Activity of the new cephalosporin CXA-101 (FR264205) against Pseudomonas aeruginosa isolates from chronically-infected cystic fibrosis patients

Chronic respiratory infection caused by Pseudomonas aeruginosa is the main driver of morbidity and mortality in cystic fibrosis (CF) patients. The development of resistance to all available antibiotics is a frequent outcome of these infections. The present study aimed to evaluate the activity of the new cephalosporin CXA-101 (FR264205) against a collection of 100 isolates obtained from 50 CF patients from two Spanish hospitals. The collection included the first (early) and the last (late) available isolate from each patient (average interval 68 ± 39 months). The MIC50 and MIC90 of CXA-101 were 0.5 and 2 mg/L and the geometric mean MIC was 0.7 mg/L; the MICs for 95% of the isolates were ≤8 mg/L (tentative breakpoint). Only meropenem yielded comparable results, although the MIC90 of this antibiotic was significantly higher (8 mg/L). CXA-101 showed conserved activity against a high proportion of isolates resistant to each of the antibiotics tested (ceftazidime, cefepime, piperacillin-tazobactam, imipenem, meropenem, levofloxacin and tobramycin), with MIC50 values of 1-2 mg/L. Moreover, CXA-101 retained good activity against multidrug-resistant strains, with MIC50 and MIC90 values of 2 and 16 mg/L. CXA-101 was also active against late CF isolates (the MIC for 96% was ≤8 mg/L); it was the only antibiotic tested to which a similar percentage of early and late isolates was susceptible. These results show that, despite a slight increase in MICs, major cross-resistance to CXA-101 did not develop during treatment of CF patients with the currently available antipseudomonal agents. Therefore, CXA-101 is envisaged as a valuable alternative for the treatment of chronic respiratory infection caused by P. aeruginosa in CF patients.

Bacterial hypermutation in cystic fibrosis, not only for antibiotic resistance

Hypermutable or mutator microorganisms are those that have an increased spontaneous mutation rate as a result of defects in DNA repair or error avoidance systems. Over the last two decades, several studies have provided strong evidence for a relevant role of mutators in the evolution of natural bacterial populations, particularly in the field of infectious diseases. Among them, chronic respiratory infection with Pseudomonas aeruginosa in cystic fibrosis (CF) patients was the first natural environment to reveal the high prevalence and important role of mutators. A remarkable positive selection of mutators during the course of the chronic infection has been reported, mainly as a result of the emergence of DNA mismatch repair system (mutS, mutL or mutU)-deficient mutants, although strains defective in the GO system (mutM, mutY and mutT) have also been observed. High frequencies of mutators have also been noted among other pathogens in the CF setting, particularly Staphylococcus aureus and Haemophilus influenzae. Enhanced antimicrobial resistance development is the most thoroughly studied consequence of mutators in CF and other chronic infections, although recent studies show that mutators may additionally have important effects on the evolution of virulence, genetic adaptation to the airways of CF patients, persistence of colonization, transmissibility, and perhaps lung function decline. Further prospective clinical studies are nevertheless still needed for an in-depth evaluation of the impact of mutators on disease progression and outcome.

Cohort study to test the predictability of the Melbourne criteria for activation of the medical emergency team

OBJECTIVE

To test the predictability of the Melbourne criteria for activation of the medical emergency team (MET) to identify children at risk of developing critical illness.

DESIGN

Cohort study.

SETTING

Admissions to all paediatric wards at the University Hospital of Wales.

OUTCOME MEASURES

Paediatric high dependency unit admission, paediatric intensive care unit admission and death.

RESULTS

Data were collected on 1000 patients. A single abnormal observation determined by the Melbourne Activation Criteria (MAC) had a sensitivity of 68.3% (95% CI 57.7 to 77.3), specificity 83.2% (95% CI 83.1 to 83.2), positive predictive value (PPV) 3.6% (95% CI 3.0 to 4.0) and negative predictive value 99.7% (95% CI 99.5 to 99.8) for an adverse outcome. Seven of the 16 children (43.8%) would not have transgressed the MAC prior to the adverse outcomes. Four hundred and sixty-nine of the 984 children (47.7%) who did not have an adverse outcome would have transgressed the MAC at least once during the admission.

CONCLUSION

The MAC has a low PPV and its full implementation would result in a large number of false positive triggers. Further research is required to determine the relative contribution of the components of this complex intervention (Paediatric Early Warning System, education and MET) on patient outcome.

