Early eradication of Pseudomonas aeruginosa in patients with cystic fibrosis

Bronchoscopy-guided antimicrobial therapy for cystic fibrosis

BACKGROUND

Early diagnosis and treatment of lower respiratory tract infections is the mainstay of management of lung disease in cystic fibrosis (CF). When sputum samples are unavailable, diagnosis relies mainly on cultures from oropharyngeal specimens; however, there are concerns about whether this approach is sensitive enough to identify lower respiratory organisms. Bronchoscopy and related procedures such as bronchoalveolar lavage (BAL) are invasive but allow the collection of lower respiratory specimens from non-sputum producers. Cultures of bronchoscopic specimens provide a higher yield of organisms compared to those from oropharyngeal specimens. Regular use of bronchoscopy and related procedures may increase the accuracy of diagnosis of lower respiratory tract infections and improve the selection of antimicrobials, which may lead to clinical benefits. This is an update of a previous review that was first published in 2013 and was updated in 2016 and in 2018.

OBJECTIVES

To evaluate the use of bronchoscopy-guided (also known as bronchoscopy-directed) antimicrobial therapy in the management of lung infection in adults and children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched three registries of ongoing studies and the reference lists of relevant articles and reviews. The date of the most recent searches was 1 November 2023.

SELECTION CRITERIA

We included randomised controlled studies involving people of any age with CF that compared the outcomes of antimicrobial therapies guided by the results of bronchoscopy (and related procedures) versus those guided by any other type of sampling (e.g. cultures from sputum, throat swab and cough swab).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed their risk of bias and extracted data. We contacted study investigators for further information when required. We assessed the certainty of the evidence using the GRADE criteria.

MAIN RESULTS

We included two studies in this updated review. One study enrolled 170 infants under six months of age who had been diagnosed with CF through newborn screening. Participants were followed until they were five years old, and data were available for 157 children. The study compared outcomes for pulmonary exacerbations following treatment directed by BAL versus standard treatment based on clinical features and oropharyngeal cultures. The second study enrolled 30 children with CF aged between five and 18 years and randomised participants to receive treatment based on microbiological results of BAL triggered by an increase in lung clearance index (LCI) of at least one unit above baseline or to receive standard treatment based on microbiological results of oropharyngeal samples collected when participants were symptomatic. We judged both studies to have a low risk of bias across most domains, although the risk of bias for allocation concealment and selective reporting was unclear in the smaller study. In the larger study, the statistical power to detect a significant difference in the prevalence of Pseudomonas aeruginosa was low because Pseudomonas aeruginosa isolation in BAL samples at five years of age in both groups were much lower than the expected rate that was used for the power calculation. We graded the certainty of evidence for the key outcomes as low, other than for high-resolution computed tomography scoring and cost-of-care analysis, which we graded as moderate certainty. Both studies reported similar outcomes, but meta-analysis was not possible due to different ways of measuring the outcomes and different indications for the use of BAL. Whether antimicrobial therapy is directed by the use of BAL or standard care may make little or no difference in lung function z scores after two years (n = 29) as measured by the change from baseline in LCI and forced expiratory volume in one second (FEV1) (low-certainty evidence). At five years, the larger study found little or no difference between groups in absolute FEV1 z score or forced vital capacity (FVC) (low-certainty evidence). BAL-directed therapy probably makes little or no difference to any measure of chest scores assessed by computed tomography (CT) scan at either two or five years (different measures used in the two studies; moderate-certainty evidence). BAL-directed therapy may make little or no difference in nutritional parameters or in the number of positive isolates of P aeruginosa per participant per year, but may lead to more hospitalisations per year (1 study, 157 participants; low-certainty evidence). There is probably no difference in average cost of care per participant (either for hospitalisations or total costs) at five years between BAL-directed therapy and standard care (1 study, 157 participants; moderate-certainty evidence). We found no difference in health-related quality of life between BAL-directed therapy and standard care at either two or five years, and the larger study found no difference in the number of isolates of Pseudomonas aeruginosa per child per year. The eradication rate following one or two courses of eradication treatment and the number of pulmonary exacerbations were comparable in the two groups. Mild adverse events, when reported, were generally well tolerated. The most common adverse event reported was transient worsening of cough after 29% of procedures. Significant clinical deterioration was documented during or within 24 hours of BAL in 4.8% of procedures.

AUTHORS' CONCLUSIONS

This review, limited to two well-designed randomised controlled studies, shows no evidence to support the routine use of BAL for the diagnosis and management of pulmonary infection in preschool children with CF compared to the standard practice of providing treatment based on results of oropharyngeal culture and clinical symptoms. No evidence is available for adults.

Extracellular vesicles secreted by primary human bronchial epithelial cells reduce Pseudomonas aeruginosa burden and inflammation in cystic fibrosis mouse lung

Cystic fibrosis (CF) results in a reduction in the volume of airway surface liquid, increased accumulation of viscous mucus, persistent antibiotic-resistant lung infections that cause chronic inflammation, and a decline in lung function. More than 50% of adults with CF are chronically colonized by Pseudomonas aeruginosa (P. aeruginosa), the primary reason for morbidity and mortality in people with CF (pwCF). Although highly effective modulator therapy (HEMT) is an important part of disease management in CF, HEMT does not eliminate P. aeruginosa or lung inflammation. Thus, new treatments are required to reduce lung infection and inflammation in CF. In a previous in vitro study, we demonstrated that primary human bronchial epithelial cells (HBECs) secrete extracellular vesicles (EVs) that block the ability of P. aeruginosa to form biofilms by reducing the abundance of several proteins necessary for biofilm formation as well as enhancing the sensitivity of P. aeruginosa to β-lactam antibiotics. In this study, using a CF mouse model of P. aeruginosa infection, we demonstrate that intratracheal administration of EVs secreted by HBEC reduced P. aeruginosa lung burden and several proinflammatory cytokines including IFN-γ, TNF-α, and MIP-1β in bronchoalveolar lavage fluid (BALF), even in the absence of antibiotics. Moreover, EVs decreased neutrophils in BALF. Thus, EVs secreted by HBEC reduce the lung burden of P. aeruginosa, decrease inflammation, and reduce neutrophils in a CF mouse model. These results suggest that HBEC via the secretion of EVs may play an important role in the immune response to P. aeruginosa lung infection.NEW & NOTEWORTHY Our findings show that extracellular vesicles secreted by primary human bronchial epithelial cells significantly reduce Pseudomonas aeruginosa burden, inflammation, and weight loss in a cystic fibrosis mouse model of infection.

Rocket-miR, a translational launchpad for miRNA-based antimicrobial drug development

IMPORTANCE

Antimicrobial-resistant infections contribute to millions of deaths worldwide every year. In particular, the group of bacteria collectively known as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp.) pathogens are of considerable medical concern due to their virulence and exceptional ability to develop antibiotic resistance. New kinds of antimicrobial therapies are urgently needed to treat patients for whom existing antibiotics are ineffective. The Rocket-miR application predicts targets of human miRNAs in bacterial and fungal pathogens, rapidly identifying candidate miRNA-based antimicrobials. The application's target audience are microbiologists that have the laboratory resources to test the application's predictions. The Rocket-miR application currently supports 24 recognized human pathogens that are relevant to numerous diseases including cystic fibrosis, chronic obstructive pulmonary disease (COPD), urinary tract infections, and pneumonia. Furthermore, the application code was designed to be easily extendible to other human pathogens that commonly cause hospital-acquired infections.

To bead or not to bead: A review of Pseudomonas aeruginosa lung infection models for cystic fibrosis

Cystic fibrosis (CF) lung disease is characterised by recurring bacterial infections resulting in inflammation, lung damage and ultimately respiratory failure. Pseudomonas aeruginosa is considered one of the most important lung pathogens in those with cystic fibrosis. While multiple cystic fibrosis animal models have been developed, many fail to mirror the cystic fibrosis lung disease of humans, including the colonisation by opportunistic environmental pathogens. Delivering bacteria to the lungs of animals in different forms is a way to model cystic fibrosis bacterial lung infections and disease. This review presents an overview of previous models, and factors to consider when generating a new P. aeruginosa lung infection model. The future development and application of lung infection models that more accurately reflect human cystic fibrosis lung disease has the potential to assist in understanding the pathophysiology of cystic fibrosis lung disease and for developing treatments.

