Typing of Pseudomonas aeruginosa strains in Norwegian cystic fibrosis patients

Pseudomonas aeruginosa: An Audacious Pathogen with an Adaptable Arsenal of Virulence Factors

Pseudomonas aeruginosa is a dominant pathogen in people with cystic fibrosis (CF) contributing to morbidity and mortality. Its tremendous ability to adapt greatly facilitates its capacity to cause chronic infections. The adaptability and flexibility of the pathogen are afforded by the extensive number of virulence factors it has at its disposal, providing P. aeruginosa with the facility to tailor its response against the different stressors in the environment. A deep understanding of these virulence mechanisms is crucial for the design of therapeutic strategies and vaccines against this multi-resistant pathogen. Therefore, this review describes the main virulence factors of P. aeruginosa and the adaptations it undergoes to persist in hostile environments such as the CF respiratory tract. The very large P. aeruginosa genome (5 to 7 MB) contributes considerably to its adaptive capacity; consequently, genomic studies have provided significant insights into elucidating P. aeruginosa evolution and its interactions with the host throughout the course of infection.

Clinical outcomes for cystic fibrosis patients with Pseudomonas aeruginosa cross-infections

INTRODUCTION

Pseudomonas aeruginosa cross-infections are related to increased morbidity and mortality in cystic fibrosis (CF).

OBJECTIVES

The aim of the study was to evaluate the incidence of cross-infections with P. aeruginosa in children with CF.

METHODOLOGY

CF patients from whom at least one P. aeruginosa strain had been isolated were included in the study. The strain genotyping was performed using pulse-field gel electrophoresis. The history of contacts between patients was established based on questionnaires.

RESULTS

The study group consisted of 75 patients (aged 1.0-19.2 years) and the material included 170 P. aeruginosa strains. Cross-infections occurred in a group of 26 patients. In this group, the risk of the predicted occurrence of forced expiratory volume in 1 second ≤ 70% was five times greater and the risk of longer cumulative hospitalization time for intravenous antibiotic therapy (>14 days/year) was almost five times greater. In the clonal groups of strains, the multidrug-resistance rate was significantly higher than in other groups. In 2011, all tested strains were susceptible to colistin, whereas in 2012, three strains from the largest clonal group showed high levels of resistance to colistin.

CONCLUSION

Cross-infections with P. aeruginosa occurred in our group of patients and were associated with poor clinical outcomes. Antimicrobial resistance rate in the strains isolated from such infections was significantly higher, and this included three strains resistant to colistin.

Genotypic characterization of Pseudomonas aeruginosa isolates from Turkish children with cystic fibrosis

Objective: To identify epidemic and other transmissible Pseudomonas aeruginosa strains, genotypic analyses are required. The aim of this study was to assess the distribution of P. aeruginosa strains within the Turkish pediatric cystic fibrosis (CF) clinic population.

Methods: Eighteen patients attending the pediatric CF clinic of Cerrahpasa Medical Faculty were investigated in the study. Throat swab and/or sputum samples were taken from each patient at 3-month intervals. The isolates of patients were analyzed by pulsed-field gel electrophoresis (PFGE). The intra- and interpatient genotypic heterogeneity of isolates was examined to determine the clonal isolates of P. aeruginosa within the cohort.

Results: A total of 108 clinical isolates of P. aeruginosa were obtained from 18 patients between May 2013 and May 2014. The pulsotypes of the first patient’s isolates could not be obtained by PFGE. From the remaining 17 patients and 101 isolates, 55 distinct pulsotypes were detected. The number of pulsotypes observed in more than one patient (minor clonal strains, cluster strains) was 8 (14.5%), and one of them colonized three patients. However, none of them was detected in more than three patients. These pulsotypes were composed of 20 isolates. In addition, with the PFGE analysis of 81 isolates, we detected 47 (85.6%) pulsotypes, which belonged to only one patient. Over different periods of this study, only 2 (11.8%) patients were colonized with the same pulsotype.

