Detection of multidrug-resistant organisms of concern including Stenotrophomonas maltophilia and Burkholderia cepacia at a referral hospital in Kenya.

Regular monitoring of bacterial susceptibility to antibiotics in clinical settings is key for ascertaining the current trends as well as re-establish empirical therapy. This study aimed to determine bacterial contaminants and their antimicrobial susceptibility patterns from medical equipment, inanimate surfaces and clinical samples obtained from Thika Level V Hospital (TLVH), Thika, in Central Kenya. Three hundred and five samples were collected between the period of March 2021 to November 2021 and comprised urine, pus swabs, catheter swabs, stool, and environmental samples. Bacterial identification and antimicrobial susceptibility were performed using VITEK 2 and disc diffusion respectively. We observed that Coagulase-negative Staphylococci (28 /160, 17.5%) were the most commonly isolated species from clinical samples followed by E. coli (22 /160 13.8%) and S. aureus (22/160, 13.8%). The bed rails were the mostly contaminated surface with S. aureus accounting for 14.2% (6/42). Among the clinical samples, pus swabs yielded the highest number of pathogens was pus (92/160). Trauma patients had the highest proportion of isolates (67/160, 41.8%). High level of antimicrobial resistance to key antimicrobials, particularly among Enterobacterales was observed. Extended Spectrum Beta Lactamase (ESBL) phenotype was noted in 65.9% (29/44) of enteric isolates. While further ESBL genetic confirmatory studies are needed, this study highlights the urgent need for actions that mitigate the spread of antibiotic-resistant bacteria.

Gut bacterium Burkholderia cepacia (BsNLG8) and immune gene Defensin A contribute to the resistance against Nicotine-induced stress in Nilaparvata lugens (Stål).

Nicotine, a naturally occurring alkaloid found in tobacco, is a potent neurotoxin extensively used to control Nilaparvata lugens (Stål), a destructive insect pest of rice crops. The insect gut harbors a wide array of resident microorganisms that profoundly influence several biological processes, including host immunity. Maintaining an optimal gut microbiota and immune homeostasis requires a complex network of reciprocal regulatory interactions. However, the underlying molecular mechanisms driving these symbiotic exchanges, particularly between specific gut microbe and immunity, remain largely unknown in insects. Our previous investigations identified and isolated a nicotine-degrading Burkholderia cepacia strain (BsNLG8) with antifungal properties. Building on those findings, we found that nicotine intake significantly increased the abundance of a symbiotic bacteria BsNLG8, induced a stronger bacteriostatic effect in hemolymph, and enhanced the nicotine tolerance of N. lugens. Additionally, nicotine-induced antimicrobial peptides (AMPs) exhibited significant antibacterial effects against Staphylococcus aureus. We adopted RNA-seq to explore the underlying immunological mechanisms in nicotine-stressed N. lugens. Bioinformatic analyses identified numerous differentially expressed immune genes, including recognition/immune activation (GRPs and Toll) and AMPs (i.e., Defensin, Lugensin, lysozyme). Temporal expression profiling (12, 24, and 48 hours) of immune genes revealed pattern recognition proteins and immune effectors as primary responders to nicotine-induced stress. Defensin A, a broad-spectrum immunomodulatory cationic peptide, exhibited significantly high expression. RNA interference-mediated silencing of Defensin A reduced the survival, enhanced nicotine sensitivity of N. lugens to nicotine, and decreased the abundance of BsNLG8. The reintroduction of BsNLG8 improved the expression of immune genes, aiding nicotine resistance of N. lugens. Our findings indicate a potential reciprocal immunomodulatory interaction between Defensin A and BsNLG8 under nicotine stress. Moreover, this study offers novel and valuable insights for future research into enhancing nicotine-based pest management programs and developing alternative biocontrol methods involving the implication of insect symbionts.

Identification of Burkholderia cepacia strains that express a Burkholderia pseudomallei-like capsular polysaccharide.

