Defining chronic Pseudomonas aeruginosa infection in cystic fibrosis

By Valerie Waters and Keith Grimwood

Cystic fibrosis (CF) is a genetic, multi-system disease due to mutations in the cystic fibrosis conductance regulator (CFTR) gene, leading to ineffective anion channel activity [1]. The resulting impaired mucociliary clearance permits initial acquisition of Pseudomonas aeruginosa and, if untreated, the establishment of persistent infection in the CF airways. It has long been recognized that chronic infection, often characterized by a mucoid P. aeruginosa phenotype, is associated with more rapid lung function decline and earlier death in individuals with CF [[2], [3], [4]]. Defining chronic P. aeruginosa infection is, therefore, an important step in identifying CF patients most at risk of lung disease progression. Traditionally, the Leed’s criteria has been used to define chronicity (as having >50% of sputum cultures being P. aeruginosa positive in the preceding 12 months), as it is the only clinically validated definition [5]. However, the Leed’s criteria are difficult to implement in young children unable to provide sputum and further limited by the required number of sputum samples and follow-up time [6].

In this issue of the Journal, studies by Heltshe et al. and Boutin et al. aim to re-define what chronic P. aeruginosa infection means in CF. In a retrospective cohort study using data from the US CF Foundation Patient Registry, Heltshe et al. followed close to 6000 early-diagnosed CF children for approximately 6 years [7]. Two-thirds acquired P. aeruginosa infection and of those, 6% had an initial mucoid phenotype. Furthermore, the majority (87%) of children who developed mucoid infection did so before meeting the definition of chronic infection (at least 3 yearly quarters P. aeruginosa positive in the preceding year). Initial P. aeruginosa infection with a mucoid phenotype has been previously described and is a recognized risk factor for failure of antimicrobial eradication therapy [[8], [9], [10]]. Whether this initial acquisition of a mucoid phenotype represents prior adaptation of P. aeruginosa in the CF host (either undetected or transmitted from a patient with chronic infection) or simply infection with an environmental strain particularly well-suited to the CF airways, is as of yet unknown [11]. It is clear, though, that mucoid P. aeruginosa does have an adaptive advantage in early CF infection as mucoidy was associated with an almost three-fold increased risk of transition to chronic infection in this current study. Despite the presence of this risk factor, however, only 13% of P. aeruginosa infected patients went on to develop chronic infection. Although Heltshe et al. did not provide details as to eradication strategies used in this cohort, this low incidence of persistent infection does speak to the overall effectiveness of current antimicrobial treatment for early P. aeruginosa infection.

Boutin et al. took their investigation a step further by using molecular methods, specifically quantitative polymerase chain reaction (qPCR), to define chronic P. aeruginosa infection [12]. In their study, patients with chronic infection had significantly higher levels of P. aeruginosa as measured by qPCR compared to those with intermittent infection. A single P. aeruginosa qPCR measurement in sputum had a sensitivity of 84% (with a specificity of 85%) in detecting chronic infection using a threshold of 103.4 colony forming units (CFU)/ml. A single sputum PCR measure had the advantage of not requiring 12 months of culture results as per the Leed’s criteria [5]. Furthermore, in their small study sample size, PCR was more discriminatory than mucoidy status in predicting chronicity, not surprisingly, given that alginate production (conferring mucoidy) is only one of several virulence factors contributing to the establishment of persistent P. aeruginosa infection in CF [13]. When used in throat swab samples, qPCR had a considerably lower sensitivity (82%) and specificity (56%) in detecting chronic infection, likely due in part to the lower bacterial burden observed in this specimen, compared to sputum. The low specificity of PCR in this setting (positive PCR, negative culture) may reflect the fact that a molecular signal may precede culture positivity. Early detection of P. aeruginosa infection, before culture conversion, in CF patients was originally suggested decades ago using serologic and, more recently, molecular methods [[14], [15], [16]]. Serology, however, has proven disappointing at identifying early P. aeruginosa infection [17]. Nevertheless, early detection may still be possible using highly-sensitive PCR techniques for identifying lower airway P. aeruginosa infection in a young, non-expectorating child. In the study by Boutin et al., P. aeruginosa detection in throat swabs by PCR alone was linked to a positive culture in sputum in three-quarters of cases. Previous studies comparing oropharyngeal cultures to bronchoalveolar lavage (BAL) cultures in children with CF demonstrated that oropharyngeal cultures had a positive predictive value of only 44%, but a negative predictive value of 95% in diagnosing lower airway P. aeruginosa infection [18]. Performing P. aeruginosa qPCR on culture negative throat swabs may further improve the diagnosis of lower airway infection in young children with CF who are unable to produce sputum, but this approach will still need to be validated by comparative studies employing BAL fluid samples. Unfortunately, using confirmatory induced sputum samples as suggested by Boutin et al., may produce unreliable results as these specimens are poor predictors of lower airway pathogens cultured from BAL specimens in young children with CF [19]. Finally, it is yet to be determined whether an earlier diagnosis of P. aeruginosa infection leads to improved eradication success rates and superior clinical outcomes.