Conclusion: Our study indicates that there was considerable genomic diversity among the P. aeruginosa isolates in our clinic. The presence of shared pulsotypes supports cross-transmission between patients.

Epidemiology, Biology, and Impact of Clonal Pseudomonas aeruginosa Infections in Cystic Fibrosis

Chronic lower airway infection with Pseudomonas aeruginosa is a major contributor to morbidity and mortality in individuals suffering from the genetic disease cystic fibrosis (CF). Whereas it was long presumed that each patient independently acquired unique strains of P. aeruginosa present in their living environment, multiple studies have since demonstrated that shared strains of P. aeruginosa exist among individuals with CF. Many of these shared strains, often referred to as clonal or epidemic strains, can be transmitted from one CF individual to another, potentially reaching epidemic status. Numerous epidemic P. aeruginosa strains have been described from different parts of the world and are often associated with an antibiotic-resistant phenotype. Importantly, infection with these strains often portends a worse prognosis than for infection with nonclonal strains, including an increased pulmonary exacerbation rate, exaggerated lung function decline, and progression to end-stage lung disease. This review describes the global epidemiology of clonal P. aeruginosa strains in CF and summarizes the current literature regarding the underlying biology and clinical impact of globally important CF clones. Mechanisms associated with patient-to-patient transmission are discussed, and best-evidence practices to prevent infections are highlighted. Preventing new infections with epidemic P. aeruginosa strains is of paramount importance in mitigating CF disease progression.

Genotypic and phenotypic relatedness of Pseudomonas aeruginosa isolates among the major cystic fibrosis patient cohort in Italy

Background

Pseudomonas aeruginosa is the predominant pathogen associated with the decline of pulmonary function in cystic fibrosis (CF) patients. Both environment-to-host acquisition and patient-to-patient transmission have been described for P. aeruginosa infection. Epidemic clones and bacterial phenotypic adaptation to the CF lung have been recognised as independent risk factors for disease progression. So far, there is no established link between genotypic prevalence and phenotypic traits. Here, we look at the major CF patient cohort in Italy to identify shared P. aeruginosa clones and associated common phenotypic traits.

Results

A comprehensive analysis of P. aeruginosa genotypes to determine the presence of high-risk shared clones and their association to specific phenotypic traits has been performed in a major Italian CF centre. Pulsed-field gel electrophoresis (PFGE) of P. aeruginosa isolates from 338 CF subjects identified 43 profiles shared by two or more patients and 214 profiles exclusive to individual patients. There was no evidence of a P. aeruginosa outbreak, but four most prevalent pulsotypes were detected. Common phenotypic traits were recorded intra-pulsotypes, but we detected heterogeneity inter-pulsotypes. Two of the four major pulsotypes included P. aeruginosa isolates with hallmarks of adaptation to the CF airways, including loss of motility, low production of siderophore, pyocyanin and proteases, and antibiotic resistance. One of these pulsotypes grouped a high percentage of hypermutable isolates. No clear correlation between epidemiological and clinical data was found.

Conclusions

We conclude that CF patients of this cohort shared common pulsotypes, but their phenotypic heterogeneity indicates an absence of specific traits associated to P. aeruginosa genotypic prevalence.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0760-1) contains supplementary material, which is available to authorized users.

