31 research outputs found
Antimicrobial and Insecticidal: Cyclic Lipopeptides and Hydrogen Cyanide Produced by Plant-Beneficial Pseudomonas Strains CHA0, CMR12a, and PCL1391 Contribute to Insect Killing.
Particular groups of plant-beneficial fluorescent pseudomonads are not only root colonizers that provide plant disease suppression, but in addition are able to infect and kill insect larvae. The mechanisms by which the bacteria manage to infest this alternative host, to overcome its immune system, and to ultimately kill the insect are still largely unknown. However, the investigation of the few virulence factors discovered so far, points to a highly multifactorial nature of insecticidal activity. Antimicrobial compounds produced by fluorescent pseudomonads are effective weapons against a vast diversity of organisms such as fungi, oomycetes, nematodes, and protozoa. Here, we investigated whether these compounds also contribute to insecticidal activity. We tested mutants of the highly insecticidal strains Pseudomonas protegens CHA0, Pseudomonas chlororaphis PCL1391, and Pseudomonas sp. CMR12a, defective for individual or multiple antimicrobial compounds, for injectable and oral activity against lepidopteran insect larvae. Moreover, we studied expression of biosynthesis genes for these antimicrobial compounds for the first time in insects. Our survey revealed that hydrogen cyanide and different types of cyclic lipopeptides contribute to insecticidal activity. Hydrogen cyanide was essential to full virulence of CHA0 and PCL1391 directly injected into the hemolymph. The cyclic lipopeptide orfamide produced by CHA0 and CMR12a was mainly important in oral infections. Mutants of CMR12a and PCL1391 impaired in the production of the cyclic lipopeptides sessilin and clp1391, respectively, showed reduced virulence in injection and feeding experiments. Although virulence of mutants lacking one or several of the other antimicrobial compounds, i.e., 2,4-diacetylphloroglucinol, phenazines, pyrrolnitrin, or pyoluteorin, was not reduced, these metabolites might still play a role in an insect background since all investigated biosynthetic genes for antimicrobial compounds of strain CHA0 were expressed at some point during insect infection. In summary, our study identified new factors contributing to insecticidal activity and extends the diverse functions of antimicrobial compounds produced by fluorescent pseudomonads from the plant environment to the insect host
Anterior-posterior view by full-body digital X-ray to rule out severe spinal injuries in Polytraumatized patients
Background
Spinal injuries are present in 16–31% of polytraumatized patients. Rapid identification of spinal injuries requiring immobilization or operative treatment is essential. The Lodox-Statscan (LS) has evolved into a promising time-saving diagnostic tool to diagnose life-threatening injuries with an anterior-posterior (AP)-full-body digital X-ray.
Methods
We aimed to analyze the diagnostic accuracy and the interrater reliability of AP-LS to detect spinal injuries in polytraumatized patients. Therefore, within 3 years, AP-LS of polytraumatized patients (ISS ≥ 16) were retrospectively analyzed by three independent observers. The sensitivity and specificity of correct diagnosis with AP-LS compared to CT scan were calculated. The diagnostic accuracy was evaluated by using the area under the ROC (receiver operating characteristic curve) for sensitivity and specificity. Interrater reliability between the three observers was calculated using Fleiss’ Kappa. The sensitivity of AP-LS was further analyzed by the severity of spinal injuries.
Results
The study group included 320 patients (48.5 years ±19.5, 89 women). On CT scan, 207 patients presented with a spinal injury (65%, total of 332 injuries). AP-LS had a low sensitivity of 9% (31 of 332, range 0–24%) and high specificity of 99% (range 98–100%). The sensitivity was highest for thoracic spinal injuries (14%). The interrater reliability was slight (κ = 0.02; 95% CI: 0.00, 0.03). Potentially unstable spinal injuries were more likely to be detected than stable injuries (sensitivity 18 and 6%, respectively).
Conclusion
This study demonstrated high specificity with low sensitivity of AP-LS in detecting spinal injuries compared to CT scan. In polytraumatized patients, AP-LS, implemented in the Advanced Trauma Life Support-algorithm, is a helpful tool to diagnose life-threatening injuries. However, if spinal injuries are suspected, performing a full-body CT scan is necessary for correct diagnosis
Protecting maize from rootworm damage with the combined application of arbuscular mycorrhizal fungi, Pseudomonas bacteria and entomopathogenic nematodes.