Simulated intravenous versus inhaled tobramycin with and without intravenous ceftazidime evaluated against hypermutable Pseudomonas aeruginosa via a dynamic biofilm model and mechanism-based modeling

Acute exacerbations of chronic respiratory infections in patients with cystic fibrosis are highly challenging due to hypermutable Pseudomonas aeruginosa, biofilm formation and resistance emergence. We aimed to systematically evaluate the effects of intravenous versus inhaled tobramycin with and without intravenous ceftazidime. Two hypermutable P. aeruginosa isolates, CW30 (MIC_CAZ 0.5mg/L, MIC_TOB 2mg/L) and CW8 (MIC_CAZ 2mg/L, MIC_TOB 8mg/L), were investigated for 120h in dynamic in vitro biofilm studies. Treatments were: intravenous ceftazidime 9g/day (33% lung fluid penetration); intravenous tobramycin 10mg/kg 24-hourly (50% lung fluid penetration); inhaled tobramycin 300mg 12-hourly, and both ceftazidime-tobramycin combinations. Total and less-susceptible planktonic and biofilm bacteria were quantified over 120h. Mechanism-based modeling was performed. All monotherapies were ineffective for both isolates, with regrowth of planktonic (≥4.7log₁₀ CFU/mL) and biofilm (>3.8log₁₀ CFU/cm²) bacteria, and resistance amplification by 120h. Both combination treatments demonstrated synergistic or enhanced bacterial killing of planktonic and biofilm bacteria. With the combination simulating tobramycin inhalation, planktonic bacterial counts of the two isolates at 120h were 0.47% and 36% of those for the combination with intravenous tobramycin; for biofilm bacteria the corresponding values were 8.2% and 13%. Combination regimens achieved substantial suppression of resistance of planktonic and biofilm bacteria compared to each antibiotic in monotherapy for both isolates. Mechanism-based modeling well described all planktonic and biofilm counts, and indicated synergy of the combination regimens despite reduced activity of tobramycin in biofilm. Combination regimens of inhaled tobramycin with ceftazidime hold promise to treat acute exacerbations caused by hypermutable P. aeruginosa strains and warrant further investigation.

Risk factors and clinical course of children with cystic fibrosis colonized with Staphylococcus aureus

BACKGROUND

The literature is limited on staphylococcal infection in children with cystic fibrosis (CF) from tropical countries. We aimed to study the risk factors and clinical course of children with CF infected with Staphylococcus aureus.

METHODS

In this chart review we compared demographic, clinical and spirometry characteristics in CF children with S. aureus alone (group A), both S. aureus and Pseudomonas aeruginosa (group B) and P. aeruginosa alone (group C) colonization.

RESULTS

We included 79 cases (group A, 22; group B, 19; group C, 38). There was no difference in age of onset of symptoms, age of diagnosis, age of first isolation and spirometry parameters before colonization between the groups. The median duration of follow-up was shorter in group A. After colonization, children in group A and group B had significantly lower mean Shwachman and Kulczycki (SK) scores (44.7±5.4 and 40.8±5.8, respectively) compared with group C (49.9±6.8). Pulmonary exacerbations and hospitalizations were significantly greater in the combined group. After colonization, group A had a significant deterioration in SK score and forced vital capacity (FVC).

CONCLUSIONS

S. aureus colonization, especially in combination with P. aeruginosa, in children with CF was associated with worsening of FVC and clinical severity score and increased pulmonary exacerbations.

In Vitro Newly Isolated Environmental Phage Activity against Biofilms Preformed by Pseudomonas aeruginosa from Patients with Cystic Fibrosis

As disease worsens in patients with cystic fibrosis (CF), Pseudomonas aeruginosa (PA) colonizes the lungs, causing pulmonary failure and mortality. Progressively, PA forms typical biofilms, and antibiotic treatments determine multidrug-resistant (MDR) PA strains. To advance new therapies against MDR PA, research has reappraised bacteriophages (phages), viruses naturally infecting bacteria. Because few in vitro studies have tested phages on CF PA biofilms, general reliability remains unclear. This study aimed to test in vitro newly isolated environmental phage activity against PA isolates from patients with CF at Bambino Gesù Children’s Hospital (OBG), Rome, Italy. After testing in vitro phage activities, we combined phages with amikacin, meropenem, and tobramycin against CF PA pre-formed biofilms. We also investigated new emerging morphotypes and bacterial regrowth. We obtained 22 newly isolated phages from various environments, including OBG. In about 94% of 32 CF PA isolates tested, these phages showed in vitro PA lysis. Despite poor efficacy against chronic CF PA, five selected-lytic-phages (Φ4_ZP1, Φ9_ZP2, Φ14_OBG, Φ17_OBG, and Φ19_OBG) showed wide host activity. The Φ4_ZP1-meropenem and Φ14_OBG-tobramycin combinations significantly reduced CF PA biofilms (p < 0.001). To advance potential combined phage-antibiotic therapy, we envisage further in vitro test combinations with newly isolated phages, including those from hospital environments, against CF PA biofilms from early and chronic infections.

Defining the Mechanistic Correlates of Protection Conferred by Whole-Cell Vaccination against Pseudomonas aeruginosa Acute Murine Pneumonia

Pseudomonas aeruginosa is a Gram-negative pathogen that causes severe pulmonary infections associated with high morbidity and mortality in immunocompromised patients. The development of a vaccine against P. aeruginosa could help prevent infections caused by this highly antibiotic-resistant microorganism.

Pseudomonas aeruginosa is a Gram-negative pathogen that causes severe pulmonary infections associated with high morbidity and mortality in immunocompromised patients. The development of a vaccine against P. aeruginosa could help prevent infections caused by this highly antibiotic-resistant microorganism. We propose that identifying the vaccine-induced correlates of protection against P. aeruginosa will facilitate the development of a vaccine against this pathogen. In this study, we investigated the mechanistic correlates of protection of a curdlan-adjuvanted P. aeruginosa whole-cell vaccine (WCV) delivered intranasally. The WCV significantly decreased bacterial loads in the respiratory tract after intranasal P. aeruginosa challenge and raised antigen-specific antibody titers. To study the role of B and T cells during vaccination, anti-CD4, -CD8, and -CD20 depletions were performed prior to WCV vaccination and boosting. The depletion of CD4⁺, CD8⁺, or CD20⁺ cells had no impact on the bacterial burden in mock-vaccinated animals. However, depletion of CD20⁺ B cells, but not CD8⁺ or CD4⁺ T cells, led to the loss of vaccine-mediated bacterial clearance. Also, passive immunization with serum from WCV group mice alone protected naive mice against P. aeruginosa, supporting the role of antibodies in clearing P. aeruginosa. We observed that in the absence of T cell-dependent antibody production, mice vaccinated with the WCV were still able to reduce bacterial loads. Our results collectively highlight the importance of the humoral immune response for protection against P. aeruginosa and suggest that the production of T cell-independent antibodies may be sufficient for bacterial clearance induced by whole-cell P. aeruginosa vaccination.

Electrochemical Detection of Pyocyanin as a Biomarker for Pseudomonas aeruginosa: A Focused Review

Pseudomonas aeruginosa (PA) is a pathogen that is recognized for its advanced antibiotic resistance and its association with serious diseases such as ventilator-associated pneumonia and cystic fibrosis. The ability to rapidly detect the presence of pathogenic bacteria in patient samples is crucial for the immediate eradication of the infection. Pyocyanin is one of PA’s virulence factors used to establish infections. Pyocyanin promotes virulence by interfering in numerous cellular functions in host cells due to its redox-activity. Fortunately, the redox-active nature of pyocyanin makes it ideal for detection with simple electrochemical techniques without sample pretreatment or sensor functionalization. The previous decade has seen an increased interest in the electrochemical detection of pyocyanin either as an indicator of the presence of PA in samples or as a tool for quantifying PA virulence. This review provides the first overview of the advances in electrochemical detection of pyocyanin and offers an input regarding the future directions in the field.

Factoring in the Complexity of the Cystic Fibrosis Lung to Understand Aspergillus fumigatus and Pseudomonas aeruginosa Interactions

Pseudomonas aeruginosa has long been established as the most prevalent respiratory pathogen in Cystic Fibrosis (CF) patients, with opportunistic infection causing profound morbidity and mortality. Recently, Aspergillus fumigatus has also been recognised as a key contributor to CF lung deterioration, being consistently associated with decreased lung function and worsened prognosis in these patients. As clinical evidence for the common occurrence of combined infection with these two pathogens increases, research into the mechanism and consequences of their interaction is becoming more relevant. Clinical evidence suggests a synergistic effect of combined infection, which translates into a poorer prognosis for the patients. In vitro results from the laboratory have identified a variety of possible synergistic and antagonistic interactions between A. fumigatus and P. aeruginosa. Here, we present a comprehensive overview of the complex environment of the CF lung and discuss how it needs to be considered to determine the exact molecular interactions that A. fumigatus and P. aeruginosa undergo during combined infection and their effects on the host.