The increasing threat of Pseudomonas aeruginosa high-risk clones

The increasing prevalence of chronic and hospital-acquired infections produced by multidrug-resistant (MDR) or extensively drug-resistant (XDR) Pseudomonas aeruginosa strains is associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of this pathogen for developing resistance through chromosomal mutations and from the increasing prevalence of transferable resistance determinants, particularly those encoding carbapenemases or extended-spectrum β-lactamases (ESBLs). P. aeruginosa has a nonclonal epidemic population structure, composed of a limited number of widespread clones which are selected from a background of a large quantity of rare and unrelated genotypes that are recombining at high frequency. Indeed, recent concerning reports have provided evidence of the existence of MDR/XDR global clones, denominated high-risk clones, disseminated in hospitals worldwide; ST235, ST111, and ST175 are likely those more widespread. Noteworthy, the vast majority of infections by MDR, and specially XDR, strains are produced by these and few other clones worldwide. Moreover, the association of high-risk clones, particularly ST235, with transferable resistance is overwhelming; nearly 100 different horizontally-acquired resistance elements and up to 39 different acquired β-lactamases have been reported so far among ST235 isolates. Likewise, MDR internationally-disseminated epidemic strains, such as the Liverpool Epidemic Strain (LES, ST146), have been noted as well among cystic fibrosis patients. Here we review the population structure, epidemiology, antimicrobial resistance mechanisms and virulence of the P. aeruginosa high-risk clones. The phenotypic and genetic factors potentially driving the success of high-risk clones, the aspects related to their detection in the clinical microbiology laboratory and the implications for infection control and public health are also discussed.

The problems of antibiotic resistance in cystic fibrosis and solutions

Chronic respiratory infection is the main cause of morbidity and mortality in cystic fibrosis (CF) patients. One of the hallmarks of these infections, led by the opportunistic pathogen Pseudomonas aeruginosa, is their long-term (lifelong) persistence despite intensive antimicrobial therapy. Antimicrobial resistance in CF is indeed a multifactorial problem, which includes physiological changes, represented by the transition from the planktonic to the biofilm mode of growth and the acquisition of multiple (antibiotic resistance) adaptive mutations catalyzed by frequent mutator phenotypes. Emerging multidrug-resistant CF pathogens, transmissible epidemic strains and transferable genetic elements (such as those encoding class B carbapenemases) also significantly contribute to this concerning scenario. Strategies directed to combat biofilm growth, prevent the emergence of mutational resistance, promote the development of novel antimicrobial agents against multidrug-resistant strains and implement strict infection control measures are thus needed.

Increasing resistance of the Liverpool Epidemic Strain (LES) of Pseudomonas aeruginosa (Psa) to antibiotics in cystic fibrosis (CF)--a cause for concern?

BACKGROUND

Transmissible Pseudomonas aeruginosa (Psa) strains such as the Liverpool Epidemic Strain (LES) are now widespread throughout UK CF clinics: their susceptibility to antibiotics is therefore important. To study this, we compared antibiogram patterns of Psa strains in our CF clinic over 5 years, looking at differences in resistance patterns between strains and changes to these over time.

METHODS

The antibiograms of sputum samples between 2004 and 2008 from patients attending our centre were included. We compared Psa isolate antibiotic resistance (to six anti-pseudomonal antibiotics) patterns for patients infected with LES with those infected with other Psa strains, both in the total population in 2004 (125 patients) and 2008 (166 patients) and also longitudinally from annual review samples 2004 to 2008 in matched and unmatched patient groups.

RESULTS

LES exhibited significantly more resistant isolates in 2004 (p<0.0001). There was an increase in antibiotic resistance in both LES and other Psa strains over time (p<0.001). Cox proportional hazards analysis of both unmatched (n=125) and matched (n=56) patients in 2004 revealed that LES infected patients were more likely to develop antibiotic resistant isolates over time (hazard ratio 8.1, p<0.001). Fewer LES isolates were classed as fully sensitive in both matched and unmatched groups at the end of study period (p<0.001).

CONCLUSION

This study shows a worrying trend in antibiotic resistance in the Psa isolates amongst patients chronically infected with LES. This highlights the need to prevent cross infection through segregation and also the need to develop new strategies to treat these organisms.

Methods to classify bacterial pathogens in cystic fibrosis

Many bacteria can be detected in CF sputum, pathogenic and commensal. Modified Koch's criteria for identification of established and emerging CF pathogens are therefore described. Methods are described to isolate bacteria and to detect bacterial biofilms in sputum or lung tissue from CF patients by means of conventional culturing and staining techniques and by the PNA FISH technique. Additionally, the confocal scanning laser microscopy technique is described for studying biofilms in vitro in a flow cell system. The recA-gene PCR and the RFLP-based identification methods are described for identification of isolates from the Burkholderia complex to the species level. DNA typing by PFGE, which can be used for any bacterial pathogen, is described as it is employed for Pseudomonas aeruginosa. A commercially available ELISA method is described for measuring IgG antibodies against P. aeruginosa in CF patients.