Burkholderia pseudomallei and Burkholderia cepacia are Gram-negative, soil-dwelling bacteria that are found in a wide variety of environmental niches. While B. pseudomallei is the causative agent of melioidosis in humans and animals, members of the B. cepacia complex typically only cause disease in immunocompromised hosts. In this study, we report the identification of B. cepacia strains isolated from either patients or soil in Laos and Thailand that express a B. pseudomallei-like 6-deoxyheptan capsular polysaccharide (CPS). These B. cepacia strains were initially identified based on their positive reactivity in a latex agglutination assay that uses the CPS-specific monoclonal antibody (mAb) 4B11. Mass spectrometry and recA sequencing confirmed the identity of these isolates as B. cepacia (formerly genomovar I). Total carbohydrates extracted from B. cepacia cell pellets reacted with B. pseudomallei CPS-specific mAbs MCA147, 3C5, and 4C4, but did not react with the B. pseudomallei lipopolysaccharide-specific mAb Pp-PS-W. Whole genome sequencing of the B. cepacia isolates revealed the presence of genes demonstrating significant homology to those comprising the B. pseudomallei CPS biosynthetic gene cluster. Collectively, our results provide compelling evidence that B. cepacia strains expressing the same CPS as B. pseudomallei co-exist in the environment alongside B. pseudomallei. Since CPS is a target that is often used for presumptive identification of B. pseudomallei, it is possible that the occurrence of these unique B. cepacia strains may complicate the diagnosis of melioidosis.IMPORTANCEBurkholderia pseudomallei, the etiologic agent of melioidosis, is an important cause of morbidity and mortality in tropical and subtropical regions worldwide. The 6-deoxyheptan capsular polysaccharide (CPS) expressed by this bacterial pathogen is a promising target antigen that is useful for rapidly diagnosing melioidosis. Using assays incorporating CPS-specific monoclonal antibodies, we identified both clinical and environmental isolates of Burkholderia cepacia that express the same CPS antigen as B. pseudomallei. Because of this, it is important that staff working in melioidosis-endemic areas are aware that these strains co-exist in the same niches as B. pseudomallei and do not solely rely on CPS-based assays such as latex-agglutination, AMD Plus Rapid Tests, or immunofluorescence tests for the definitive identification of B. pseudomallei isolates.

Evaluation of the production and extraction of polyhydroxybutyrate from volatile fatty acids by means of mixed cultures and B. cepacia.

The global consumption of plastics generates accelerated environmental pollution in landfills and marine ecosystems. Biopolymers are the materials with the greatest potential to replace synthetic polymers in the market due to their good biodegradability, however, there are still several disadvantages, mainly related to their production cost. Considering the above, the generation of biodegradable and biocompatible bioplastics stands out as an alternative solution, some of which are made from renewable raw materials, including polyhydroxyalkanoates PHAs. Although much research has been done on bacteria with the capacity for intracellular accumulation of PHAs, among others, it is also possible to produce PHAs using mixed microbial cultures instead of a single microorganism, using natural microbial consortia that have the capacity to store high amounts of PHAs. In this contribution, three methods for the extraction and purification of PHAs produced by fermentation using volatile fatty acids as a carbon source at different concentrations were evaluated, using the pure strain Burkholderia cepacia 2G-57 and the mixed cultures of the activated sludge from the El Salitre WWTP, in order to select the best method from the point of view of environmental sustainability as this will contribute to the scalability of the process. The mixed cultures were identified by sequencing of the 16S gene. A yield of 89% was obtained from the extraction and purification of PHA using acetic acid as a solvent, which according to its properties is "greener" than chloroform. The polymer obtained was identified as polyhydroxybutylated PHB.

Burkholderia cepacia: A Rare Source of Endocarditis.

A 37-year-old male with a past medical history of previous mitral valve replacement due to bacterial endocarditis and intravenous (IV) drug use was found to have Burkholderia cepacia bacteremia. Transesophageal echocardiogram revealed large mitral and tricuspid valve vegetations. Medical management was initially attempted but his bacteremia persisted, and he required urgent prosthetic mitral valve replacement and native tricuspid valve replacement. Prosthetic valve endocarditis has been associated with surgery in 48.9% of patients and a mortality of 22.8%. In patients with prosthetic valve endocarditis due to B. cepacia, valve replacement occurred in approximately 61.5% of patients and mortality is estimated to be 33.3%. To our knowledge, this is one of only a few prosthetic valve endocarditis cases caused solely by B. cepacia and our case is the first to affect multiple valves including prosthetic and native valves.