In summary, the recent studies by Heltshe et al. and Boutin et al. further our understanding of how chronic P. aeruginosa infection develops in CF and how to better recognize it [7,12]. Ultimately, prevention of chronic P. aeruginosa infection and its deleterious effects on lung function and survival is the goal.

Original article in Journal of Cystic Fibrosis here.

Potential Therapy for Infections in CF Gets Patent

AB569Arch Biopartners’ treatment candidate for bacterial infections in patients with cystic fibrosis, chronic obstructive pulmonary disease (COPD), and other respiratory conditions, has received a U.S. patent.

The U.S. Patent and Trademark Office issued patent 9,925,206 to the University of Cincinnati, which granted Arch Biopartners an exclusive commercial license on all patents related to AB569. The inventor is Daniel Hassett, PhD, a principal scientist at Arch and professor at the University of Cincinnati College Of Medicine.

“This patent issuance, which protects the composition of AB569, gives Arch a stronger commercial position to pursue treating not just CF patients, but also the millions of other patients that have chronic antibiotic resistant lung infections including those with COPD,” Richard Muruve, CEO of Arch, said in a press release. “It also opens the door for Arch to develop treatments for many other indications where antibiotic resistance is a problem, such as urinary tract infections and wound care.”

Bacterial infections in the lungs are a serious problem in patients with CF, COPD, or ventilator-associated pneumonia. Cystic fibrosis patients are susceptible to bacterial respiratory infections as a result of abnormal mucus production in the lungs and airways.

In particular, the bacterium Pseudomonas aeruginosa (P. aeruginosa) affects most adult CF patients and 40 percent of CF children ages 6 to 10. The mucoid form of P. aeruginosa is highly resistant to conventional antibiotics and immune-mediated killing. It causes a rapid decline in lung function and a poor overall clinical prognosis.

Antibiotic use in the treatment of CF and COPD patients with chronic bacterial respiratory infections is increasing, which correlates with a higher prevalence of antibiotic-resistant strains.

AB569 is a non-antibiotic therapy made of sodium nitrite and ethylenediaminetetraacetic acid (EDTA), two compounds approved by the U.S. Food and Drug Administration (FDA) for human use. The treatment has a different mechanism of action from antibiotics that may increase effectiveness, Arch believes.

“AB569 has two active ingredients that produce a dramatic and synergistic effect at killing many antibiotic resistant bacteria including Pseudomonas aeruginosa (P. aeruginosa), which commonly causes severe chronic infections in the lungs of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) patients,” Hassett said. “AB569 has the potential to make a significant medical impact on treating infection where traditional antibiotics fail.”

In preclinical experiments, the therapy showed significant ability to kill several types of Gram-negative and Gram-positive bacteria.

The safety and pharmacokinetics of a single administration of nebulized AB569 are now being evaluated in a Phase 1 clinical trial with up to 25 healthy volunteers at the Cincinnati Veterans Affairs Medical Center (CVAMC). Pharmacokinetics refers to how a drug is absorbed, distributed, metabolized, and expelled by the body. Enrollment of volunteers started in February.

If the Phase 1 study provides positive results, the company plans to start a Phase 2 trial to test the effectiveness of AB569 in the treatment of chronic lung infections caused by P. aeruginosa and other bacterial pathogens in CF and/or COPD patients.

AB569 previously received orphan drug status from the FDA for the treatment of CF patients infected with P. aeruginosa, and orphan medicinal product designation from the European Medicines Agency.

For original article, click here.

Study Links CF Patients’ Airway Bacteria with Disease Outcomes

By: Diogo Pinto

Researchers have linked variations in the mix of microorganisms in cystic fibrosis patients’ airways to their disease outcomes.

The findings in the journal PLOS One were in an article titled “Fluctuations in airway bacterial communities associated with clinical states and disease stages in cystic fibrosis.

CF patients typically have particular strains of bacterial and fungus in their airways. The usual bacteria suspects include PseudomonasAchromobacterBurkholderiaHaemophilusStaphylococcus, and Stenotrophomonas.

Other bacteria and fungi also inhabit CF patients’ airways, however. These include anaerobic species that do not need oxygen to grow and spread.

Not only do the microbial communities in CF patients’ airways vary by type of microorganism, but also in the relative abundance of each species.

Researchers decide to see if the prevalence and relative abundance of typical CF pathogens and anaerobic microorganisms play a role in the severity of patients’ disease and their lung function.

