected CF isolates have been found, this regulator might be important for the production of NMVs in the CF environment.IMPORTANCE Within the cystic fibrosis (CF) lung, bacteria experience high-osmolarity conditions due to an ion unbalance resulting from defects in CF transmembrane conductance regulator (CFTR) protein activity in epithelial cells. Understanding how bacterial CF pathogens thrive in this environment might help the development of new therapeutic interventions to prevent chronic respiratory infections. Here, we show that the OmpR response regulator of one of the species found in CF respiratory infections, Burkholderia multivorans, is involved in the emergence of nonmucoid colony variants and is important for osmoadaptation by regulating several cell envelope components. Specifically, genetic, phenotypic, genomic, and transcriptomic approaches uncover OmpR as a regulator of cell wall remodeling under stress conditions, with implications in several phenotypes such as exopolysaccharide production, motility, antibiotic resistance, adhesion, and virulence.

Successful Treatment of Persistent Burkholderia cepacia Complex Bacteremia with Ceftazidime-Avibactam.

We report our clinical experience treating a 2-month-old infant with congenital diaphragmatic hernia who experienced prolonged bacteremia with Burkholderia cepacia complex (Bcc) despite conventional antibiotic therapy and appropriate source control measures. The infection resolved after initiation of ceftazidime-avibactam. Whole-genome sequencing revealed that the isolate most closely resembled B. contaminans and identified the mechanism of resistance that likely contributed to clinical cure with this agent. Ceftazidime-avibactam should be considered salvage therapy for Bcc infections if other treatment options have been exhausted.

Epidemiology of device-associated infections in an intensive care unit of a teaching hospital in Nepal: A prospective surveillance study from a developing country.

BACKGROUND: Device-associated health care-acquired infections (DA-HAIs) in intensive care unit patients are a major cause of morbidity, mortality, and increased health care costs. METHODS: A prospective, structured clinicomicrobiological surveillance was carried out for 3 common DA-HAIs: ventilator-associated pneumonia (VAP), central line-associated bloodstream infection (CLABSI), and catheter-associated urinary tract infection (CAUTI) present in the patients of an intensive care unit of a teaching hospital in Nepal. DA-HAIs were identified using the Centers for Disease Control and Prevention definitions, and their rates were expressed as number of DA-HAIs per 1,000 device-days. RESULTS: Overall incidence rate of DA-HAIs was 27.3 per 1,000 patient-days occurring in 37.1% of patients. The device utilization ratio for mechanical ventilation, central line catheter, and urinary catheter was 0.83, 0.63, and 0.78, respectively. The rates of VAP, CLABSI, and CAUTI were 21.40, 8.64, and 5.11 per 1,000 device-days, respectively. Acinetobacter spp (32.7%), Klebsiella spp (23.6%), Burkholderia cepacia complex (12.7%), and Escherichia coli (10.9%) were the common bacterial pathogens. Most of the bacterial isolates associated with DA-HAIs were found to be multidrug-resistant. CONCLUSIONS: Incidence of DA-HAIs in the study intensive care unit was high compared with that of developed countries. Formulation and implementation of standard infection control protocols, active surveillance of DA-HAIs, and antimicrobial stewardship are urgently needed in our country.

Use of Synthetic Hybrid Strains To Determine the Role of Replicon 3 in Virulence of the Burkholderia cepacia Complex.

The Burkholderia cepacia complex (Bcc) displays a wealth of metabolic diversity with great biotechnological potential, but the utilization of these bacteria is limited by their opportunistic pathogenicity to humans. The third replicon of the Bcc, megaplasmid pC3 (0.5 to 1.4 Mb, previously chromosome 3), is important for various phenotypes, including virulence, antifungal, and proteolytic activities and the utilization of certain substrates. Approximately half of plasmid pC3 is well conserved throughout sequenced Bcc members, while the other half is not. To better locate the regions responsible for the key phenotypes, pC3 mutant derivatives of Burkholderia cenocepacia H111 carrying large deletions (up to 0.58 Mb) were constructed with the aid of the FLP-FRT (FRT, flippase recognition target) recombination system from Saccharomyces cerevisiae The conserved region was shown to confer near-full virulence in both Caenorhabditis elegans and Galleria mellonella infection models. Antifungal activity was unexpectedly independent of the part of pC3 bearing a previously identified antifungal gene cluster, while proteolytic activity was dependent on the nonconserved part of pC3, which encodes the ZmpA protease. To investigate to what degree pC3-encoded functions are dependent on chromosomally encoded functions, we transferred pC3 from Burkholderia cenocepacia K56-2 and Burkholderia lata 383 into other pC3-cured Bcc members. We found that although pC3 is highly important for virulence, it was the genetic background of the recipient that determined the pathogenicity level of the hybrid strain. Furthermore, we found that important phenotypes, such as antifungal activity, proteolytic activity, and some substrate utilization capabilities, can be transferred between Bcc members using pC3.IMPORTANCE The Burkholderia cepacia complex (Bcc) is a group of closely related bacteria with great biotechnological potential. Some strains produce potent antifungal compounds and can promote plant growth or degrade environmental pollutants. However, their agricultural potential is limited by their opportunistic pathogenicity, particularly for cystic fibrosis patients. Despite much study, their virulence remains poorly understood. The third replicon, pC3, which is present in all Bcc isolates and is important for pathogenicity, stress resistance, and the production of antifungal compounds, has recently been reclassified from a chromosome to a megaplasmid. In this study, we identified regions on pC3 important for virulence and antifungal activity and investigated the role of the chromosomal background for the function of pC3 by exchanging the megaplasmid between different Bcc members. Our results may open a new avenue for the construction of antifungal but nonpathogenic Burkholderia hybrids. Such strains may have great potential as biocontrol strains for protecting fungus-borne diseases of plant crops.