Highly specific Electrochemical Sensing of Pseudomonas aeruginosa in patients suffering from corneal ulcers: A comparative study

Pseudomonas aeruginosa is the most common pathogenic gram-negative bacteria causing corneal ulcers globally. In severe cases, often after trauma and eye injury, corneal destruction progresses rapidly and may be completed within 24–48 h causing blindness. In our preliminary work, we have established an ultrasensitive polyaniline (PANI)/gold nanoparticles (Au NPs)/indium tin oxide (ITO) modified sensor for rapid detection of pyocyanin (PYO) in P. aeruginosa infections with a linear range from 238 μM to 1.9 μM and a detection limit of 500 nM. In the present study, we evaluated the efficiency of the established modified electrochemical sensor in the diagnosis of P. aeruginosa in 50 samples collected from patients suffering from corneal ulcers. The obtained results were compared with the results gained by the screen-printed electrode, conventional techniques, automated identification method, and the amplification of the 16 s rRNA gene by PCR as a gold standard test for P. aeruginosa identification. We have found that the electrochemical detection of PYO by square wave voltammetry technique using PANI/Au NPs modified ITO electrode was the only technique showing 100% agreement with the molecular method in sensitivity, specificity, positive and negative predictive values when compared with the SPE, conventional and automated methods.

Intranasal Peptide-Based FpvA-KLH Conjugate Vaccine Protects Mice From Pseudomonas aeruginosa Acute Murine Pneumonia

Pseudomonas aeruginosa is an opportunistic pathogen causing acute and chronic respiratory infections associated with morbidity and mortality, especially in patients with cystic fibrosis. Vaccination against P. aeruginosa before colonization may be a solution against these infections and improve the quality of life of at-risk patients. To develop a vaccine against P. aeruginosa, we formulated a novel peptide-based P. aeruginosa subunit vaccine based on the extracellular regions of one of its major siderophore receptors, FpvA. We evaluated the effectiveness and immunogenicity of the FpvA peptides conjugated to keyhole limpet hemocyanin (KLH) with the adjuvant curdlan in a murine vaccination and challenge model. Immunization with the FpvA-KLH vaccine decreased the bacterial burden and lung edema after P. aeruginosa challenge. Vaccination with FpvA-KLH lead to antigen-specific IgG and IgM antibodies in sera, and IgA antibodies in lung supernatant. FpvA-KLH immunized mice had an increase in recruitment of CD11b⁺ dendritic cells as well as resident memory CD4⁺ T cells in the lungs compared to non-vaccinated challenged mice. Splenocytes isolated from vaccinated animals showed that the FpvA-KLH vaccine with the adjuvant curdlan induces antigen-specific IL-17 production and leads to a Th17 type of immune response. These results indicate that the intranasal FpvA-KLH conjugate vaccine can elicit both mucosal and systemic immune responses. These observations suggest that the intranasal peptide-based FpvA-KLH conjugate vaccine with curdlan is a potential vaccine candidate against P. aeruginosa pneumonia.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Progressive lung damage from recurrent exacerbations is the major cause of mortality and morbidity in cystic fibrosis. Life expectancy of people with cystic fibrosis has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient. The risk of systemic side effects such as allergic reactions to antibiotics also increases with prolonged courses and the use of aminoglycosides requires frequent monitoring to minimise some of their side effects. However, some organisms which infect people with cystic fibrosis are known to be multi-resistant to antibiotics, and may require a longer course of treatment. This is an update of previously published reviews.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings. Most recent search of the Group's Cystic Fibrosis Trials Register: 30 May 2019.We also searched online trials registries. Most recent search of the ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) portal: 06 January 2019.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified for inclusion. A trial looking at the standardised treatment of pulmonary exacerbations is currently ongoing and will be included when the results are published.  MAIN RESULTS: No eligible trials were included.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and adherence, result in a reduced incidence of drug reactions and be less costly. However, the shorter duration may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications. The currently ongoing STOP2 trial is expected to provide some guidance on these questions when published.

Pseudomonas aeruginosa eradication therapy and risk of acquiring Aspergillus in young children with cystic fibrosis

Background

While Aspergillus detection rates in adults, adolescents and older children with cystic fibrosis (CF) have increased, the risk of acquiring this fungal pathogen in young children is unknown.

Aim

To determine the risk and explanatory factors of acquiring Aspergillus in children with CF by age 5 years.

Methods

Cross-sectional analysis of clinical, bronchoalveolar lavage and treatment data from the Australasian Cystic Fibrosis Bronchoalveolar Lavage study was used to identify predictive factors for detecting Aspergillus at age 5 years. A parametric repeated time-to-event model quantitatively described the risk and factors associated with acquiring Aspergillus and Pseudomonas aeruginosa from birth until age 5 years.

Results

Cross-sectional analysis found that the number of P. aeruginosa eradication courses increased the odds of detecting Aspergillus at age 5 years (OR 1.61, 95% CI 1.23 to 2.12). The median (IQR) age for the first P. aeruginosa positive culture was 2.38 (1.32–3.79) years and 3.69 (1.68–4.74) years for the first Aspergillus positive culture. The risk of P. aeruginosa and Aspergillus events changes with time after the first year of study entry. It also decreases for P. aeruginosa after completing P. aeruginosa eradication (HR 0.15, 95% CI 0.00 to 0.79), but increases for Aspergillus events (HR 2.75, 95% CI 1.45 to 5.41). The risk of acquiring both types of events increases after having had a previous event.

Conclusion

In young children with CF, completing P. aeruginosa eradication therapy and previous Aspergillus events are associated with increased risk of acquiring Aspergillus.

The ionophore oxyclozanide enhances tobramycin killing of Pseudomonas aeruginosa biofilms by permeabilizing cells and depolarizing the membrane potential

OBJECTIVES

To assess the ability of oxyclozanide to enhance tobramycin killing of Pseudomonas aeruginosa biofilms and elucidate its mechanism of action.

METHODS

Twenty-four hour biofilms formed by the P. aeruginosa strain PAO1 and cystic fibrosis (CF) isolates were tested for susceptibility to oxyclozanide and tobramycin killing using BacTiter-Glo™ and cfu. Biofilm dispersal was measured using crystal violet staining. Membrane potential and permeabilization were quantified using DiOC2(3) and TO-PRO-3, respectively.

RESULTS

Here we show that the ionophore anthelmintic oxyclozanide, combined with tobramycin, significantly increased killing of P. aeruginosa biofilms over each treatment alone. This combination also significantly accelerated the killing of cells within biofilms and stationary phase cultures and it was effective against 4/6 CF clinical isolates tested, including a tobramycin-resistant strain. Oxyclozanide enhanced the ability of additional aminoglycosides and tetracycline to kill P. aeruginosa biofilms. Finally, oxyclozanide permeabilized cells within the biofilm, reduced the membrane potential and increased tobramycin accumulation within cells of mature P. aeruginosa biofilms.

CONCLUSIONS

Oxyclozanide enhances aminoglycoside and tetracycline activity against P. aeruginosa biofilms by reducing membrane potential, permeabilizing cells and enhancing tobramycin accumulation within biofilms. We propose that oxyclozanide counteracts the adaptive resistance response of P. aeruginosa to aminoglycosides, increasing both their maximum activity and rate of killing. As oxyclozanide is widely used in veterinary medicine for the treatment of parasitic worm infections, this combination could offer a new approach for the treatment of biofilm-based P. aeruginosa infections, repurposing oxyclozanide as an anti-biofilm agent.

Nebulized gentamicin in combination with systemic antibiotics for eradicating early Pseudomonas aeruginosa infection in children with cystic fibrosis

OBJECTIVES

Chronic Pseudomonas aeruginosa (Pa) infection in cystic fibrosis (CF) can be prevented with early eradication treatment. In resource-constrained environments, low-cost, off-label nebulized antibiotics, including intravenous gentamicin solution, are often used for eradication therapy. This study aimed to describe the characteristics and clinical course of children with CF and early Pa infection, treated with a Pa eradication protocol combining inhaled gentamicin and systemic antibiotics.

STUDY DESIGN

Retrospective descriptive study.

PATIENT-SUBJECT SELECTION

All children (0-18 years) attending a CF clinic in South Africa, with early Pa infections between January 2005 and March 2015, who received nebulized gentamicin-based Pa eradication treatment.

METHODOLOGY

Data were described and compared between those with successful versus unsuccessful eradication, using descriptive and inferential statistics appropriate to normality of distribution.

RESULTS

One hundred and forty-nine children were managed in the CF Clinic over the study period, of whom 44 (29.5%; 28 [63.6%] male) had early Pa infections treated with a gentamicin-based eradication regimen. Thirty-nine (88.6%) patients had successful Pa eradication at 12 months follow-up; of which 28 (71.8%) had Pa reinfection at a median of 37.0 (21.0-101.0) months after initial treatment. Six patients (13%) acquired chronic Pa infection during the median follow-up period of 77 months. Older age was associated with Pa eradication failure and chronic Pa infection. There were no clinically significant adverse events associated with gentamicin inhalational therapy.