When is Burkholderia cepacia complex truly eradicated in adults with cystic fibrosis? A 20-year follow up study.

BACKGROUND: Burkholderia cepacia complex (BCC) infection in cystic fibrosis (CF) is associated with increased morbidity and mortality. Current UK guidance recommends segregation of people with CF according to infection status. To date there is no universally agreed consensus on the number of negative samples or time interval since last isolation of BCC for eradication to be deemed successful. METHODS: All cases of new BCC isolation at Manchester Adult Cystic Fibrosis Centre were followed-up between May 2002-May 2022. The number of subsequent positive and negative sputum samples for BCC were recorded, as well as eradication treatment received. Eradication was deemed successful if there were ≥3 negative sputum samples and no further positive sputum samples for the same species and strain ≥12 months until the end of follow-up. RESULTS: Of 46 new BCC isolation, 25 were successfully eradicated and 21 resulted in chronic infection. 5 (16.7%) cases with exclusively negative sputum samples 6-12 months after initial isolation had subsequent samples that were culture-positive for BCC and 3 (10.7%) cases with exclusively negative sputum samples after 12-24 months had subsequent culture-positive samples. Cases where BCC was eradicated had a greater median number of days of eradication treatment (42, IQR 21-63) compared to those in whom BCC isolation resulted in chronic infection (28, IQR 14-42), p = 0.04. CONCLUSIONS: A cautious approach to segregation should be maintained after new isolation of BCC in CF, as some individuals with ≥3 negative samples 12-24 months after initial isolation had subsequent sputum samples culture-positive for BCC.

Burkholderia cepacia skin-related ulceration: a case report.

Treatment of infected wounds remains a major challenge for clinicians. Antimicrobial stewardship is an important pillar in wound treatment and, as the role of bacteria in wound repair is not well understood, new treatment options and products are constantly being developed to tackle local infection and biofilm. This case report describes a case of antibiotic-resistant Burkholderia cepacia skin infection and subsequent leg ulceration in an 86-year-old man during the COVID pandemic in Italy, which was successfully treated in a conservative way using 1% acetic acid and silver oxysalts in conjunction with compression bandage.

Burkholderia cepacia complex as a cause of community acquired bacteremia in a young immuncompetent male.

Burkholderia cepacia complex (BCC) is a well-recognized cause of nosocomial infections. We describe here a young healthy male who presented with fever and chest pain with ECG changes of acute pericarditis. Two sets of blood cultures at separate timings grew gram negative bacilli identified as BCC by molecular methods. The patient responded to intravenous ceftazidime despite high ceftazidime MIC's. The source of infection was probably contaminated nasal spray/nasal saline wash which he used after a balloon sinoplasty procedure one month ago. Issues related to accurate identification and susceptibility testing of BCC are also discussed.

Biocontrol of biofilm forming Burkholderia cepacia using a quorum quenching crude lactonase enzyme extract from a marine Chromohalobacter sp. strain D23.

