In this work, surface‐enhanced Raman spectroscopy (SERS) method based on uncoated spherical gold nanoparticles as SERS substrate was applied for the detection and discrimination of three different ...bacterial strains: Gram‐positive Bacillus subtilis and Lactobacillus rhamnosus GG and Gram‐negative Escherichia coli. The exploitation of bacteria SERS spectra by multivariate data analysis (principal component analysis and partial least squares – discriminant analysis) proved the robustness of the developed method and its suitability to discriminate between the three different strains despite their relatively similar Raman signals. The SERS performance of the developed method was compared with that of the classical silver nanoparticles indicating a better bacteria signal enhancement, up to 15 times higher in case of E. coli, likely due to stronger interactions of gold nanoparticles with components such as purine molecules that show dominant bands in the bacterial SERS spectra.
Label‐free surface‐enhanced Raman spectroscopy analysis of bacteria using metallic nanoparticles consists in simply mixing bacteria with nanoparticles and then acquire the spectral fingerprints of the microorganisms. Using this strategy, discrimination between three different strains, namely, Gram‐positive Bacillus subtilis and Lactobacillus rhamnosus GG and Gram‐negative Escherichia coli was achieved using both uncoated spherical gold nanoparticles and multivariate data analysis techniques.
Cystic fibrosis (CF) is the most common life-threatening genetic disease among Caucasians. CF patients suffer from chronic lung infections due to the presence of thick mucus, caused by cftr gene ...dysfunction. The two most commonly found bacteria in the mucus of CF patients are Staphylococcus aureus and Pseudomonas aeruginosa. It is well known that early-infecting P. aeruginosa strains produce anti-staphylococcal compounds and inhibit S. aureus growth. More recently, it has been shown that late-infecting P. aeruginosa strains develop commensal-like/coexistence interaction with S. aureus. The aim of this study was to decipher the impact of P. aeruginosa strains on S. aureus. RNA sequencing analysis showed 77 genes were specifically dysregulated in the context of competition and 140 genes in the context of coexistence in the presence of P. aeruginosa. In coexistence, genes encoding virulence factors and proteins involved in carbohydrates, lipids, nucleotides and amino acids metabolism were downregulated. On the contrary, several transporter family encoding genes were upregulated. In particular, several antibiotic pumps belonging to the Nor family were upregulated: tet38, norA and norC, leading to an increase in antibiotic resistance of S. aureus when exposed to tetracycline and ciprofloxacin and an enhanced internalization rate within epithelial pulmonary cells. This study shows that coexistence with P. aeruginosa affects the S. aureus transcriptome and virulence.
Cystic fibrosis (CF) is a serious genetic disease that leads to premature death, mainly due to impaired lung function. CF lungs are characterized by ongoing inflammation, impaired immune response, ...and chronic bacterial colonization.
(SA) and
(PA) are the two most predominant bacterial agents of these chronic infections. Both can colonize the lungs for years by developing host adaptation strategies. In this review, we examined the mechanisms by which SA and PA adapt to the host immune response. They are able to bypass the physical integrity of airway epithelia, evade recognition, and then modulate host immune cell proliferation. They also modulate the immune response by regulating cytokine production and by counteracting the activity of neutrophils and other immune cells. Inhibition of the immune response benefits not only the species that implements them but also other species present, and we therefore discuss how these mechanisms can promote the establishment of coinfections in CF lungs.
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Boronic esters are versatile building blocks extensively used in organic chemistry and essential to a variety of coupling reactions. In this work, the hydroboration reactions of ...alkynes were performed without metal catalysts using concomitant microwave irradiation that allowed a significantly reduced reaction time. Another interesting outcome of this study was that the reaction could be carried out under solvent-free conditions, highlighting the environmentally-friendly nature of our method. A wide scope of aryl- and alkylboronic acid pinacol esters were easily synthesized from the corresponding alkynes.
In Cystic Fibrosis (CF), a rapid and standardized definition of chronic infection would allow a better management of Pseudomonas aeruginosa (Pa) infections, as well as a quick grouping of patients ...during clinical trials allowing better comparisons between studies. With this purpose, we compared the metabolic profiles of 44 in vitro cultures of Pa strains isolated from CF patients at different stages of infection in order to identify metabolites differentially synthetized according to these clinical stages. Compounds produced and secreted by each strain in the supernatant of a liquid culture were analysed by metabolomic approaches (UHPLC-DAD-ESI/QTOF, UV and UPLC-Orbitrap, MS). Multivariate analyses showed that first colonization strains could be differentiated from chronic colonization ones, by producing notably more Alkyl-Quinolones (AQs) derivatives. Especially, five AQs were discriminant: HQC5, HQNOC7, HQNOC7:1, db-PQS C9 and HQNOC9:1. However, the production of HHQ was equivalent between strain types. The HHQ/HQNOC9:1 ratio was then found to be significantly different between chronic and primo-colonising strains by using both UV (p = 0.003) and HRMS data (p = 1.5 × 10
). Our study suggests that some AQ derivatives can be used as biomarkers for an improved management of CF patients as well as a better definition of the clinical stages of Pa infection.