They analyzed 631 sputum samples collected over 10 years from 111 patients.

The team classified the stage of patients’ disease on the basis of their lung function scores. The yardstick they used was forced expiratory volume in one second, or FEV1. They considered an early stage of the disease to be an FEV1 score higher than 70, an intermediate stage a score of 40 to 70, and an advanced stage a score lower than 40.

Researchers classified disease aggressiveness — mild, moderate or severe — on the basis of change in FEV1 relative to age.

They discovered a link between variations in the prevalance of the six typical CF pathogens, plus nine anaerobic species, and changes in a patient’s disease stage and lung function.

To continue reading, click here. 

Antibiotic resistance evolution of Pseudomonas aeruginosain cystic fibrosis patients

By Francesca Lucca, Margherita Guarnieri, Mirco Ros, Giovanni Muffato, Roberto Rigoli, and Liviana Da Dalt

Below is a study hoping to define and answer the questions of Pseudomonas aeruginosain, its evolution and the resistance from different antibiotics. The study took place between 2010-2013. Though the study may have some time clauses I believe there are some strong findings for the CF community moving forward.
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Introduction

Pseudomonas aeruginosa is the predominant pathogen responsible of chronic colonization of the airways in cystic fibrosis (CF) patients. There are few European data about antibiotic susceptibility evolution of P aeruginosa in CF patients.

Objectives

The aim of this study is to evaluate the evolution of antibiotic resistance in the period 2010‐2013 in CF patients chronically colonized by P aeruginosa and to highlight the characteristics of this evolution in patients younger than 20 years.

Methods

Clinical and microbiological data were extracted from two electronic databases and analyzed. Antibiotic resistance was defined according to European Committee of Antimicrobial Susceptibility Testing for levofloxacin, ciprofloxacin, meropenem, amikacin and ceftazidime. The between‐group comparison was drawn with the Chi‐square test for proportions, with the T‐test for unpaired samples for normally distributed data and with Mann‐Whitney test for non‐normally distributed data. Significancy was defined by P < .05.

Results

Fifty‐seven CF patients, including thirteen subjects aged less than 20 years, were enrolled. P.. aeruginosa antibiotic sensitivity decreased significantly for fluoroquinolones, mainly in patients aged <20 years, while it increased for amikacin and colistin. The analysis of minimum inhibitory concentration confirmed these trends. In pediatric patients treated with more than three antibiotic cycles per year, greater resistance was found, except for amikacin and colistin.

Conclusion

An evolution in P aeruginosa antibiotic resistances is observed in the 4‐year period studied. Responsible and informed use of antibiotics is mandatory in CF.
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Read the whole clinical journal here. 

Antibiotic resistance evolution of Pseudomonas aeruginosa in cystic fibrosis patients (2010‐2013) Francesca Lucca,Margherita Guarnieri,Mirco Ros,Giovanna Muffato,Roberto Rigoli,Liviana Da Dalt. First published: 1 April 2018. https://doi.org/10.1111/crj.12787

How One Conversation Led Me to Being More Intentional About My Life

By: Ella Balasa

Would I ever live long enough to fall in love? Would I be able to graduate college? Would I be remembered for making some kind of impact on the world before I was gone? Would I get to travel to destinations where the breaking waves crashed against a rocky shore and the sea mist sprayed as I breathed deeply, and beside me stood …

Gabriella-Balasa-Beach-Featured-Rectangle

I’m startled back to reality. I sit in a hospital bed, surrounded by my parents in chairs on either side of me. I’m on the lumpy foam mattress, where I sit cross legged and my butt sinks at least 4 inches straining my back and adding to the pain the past few weeks — and this conversation — have caused me. My dad sits, lips pursed as normal when he listens intently. We are all listening to my doctor talk about my declining health, about my recent episode of pneumonia, and what my future may hold.

“No one knows the future,” I think, as the doctor speaks. My mind jumps again to that ocean scene, only it isn’t me standing on the shore, I’m now observing the scene from above, as if in spirit. Observing a couple embrace and I feel a strange sense of sadness, anger, and jealousy.

“It’s time to consider a lung transplant.” Those words, uttered from my pediatric CF doctor 6 years ago, made me, in an instant, think about all the joys of life I hadn’t gotten to experience yet.

Why me? That’s the first thought many people have when they can’t accept the reality of what’s happening. We try to answer unanswerable questions.

Later that summer, my parents and I followed doctors’ advice and scheduled a week-long transplant evaluation. A week of what I still consider to be grueling medical tests, even compared to other lung complications I have developed since. In the end, the transplant evaluators concluded I was not quite in the transplant window at the time. That fall, my health started to stabilize. I started my second year of college and I felt myself withdraw from the world.