Biofilm plays advantageous role in Burkholderia cepacia by exerting multi-drug resistance. As quorum sensing (QS) system regulates biofilm formation and pathogenicity in B. cepacia strains, quorum quenching (QQ) may be a novel strategy to control persistent B. cepacia infections. In these regards, 120 halophilic bacteria were isolated from marine sample and tested using Chromobacterium violaceum and C. violaceum CV026-based bioassays initially, showing reduced violacein synthesis by QQ enzyme by 6 isolates. Among them, Chromohalobacter sp. D23 significantly degraded both C6-homoserine lactone (C6-HSL) and C8-HSL due to potent lactonase activity, which was detected by C. violaceum CV026 biosensor. Further high-performance liquid chromatography (HPLC) study confirmed degradation of N-acyl homoserine lactones (N-AHLs) particularly C6-HSL and C8-HSL by crude lactonase enzyme. Chromohalobacter sp. D23 reduced biofilm formation in terms of decreased total biomass and viability in biofilm-embedded cells in B. cepacia significantly which was also evidenced by fluorescence microscopic images. An increase in antibiotic susceptibility of B. cepacia biofilm was achieved when crude lactonase enzyme of Chromohalobacter sp. strain D23 was combined with chloramphenicol (1-5 × MIC). Chromohalobacter sp. D23 also showed prominent decrease in QS-mediated synthesis of virulence factors such as extracellular polymeric substances (EPS), extracellular protease, and hemolysin in B. cepacia. Again crude lactonase enzyme of Chromohalobacter sp. strain D23 inhibited B. cepacia biofilm formation inside nasal oxygen catheters in vitro. Finally, antibiotic susceptibility test and virulence tests revealed sensitivity of Chromohalobacter sp. strain D23 against a wide range of conventional antibiotics as well as absence of gelatinolytic, hemolytic, and serum coagulating activities. Therefore, the current study shows potential quorum quenching as well as anti-biofilm activity of Chromohalobacter sp. D23 against B. cepacia.

Outbreak investigation of NDM-producing Burkholderia cepacia causing neonatal sepsis in Pakistan.

Aim: To investigate the outbreak of Burkholderia cepacia complex (BCC), mortality, antimicrobial resistance and associated risk factors in the neonatal intensive care unit. Method: Eighteen blood culture samples from neonates and twenty swab samples from different neonatal intensive care unit surfaces were collected. The VITEK 2 was used to confirm the isolates and generate the antibiogram. PCR was used to identify blaNDM. Results: Eighteen samples tested positive for BCC, and 10/18 (55.5%) of the neonates died. 13/18 (72%) of the neonates had late-onset neonatal sepsis, and 10/18 (55%) had low birth weight. Resistance to minocycline and chloramphenicol was 100%, 72.2% to meropenem; 72.2% NDM gene was found in neonates and was 20% from the environment. Conclusion: Outbreak of NDM-producing BCC resulting in high neonatal mortality in NICU.

Neonatal septicemia, or blood poisoning, is a dangerous illness in newborns. It is caused by bacteria or other infections entering the blood and spreading. Pregnancy, labor, delivery and exposure after birth can result in infection of the newborn. Neonatal septicemia kills 700,000 babies worldwide, mostly in low- and middle-income countries. Burkholderia cepacia complex bacteria can cause infections in people with weaker immune systems or other disorders. They are particularly dangerous in hospitals, as they can cause chronic lung problems. This study collected blood samples from newborns with blood poisoning. Most samples that contained Burkholderia cepacia complex were not susceptible to drugs. Four of the newborns carried the same bacteria, indicating that hospital staff should practice hand washing and equipment and environmental cleaning to prevent the spread of the bacteria.

Hormesis of glyphosate on ferulic acid metabolism and antifungal volatile production in rice root biocontrol endophyte Burkholderia cepacia LS-044.

Glyphosate (GP, N-phosphonomethyl glycine) is one of the most popular organophosphate herbicides widely used in agricultural practices worldwide. There have been extensive reports on the biohazard attributes and hormetic impacts of GP on plant and animal systems. However, the effects of GP on plant growth-promoting microbes and its ecological relevance remain unknown. Here, we show that GP does exert a hormetic impact on Burkholderia cepacia LS-044, a rice (Oryza sativa ssp. japonica cv. Tainung 71) root endophytic isolate. We used increasing doses of ferulic acid (FA, 1-25 mM) and GP (0.5-5 mM) to test the growth and antifungal volatile production in LS-044 by electrochemical, liquid chromatographic, gas chromatographic and spectrophotometric means. GP treatment at a low dose (0.5 mM) increased FA utilization and significantly (P < 0.0001) enhanced antifungal volatile activity in LS-044. Although FA (1 mM) was rapidly utilized by LS-044, no chromatographically detectable utilization of GP was observed at tested doses (0.5-5 mM). LS-044 emitted predominant amounts of tropone in addition to moderate-to-minor amounts of diverse ketones and/or their derivatives (acetone, acetophenone, 2-butanone, 1-propanone, 1-(2-furanyl-ethanone, 1-phenyl-1-propanone and 1-(3-pyridinyl)-1-propanone), d-menthol, 2-methoxy-3-(1-methylethyl)-pyrazine, dimethyl disulfide, pyridine and ammonium carbamate when grown under GP supplement. GP hormesis on LS-044 induced phenotypic variations in O. sativa ssp. japonica cv. Tainan 11 as evident through seed germination assay. Genes involved in the transformation of FA, and a key gene encoding 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) with Gly-94 and Tyr-95 residues localized at active site most likely rendering EPSPS sensitivity to GP, were detected in LS-044. This is the first report on the GP hormesis influencing morphological and metabolic aspects including volatile emission in a biocontrol bacterium that could modulate rice plant phenotype.

