Activity of Imipenem-Relebactam against Multidrug- and Extensively Drug-Resistant Burkholderia cepacia Complex and Burkholderia gladioli.

The Burkholderia cepacia complex (Bcc) and Burkholderia gladioli are opportunistic pathogens that most commonly infect persons with cystic fibrosis or compromised immune systems. Members of the Burkholderia genus are intrinsically multidrug resistant (MDR), possessing both a PenA carbapenemase and an AmpC ß-lactamase, rendering treatment of infections due to these species problematic. Here, we tested the ß-lactam-ß-lactamase inhibitor combination imipenem-relebactam against a panel of MDR Bcc and B. gladioli strains. The addition of relebactam to imipenem dramatically lowered the MICs for Bcc and B. gladioli: only 16% of isolates tested susceptible to imipenem, while 71.3% were susceptible to the imipenem-relebactam combination. While ceftazidime-avibactam remained the most potent combination drug against this panel of Bcc and B. gladioli strains, imipenem-relebactam was active against 71.4% of the ceftazidime-avibactam-resistant isolates. Relebactam demonstrated potent inactivation of Burkholderia multivorans PenA1, with an apparent Ki (Kiapp) value of 3.2 µM. Timed mass spectrometry revealed that PenA1 formed a very stable adduct with relebactam, without any detectable desulfation for as long as 24 h. Based on our results, imipenem-relebactam may represent an alternative salvage therapy for Bcc and B. gladioli infections, especially in cases where the isolates are resistant to ceftazidime-avibactam.

Multimodal Molecular Imaging and Identification of Bacterial Toxins Causing Mushroom Soft Rot and Cavity Disease.

Soft rot disease of edible mushrooms leads to rapid degeneration of fungal tissue and thus severely affects farming productivity worldwide. The bacterial mushroom pathogen Burkholderia gladioli pv. agaricicola has been identified as the cause. Yet, little is known about the molecular basis of the infection, the spatial distribution and the biological role of antifungal agents and toxins involved in this infectious disease. We combine genome mining, metabolic profiling, MALDI-Imaging and UV Raman spectroscopy, to detect, identify and visualize a complex of chemical mediators and toxins produced by the pathogen during the infection process, including toxoflavin, caryoynencin, and sinapigladioside. Furthermore, targeted gene knockouts and in vitro assays link antifungal agents to prevalent symptoms of soft rot, mushroom browning, and impaired mycelium growth. Comparisons of related pathogenic, mutualistic and environmental Burkholderia spp. indicate that the arsenal of antifungal agents may have paved the way for ancestral bacteria to colonize niches where frequent, antagonistic interactions with fungi occur. Our findings not only demonstrate the power of label-free, in vivo detection of polyyne virulence factors by Raman imaging, but may also inspire new approaches to disease control.

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.

"Switching Partners": Piperacillin-Avibactam Is a Highly Potent Combination against Multidrug-Resistant Burkholderia cepacia Complex and Burkholderia gladioli Cystic Fibrosis Isolates.

In persons with cystic fibrosis (CF), airway infection with Burkholderia cepacia complex (Bcc) species or Burkholderia gladioli presents a significant challenge due to inherent resistance to multiple antibiotics. Two chromosomally encoded inducible ß-lactamases, a Pen-like class A and AmpC are produced in Bcc and B. gladioli Previously, ceftazidime-avibactam demonstrated significant potency against Bcc and B. gladioli isolated from the sputum of individuals with CF; however, 10% of the isolates tested resistant to ceftazidime-avibactam. Here, we describe an alternative antibiotic combination to overcome ceftazidime-avibactam resistance. Antimicrobial susceptibility testing was performed on Bcc and B. gladioli clinical and control isolates. Biochemical analysis was conducted on purified PenA1 and AmpC1 ß-lactamases from Burkholderia multivorans ATCC 17616. Analytic isoelectric focusing and immunoblotting were conducted on cellular extracts of B. multivorans induced by various ß-lactams or ß-lactam-ß-lactamase inhibitor combinations. Combinations of piperacillin-avibactam, as well as piperacillin-tazobactam plus ceftazidime-avibactam (the clinically available counterpart), were tested against a panel of ceftazidime-avibactam nonsusceptible Bcc and B. gladioli The piperacillin-avibactam and piperacillin-tazobactam-ceftazidime-avibactam combinations restored susceptibility to 99% of the isolates tested. Avibactam is a potent inhibitor of PenA1 (apparent inhibitory constant [Kiapp] = 0.5 µM), while piperacillin was found to inhibit AmpC1 (Kiapp = 2.6 µM). Moreover, piperacillin, tazobactam, ceftazidime, and avibactam, as well as combinations thereof, did not induce expression of blapenA1 and blaampC1 in the B. multivorans ATCC 17616 background. When ceftazidime-avibactam is combined with piperacillin-tazobactam, the susceptibility of Bcc and B. gladioli to ceftazidime and piperacillin is restored in vitro Both the lack of blapenA1 induction and potent inactivation of PenA1 by avibactam likely provide the major contributions toward susceptibility. With in vivo validation, piperacillin-tazobactam-ceftazidime-avibactam may represent salvage therapy for individuals with CF and highly drug-resistant Bcc and B. gladioli infections.

