Modifications in the ultrastructure ofAspergillus fumigatusdue to the presence of living cells ofPseudomonas aeruginosa

Clinical characteristics of Pseudomonas and Aspergillus co-infected cystic fibrosis patients: A UK registry study

BACKGROUND

Pseudomonas aeruginosa (Pa) and Aspergillus species (Asp) are the most common bacterial and fungal organisms respectively in CF airways. Our aim was to examine impacts of Asp infection and Pa/Asp co-infection.

METHODS

Patients on the UK CF Registry in 2016 were grouped into: absent (Pa-), intermittent (Pai) or chronic Pa (Pac), each with Asp positive (Asp+) or negative (Asp-). Primary outcome was best percentage predicted FEV₁ (ppFEV₁) that year. Secondary outcomes were intravenous (IV) antibiotic courses, growth (height, weight, BMI) and additional disease complications. Associations between outcomes and infection-status were assessed using regression models adjusting for significant confounders (age, sex, Phe508del homozygosity and CF-related diabetes (CFRD)).

RESULTS

9,270 patients were included (median age 19 [IQR 9-30] years, 54% male, 50% Phe508del/F508del). 4,142 patients (45%) isolated Pa, 1,460 (16%) Asp. Pa-/Asp+ subjects had an adjusted ppFEV₁ that was 5.9% lower than Pa-/Asp- (p < 0.0001). In patients with Pai or Pac, there was no additional impact of Asp on ppFEV₁. However, there was a higher probability that Pac/Asp+ patients had required IV antibiotics than Pac/Asp- group (OR 1.23 [1.03-1.48]). Low BMI, ABPA, CF-liver disease and CFRD were all more frequent with Asp alone than Pa-/Asp-, though not more common in Pac/Asp+ than Pac/Asp-.

CONCLUSIONS

Co-infection with Pa and Asp was not associated with reduced lung function compared with Pa alone, but was associated with additional use of IV antibiotics. Asp infection itself is associated with several important indicators of disease severity. Longitudinal analyses should explore the impact of co-infection on disease progression.

Perspectives of Phage Therapy in Non-bacterial Infections

While the true value of phage therapy (PT) in human bacterial infections still awaits formal confirmation by clinical trials, new data have been accumulating indicating that in the future PT may be applied in the treatment of non-bacterial infections. Thus, "phage guests" may interact with eukaryotic cells and such interactions with cells of the immune system may protect human health (Guglielmi, 2017) and cause clinically useful immunomodulatory and anti-inflammatory effects when administered for therapeutic purposes (Górski et al., 2017; Van Belleghem et al., 2017). Recently, a vision of how these effects could translate into advances in novel means of therapy in a variety of human pathologies secondary to immune disturbances and allergy was presented (Górski et al., 2018a). In this article we present what is currently known about anti-microbial effects of phage which are not directly related to their antibacterial action and how these findings could be applied in the future in treatment of viral and fungal infections.

Dirhamnolipids secreted from Pseudomonas aeruginosa modify anjpegungal susceptibility of Aspergillus fumigatus by inhibiting β1,3 glucan synthase activity

Pseudomonas aeruginosa and Aspergillus fumigatus are the two microorganisms responsible for most of the chronic infections in cystic fibrosis patients. P. aeruginosa is known to produce quorum-sensing controlled rhamnolipids during chronic infections. Here we show that the dirhamnolipids secreted from P. aeruginosa (i) induce A. fumigatus to produce an extracellular matrix, rich in galactosaminogalactan, 1,8-dihydroxynaphthalene (DHN)- and pyo-melanin, surrounding their hyphae, which facilitates P. aeruginosa binding and (ii) inhibit A. fumigatus growth by blocking β1,3 glucan synthase (GS) activity, thus altering the cell wall architecture. A. fumigatus in the presence of diRhls resulted in a growth phenotype similar to that upon its treatment with anjpegungal echinocandins, showing multibranched hyphae and thicker cell wall rich in chitin. The diRhl structure containing two rhamnose moieties attached to fatty acyl chain is essential for the interaction with β1,3 GS; however, the site of action of diRhls on GS is different from that of echinocandins, and showed synergistic anjpegungal effect with azoles.

Pf4 bacteriophage produced by Pseudomonas aeruginosa inhibits Aspergillus fumigatus metabolism via iron sequestration

Pseudomonas aeruginosa (Pa) and Aspergillus fumigatus (Af) are major human pathogens known to interact in a variety of disease settings, including airway infections in cystic fibrosis. We recently reported that clinical CF isolates of Pa inhibit the formation and growth of Af biofilms. Here, we report that the bacteriophage Pf4, produced by Pa, can inhibit the metabolic activity of Af biofilms. This phage-mediated inhibition was dose dependent, ablated by phage denaturation, and was more pronounced against preformed Af biofilm rather than biofilm formation. In contrast, planktonic conidial growth was unaffected. Two other phages, Pf1 and fd, did not inhibit Af, nor did supernatant from a Pa strain incapable of producing Pf4. Pf4, but not Pf1, attaches to Af hyphae in an avid and prolonged manner, suggesting that Pf4-mediated inhibition of Af may occur at the biofilm surface. We show that Pf4 binds iron, thus denying Af a crucial resource. Consistent with this, the inhibition of Af metabolism by Pf4 could be overcome with supplemental ferric iron, with preformed biofilm more resistant to reversal. To our knowledge, this is the first report of a bacterium producing a phage that inhibits the growth of a fungus and the first description of a phage behaving as an iron chelator in a biological system.