CONCLUSIONS

Nebulized gentamicin solution combined with systemic antibiotics appears to be safe and has comparable efficacy to other strategies in eradicating early Pa infections in children with CF.

No benefit of longer eradication therapy of Pseudomonas aeruginosa primoinfections in pediatric cystic fibrosis

OBJECTIVE

Patients with cystic fibrosis are more susceptible than members of the general population to lung infections. Infections with Pseudomonas aeruginosa require particular attention, because they may accelerate the deterioration of lung function if not adequately treated. This study assessed the eradication rate of P. aeruginosa primoinfections, with a protocol of inhaled tobramycin and oral ciprofloxacin over a 3 months' period.

RESULTS

Retrospective single-center study from June 1st, 2007 to December 31st, 2015. Inclusion of 28 pediatric patients (11 females, 17 males), with a total of 49 primoinfections. Overall success rate of 67.3%, which is similar or even inferior to figures published in the literature.

Bronchoscopy-guided antimicrobial therapy for cystic fibrosis

BACKGROUND

Early diagnosis and treatment of lower respiratory tract infections are the mainstay of management of lung disease in cystic fibrosis. When sputum samples are unavailable, treatment relies mainly on cultures from oropharyngeal specimens; however, there are concerns regarding the sensitivity of these to identify lower respiratory organisms.Bronchoscopy and related procedures (including bronchoalveolar lavage) though invasive, allow the collection of lower respiratory specimens from non-sputum producers. Cultures of bronchoscopic specimens provide a higher yield of organisms compared to those from oropharyngeal specimens. Regular use of bronchoscopy and related procedures may help in a more accurate diagnosis of lower respiratory tract infections and guide the selection of antimicrobials, which may lead to clinical benefits.This is an update of a previous review.

OBJECTIVES

To evaluate the use of bronchoscopy-guided antimicrobial therapy in the management of lung infection in adults and children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of latest search: 30 August 2018.We also searched three registries of ongoing studies and the reference lists of relevant articles and reviews. Date of latest search: 10 April 2018.

SELECTION CRITERIA

We included randomized controlled studies including people of any age with cystic fibrosis, comparing outcomes following therapies guided by the results of bronchoscopy (and related procedures) with outcomes following therapies guided by the results of any other type of sampling (including cultures from sputum, throat swab and cough swab).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed their risk of bias and extracted data. We contacted study investigators for further information. The quality of the evidence was assessed using the GRADE criteria.

MAIN RESULTS

The search identified 11 studies, but we only included one study enrolling infants with cystic fibrosis under six months of age and diagnosed through newborn screening (170 enrolled); participants were followed until they were five years old (data from 157 children). The study compared outcomes following therapy directed by bronchoalveolar lavage for pulmonary exacerbations with standard treatment based on clinical features and oropharyngeal cultures.We considered this study to have a low risk of bias; however, the statistical power to detect a significant difference in the prevalence of Pseudomonas aeruginosa was limited due to the prevalence (of Pseudomonas aeruginosa isolation in bronchoalveolar lavage samples at five years age) being much lower in both the groups compared to that which was expected and which was used for the power calculation. The sample size was adequate to detect a difference in high-resolution computed tomography scoring. The quality of evidence for the key parameters was graded as low except high-resolution computed tomography scoring and cost of care analysis, which were graded as moderate quality.At five years of age, there was no clear benefit of bronchoalveolar lavage-directed therapy on lung function z scores or nutritional parameters. Evaluation of total and component high-resolution computed tomography scores showed no significant difference in evidence of structural lung disease in the two groups.In addition, this study did not show any difference between the number of isolates of Pseudomonas aeruginosa per child per year diagnosed in the bronchoalveolar lavage-directed therapy group compared to the standard therapy group. The eradication rate following one or two courses of eradication treatment was comparable in the two groups, as were the number of pulmonary exacerbations. However, the number of hospitalizations was significantly higher in the bronchoalveolar lavage-directed therapy group, but the mean duration of hospitalizations was significantly less compared to the standard therapy group.Mild adverse events were reported in a proportion of participants, but these were generally well-tolerated. The most common adverse event reported was transient worsening of cough after 29% of procedures. Significant clinical deterioration was documented during or within 24 hours of bronchoalveolar lavage in 4.8% of procedures.

AUTHORS' CONCLUSIONS

This review, limited to a single, well-designed randomized controlled study, shows no clear evidence to support the routine use of bronchoalveolar lavage for the diagnosis and management of pulmonary infection in pre-school children with cystic fibrosis compared to the standard practice of providing treatment based on results of oropharyngeal culture and clinical symptoms. No evidence was available for adult and adolescent populations.

Triclosan Is an Aminoglycoside Adjuvant for Eradication of Pseudomonas aeruginosa Biofilms

One of the most important clinical obstacles in cystic fibrosis (CF) treatment is antibiotic treatment failure due to biofilms produced by Pseudomonas aeruginosa The ability of this pathogen to survive eradication by tobramycin and pathoadapt into a hyperbiofilm state leading to chronic infections is key to its success. Retrospective studies have demonstrated that preventing this pathoadaptation by improving eradication is essential to extend the lives of CF patients. To identify adjuvants that enhance tobramycin eradication of P. aeruginosa, we performed a high-throughput screen of 6,080 compounds from four drug-repurposing libraries. We identified that the Food and Drug Administration (FDA)-approved compound triclosan, in combination with tobramycin, resulted in a 100-fold reduction of viable cells within biofilms at 6 h, but neither compound alone had significant antimicrobial activity against biofilms. This synergistic treatment significantly accelerated the killing of biofilms compared to that with tobramycin treatment alone, and the combination was effective against 6/7 CF clinical isolates compared to tobramycin treatment alone, including a tobramycin-resistant strain. Further, triclosan and tobramycin killed persister cells, causing a 100-fold reduction by 8 h and complete eradication by 24 h. Triclosan also enhances tobramycin killing of multiple Burkholderia cenocepacia and Staphylococcus aureus clinical isolates grown as biofilms. Additionally, triclosan showed synergy with other aminoglycosides, such as gentamicin or streptomycin. Triclosan is a well-tolerated aminoglycoside adjuvant shown to be safe for human use that could improve the treatment of biofilm-based infections.

Challenges and Promises for Planning Future Clinical Research Into Bacteriophage Therapy Against Pseudomonas aeruginosa in Cystic Fibrosis. An Argumentative Review

Although early aggressive and prolonged treatment with specific antibiotics can extend survival in patients with cystic fibrosis (CF) colonized by opportunistic Pseudomonas aeruginosa (PA), antibiotics fail to eradicate the infecting multidrug-resistant (MDR) PA strains in CF. Century-long research has suggested treating patients with bacteriophages (phages, prokaryotic viruses) naturally hosted by bacteria. Although the only phage types used in therapy, lytic phages, lyse PA aggregated in biofilm matrix by depolymerase degrading enzymes, how they can effectively, safely, and persistently do so in patients with CF is unclear. Even though advanced techniques for formulating phage cocktails, training phages and collecting phage libraries have improved efficacy in vitro, whether personalized or ready-to-use therapeutic approaches or phages and antibiotics combined are effective and safe in vivo, and can reduce PA biofilms, remains debatable. Hence, to advance clinical research on phage therapy in clinical trials, also involving mucoid and non-mucoid multidrug-resistant PA in CF, and overcome problems in Western international regulations, we need reliable and repeatable information from experiments in vitro and in vivo on phage characterization, cocktail selection, personalized approaches, and phages combined with antibiotics. These findings, challenges, and promises prompted us to undertake this argumentative review to seek up-to-date information from papers describing lytic phage activity tested in vitro on PA laboratory strains, and PA strains from chronic infections including CF. We also reviewed in vivo studies on phage activity on pulmonary and non-pulmonary animal host models infected by laboratory or CF PA strains. Our argumentative review provides essential information showing that future phage clinical research in CF should use well-characterized and selected phages isolated against CF PA, tested in vitro under dynamic conditions in cocktails or combined with antibiotics, and in vivo on non-pulmonary and pulmonary host models infected with mucoid and non-mucoid CF MDR PA. Our findings should encourage pharmaceutical industries to conduct clinical trials in vitro and in vivo testing patented genomic engineered phages from phage libraries combined with antibiotics to treat or even prevent multidrug-resistant PA in CF, thus helping international regulatory agencies to plan future clinical research on phage therapy in CF.