Comparison of enzymatic activities of lipases from Burkholderia plantarii and Burkholderia cepacia.

Lipases (EC 3.1.1.3) are enzymes used in the oils and fats industries to modify the physicochemical properties of triacylglycerol (TAG). Lipase-catalyzed interesterification at high temperatures is an effective method for modifying the physicochemical properties of TAG. The lipase from Burkholderia plantarii (BpL) exhibits excellent catalytic activity for non-regiospecific interesterification at high temperatures, with depressed lipase hydrolytic activity. The detailed catalytic mechanism for reactions involving catalytic residues has not been elucidated because of the lack of a conventional method for estimating interesterification activity. We used our original water-in-oil emulsion system to estimate the interesterification activity of lipases. BpL showed 10% hydrolytic and 140% interesterification activities compared to the lipase from Burkholderia cepacia, which has a high sequence homology with BpL. By comparing the sequence and crystal structure data of the lipases, we clarified that two amino acids near the active center are one of the factors controlling the hydrolytic and interesterification activities of the enzyme.

Burkholderia cepacia infections at sites other than the respiratory tract: A large case series from a tertiary hospital in Madurai.

Sparsely reported extrapulmonary Burkholderia cepacia complex (Bcc) infections highlights the importance of this study. This was a retrospective chart review of 37 patients with extrapulmonary Bcc infections admitted between December 2019 and July 2022 in a tertiary hospital. Males accounted for 70% of cases. 78% had atleast one underlying comorbid illness. Among 37 isolates, 22 were from blood, others include exudates, urine and peritoneal fluid. Susceptibility rates of ceftazidime, meropenem, minocycline, cotrimoxazole and levofloxacin were 88, 88, 70, 65.7 and 56.7% respectively. Eleven died of septic shock and 24 patients (64.8%) had good outcomes, while two were lost to followup.

Identification of Burkholderia cepacia Complex by PCR: A Simple Way.

United States Pharmacopeia (USP) General Chapter <60> for the detection of Burkholderia cepacia complex (Bcc) members in nonsterile products became official in December 2019. This isolation method requires confirmation of the identity of any growth found on Burkholderia cepacia Selective Agar (BCSA) by additional identification tests (refer to the Interpretation section). This article presents a singleplex polymerase chain reaction (PCR) method to rapidly confirm the membership of any microbial grown on BCSA (and other nutrient medium) in the Bcc group. This method is cost effective as it does not require expensive equipment or reagents; therefore, it can be easily adopted in the industry without an important investment. We validated this singleplex PCR Bcc identification method with previously published PCR primers with an expanded panel of 37 clinical and environmental Bcc isolates. The sources and repositories of these Bcc isolates include contaminated health products and medical devices, patients infected with cystic fibrosis, the National Microbiology Laboratory (NML) internal strain bank, and the American Type Culture Collection (ATCC). All 37 isolates that belong to the Bcc tested positive using our confirmatory identification method. Twenty-two negative controls including four isolates belonging to the genus Burkholderia tested negative as expected. Our work indicates that this singleplex PCR is an efficient confirmatory method for Bcc identification, and it can successfully supplement USP <60> for Bcc isolates identification found in pharmaceutical products.