Travelling with cystic fibrosis: recommendations for patients and care team members

There are no European Guidelines on issues specifically related to travel for people with cystic fibrosis (CF). The contributors to these recommendations included 30 members of the ECORN-CF project. The document is endorsed by the European Cystic Fibrosis Society and sponsored by the Executive Agency of Health and Consumers of the European Union and the Christiane Herzog Foundation. The main goal of this paper is to provide patient-oriented advice that complements medical aspects by offering practical suggestions for all aspects involved in planning and taking a trip. The report consists of three main sections, preparation for travel, important considerations during travel and at the destination, and issues specific to immunocompromised travellers. People with CF should be encouraged to consult with their CF centre prior to travel to another country. The CF centre can advise on the necessary preparation for travel, the need for vaccinations, essential medications that should be brought on the trip and also provide information relating to CF care in the region and plan of action in case of an emergency.

Challenging and emerging pathogens in cystic fibrosis

Cystic fibrosis (CF) lung disease is characterised by chronic inflammation and infection. Patients are predominantly infected by specific pathogens, of which Staphylococcus aureus and Pseudomonas aeruginosa are the most important. In recent years however there has been an increasing number of reports on potentially emerging and challenging pathogens like Stenotrophomonas maltophilia, Non-tuberculous mycobacteria, highly prevalent P. aeruginosa clones, methicillin resistant Staphylococcus aureus and Burkholderia cepacia. Also, a role for viral infections in the pathogenesis of CF lung disease has increasingly been recognised. It is not always clear whether or how these pathogens influence the progression of CF lung disease and how they should be treated. In this review, the epidemiology and clinical impact of these pathogens is discussed. Furthermore, treatment strategies of these pathogens in a CF setting are reviewed.

A diagnostic PCR assay for the detection of an Australian epidemic strain of Pseudomonas aeruginosa

Background

Chronic lung infection with the bacterium Pseudomonas aeruginosa is one of the hallmarks of cystic fibrosis (CF) and is associated with worsening lung function, increased hospitalisation and reduced life expectancy. A virulent clonal strain of P. aeruginosa (Australian epidemic strain I; AES-I) has been found to be widespread in CF patients in eastern Australia.

Methods

Suppression subtractive hybridization (SSH) was employed to identify genetic sequences that are present in the AES-I strain but absent from the sequenced reference strain PAO1. We used PCR to evaluate the distribution of several of the AES-I loci amongst a collection of 188 P. aeruginosa isolates which was comprised of 35 AES-I isolates (as determined by PFGE), 78 non-AES-I CF isolates including other epidemic CF strains as well as 69 P. aeruginosa isolates from other clinical and environmental sources.

Results

We have identified a unique AES-I genetic locus that is present in all 35 AES-I isolates tested and not present in any of the other 153 P. aeruginosa strains examined. We have used this unique AES-I locus to develop a diagnostic PCR and a real-time PCR assay to detect the presence of P. aeruginosa and AES-I in patient sputum samples.

Conclusions

We have developed diagnostic PCR assays that are 100% sensitive and 100% specific for the P. aeruginosa strain AES-I. We have also shown that Whatman FTA^® Elute cards may be used with PCR-based assays to rapidly detect the presence of P. aeruginosa strains in CF sputum.

Effects of a short-term rehabilitation program on airway inflammation in children with cystic fibrosis

BACKGROUND

Respiratory therapy in cystic fibrosis (CF) consists of airway clearance, infection control, and reduction of airway inflammation. It is well recognized that physical activity as well as daily chest physiotherapy, enhance airway clearance. We investigated the effects of pulmonary rehabilitation, including physical activity and chest physiotherapy, on airway inflammation in children with CF.