Diabrotica virgifera virgifera LeConte, the western corn rootworm (WCR), is the most destructive pest of maize in North America, and has recently spread across central Europe. Its subterranean larval stages are hard to reach with pesticides and it has evolved resistance to conventional management practices. The application of beneficial soil organisms is being considered as a sustainable and environmental friendly alternative. In a previous study, the combined application in wheat fields of arbuscular mycorrhizal fungi, entomopathogenic Pseudomonas bacteria, and entomopathogenic nematodes was found to promote growth and protection against a natural pest infestation, without negative cross effects. Because of the insect-killing capacity of the bacteria and nematodes, we hypothesized that the application of these organisms would have similar or even greater beneficial effects in WCR-infested maize fields. During three consecutive years (2015-2017), we conducted trials in Missouri (USA) in which we applied the three organisms, alone or in combinations, in plots that were artificially infested with WCR and in non-infested control plots. For two of the three trials, we found that in plots treated with entomopathogenic nematodes and/or entomopathogenic Pseudomonas bacteria, roots were less damaged than the roots of plants in control plots. During one year, WCR survival was significantly lower in plots treated with Pseudomonas than in control plots, and the surviving larvae that were recovered from these plots were lighter. The bacterial and nematodes treatments also enhanced yield, assessed as total grain weight, in one of the trials. The effects of the treatments varied considerable among the three years, but they were always positive for the plants
C-clamp and pelvic packing for control of hemorrhage in patients with pelvic ring disruption
BACKGROUND: Exsanguinating hemorrhage is the major cause of death in patients with pelvic ring disruption.
AIMS: The aim of this study was to document outcomes after the stabilization of pelvic ring injuries by a C-clamp and control of hemorrhage by pelvic packing. Physiological parameters were tested as prognostic factors.
SETTING AND DESIGN: This was a retrospective study at a level I trauma center. The study period was from January 1996 to December 2007.
MATERIALS AND METHODS: Fifty patients with pelvic ring disruption and hemorrhagic shock were analyzed. The pelvic rings were fixed by a C-clamp, and patients with ongoing hemorrhage underwent laparotomy and extra- and/or intra-peritoneal pelvic packing. Clinical parameters (heart rate, mean arterial pressure) and physiological parameters (lactate levels, hemoglobin, hematocrit) were documented at admission and at different time points during the initial treatment (1, 2, 3, 4, 6, 8, and 12h after admission).
RESULTS: Within 12 h of admission, 16 patients died (nonsurvivors) due to hemorrhagic shock (n=13) or head injuries (n=3). In this group, 12 patients underwent laparotomy with pelvic packing. Thirty-four patients survived the first 12 h (early survivors) after fixation by a C-clamp and additional packing in 23 patients. Four of these patients died 12.3±7.1 days later due to multiple organ failure (n=3) or severe head injury (n=1). The blood lactate level at admission was significantly higher in the group of nonsurvivors (7.2±0.8 mmol/L) compared to the early survivors (4.3±0.5 mmol/L, P<0.05). While hemoglobin values improved within the first 2 h in nonsurvivors, lactate levels continued to increase.
CONCLUSION: Pelvic packing in addition to the C-clamp fixation effectively controls severe hemorrhage in patients with pelvic ring disruption. Early sequential measurements of blood lactate levels can be used to estimate the severity of shock and the response to the shock treatment
Direct anterior decompression of L4 and L5 nerve root in sacral fractures using the pararectus approach: a technical note.
PURPOSE
To describe a new surgical technique for neurolysis and decompression of L4 and L5 nerve root entrapment after vertical sacral fractures via the pararectus approach for acetabular fractures, and to present four case examples.
PATIENTS AND METHODS
We retrospectively evaluated four patients suffering radiculopathy from entrapment of the L4 or L5 nerve root in vertical sacral fractures between January and December 2016. The mean follow-up period after surgery was 18 (range 7-27) months. All patients underwent direct decompression and neurolysis of the L4 and L5 nerve roots via the single-incision, intrapelvic, extraperitoneal pararectus approach.
RESULTS
In all patients, the L4 and L5 nerve root was successfully visualized and decompressed, proving feasibility of the pararectus approach for this indication. No patient presented with a neural tear. Complete neurologic recovery was present in one patient at last follow-up; two patients had incomplete recovery of their radiculopathy; and one patient had no improvement after nerve root decompression.
CONCLUSIONS
The pararectus approach allows for sufficient visualisation and direct decompression and neurolysis of the L4 and L5 nerve root entrapped in vertical sacral fractures. Although neurologic recovery was not achieved in all patients in this small case series, the approach may be a suitable alternative to posterior approaches and other anterior approaches such as the lateral window of the ilioinguinal approach
The conserved iol gene cluster in Pseudomonas is involved in rhizosphere competence
The Pseudomonas genus has shown great potential as a sustainable solution to support agriculture through its plant-growth-promoting and biocontrol activities. However, their efficacy as bioinoculants is limited by unpredictable colonization in natural conditions. Our study identifies the iol locus, a gene cluster in Pseudomonas involved in inositol catabolism, as a feature enriched among superior root colonizers in natural soil. Further characterization revealed that the iol locus increases competitiveness, potentially caused by an observed induction of swimming motility and the production of fluorescent siderophore in response to inositol, a plant-derived compound. Public data analyses indicate that the iol locus is broadly conserved in the Pseudomonas genus and linked to diverse host-microbe interactions. Together, our findings suggest the iol locus as a potential target for developing more effective bioinoculants for sustainable agriculture