In the context of infection, Pseudomonas aeruginosa and Staphylococcus aureus are frequently co-isolated, particularly in cystic fibrosis (CF) patients. Within lungs, the two pathogens exhibit a ...range of competitive and coexisting interactions. In the present study, we explored the impact of S. aureus on the physiology of P. aeruginosa in the context of coexistence. Transcriptomic analyses showed that S. aureus significantly and specifically affects the expression of numerous genes involved in P. aeruginosa carbon and amino acid metabolism. In particular, 65% of the strains presented considerable overexpression of the genes involved in the acetoin catabolic (aco) pathway. We demonstrated that acetoin is (i) produced by clinical S. aureus strains, (ii) detected in sputa from CF patients and (iii) involved in P. aeruginosa's aco system induction. Furthermore, acetoin is catabolized by P. aeruginosa, a metabolic process that improves the survival of both pathogens by providing a new carbon source for P. aeruginosa and avoiding the toxic accumulation of acetoin on S. aureus. Due to its beneficial effects on both bacteria, acetoin catabolism could testify to the establishment of trophic cooperation between S. aureus and P. aeruginosa in the CF lung environment, thus promoting their persistence.
(SA) is the major colonizer of the lungs of cystic fibrosis (CF) patients during childhood and adolescence. As patients age, the prevalence of SA decreases and
(PA) becomes the major pathogen ...infecting adult lungs. Nonetheless, SA remains significant and patients harboring both SA and PA are frequently found in the worldwide cohort. The overall impact of co-infection remains controversial. Furthermore, co-infecting isolates may compete or coexist. The aim of this study was to analyse if co-infection and the coexistence of SA and PA could lead to worse clinical outcomes. The clinical and bacteriological data of 212 Lyon CF patients were collected retrospectively, and patients were ranked into three groups, SA only (
= 112), PA only (
= 48) or SA plus PA (
= 52). In addition, SA and PA isolates from co-infected patients were tested
to define their interaction profile. Sixty five percent (
= 34) of SA/PA pairs coexist. Using univariate and multivariate analysis, we confirm that SA patients have a less severe clinical condition than others, and PA induces a poor outcome independently of the presence of SA. Regarding co-infection, no significant difference in clinical outcomes was observed between patients with coexisting pairs and patients with competitive pairs. However, when compared to SA mono-infected patients, patients with coexisting pair presented higher frequency and length of hospitalizations and more exacerbations. We suggest that coexistence between SA and PA may be an important step in the natural history of lung bacterial colonization within CF patients.
A multi-step procedure has been described which afforded satisfactory yields of N,N′-disubstituted cinnamamides derived from N-Boc-protected amino acids (Boc-Gly, Boc-Val, Boc-Phe). The key step of ...this synthesis was a regioselective RedAl reduction of an amide function in presence of a carbamate group. Next, these cinnamamides were evaluated in co-admnistration with ciprofloxacin as efflux pump inhibitors against two S. aureus strains, NorA overexpressing SA1199B and wild type SA1199. In parallel, their intrinsic toxicity was appreciated on human lung fibroblast MRC5 cells. Therefore, the cinnamamide combining both carbamate and indol-3-yl groups, was found to be the most active and one of the less toxic EPI and constituted a promising hit.
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•Cinnamamides potentiate ciprofloxacin activity as efflux pump inhibitors.•Synthesis from N-Boc amino acids with a RedAl selective reduction as a key step.•EPI activity could be related to the presence of the NorA pump.
We previously reported the distribution of Achromobacter spp. (species and Sequence Types (ST)) in our French Cystic Fibrosis (CF) centre. In the present study we collected 109 Achromobacter isolates ...(1/patient) from 9 other French CF Centres for species identification, antimicrobial susceptibility testings and Multilocus-Sequence-Typing (MLST) analysis. Ten species were detected, A. xylosoxidans being the most predominant one (73.4% of the isolates). Piperacillin-tazobactam, ceftazidime, imipenem, meropenem and ciprofloxacin were respectively active against 88, 70, 79, 72 and 23% of the isolates. Among the 79 A. xylosoxidans isolates, 46 STs were detected. Interestingly, ST 137, recovered in 4 centres (5 patients), was previously detected in our centre (2 patients). The strains from the 7 patients belonged to the same pulsotype (pulsed-field-gel-electrophoresis analysis) and harboured acquired resistance to meropenem, ceftazidime, ciprofloxacin, and except for 2 isolates, to imipenem and piperacillin-tazobactam. This is the first description in France of a circulating multiresistant A. xylosoxidans strain.
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