An Oxygen-Sensing Two-Component System in the Burkholderia cepacia Complex Regulates Biofilm, Intracellular Invasion, and Pathogenicity.

Burkholderia dolosa is a member of the Burkholderia cepacia complex (BCC), which is a group of bacteria that cause chronic lung infection in patients with cystic fibrosis (CF) and can be associated with outbreaks carrying high morbidity and mortality. While investigating the genomic diversity of B. dolosa strains collected from an outbreak among CF patients, we previously identified fixL as a gene showing signs of strong positive selection. This gene has homology to fixL of the rhizobial FixL/FixJ two-component system. The goals of this study were to determine the functions of FixLJ and their role in virulence in B. dolosa. We generated a fixLJ deletion mutant and complemented controls in B. dolosa strain AU0158. Using a fixK-lacZ reporter we found that FixLJ was activated in low oxygen in multiple BCC species. In a murine pneumonia model, the B. dolosa fixLJ deletion mutant was cleared faster from the lungs and spleen than wild-type B. dolosa strain AU0158 at 7 days post infection. Interestingly, the fixLJ deletion mutant made more biofilm, albeit with altered structure, but was less motile than strain AU0158. Using RNA-seq with in vitro grown bacteria, we found ~11% of the genome was differentially expressed in the fixLJ deletion mutant relative to strain AU0158. Multiple flagella-associated genes were down-regulated in the fixLJ deletion mutant, so we also evaluated virulence of a fliC deletion mutant, which lacks a flagellum. We saw no difference in the ability of the fliC deletion mutant to persist in the murine model relative to strain AU0158, suggesting factors other than flagella caused the phenotype of decreased persistence. We found the fixLJ deletion mutant to be less invasive in human lung epithelial and macrophage-like cells. In conclusion, B. dolosa fixLJ is a global regulator that controls biofilm formation, motility, intracellular invasion/persistence, and virulence.

Pseudoalteromonas haloplanktis produces methylamine, a volatile compound active against Burkholderia cepacia complex strains.

The Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125 has been reported to produce several Volatile Organic Compounds (VOCs), which are able to inhibit the growth of Burkholderia cepacia complex (Bcc) strains, opportunistic pathogens responsible for the infection of immune-compromised patients. However, no specific antibacterial VOCs have been identified to date. The purpose of the present study was to identify specific VOCs that contribute to Bcc inhibition by the Antarctic strain. When grown on defined medium containing D-gluconate and L-glutamate as carbon, nitrogen and energy sources, P. haloplanktis TAC125 is unable to inhibit the growth of Bcc strains. However, single addition of several amino acids to the defined medium restores the P. haloplanktis TAC125 inhibition ability. With the aim of identifying specific volatile compound/s responsible for Bcc inhibition, we set up an apparatus for VOC capture, accumulation, and storage. P. haloplanktis TAC125 was grown in an automatic fermenter which was connected to a cooling system to condense VOCs present in the exhaust air outlet. Upon addition of methionine to the growth medium, the VOC methylamine was produced by P. haloplanktis TAC125. Methylamine was found to inhibit the growth of several Bcc strains in a dose-dependent way. Although it was reported that P. haloplanktis TAC125 produces VOCs endowed with antimicrobial activity, this is the first demonstration that methylamine probably contributes to the anti-Bcc activity of P. haloplanktis TAC125 VOCs.

Clinical and in vitro evidence for the antimicrobial therapy in Burkholderia cepacia complex infections.

Treatment of infections caused by Burkholderia cepacia complex (Bcc) in cystic fibrosis (CF) patients poses a complex problem. Bcc is multidrug-resistant due to innate and acquired mechanisms of resistance. As CF patients receive multiple courses of antibiotics, susceptibility patterns of strains from CF patients may differ from those noted in strains from non-CF patients. Thus, there was a need for assessing in vitro and clinical data to guide antimicrobial therapy in these patients. A systematic search of literature, followed by extraction and analysis of available information from human and in vitro studies was done. The results of the analysis are used to address various aspects like use of antimicrobials for pulmonary and non-pulmonary infections, use of combination versus monotherapy, early eradication, duration of therapy, route of administration, management of biofilms, development of resistance during therapy, pharmacokinetics-pharmacodynamics correlations, therapy in post-transplant patients and newer drugs in Bcc-infected CF patients.