The Relationship Between Safety Attitudes and Occupational Accidents

This research provides empirical evidence on the relationships between employee attitudes to safety issues and accident indicators in a Spanish context. The research attempts to review to what degree those attitudes reflect a collective, or shared, climate for safety within a number of organizations. Data were gathered from workers in a number of industries in Valencia (Spain) by questionnaire. A total of 1,234 valid questionnaires were completed and formed the basis for subsequent analysis. Analysis of the attitude dimensions found a similar structure to that found in previous research in other countries, as well as identifying those dimensions shared within groups, more likely to represent safety climate. In terms of explaining accidents, the data showed that variables dealing with the work environment, in particular the presence of Workplace Hazards, and the individual’s approach to working safely were directly related to accident outcomes, explaining 19% of the variability in accident history. These variables were, in turn, related to the assessment of safety climate, suggesting that individual attitude variables act as a mediator between climate and accident occurrence. This paper represents one of the few attempts to explain the influence of safety climate, work environment, and individual attitudes on accident outcomes in the Spanish environment, using a theoretical model developed and validated in another European context.

Inhibition of the two-photon absorption response exhibited by a bilayer TiO2 film with embedded Au nanoparticles

We use two different synthesis approaches for the preparation of TiO(2) films in order to study their resulting third order optical nonlinearity, and its modification by the inclusion of Au nanoparticles in one of the samples. An ultrasonic spray pyrolysis method was used for preparing a TiO(2) film in which we found two-photon absorption as a dominant nonlinear effect for 532 nm and 26 ps pulses; and a purely electronic nonlinearity at 830 nm for 80 fs pulses. A strong optical Kerr effect and the inhibition of the nonlinear optical absorption in 532 nm can be obtained for the first sample if Au nanoparticles embedded in a second TiO(2) film prepared by a sol-gel technique are added to it. We used an optical Kerr gate, z-scan, a multi-wave mixing experiment and an input-output transmittance experiment for measuring the optical nonlinearities.

Composite renal cell carcinoma with clear cell renal cell carcinomatous and carcinoid tumoral elements: a first case report

Renal endocrine tumours are extremely rare, and carcinoid tumoral elements in renal cell carcinoma have never been reported. This is the first report of a composite renal cell carcinoma containing a clear cell renal cell carcinoma associated with carcinoid tumoral elements, in a patient with synchronous metastatic disease. In the absence of specific radiological and clinical manifestations, typical morphological features as well as an immunostaining profile of neuroendocrine differentiation were identified by microscopy. Secondary nodal and liver localisations were characterised by carcinoid elements only. Despite antiangiogenic therapy, liver metastasis progressed, suggesting that adjuvant therapy cannot be based on the presence of the clear cell renal cell carcinoma component. In this context, extensive tissue sampling is recommended to reveal the endocrine component that is the most aggressive element of such a composite carcinoma.

Tissue tropism and promoter sequence variation in caprine arthritis encephalitis virus infected goats

Caprine arthritis encephalitis virus is a lentivirus that infects goats and is closely related to maedi-visna virus of sheep. Infection with CAEV results in multiple discrete disease manifestations in goats which can include chronic arthritis, mastitis, pneumonia or encephalomyelitis. Presently, no satisfactory mechanistic rationale for viral tropism has been put forward. We propose that specific sequences in the lentiviral promoter (U3 region of the viral long terminal repeat) are associated with viral tissue tropism and subsequent disease expression. A total of 41 distinct CAE viral promoter regions were amplified, sequenced and phylogenetically compared from the tissues of 24 CAEV-infected goats demonstrating a variety of disease manifestations. Phylogenetically, we identified no tendency for clustering of these promoter sequences into tissue-specific groups. These results therefore do not provide evidence for the study hypothesis. However, multiple motifs within the U3 promoter region were highly conserved both within the entire collection of sequences and within tissue-specific groups.

Tuning the aspect ratio of silver nanospheroids embedded in silica

A method is proposed to control the aspect ratio (epsilon) of elongated nanoparticles obtained by ion implantation in a transparent matrix. The procedure was tested for Ag spheroids in silica and we could accurately change epsilon in the range from the maximum value obtained by the ion implantation (around 3.0 in this case) to 1.0 (spherical shape). The values of epsilon were determined in several steps from optical extinction spectroscopy measurements, by fitting the modification and splitting of the surface plasmon resonance peak, using the T-matrix method. In the initial (maximum deformation) and final (undeformed) states, transmission electron microscopy images were obtained, showing a good agreement with the T-matrix results in both cases.

Prospective cohort study to test the predictability of the Cardiff and Vale paediatric early warning system

OBJECTIVE

To develop and test the predictability of a paediatric early warning score to identify children at risk of developing critical illness.

DESIGN

Prospective cohort study.

SETTING

Admissions to all paediatric wards at the University Hospital of Wales.

OUTCOME MEASURES

Respiratory arrest, cardiac arrest, paediatric high-dependency unit admission, paediatric intensive care unit admission and death.

RESULTS

Data were collected on 1000 patients. A single abnormal observation determined by the Cardiff and Vale paediatric early warning system (C&VPEWS) had a 89.0% sensitivity (95% CI 80.5 to 94.1), 63.9% specificity (95% CI 63.8 to 63.9), 2.2% positive predictive value (95% CI 2.0 to 2.3) and a 99.8% negative predictive value (95% CI 99.7 to 99.9) for identifying children who subsequently had an adverse outcome. The area under the receiver operating characteristic curve for the C&VPEWS score was 0.86 (95% CI 0.82 to 0.91).