To continue reading, visit CFF community blog.

Potential Nitric Oxide Treatment for Resistant Bacterial Infections Gets Patent

A possible inhalable treatment for antibiotic-resistant bacterial infections in people with cystic fibrosis due to Pseudomonas aeruginosa now has a U.S. patent and is being readied for a first clinical trial, Novoclem Therapeutics announced.

The patent (No. 9,850,322) was issued to the University of North Carolina (UNC) at Chapel Hill where the potential therapy, BIOC51, was discovered, and covers a technology known as water-soluble polyglucosamine compositions that release nitric oxideContinue reading Potential Nitric Oxide Treatment for Resistant Bacterial Infections Gets Patent

Supercharged antibiotics could turn tide against superbugs

An old drug supercharged by University of Queensland researchers has emerged as a new antibiotic that could destroy some of the world’s most dangerous superbugs.

The supercharge technique , led by Dr Mark Blaskovich and Professor Matt Cooper from UQ’s Institute for Molecular Bioscience (IMB), potentially could revitalise other antibiotics. Continue reading Supercharged antibiotics could turn tide against superbugs

A Breath of Fresh Air for Biotechs Working on Cystic Fibrosis Therapies

Researchers from the University of Zurich have determined the structure of a chloride channel, which could be a target for new drugs to treat cystic fibrosis.

Researchers at the University of Zurich have found a new target for future cystic fibrosis treatments. The study, published in Nature, has uncovered the structure of a protein that could help to correct the mechanism underlying the buildup of sticky mucus in patients’ lungs. This could give rise to a new wave of therapeutics for the condition, which at the moment lacks disease-modifying treatments.

Cystic fibrosis is a severe genetic disease affecting the lungs, for which there is currently no cure. It is caused by a malfunctioning chloride channel, CFTR, which prevents the secretion of chloride by cells, leading to the production of thick, sticky mucus in the lung. The condition affects around 70,000 people worldwide, who suffer from chronic infections and require daily physiotherapy.

However, one potential approach to treat cystic fibrosis is to activate the calcium-activated chloride channel, TMEM16A, as an alternative route for chloride efflux. As TMEM16A is located within the same epithelium as CFTR, its activation could rehydrate the mucus layer. The research group used cryo-electron microscopy to decipher the structure of TMEM16A, which is part of a protein family that facilitates the flow of negatively charged ions or lipids across the cell membrane.

The changes that occur in the lungs of cystic fibrosis patients.

TMEM16A is found in many of our organs, playing a key role in muscle contraction and pain perception, as well as in the lungs. It forms an hourglass-shaped protein-enclosed channel, which when bound by positively charged calcium ions, opens to let chloride ions to pass through the membrane.

Current treatments for cystic fibrosis include bronchodilators, mucus thinners, antibiotics, and physiotherapy, which only control symptoms. However, biotechs around Europe are beginning to make progress, with ProQR completing a Phase Ib trial and Galapagos and Abbvie’s triple combination therapy entering Phase I. Antabio has also received €7.6M from CARB-X to develop a new antibiotic against Pseudomonas infections.

The identification of a new target provides patients and biotechs alike with renewed hope of new and effective cystic fibrosis treatments, or even a cure. It will be interesting to see whether small molecules or gene therapy specialists could take advantage of this information.

Original article: https://labiotech.eu/cystic-fibrosis-treatment-target/

A Brief Historical Timeline of CF Research to Date

Cystic fibrosis care has seen such rapid advances that the average CF patient has experienced a dramatic evolution in treatment strategies in their lifetime. Here are some of the biggest milestones that shaped modern-day CF treatments.

Continue reading A Brief Historical Timeline of CF Research to Date

Home Spirometers: A Useful Tool in Tracking CF Symptoms and Progress

Guest Blog By: Meranda Honaker

Over the last several months my health has continued to decline despite being compliant and diligent with my healthcare routine. In July I developed a fever during a trip to Boston to speak to a biotech company about my journey with cystic fibrosis. I developed a fever and by the end of my visit, I was unable to walk up steps without severe dyspnea. I was so exhausted from feeling sick I would return to my hotel room to lay in the bed for hours to rest. My chest pain and shortness of breath became so severe in the coming days that I could no longer take a deep breath. I checked my SpiroPd home spirometer which displayed a definite decline in my lung function. I immediately contacted my CF clinic to see my CF doctor. Initially, despite feeling bad, I assumed I was feeling poorly and decided not to rush to CF clinic. Sometimes I have a bad day or few bad days health wise and begin to improve on my own. Once I saw my lung function had declined I knew I needed to be seen in CF clinic rather than waiting it out.
Continue reading Home Spirometers: A Useful Tool in Tracking CF Symptoms and Progress