Paper-based sensors for rapid detection of virulence factor produced by Pseudomonas aeruginosa

Pyocyanin is a toxin produced by Pseudomonas aeruginosa. Here we describe a novel paper-based electrochemical sensor for pyocyanin detection, manufactured with a simple and inexpensive approach based on electrode printing on paper. The resulting sensors constitute an effective electrochemical method to quantify pyocyanin in bacterial cultures without the conventional time consuming pretreatment of the samples. The electrochemical properties of the paper-based sensors were evaluated by ferri/ferrocyanide as a redox mediator, and showed reliable sensing performance. The paper-based sensors readily allow for the determination of pyocyanin in bacterial cultures with high reproducibility, achieving a limit of detection of 95 nM and a sensitivity of 4.30 μA/μM in standard culture media. Compared to the similar commercial ceramic based sensors, it is a 2.3-fold enhanced performance. The simple in-house fabrication of sensors for pyocyanin quantification allows researchers to understand in vitro adaptation of P. aeruginosa infections via rapid screenings of bacterial cultures that otherwise are expensive and time-consuming.

Healthcare Cost and Utilization before and after Diagnosis of Pseudomonas aeruginosa among Patients with Non-Cystic Fibrosis Bronchiectasis in the U.S

Non-cystic fibrosis bronchiectasis (NCFBE) is a rare, chronic lung disease characterized by bronchial inflammation and permanent airway dilation. Chronic infections with P. aeruginosa have been linked to higher morbidity and mortality. To understand the impact of P. aeruginosa in NCFBE on health care costs and burden, we assessed healthcare costs and utilization before and after P. aeruginosa diagnosis. Using data from 2007 to 2013 PharMetrics Plus administrative claims, we included patients with ≥2 claims for bronchiectasis and >1 claim for P. aeruginosa; then excluded those with a claim for cystic fibrosis. Patients were indexed at first claim for P. aeruginosa and were required to have >12 months before and after the index P. aeruginosa. The mean differences in utilization and costs were assessed using paired Student's t-tests for statistical significance. Mean total healthcare costs per patient were $36,213 pre-P. aeruginosa diagnosis versus $67,764 post-P. aeruginosa, an increase of 87% (p < 0.0001). Inpatient costs represented the largest proportion of total healthcare costs post-P. aeruginosa (54%) with an increase of four hospitalizations per patient (p < 0.0001). NCFBE patients with evidence of P. aeruginosa incur substantially greater healthcare costs and utilization after P. aeruginosa diagnosis. Future research should explore methods of earlier identification of NCFBE patients with P. aeruginosa, as this may lead to fewer severe exacerbations, thereby resulting in a reduction in hospitalizations and healthcare costs.

Assessment of serology and spirometry and the combination of both to complement microbiological isolation for earlier detection of Pseudomonas aeruginosa infection in children with cystic fibrosis

Background

The aim of this study was to assess whether serology and spirometry and the combination of both can complement culture-based detection for earlier recognition of Pseudomonas aeruginosa infection in children with cystic fibrosis.

Methods

A 4 year longitudinal prospective study that included 67 Slovenian children with cystic fibrosis with a mean age of 10.5 years was conducted. Serology, spirometry and a scoring system combining serology and spirometry were assessed and compared. Infection was confirmed with isolation of Pseudomonas aeruginosa from respiratory samples.

Results

There was a significantly positive correlation between serology and the combination of serology and spirometry and Pseudomonas aeruginosa isolation (P < 0.01 for both) and a significantly negative correlation between spirometry and Pseudomonas aeruginosa isolation (P < 0.05). An increase in serology for 1 ELISA unit increased the possibility of Pseudomonas aeruginosa isolation 1.6 times. A fall in FEV1% predicted for 10% increased the possibility of Pseudomonas aeruginosa isolation 9.8 times. Binary logistic regression analysis was used to determine the odds ratios and 95% confidence intervals for all three approaches. Serology had the highest specificity (0.80) and the combination of serology and spirometry the highest sensitivity (0.90). Both had a high negative predictive value (0.93 and 0.79 respectively).

Conclusion

Using serology and the combination of serology and lung function measurement can be beneficial for earlier detection of infection with Pseudomonas aeruginosa in children with cystic fibrosis when done simultaneously with standard culture-based detection from respiratory samples.

The Approach to Pseudomonas aeruginosa in Cystic Fibrosis

There is a high prevalence of Pseudomonas aeruginosa in patients with cystic fibrosis and clear epidemiologic links between chronic infection and morbidity and mortality exist. Prevention and early identification of infection are critical, and stand to improve with the advent of new vaccines and laboratory methods. Once the organism is identified, a variety of treatment options are available. Aggressive use of antipseudomonal antibiotics is the standard of care for acute pulmonary exacerbations in cystic fibrosis, and providers must take into account specific patient characteristics when making treatment decisions related to antibiotic selection, route and duration of administration, and site of care.

Duration of intravenous antibiotic therapy in people with cystic fibrosis

BACKGROUND

Respiratory disease is the major cause of mortality and morbidity in cystic fibrosis. Life expectancy of people with cystic fibrosis has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient and the incidence of allergic reactions to antibiotics also increases with prolonged courses. The use of aminoglycosides requires frequent monitoring to avoid some of their side effects. However, some organisms which infect people with cystic fibrosis are known to be multi-resistant to antibiotics, and may require a longer course of treatment. This is an update of previously published reviews.

OBJECTIVES

To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings.Most recent search of the Group's Cystic Fibrosis Trials Register: 05 May 2016.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents.

DATA COLLECTION AND ANALYSIS

No eligible trials were identified.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and compliance; result in a reduced incidence of drug reactions; and be less costly. However, this may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications.

Novel cationic peptide TP359 down-regulates the expression of outer membrane biogenesis genes in Pseudomonas aeruginosa: a potential TP359 anti-microbial mechanism

Background

Antimicrobial peptides (AMPs) are a class of antimicrobial agents with broad-spectrum activities. Several reports indicate that cationic AMPs bind to the negatively charged bacterial membrane causing membrane depolarization and damage. However, membrane depolarization and damage may be insufficient to elicit cell death, thereby suggesting that other mechanism(s) of action could be involved in this phenomenon. In this study, we investigated the antimicrobial activity of a novel antimicrobial peptide, TP359, against two strains of Pseudomonas aeruginosa, as well as its possible mechanisms of action.

Results

TP359 proved to be bactericidal against P. aeruginosa as confirmed by the reduced bacteria counts, membrane damage and cytoplasmic membrane depolarization. In addition, it was non-toxic to mouse J774 macrophages and human lung A549 epithelial cells. Electron microscopy analysis showed TP359 bactericidal effects by structural changes of the bacteria from viable rod-shaped cells to those with cell membrane damages, proceeding into the efflux of cytoplasmic contents and emergence of ghost cells. Gene expression analysis on the effects of TP359 on outer membrane biogenesis genes underscored marked down-regulation, particularly of oprF, which encodes a major structural and outer membrane porin (OprF) in both strains studied, indicating that the peptide may cause deregulation of outer membrane genes and reduced structural stability which could lead to cell death.

Conclusion

Our data shows that TP359 has potent antimicrobial activity against P aeruginosa. The correlation between membrane damage, depolarization and reduced expression of outer membrane biogenesis genes, particularly oprF may suggest the bactericidal mechanism of action of the TP359 peptide.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0808-2) contains supplementary material, which is available to authorized users.

A Proof of Concept Study to Detect Urease Producing Bacteria in Lungs Using Aerosolized 13C-Urea

This is a "proof of concept" study to determine whether inhalation of ¹³C-urea can be safely used to detect the presence of urease producing bacteria in the airways of patients with cystic fibrosis (CF) by detecting ¹³CO₂ in breath. This was a prospective, 2-part, open label, single-center, single-arm, single-administration, dose-escalation investigational device exemption trial. First, the safety of 20 and 50 mg inhaled ¹³C-urea was evaluated in 6 healthy adult participants. Then, 3 adult CF participants colonized with Pseudomonas aeruginosa were enrolled for each dose of inhaled ¹³C-urea. The safety of inhaled ¹³C-urea was assessed by spirometry and physical examination. ¹³C-urea was administered using a jet nebulizer, followed by serial spirometry (10 min and 30 min post inhalation) and collection of exhaled breath at 5, 10, and 15 min post inhalation. There was no clinical significant change in any of the spirometry values compared to baseline in healthy participants and CF patients. Mean of ¹³CO₂/¹²CO₂ delta over baseline (DOB) values in CF participants at 5, 10, and 15 min post inhalation was as follows: 20 mg dose 4‰ (2.2‰-4.9‰), 1‰ (1.0‰-1.4‰), and 1‰ (0.4‰-1.5‰); 50 mg dose: 10‰ (6.2‰-14.5‰), 3‰ (2.1‰-4.3‰), and 1.5‰ (0.6‰-2.3‰). Inhaled ¹³C-urea for detection of urease producing bacteria was safe, and preliminary data suggest that ¹³CO₂/¹²CO₂ DOB values may be higher in CF patients with P. aeruginosa at 5-10 min after inhalation of ¹³C-urea. A future direction is to investigate use of inhaled ¹³C-urea in young children who have difficulty producing sputum for culturing.