Intracutaneous tests with recombinant allergens in cystic fibrosis patients with allergic bronchopulmonary aspergillosis and Aspergillus allergy

Allergic bronchopulmonary aspergillosis (ABPA), an intensive inflammatory reaction to Aspergillus fumigatus, can cause irreversible lung damage in patients with cystic fibrosis (CF). The aim of this study was to assess if intracutaneous testing with recombinant A. fumigatus allergens (rAsp f ) allowed a reliable diagnosis of ABPA. Fifty patients with CF were tested, 12 suffering from ABPA, 21 with allergy to A. fumigatus, and 17 CF control patients not sensitized to A. fumigatus. All patients with ABPA reacted to at least one of the two intracellular A. fumigatus allergens rAsp f 4, a 30-kD protein of unknown biologic function, and rAsp f 6, a 23-kD manganese superoxide dismutase, at a concentration of 10(-2) microg/ml. The intracutaneous tests were negative or only marginally positive in the patients with allergy to A. fumigatus and completely negative in the CF control patients. The differential responses to the recombinant A. fumigatus allergens were in perfect agreement with our previous serologic results, so that rAsp f 4 and rAsp f 6 can be considered specific markers for ABPA. Early diagnosis of the disease might help to prevent irreversible lung damage and minimize possible steroid-mediated side effects as a consequence of an optimized control of the disease.

Allergic bronchopulmonary aspergillosis in cystic fibrosis: reported prevalence, regional distribution, and patient characteristics. Scientific Advisory Group, Investigators, and Coordinators of the Epidemiologic Study of Cystic Fibrosis

OBJECTIVES

Using the large database from the Epidemiologic Study of Cystic Fibrosis (ESCF), the objectives of this study were to (1) estimate the reported prevalence of allergic bronchopulmonary aspergillosis (ABPA) in patients with cystic fibrosis (CF); (2) compare reported prevalence rates across geographic regions; (3) compare reported prevalence rates between patient subgroups based on demographic and disease characteristics; and (4) describe the ABPA group with regard to their sex, age, and disease severity.

STUDY DESIGN

All patients > or = 5 years of age enrolled in ESCF between December 1993 and May 1996 were eligible. Criteria for the diagnosis of ABPA were defined by the ESCF guidelines. Prevalence rates for ABPA were calculated, and potential risk factors for the diagnosis of ABPA were analyzed, including sex, age, pulmonary function, diagnosis of asthma, presence of wheeze, and positive respiratory culture for Pseudomonas.

RESULTS

There were 14,210 eligible patients enrolled in ESCF during this period, and ABPA was diagnosed in 281 patients (2%). Regional prevalence varied from 0.9% in the Southwest to 4.0% in the West. Increased prevalence rates occurred in female patients, the adolescent age group, and subjects with lower lung function, wheeze, asthma, and positive Pseudomonas cultures. Although most ABPA patients had evidence of airway obstruction, 10% had an FEV1 of > 100% of predicted. The rates of wheeze (17%) and asthma (30%) were lower than expected in the ABPA group.

CONCLUSIONS

This observational study found a reported prevalence rate of ABPA of 2% of CF patients in a large database. This rate was lower than the 5 to 15% rate reported in smaller studies, suggesting that ABPA is underdiagnosed in the CF population. There was wide regional variation in reported prevalence rates, which is unexplained at this time. The characteristics of the patients with ABPA and the epidemiologic risk factors for diagnosis of ABPA were described. Simplified diagnostic criteria were adapted for ESCF with the intent of increasing awareness of ABPA among the participants in this study.

Growth inhibition of pathogenic yeasts by Pseudomonas aeruginosa in vitro: clinical implications in blood cultures

The interaction between yeasts and bacteria may have clinical implications in polymicrobial septicaemia. The in vitro effect of Pseudomonas aeruginosa on five pathogenic yeast species, Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata and Cryptococcus neoformans, was investigated. Yeast inhibition assays were performed in an aerobic blood culture medium, inoculated with yeast cells (inoculum 1-10 CFU ml-1) and bacterial cells (inoculum 10-10(7) CFU ml-1). Interactions between P. aeruginosa and yeasts were determined after incubation by enumeration of pure and mixed cultures. Growth of all isolates tested was completely or partially inhibited by P. aeruginosa in blood culture medium, the phenomenon depending on the yeast genus and bacterial inoculum. Suppression of fungal growth was also observed in bacterial culture filtrate. This in vitro antifungal activity may preclude yeast recovery from blood cultures in mixed infections.

Two common fungi associated with farmer's lung: fine structure of Aspergillus fumigatus and Aspergillus umbrosus

The fine structure of Aspergillus fumigatus and Aspergillus umbrosus by transmission electron microscopy (TEM) is described. The fine structure of the ascosporic and asexual stages of A. umbrosus is described for the first time. Dense, homogenous material and fibers were detected on the outer hyphal cell wall of the Aspergilli. Septal pores were found in the hypha of A. umbrosus. Two wall layers were detected in the cell wall of the conidia of the both Aspergilli. The ascospores of A. umbrosus contained thick cell wall and the surface of which was smoother than that of the conidia.