CONCLUSION

Identifying children likely to develop critical illness can be difficult. The assessment tool developed from the advanced paediatric life support guidelines on identifying sick children appears to be sensitive but not specific. If the C&VPEWS was used as a trigger to activate a rapid response team to assess the child, the majority of calls would be unnecessary.

Modification of the nonlinear optical absorption and optical Kerr response exhibited by nc-Si embedded in a silicon-nitride film

We studied the absorptive and refractive nonlinearities at 532 nm and 26 ps pulses for silicon-nitride films containing silicon nanoclusters (nc-Si) prepared by remote plasma-enhanced chemical vapor deposition (RPECVD). Using a self-diffraction technique, we measured for the as-grown sample beta=7.7x10(-9)m/W, n(2)=1.8x10(-16)m(2)/W, and /chi(3)1111/ = 4.6x10(-10)esu; meanwhile, when the sample was exposed to an annealing process at 1000 degrees C during one hour in a nitrogen atmosphere, we obtained beta=-5x10(-10)m/W, n2=9x10(-17)m(2)/W, and /chi(3)1111/=1.1x10(-10)esu. A pure electronic nonlinear refraction was identified and a large threshold ablation of 41 J/cm(-2) was found for our films. By fitting nonlinear optical transmittance measurements, we were able to estimate that the annealed sample exhibits a response time close to 1 fs. We report an enhancement in the photoluminescence (PL) signal after the annealing process, as well as a red-shift due to an increment in size of the nc-Si during the thermal process.

Photoluminescence of as-grown silicon nanocrystals embedded in silicon nitride: influence of atomic hydrogen abundance

Silicon nanocrystals embedded in silicon nitride films were grown by direct plasma enhanced chemical vapor deposition at 300 degrees C, using mixtures of SiH2Cl2/NH3/H2/Ar. The films composition and chemical stability was tested by Fourier Transform Infrared Spectroscopy and Rutherford Backscattering Spectroscopy. The influence of hydrogen abundance during the deposition process on the photoluminescence of as-grown samples was studied as a function of the radiofrequency power and hydrogen dilution flow rate. In situ Optical Emission Spectroscopy allowed the diagnostic of the species in the plasma region and their general trends as a function of the radiofrequency power. The changes in the hydrogen content and silicon incorporation to the film as a function of the radiofrequency power were discussed in terms of silicon nanocrystals formation and growth in the silicon nitride matrix. The photoluminescence emission from the as-grown samples was found to red-shift with increasing hydrogen abundance. This observation is consistent with the increase in silicon content associated to nc-Si of larger size. On the other hand, the photoluminescence intensity was observed to decrease for very high radiofrequency powers and hydrogen dilutions. High Resolution Transmission Electron Microscopy confirmed the presence of silicon nanocrystals embedded in the amorphous silicon nitride matrix and allowed the correlation between the nanocrystals size and the photoluminescence emission energy using the quantum confinement model.

Genetic adaptation of Pseudomonas aeruginosa to the airways of cystic fibrosis patients is catalyzed by hypermutation

In previous work (E. E. Smith, D. G. Buckley, Z. Wu, C. Saenphimmachack, L. R. Hoffman, D. A. D'Argenio, S. I. Miller, B. W. Ramsey, D. P. Speert, S. M. Moskowitz, J. L. Burns, R. Kaul, and M. V. Olson, Proc. Natl. Acad. Sci. USA 103:8487-8492, 2006) it was shown that Pseudomonas aeruginosa undergoes intense genetic adaptation during chronic respiratory infection (CRI) in cystic fibrosis (CF) patients. We used the same collection of isolates to explore the role of hypermutation in this process, since one of the hallmarks of CRI is the high prevalence of DNA mismatch repair (MMR) system-deficient mutator strains. The presence of mutations in 34 genes (many of them positively linked to adaptation in CF patients) in the study collection of 90 P. aeruginosa isolates obtained longitudinally from 29 CF patients was not homogeneous; on the contrary, mutations were significantly concentrated in the mutator lineages, which represented 17% of the isolates (87% MMR deficient). While sequential nonmutator lineages acquired a median of only 0.25 mutation per year of infection, mutator lineages accumulated more than 3 mutations per year. On the whole-genome scale, data for the first fully sequenced late CF isolate, which was also shown to be an MMR-deficient mutator, also support these findings. Moreover, for the first time the predicted amplification of mutator populations due to hitchhiking with adaptive mutations in the course of natural human infections is clearly documented. Interestingly, increased accumulation of mutations in mutator lineages was not a consequence of overrepresentation of mutations in genes involved in antimicrobial resistance, the only adaptive trait linked so far to hypermutation in CF patients, demonstrating that hypermutation also plays a major role in P. aeruginosa genome evolution and adaptation during CRI.