Bronchoscopy-guided antimicrobial therapy for cystic fibrosis

BACKGROUND

Early diagnosis and treatment of lower respiratory tract infections are the mainstay of management of lung disease in cystic fibrosis. When sputum samples are unavailable, treatment relies mainly on cultures from oropharyngeal specimens; however, there are concerns regarding the sensitivity of these to identify lower respiratory organisms.Bronchoscopy and related procedures (including bronchoalveolar lavage) though invasive, allow the collection of lower respiratory specimens from non-sputum producers. Cultures of bronchoscopic specimens provide a higher yield of organisms compared to those from oropharyngeal specimens. Regular use of bronchoscopy and related procedures may help in a more accurate diagnosis of lower respiratory tract infections and guide the selection of antimicrobials, which may lead to clinical benefits.This is an update of a previous review.

OBJECTIVES

To evaluate the use of bronchoscopy-guided antimicrobial therapy in the management of lung infection in adults and children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched two registries of ongoing studies and the reference lists of relevant articles and reviews.Date of latest search: 28 August 2015.

SELECTION CRITERIA

We included randomized controlled studies including people of any age with cystic fibrosis, comparing outcomes following therapies guided by the results of bronchoscopy (and related procedures) with outcomes following therapies guided by the results of any other type of sampling (including cultures from sputum, throat swab and cough swab).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed their risk of bias and extracted data. We contacted study investigators for further information.

MAIN RESULTS

The search identified nine studies, but only one study with data from 157 participants (170 people were enrolled) was eligible for inclusion in the review. This study compared outcomes following therapy directed by bronchoalveolar lavage for pulmonary exacerbations during the first five years of life with standard treatment based on clinical features and oropharyngeal cultures. The study enrolled infants with CF who were under six months of age and diagnosed through newborn screening and followed them until they were five years old.We considered this study to have a low risk of bias; however, the statistical power to detect a significant difference in the prevalence of Pseudomonas aeruginosa was limited due to the prevalence (of Pseudomonas aeruginosa isolation in bronchoalveolar lavage samples at five years age) being much lower in both the groups compared to that which was expected and which was used for the power calculation. The sample size was adequate to detect a difference in high-resolution computed tomography scoring. The quality of evidence for the key parameters was graded as moderate except high-resolution computed tomography scoring and cost of care analysis, which were graded as high quality.At five years of age, there was no clear benefit of bronchoalveolar lavage-directed therapy on lung function z scores or nutritional parameters. Evaluation of total and component high-resolution computed tomography scores showed no significant difference in evidence of structural lung disease in the two groups.In addition, this study did not show any difference between the number of isolates of Pseudomonas aeruginosa per child per year diagnosed in the bronchoalveolar lavage-directed therapy group compared to the standard therapy group. The eradication rate following one or two courses of eradication treatment was comparable in the two groups, as were the number of pulmonary exacerbations. However, the number of hospitalizations was significantly higher in the bronchoalveolar lavage-directed therapy group, but the mean duration of hospitalizations was significantly less compared to the standard therapy group.Mild adverse events were reported in a proportion of participants, but these were generally well-tolerated. The most common adverse event reported was transient worsening of cough after 29% of procedures. Significant clinical deterioration was documented during or within 24 hours of bronchoalveolar lavage in 4.8% of procedures.

AUTHORS' CONCLUSIONS

This review, limited to a single, well designed randomized-controlled study, shows no clear evidence to support the routine use of bronchoalveolar lavage for the diagnosis and management of pulmonary infection in pre-school children with cystic fibrosis compared to the standard practice of providing treatment based on results of oropharyngeal culture and clinical symptoms. No evidence was available for adult and adolescent populations.

Complete Genome Sequence of Pseudomonas aeruginosa PA1, Isolated from a Patient with a Respiratory Tract Infection

We report the 6,498,072-bp complete genome sequence of Pseudomonas aeruginosa PA1, which was isolated from a patient with a respiratory tract infection in Chongqing, People's Republic of China. Whole-genome sequencing was performed using single-molecule real-time (SMRT) technology, and de novo assembly revealed a single contig with 396-fold sequence coverage.

[Management of multiresistant pathogens in urology]

Epidemiological data from recent years confirm the increasing problem of antimicrobial resistance not only for healthcare-associated, gram-positive pathogens but also for gram-negative bacteria. In particular, the progressive increase in resistance to third generation cephalosporins and carbapenems in Enterobacteriaceae is of great concern. With its contribution to infectious morbidity, mortality and financial costs to healthcare systems worldwide, multidrug-resistant pathogens emerge more and more as a public health issue of substantial socioeconomic importance. The Commission for Hospital Hygiene and Infection Prevention (KRINKO) at the Robert Koch Institute (RKI) decided to formulate novel definitions for multidrug-resistance in order to develop hygiene measures for infections and colonization with multidrug-resistant gram-negative bacilli.

Normal and Cystic Fibrosis Human Bronchial Epithelial Cells Infected with Pseudomonas aeruginosa Exhibit Distinct Gene Activation Patterns

BACKGROUND AND AIMS

In cystic fibrosis (CF), Pseudomonas aeruginosa is not eradicated from the lower respiratory tract and is associated with epithelial inflammation that eventually causes tissue damage. To identify the molecular determinants of an effective response to P. aeruginosa infection, we performed a transcriptomic analysis of primary human bronchial epithelial cells from healthy donors (CTRL) 2, 4, and 6 h after induced P. aeruginosa infection. Compared to noninfected cells, infected cells showed changes in gene activity, which were most marked 6 h postinfection and usually consisted in upregulation.

RESULTS

By comparing for each time point of infection, the transcriptomic response of epithelial cells from CF patients and healthy donors, we identified 851, 638, 667, and 980 differentially expressed genes 0, 2, 4, and 6 h postinfection, respectively. Gene selection followed by bioinformatic analysis showed that most of the differentially expressed genes, either up- or downregulated, were in the protein-binding and catalytic gene-ontology categories. Finally, we established that the protein products of the genes exhibiting the greatest differential upregulation (CSF2, CCL2, TNF, CSF3, MMP1, and MMP10) between CF patients and CTRL were produced in higher amounts by infected cells from CF patients versus CTRL.

CONCLUSIONS

The differentially expressed genes in CF patients may constitute a signature for a detrimental inflammatory response and for an inefficient P. aeruginosa host-cell response.

Candida albicans chronic colonisation in cystic fibrosis may be associated with inhaled antibiotics

Candida albicans is increasingly recognised as a coloniser of the respiratory tract in cystic fibrosis (CF) patients. Yet, the potential role, if any, of the micro-organism in the progress of the disease remains unclear. In this study, we investigated the association between inhaled antibiotics and C. albicans chronic colonisation in patients with CF. A cohort of 121 CF patients born from 1988 to 1996 was, respectively, studied. The medical records of each patient were reviewed from the first time they attended the CF Centre until the occurrence of C. albicans chronic colonisation or their last visit for the year 2010. Chronic colonisation was defined as the presence of C. albicans in more than 50% of cultures in a given year. A number of possible confounders were included in the multivariate logistic regression analysis to identify an independent association between inhaled antibiotics and C. albicans chronic colonisation. Fifty-four (44.6%) of the 121 patients enrolled in the study developed chronic colonisation by the micro-organism. Multivariate logistic regression analysis determined the independent effect of inhaled antibiotic treatment on the odds of chronic colonisation (OR 1.112, 95% CI [1.007-1.229], P = 0.036). Candida albicans chronic colonisation may be associated with the duration of inhaled antibiotic treatment.

How to use: bacterial cultures in diagnosing lower respiratory tract infections in cystic fibrosis

Respiratory infections are the leading cause of morbidity and mortality in cystic fibrosis. Certain bacteria, such as Pseudomonas aeruginosa, are associated with a worse clinical outcome than others, but can be completely eradicated if identified and treated early. The diagnosis of lower respiratory tract infections can be challenging in the non-expectorating patient, in whom upper airway samples, such as cough swabs, are a surrogate for lower airway sampling. However, the results of these often do not fit with the clinical picture, presenting a management dilemma. Frequently, clinicians are faced with a negative culture result in a progressively symptomatic patient and vice versa. When judging the clinical significance of a positive upper airway culture result in an asymptomatic patient, it is important to consider the prognostic significance of the organism cultured. Given that the reported sensitivity of upper airway swabs (which includes throat swabs) is variable, ranging from 35.7% to 71% for Pseudomonas aeruginosa, 50% to 86% for Staphylococcus aureus and 11% to 92% for Haemophilus influenza, upper airway samples may fail to identify lower airway infections. Therefore, in symptomatic children, a repeatedly negative upper airway swab should not be considered as reassuring, and alternative sampling methods, such as induced sputum or bronchoalveolar lavage, should be considered. Here we use some examples of common scenarios to illustrate how best to use bacterial cultures to aid management decisions in cystic fibrosis.