Burkholderia cepacia immobilized onto rGO as a biomaterial for the removal of naphthalene from wastewater.

As one of the polycyclic aromatic hydrocarbons (PAHs), naphthalene is of serious environmental concern due to its carcinogenicity, persistence and refractory degradation. In this study, a new functional biomaterial based on Burkholderia cepacia (BK) immobilized on reduced graphene oxide (rGO) was prepared, resulting in the removal of 99.0% naphthalene within 48 h. This was better than the 67.3% for free BK and 55.6% for rGO alone. Various characterizations indicated that reduced graphene oxide-Burkholderia cepacia (rGO-BK) was successfully synthesized and secreted non-toxic and degradable surfactants which participated in the degradation of naphthalene. The adsorption kinetics and degradation kinetics conformed best to non-linear pseudo-second-order and pseudo-first-order kinetic models, respectively. Demonstrated in this work is that removing naphthalene by rGO-BK involved both chemically dominated adsorption and biodegradation. As well, GC-MS analysis revealed two things: firstly, that the degraded products of naphthalene were dibutyl phthalate, diethyl phthalate, phthalic acid, and benzoic acid; and secondly, two potentially viable biodegradation pathways of naphthalene by rGO-BK could be proposed. Finally, for practical application experiment, the rGO-BK was exposed to river water samples and generated 99% removal efficiency of naphthalene, so this study offers new insights into biomaterials that can remove naphthalene.

The Conformational Transitions and Dynamics of Burkholderia cepacia Lipase Regulated by Water-Oil Interfaces.

Structural dynamics and conformational transitions are crucial for the activities of enzymes. As one of the most widely used industrial biocatalysts, lipase could be activated by the water-oil interfaces. The interface activations were believed to be dominated by the close-to-open transitions of the lid subdomains. However, the detailed mechanism and the roles of structure transitions are still under debate. In this study, the dynamic structures and conformational transitions of Burkholderia cepacia lipase (LipA) were investigated by combining all-atom molecular dynamics simulations, enhanced sampling simulation, and spectrophotometric assay experiments. The conformational transitions between the lid-open and lid-closed states of LipA in aqueous solution are directly observed by the computational simulation methods. The interactions between the hydrophobic residues on the two lid-subdomains are the driven forces for the LipA closing. Meanwhile, the hydrophobic environment provided by the oil interfaces would separate the interactions between the lid-subdomains and promote the structure opening of LipA. Moreover, our studies demonstrate the opening of the lids structure is insufficient to initiate the interfacial activation, providing explanations for the inability of interfacial activation of many lipases with lid structures.

Burkholderia cepacia-contaminated dentures possibly cause pneumonia.

We report a case in which a patient was suspected of developing pneumonia due to wearing dentures that were immersed in a storage solution contaminated with 3.0 × 108 colony-forming units (cfu)/mL of Burkholderia cepacia. It is highly possible that the contaminated denture solution entered the trachea and caused the pneumonia, possibly due to the prolonged supine positioning of the patient. We demonstrated that B. cepacia isolated from the sputum and B. cepacia isolated from the denture storage solution had the same DNA fingerprint, and that the patient recovered from pneumonia after stopping the use of dentures. These findings suggest the storage solution as the main source of infection.

Burkholderia cepacia CS8 improves phytoremediation potential of Calendula officinalis for tannery solid waste polluted soil.