Arsinothricin, an arsenic-containing non-proteinogenic amino acid analog of glutamate, is a broad-spectrum antibiotic.

The emergence and spread of antimicrobial resistance highlights the urgent need for new antibiotics. Organoarsenicals have been used as antimicrobials since Paul Ehrlich's salvarsan. Recently a soil bacterium was shown to produce the organoarsenical arsinothricin. We demonstrate that arsinothricin, a non-proteinogenic analog of glutamate that inhibits glutamine synthetase, is an effective broad-spectrum antibiotic against both Gram-positive and Gram-negative bacteria, suggesting that bacteria have evolved the ability to utilize the pervasive environmental toxic metalloid arsenic to produce a potent antimicrobial. With every new antibiotic, resistance inevitably arises. The arsN1 gene, widely distributed in bacterial arsenic resistance (ars) operons, selectively confers resistance to arsinothricin by acetylation of the α-amino group. Crystal structures of ArsN1 N-acetyltransferase, with or without arsinothricin, shed light on the mechanism of its substrate selectivity. These findings have the potential for development of a new class of organoarsenical antimicrobials and ArsN1 inhibitors.

In Vitro Activity of Ceftolozane-Tazobactam and Other Antimicrobial Agents against Burkholderia cepacia Complex and Burkholderia gladioli.

We tested the activities of ceftolozane-tazobactam and 13 other antimicrobial agents against 221 strains of Burkholderia cepacia complex and Burkholderia gladioli Most strains (82%) were cultured from persons with cystic fibrosis, and most (85%) were recovered since 2011. The ceftolozane-tazobactam MIC was ≤8 µg/ml for 77% of the strains. However, the MIC range was broad (≤0.5 to >64 µg/ml; MIC50/90, 2/32 µg/ml). Significant differences in susceptibility to some antimicrobial agents were observed between species.

Burkholderia gladioli infection isolated from the blood cultures of newborns in the neonatal intensive care unit.

Burkholderia gladioli was described as a plant pathogen, and it is a rare cause of infection in humans that is primarily associated with human pulmonary infections, such as chronic granulomatous disease and cystic fibrosis. The neonatal respiratory system is not fully developed and cannot expel bacterial aerosol properly. A total of 2,676 newborns in the neonatal intensive care unit were retrospectively analysed in Putian City, Fujian Province, China, from 2011 to 2014. All of the blood samples were tested for C-reactive protein (CRP), procalcitonin (PCT) and white blood cell (WBC). B. gladioli infections were determined and analysed using a blood culture system. Antibiotic susceptibility testing was performed using the K-B method. Of the 2,676 participants, 87 (3.25 %) had a positive B. gladioli blood culture that occurred >72 h after birth, including a premature group (54.0 %, asphyxia [vs. 9.20 %], fever [vs. 13.80 %], pneumonia [vs. 6.90 %] and hyperbilirubinaemia [vs. 8.05 %]) and newborns with necrotising enterocolitis (NEC) (vs. 5.75 %). The mean ± standard deviation (SD) of the CRP level was 12.31 ± 0.26 mg/L and that of the PCT level was 1.53 ± 0.21 ng/ml in the 87 B. gladioli-infected newborns. Most of the B. gladioli isolates were sensitive to many antimicrobial agents and did not lead to serious consequences. All of the B. gladioli-infected newborns were unhealthy, especially the premature infants. B. gladioli might be a causative bacteraemia agent in neonates, it appears to have pathogenic potential in newborns and its sensitivity to antibiotics may be a beneficial factor.

Microbiological and epidemiological features of clinical respiratory isolates of Burkholderia gladioli.

Burkholderia gladioli, primarily known as a plant pathogen, is involved in human infections, especially in patients with cystic fibrosis (CF). In the present study, the first respiratory isolates recovered from 14 French patients with CF and 4 French patients without CF, identified by 16S rRNA gene analysis, were tested for growth on B. cepacia selective media, for identification by commercial systems, and for their antimicrobial susceptibilities, and were compared by pulsed-field gel electrophoresis (PFGE). Patients' data were collected. All 18 isolates grew on oxidation-fermentation-polymyxin B-bacitracin-lactose medium and Pseudomonas cepacia agar, but only 13 grew on Burkholderia cepacia selective agar. API 20NE strips did not differentiate B. gladioli from B. cepacia, whereas Vitek 2 GN cards correctly identified 15 isolates. All isolates were susceptible to piperacillin, imipenem, aminoglycosides, and ciprofloxacin and were far less resistant to ticarcillin than B. cepacia complex organisms. Fifteen PFGE types were observed among the 18 isolates, but shared types were not identified among epidemiologically related patients. The microbiological follow-up of CF patients showed that colonization was persistent in 3 of 13 documented cases; B. gladioli was isolated from posttransplantation cultures of blood from 1 patient. Among the patients without CF, B. gladioli was associated with intubation (three cases) or bronchiectasis (one case). In summary, the inclusion of B. gladioli in the databases of commercial identification systems should improve the diagnostic capabilities of those systems. In CF patients, this organism is more frequently involved in transient infections than in chronic infections, but it may be responsible for complications posttransplantation; patient-to-patient transmission has not been demonstrated to date. Lastly, B. gladioli appears to be naturally susceptible to aminoglycosides and ciprofloxacin, although resistant isolates may emerge in the course of chronic infections.