METHODS

Eighteen children with stable CF (six females), aged 8.2-16.2 years, participating in a 3-week multidisciplinary inpatient rehabilitation program were recruited. Assessment at the beginning and the end of the program included clinical score, pulmonary function test, exhaled breath condensate (EBC) and sputum analysis. Sputum supernatant and EBC were analyzed for interleukin (IL)-1b, 6, 8, 10, 12, tumor necrosis factor-alpha (TNF-alpha) and LTB4.

RESULTS

Median (IQR) symptom scores decreased from 19 [23] to 16 [21], P = 0.005. Vital capacity and FVC increased significantly (P < 0.05). However no difference was found for the total sputum cells and sputum as well as EBC cytokines between the two visits. Significant correlations were found for sputum IL-1 (+), IL-6 (-), and IL-8 (+) to total sputum cell count and neutrophils and for IL-8 to TNF-alpha.

CONCLUSIONS

We have shown that a short-term inpatient rehabilitation for children with stable CF with intensive physical activity mainly improve subjective clinical symptoms and measures of lung function such as VC and FVC but does not influence airflow obstruction and airway inflammation as assessed by sputum and EBC analysis.

Pseudomonas aeruginosa population structure revisited

At present there are strong indications that Pseudomonas aeruginosa exhibits an epidemic population structure; clinical isolates are indistinguishable from environmental isolates, and they do not exhibit a specific (disease) habitat selection. However, some important issues, such as the worldwide emergence of highly transmissible P. aeruginosa clones among cystic fibrosis (CF) patients and the spread and persistence of multidrug resistant (MDR) strains in hospital wards with high antibiotic pressure, remain contentious. To further investigate the population structure of P. aeruginosa, eight parameters were analyzed and combined for 328 unrelated isolates, collected over the last 125 years from 69 localities in 30 countries on five continents, from diverse clinical (human and animal) and environmental habitats. The analysed parameters were: i) O serotype, ii) Fluorescent Amplified-Fragment Length Polymorphism (FALFP) pattern, nucleotide sequences of outer membrane protein genes, iii) oprI, iv) oprL, v) oprD, vi) pyoverdine receptor gene profile (fpvA type and fpvB prevalence), and prevalence of vii) exoenzyme genes exoS and exoU and viii) group I pilin glycosyltransferase gene tfpO. These traits were combined and analysed using biological data analysis software and visualized in the form of a minimum spanning tree (MST). We revealed a network of relationships between all analyzed parameters and non-congruence between experiments. At the same time we observed several conserved clones, characterized by an almost identical data set. These observations confirm the nonclonal epidemic population structure of P. aeruginosa, a superficially clonal structure with frequent recombinations, in which occasionally highly successful epidemic clones arise. One of these clones is the renown and widespread MDR serotype O12 clone. On the other hand, we found no evidence for a widespread CF transmissible clone. All but one of the 43 analysed CF strains belonged to a ubiquitous P. aeruginosa "core lineage" and typically exhibited the exoS(+)/exoU(-) genotype and group B oprL and oprD alleles. This is to our knowledge the first report of an MST analysis conducted on a polyphasic data set.

Pseudomonas aeruginosa genotype prevalence in Dutch cystic fibrosis patients and age dependency of colonization by various P. aeruginosa sequence types

The patient-to-patient transmission of highly prevalent Pseudomonas aeruginosa clones which are associated with enhanced disease progression has led to strict segregation policies for cystic fibrosis (CF) patients in many countries. However, little is known about the population structure of P. aeruginosa among CF patients. The aim of the present cross-sectional study was to determine the prevalence and genetic relatedness of P. aeruginosa isolates from CF patients who visited two major CF centers in The Netherlands in 2007 and 2008. These patients represented 45% of the Dutch CF population. P. aeruginosa carriage in the respiratory tract was determined by standard microbiological culture techniques, and all phenotypically different isolates in the first specimens recovered in 2007 and 2008 were genotyped by multilocus sequence typing. A total of 313 (57%) of 551 patients whose samples were cultured carried P. aeruginosa. Two sequence types (STs), ST406 and ST497, were found in 15% and 5% of the patients, respectively, and 60% of the patients harbored a strain that was also found in at least two other patients. The risk ratios for carrying ST406 and ST497 were 17.8 (95% confidence interval [CI], 7.2 to 43.6) for those aged between 15 and 24 years and 6 (95% CI, 1.4 to 26.1) for those aged >25 years. ST406 and ST497 were not genetically linked to previously described epidemic clones, which were also not found in this CF population. The population structure of P. aeruginosa in Dutch CF patients is characterized by the presence of two prevalent STs that are associated with certain age groups and that are not genetically linked to previously described epidemic clones.