Microbes have shown potential for the bioremediation of tannery waste polluted soil. During our previous study, it was observed that heavy metal resistant Burkholderia cepacia CS8 augmented growth and phytoremediation capability of an ornamental plant. Objective of the present research work was to evaluate the capability of B. cepacia CS8 assisted Calendula officinalis plants for the phytoremediation of tannery solid waste (TSW) polluted soil. The TSW treatment significantly reduced growth attributes and photosynthetic pigments in C. officinalis. However, supplementation of B. cepacia CS8 which exhibited substantial tolerance to the TSW amended soil, augmented growth traits, carotenoid, proline, and antioxidant enzymes level in C. officinalis under toxic and nontoxic regimes. Inoculation of B. cepacia CS8 augmented plant growth (shoot length 13%, root length 11%), physiological attributes (chlorophyll a 14%, chlorophyll b 17%), antioxidant enzyme activities (peroxidase 24%, superoxide dismutase 31% and catalase 19%), improved proline 36%, phenol 32%, flavonoids 14% and declined malondialdehyde (MDA) content 15% and hydrogen peroxide (H2O2) level 12% in C. officinalis at TSW10 stress compared with relevant un-inoculated plants of TSW10 treatment. Moreover, B. cepacia CS8 application enhanced labile metals in soil and subsequent metal uptake, such as Cr 19%, Cd 22%, Ni 35%, Fe 18%, Cu 21%, Pb 34%, and Zn 30%, respectively in C. officinalis plants subjected to TSW10 stress than that of analogous un-inoculated treatment. Higher plant stress tolerance and improved phytoremediation potential through microbial inoculation will assist in the retrieval of agricultural land in addition to the renewal of native vegetation.

During the current study, it was observed that combination of Calendula officinalis and metal tolerant Burkholderia cepacia CS8 not only improved plant growth but also helped phyto-extraction of pollutants present in the tannery solid waste polluted soil. According to our information, research work describing the phytoremediation potential of native metal tolerant microbes and ornamental plants has not been reported in Pakistan.

Investigating chirality in quorum sensing by analysis of Burkholderia cepacia and Vibrio fischeri with comprehensive chiral LC-MS/MS and GC-MS/MS methods.

N-acyl homoserine lactones (N-HLs) are signaling molecules used by Gram-negative bacteria in a phenomenon called quorum sensing. Bacteria will detect N-HLs as a way of monitoring their population which, upon reaching a critical level, will express a specific phenotype. An example is the expression of bioluminescence by Vibrio fischeri. Most studies have not considered the chirality of these molecules nor have they used highly sensitive detection methods. Here, the production of d,l-N-HLs are monitored for V. fischeri, Burkholderia cepacia, Pseudomonas fluorescens, and P. putida, using highly sensitive tandem mass spectrometry analysis. Novel N-HLs are reported for both V. fischeri and B. cepacia, including a plethora of previously unknown d-N-HLs, including the first d-N-HLs containing oxo and hydroxy functionalities. Anomalously, N-HLs were not detected in any cultures of P. fluorescens and P. putida, which are species that previously were reported to produce N-HLs. However, it is apparent that differences in the reported occurrence and levels of N-HLs can result from (a) different strains of bacteria, (b) different growth media and environmental conditions, and (c) sometimes false-positive results from detection methodologies. Time studies of V. fischeri suggest the possibility that separate synthetic and elimination pathways exist between d- and l-N-HLs. Possible biological processes that could be the source of d-N-HL production are considered.

Compilation of the Antimicrobial Compounds Produced by Burkholderia Sensu Stricto.

Due to the increase in multidrug-resistant microorganisms, the investigation of novel or more efficient antimicrobial compounds is essential. The World Health Organization issued a list of priority multidrug-resistant bacteria whose eradication will require new antibiotics. Among them, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae are in the "critical" (most urgent) category. As a result, major investigations are ongoing worldwide to discover new antimicrobial compounds. Burkholderia, specifically Burkholderia sensu stricto, is recognized as an antimicrobial-producing group of species. Highly dissimilar compounds are among the molecules produced by this genus, such as those that are unique to a particular strain (like compound CF66I produced by Burkholderia cepacia CF-66) or antimicrobials found in a number of species, e.g., phenazines or ornibactins. The compounds produced by Burkholderia include N-containing heterocycles, volatile organic compounds, polyenes, polyynes, siderophores, macrolides, bacteriocins, quinolones, and other not classified antimicrobials. Some of them might be candidates not only for antimicrobials for both bacteria and fungi, but also as anticancer or antitumor agents. Therefore, in this review, the wide range of antimicrobial compounds produced by Burkholderia is explored, focusing especially on those compounds that were tested in vitro for antimicrobial activity. In addition, information was gathered regarding novel compounds discovered by genome-guided approaches.