A conserved suppressor mutation in a tryptophan auxotroph results in dysregulation of Pseudomonas quinolone signal synthesis

Pseudomonas aeruginosa is a common nosocomial pathogen that relies on three cell-to-cell signals to regulate multiple virulence factors. The Pseudomonas quinolone signal (PQS; 2-heptyl-3-hydroxy-4-quinolone) is one of these signals, and it is known to be important for P. aeruginosa pathogenesis. PQS is synthesized in a multistep reaction that condenses anthranilate and a fatty acid. In P. aeruginosa, anthranilate is produced via the kynurenine pathway and two separate anthranilate synthases, TrpEG and PhnAB, the latter of which is important for PQS synthesis. Others have previously shown that a P. aeruginosa tryptophan auxotroph could grow on tryptophan-depleted medium with a frequency of 10(-5) to 10(-6). These revertants produced more pyocyanin and had increased levels of phnA transcript. In this study, we constructed similar tryptophan auxotroph revertants and found that the reversion resulted from a synonymous G-to-A nucleotide mutation within pqsC. This change resulted in increased pyocyanin and decreased PQS, along with an increase in the level of the pqsD, pqsE, and phnAB transcripts. Reporter fusion and reverse transcriptase PCR studies indicated that a novel transcript containing pqsD, pqsE, and phnAB occurs in these revertants, and quantitative real-time PCR experiments suggested that the same transcript appears in the wild-type strain under nutrient-limiting conditions. These results imply that the PQS biosynthetic operon can produce an internal transcript that increases anthranilate production and greatly elevates the expression of the PQS signal response protein PqsE. This suggests a novel mechanism to ensure the production of both anthranilate and PQS-controlled virulence factors.

Treatment of pseudomonas and Staphylococcus bronchopulmonary infection in patients with cystic fibrosis

The optimal antibiotic regimen is unclear in management of pulmonary infections due to pseudomonas and staphylococcus in cystic fibrosis (CF). We systematically searched all the published literature that has considered the evidence for antimicrobial therapies in CF till June 2013. The key findings were as follows: inhaled antipseudomonal antibiotic improves lung function, and probably the safest/most effective therapy; antistaphylococcal antibiotic prophylaxis increases the risk of acquiring P. aeruginosa; azithromycin significantly improves respiratory function after 6 months of treatment; a 28-day treatment with aztreonam or tobramycin significantly improves respiratory symptoms and pulmonary function; aztreonam lysine might be superior to tobramycin inhaled solution in chronic P. aeruginosa infection; oral ciprofloxacin does not produce additional benefit in those with chronic persistent pseudomonas infection but may have a role in early or first infection. As it is difficult to establish a firm recommendation based on the available evidence, the following factors must be considered for the choice of treatment for each patient: antibiotic related (e.g., safety and efficacy and ease of administration/delivery) and patient related (e.g., age, clinical status, prior use of antibiotics, coinfection by other organisms, and associated comorbidities ones).

Bronchoscopy-guided antimicrobial therapy for cystic fibrosis

BACKGROUND

Early diagnosis and treatment of lower respiratory tract infections, particularly those with Pseudomonas aeruginosa, are the mainstay of management of lung disease in cystic fibrosis. When sputum samples are unavailable, treatment relies mainly on cultures from oropharyngeal specimens; however, there are concerns regarding the sensitivity of these to identify lower respiratory organisms.Bronchoscopy and related procedures (including bronchoalveolar lavage) though invasive, allow the collection of lower respiratory specimens from non-sputum producers. Cultures of bronchoscopic specimens provide a higher yield of organisms compared to those from oropharyngeal specimens. Regular use of bronchoscopy and related procedures may help in a more accurate diagnosis of lower respiratory tract infections and guide the selection of antimicrobials, which may lead to clinical benefits.

OBJECTIVES

To evaluate the use of bronchoscopy-guided antimicrobial therapy in the management of lung infection in adults and children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched two registries of ongoing studies and the reference lists of relevant articles and reviews.Date of latest search: 28 November 2013.

SELECTION CRITERIA

We included randomized controlled studies including patients of any age with cystic fibrosis, comparing outcomes following therapies guided by the results of bronchoscopy (including bronchoalveolar lavage or protected bronchial brush sampling) with outcomes following therapies guided by the results of any other type of sampling (including cultures from sputum, throat swab and cough swab).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed their risk of bias and extracted data. We contacted study investigators for further information.

MAIN RESULTS

The search identified nine studies, but only one study with data from 157 participants (170 patients were enrolled) was eligible for inclusion in the review. This study compared outcomes following therapy directed by bronchoalveolar lavage for pulmonary exacerbations during the first five years of life with standard treatment based on clinical features and oropharyngeal cultures. The study enrolled infants with CF who were under six months of age and diagnosed through newborn screening and followed them until they were five years old.We considered this study to have a low risk of bias; however, the statistical power to detect a significant difference in the prevalence of Pseudomonas aeruginosa was limited due to the prevalence (of Pseudomonas aeruginosa isolation in bronchoalveolar lavage samples at five years age) being much lower in both the groups compared to that which was expected and which was used for the power calculation. The sample size was adequate to detect a difference in high-resolution computed tomography scoring. The quality of evidence for the key parameters was graded as moderate except for high-resolution computed tomography scoring, which was graded as high.At five years of age, there was no clear benefit of bronchoalveolar lavage-directed therapy on lung function z scores or nutritional parameters. Evaluation of total and component high-resolution computed tomography scores showed no significant difference in evidence of structural lung disease in the two groups.In addition, this study did not show any difference between the number of isolates of Pseudomonas aeruginosa per child per year diagnosed in the bronchoalveolar lavage-directed therapy group compared to the standard therapy group. The eradication rate following one or two courses of eradication treatment was comparable in the two groups, as were the number of pulmonary exacerbations. However, the number of hospitalizations was significantly higher in the bronchoalveolar lavage-directed therapy group, but the mean duration of hospitalizations was significantly less compared to the standard therapy group.Mild adverse events were reported in a proportion of patients, but these were generally well-tolerated. The most common adverse event reported was transient worsening of cough after 29% of procedures. Significant clinical deterioration was documented during or within 24 hours of bronchoalveolar lavage in 4.8% of procedures.

AUTHORS' CONCLUSIONS

This review, which only includes a single study, shows that there is no clear evidence to support the routine use of bronchoalveolar lavage for the diagnosis and management of pulmonary infection in pre-school children with cystic fibrosis compared to the standard practice of providing treatment based on results of oropharyngeal culture and clinical symptoms. No evidence was available for adult and adolescent populations.

Proposal of a quantitative PCR-based protocol for an optimal Pseudomonas aeruginosa detection in patients with cystic fibrosis

Background

The lung of patients with cystic fibrosis (CF) is particularly sensitive to Pseudomonas aeruginosa. This bacterium plays an important role in the poor outcome of CF patients. During the disease progress, first acquisition of P. aeruginosa is the key-step in the management of CF patients. Quantitative PCR (qPCR) offers an opportunity to detect earlier the first acquisition of P. aeruginosa by CF patients. Given the lack of a validated protocol, our goal was to find an optimal molecular protocol for detection of P. aeruginosa in CF patients.

Methods

We compared two formerly described qPCR formats in early detection of P. aeruginosa in CF sputum samples: a qPCR targeting oprL gene, and a multiplex PCR targeting gyrB and ecfX genes.

Results

Tested in vitro on a large panel of P. aeruginosa isolates and others gram-negative bacilli, oprL qPCR exhibited a better sensitivity (threshold of 10 CFU/mL versus 730 CFU/mL), whereas the gyrB/ecfX qPCR exhibited a better specificity (90% versus 73%). These results were validated ex vivo on 46 CF sputum samples positive for P. aeruginosa in culture. Ex vivo assays revealed that qPCR detected 100 times more bacterial cells than culture-based method did.

Conclusion

Based on these results, we proposed a reference molecular protocol combining the two qPCRs, which offers a sensitivity of 100% with a threshold of 10 CFU/mL and a specificity of 100%. This combined qPCR-based protocol can be adapted and used for other future prospective studies.

SNaPaer: a practical single nucleotide polymorphism multiplex assay for genotyping of Pseudomonas aeruginosa

Multilocus sequence typing (MLST) represents the gold standard genotyping method in studies concerning microbial population structure, being particularly helpful in the detection of clonal relatedness. However, its applicability on large-scale genotyping is limited due to the high cost and time spent on the task. The selection of the most informative nucleotide positions simplifies genomic characterization of bacteria. A simple and informative multiplex, SNaPaer assay, was developed and genotyping of Pseudomonas aeruginosa was obtained after a single reaction of multiplex PCR amplification and mini-sequencing. This cost-effective technique allowed the analysis of a Portuguese set of isolates (n = 111) collected from three distinct hospitals and the genotyping data could be obtained in less than six hours. Point mutations were shown to be the most frequent event responsible for diversification of the Portuguese population sample. The Portuguese isolates corroborated the epidemic hypothesis for P. aeruginosa population. SNaPaer genotyping assay provided a discriminatory power of 0.9993 for P. aeruginosa, by testing in silico several hundreds of MLST profiles available online. The newly proposed assay targets less than 0.01% of the total MLST length and guarantees reproducibility, unambiguous analysis and the possibility of comparing and transferring data between different laboratories. The plasticity of the method still supports the addition of extra molecular markers targeting specific purposes/populations. SNaPaer can be of great value to clinical laboratories by facilitating routine genotyping of P. aeruginosa.

Comparison of real time diagnostic chemistries to detect Pseudomonas aeruginosa in respiratory samples from cystic fibrosis patients

BACKGROUND

Early eradication therapy is key to keeping the airways Pseudomonas aeruginosa infection-free and rapid identification is essential.

METHODS

We used rapid DNA extraction and qPCR assays to detect bacterial, P. aeruginosa and strain-specific targets in samples using two qPCR chemistries. Using 459 respiratory samples from adult and children CF patients, we compared two qPCR methods to culture-based methods in terms of sensitivity and time to result.

RESULTS

For adult samples, there was 100% concordance between methods. There was no clear pattern in fluctuations in P. aeruginosa number during exacerbation. In child samples, qPCR methods identified additional P. aeruginosa positive samples. The time-to-result was reduced by over 24h and copy number and colony forming unit could differ dramatically in some samples.

CONCLUSION

If adopted, these methods could significantly improve early P. aeruginosa detection in diagnostic laboratories and therefore play a pivotal role in prolonging infection-free airways in CF patients.

Evolution and impact of bacterial drug resistance in the context of cystic fibrosis disease and nosocomial settings

The use of antibiotics is unavoidable in trying to treat acute infections and in the prevention and control of chronic infections. Over the years, an ever increasing number of infections has escalated the use of antibiotics, which has necessitated action against an emerging bacterial resistance. There seems to be a continuous acquisition of new resistance mechanisms among bacteria that switch niches between human, animals, and the environment. An antibiotic resistant strain emerges when it acquires the DNA that confers the added capacity needed to survive in an unusual niche. Once acquired, a new resistance mechanism evolves according to the dynamics of the microenvironment; there is then a high probability that it is transferred to other species or to an avirulent strain of the same species. A well understood model for studying emerging antibiotic resistance and its impact is Pseudomonas aeruginosa, an opportunistic pathogen which is able to cause acute and chronic infections in nosocomial settings. This bacterium has a huge genetic repertoire consisting of genes that encode both innate and acquired antibiotic resistance traits. Besides acute infections, chronic colonization of P. aeruginosa in the lungs of cystic fibrosis (CF) patients plays a significant role in morbidity and mortality. Antibiotics used in the treatment of such infections has increased the longevity of patients over the last several decades. However, emerging multidrug resistant strains and the eventual increase in the dosage of antibiotic(s) is of major concern. Though there are various infections that are treated by single/combined antibiotics, the particular case of P. aeruginosa infection in CF patients serves as a reference for understanding the impact of overuse of antibiotics and emerging antibiotic resistant strains. This mini review presents the need for judicious use of antibiotics to treat various types of infections, protecting patients and the environment, as well as achieving a better treatment outcome.

Current dilemmas in antimicrobial therapy in cystic fibrosis

The majority of cystic fibrosis (CF)-related morbidity and mortality is caused by pulmonary damage due to recurrent and chronic infections. Considerable improvements in the survival of individuals with CF have been achieved in recent decades, some of which may be due to better management of common pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. While the search continues for the optimal approach for prophylaxis, eradication and maintenance treatment of infections, there are several unanswered questions, posing dilemmas related to various therapeutic choices. Microbes pose additional challenges by adapting to CF lungs and developing treatment resistance. Several new, highly antimicrobial-resistant pathogens have emerged. Their pathogenic role in the progression of CF lung disease is not yet clear and effective treatment approaches have not been defined. There is an urgent need for well-designed comparative clinical trials of new antibiotic strategies.

Targeting bacterial integration host factor to disrupt biofilms associated with cystic fibrosis

BACKGROUND

This study aims to identify whether the bacterial protein, Integration Host Factor (IHF), is present within sputum solids collected from cystic fibrosis (CF) patients and thus might contribute to the structural stability of biofilms within the lungs.

METHODS

The presence of IHF in sputum was determined by immunohistochemistry. The role of IHF in stabilizing biofilms within sputum was tested in vitro wherein anti-IHF was used to attempt to dissolve sputum solids.

RESULTS

Thirty-seven of 44 sputum samples (84%) were positive for anti-IHF staining. Treatment with anti-IHF or DNase of 6 representative samples, dissolved sputum solids significantly better than treatment with normal saline in vitro, and strong synergism was observed when these agents were used in combination.

CONCLUSIONS

IHF was detected in the majority of sputum samples from patients with CF and in vitro treatment with anti-IHF induced dissolution of sputum solids. These data support further investigation of IHF as a potential therapeutic target for patients with CF.

In vitro prevention of Pseudomonas aeruginosa early biofilm formation with antibiotics used in cystic fibrosis patients

The ability of antibiotics used in bronchopulmonary infections in cystic fibrosis (CF) patients to prevent Pseudomonas aeruginosa early biofilm formation was studied using a biofilm microtitre assay with 57 non-mucoid P. aeruginosa isolates (44 first colonisers and 13 recovered during the initial intermittent colonisation stage) obtained from 35 CF patients. Minimum biofilm inhibitory concentrations (BICs) of levofloxacin, ciprofloxacin, imipenem, ceftazidime, tobramycin, colistin and azithromycin were determined by placing a peg lid with a formed biofilm onto microplates containing antibiotics. A modification of this protocol consisting of antibiotic challenge during biofilm formation was implemented in order to determine the biofilm prevention concentration (BPC), i.e. the minimum concentration able to prevent biofilm formation. The lowest BPCs were for fluoroquinolones, tobramycin and colistin and the highest for ceftazidime and imipenem. The former antibiotics had BPCs identical to or only slightly higher than their minimum inhibitory concentrations (MICs) determined by standard Clinical and Laboratory Standards Institute (CLSI) microdilution and were also active on formed biofilms as reflected by their low BIC values. In contrast, ceftazidime and imipenem were less effective for prevention of biofilm formation and on formed biofilms. In conclusion, the new BPC parameter determined in non-mucoid P. aeruginosa isolates recovered during early colonisation stages in CF patients supports early aggressive antimicrobial treatment guidelines in first P. aeruginosa-colonised CF patients.

Challenges with current inhaled treatments for chronic Pseudomonas aeruginosa infection in patients with cystic fibrosis

BACKGROUND

Pseudomonas aeruginosa (Pa) is the predominant pathogen infecting the airways of patients with cystic fibrosis (CF). Initial colonization is usually transient and associated with non-mucoid strains, which can be eradicated if identified early. This strategy can prevent, or at least delay, chronic Pa infection, which eventually develops in the majority of patients by their late teens or early adulthood. This article discusses the management and latest treatment developments of Pa lung infection in patients with CF, with a focus on nebulized antibiotic therapy.

METHODS

PubMed was searched to identify English language articles published up until August 2011 using combinations of the following key words: 'antibiotics', 'chronic', 'cystic fibrosis', 'eradication', 'exacerbations', 'guidelines', 'inhaled', 'intravenous', 'lung infection', 'burden', 'adherence', 'patient segregation', 'pseudomonas aeruginosa' and 'resistance'.

FINDINGS

Antibiotics form a central part of the treatment regimens for chronic Pa lung infection. Current treatment guidelines recommend that patients with chronic pulmonary infection with Pa should receive long-term inhaled anti-pseudomonal therapy to preserve lung function, and to reduce the frequency of pulmonary exacerbations and hospital admissions. While antibiotic resistance seems to increase with frequent antibiotic use, this does not appear to impact on clinical outcome. Negative aspects of therapy include the time needed for drug administration and subsequent cleaning of the equipment. These factors cause a significant treatment burden and impact on adherence. The availability of more convenient formulations and delivery vehicles for anti-pseudomonal antibiotics may help overcome some of these challenges.

CONCLUSIONS

Current challenges in the management of CF patients with chronic Pa lung infection are numerous. The availability of novel anti-pseudomonal antibiotic formulations/devices is anticipated to improve treatment adherence in patients with CF, and could improve clinical outcomes. Thus, there is hope for improved survival in individuals with CF suffering from chronic pulmonary infection with Pa.