Infection control in cystic fibrosis: cohorting, cross-contamination, and the respiratory therapist

Cystic fibrosis (CF) is a complex genetic disease characterized by lung infections that lead to early morbidity and death. Pathogens that commonly infect the lungs of patients with CF include Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, and Burkholderia cepacia. Aggressively treating pulmonary infection with antibiotics has contributed to improved survival in patients with CF but has also promoted multiple-drug-resistant bacteria. Other complexities include the ability of bacteria to form biofilms, which makes them more resistant to antibiotics, and emerging pathogens in CF, of which the clinical importance is not yet clear. Increasing evidence of patient-to-patient transmission of CF pathogens led the Cystic Fibrosis Foundation to produce evidence-based infection-control recommendations, which stress 4 principles: standard precautions, transmission-based precautions, hand hygiene, and care of respiratory equipment. Respiratory therapists need to know and follow these infection-control recommendations. Cohorting patients infected with B. cepacia complex is one of several interventions successful at keeping the spread of this pathogen low, but cohorting patients who are infected/colonized with other microbes is controversial, the main argument of which is not being certain of a patient's present respiratory culture status at any given patient visit.

Differences in prevalence and treatment of Pseudomonas aeruginosa in cystic fibrosis centres in Denmark, Norway and Sweden

BACKGROUND

Chronic Pseudomonas aeruginosa (PA) infection causes increased morbidity and mortality in cystic fibrosis (CF). This study aimed to answer the following questions: Does the prevalence of chronic infection with PA differ between the CF centres in Scandinavia? Which differences exist concerning segregation and treatment of PA?

METHODS

989 patients (86%) from all eight CF-centres in Scandinavia were included. Demographic and clinical data, including PA colonisation status based on cultures and serology, were recorded at inclusion. The patients were followed prospectively for 1 year, recording number of days with anti-PA antibiotic treatment.

RESULTS

In all pancreatic insufficient (PI) patients (n=890) the prevalence of chronic PA infection at each centre ranged from 25.8% to 48.9%, but were not significantly different. In PI patients <19 years the prevalence was 14.5% in Copenhagen compared to 30.9% in the Swedish centres pooled (p=0.001). In intermittently colonised PI patients <19 years the median number of days per year on anti-PA antibiotics was almost 6 times higher in Copenhagen (mean 86 (110), median 61 days) compared to the Swedish centres pooled (mean 27 (52), median 11 days) (p=0.037). The pulmonary function was similar.

CONCLUSIONS

It is possible to maintain a very low prevalence of chronic PA infection in CF patients <19 years. We speculate that this was most likely due to a very intensive treatment of intermittently colonised patients with inhaled anti-PA antibiotics over prolonged periods of time in some centres. Since lung function was similar in centres with less intensive use of inhaled antibiotics, studies comparing different treatment modalities and other parts of CF care are needed to define the best clinical practice, including how to use antibiotics in the most rational way.

Compliance in cystic fibrosis: an examination of infection control guidelines

The goal of this research was to begin the process of evaluating acceptability of infection control (IC) recommendations to CF patients and their families, determine whether compliance with IC guidelines differs from compliance with traditional CF medical treatment with respect to the variables predictive of compliance, and assess which patients are most likely to comply with IC recommendations. Participants were recruited during routine outpatient visits at a regional CF center located in a pediatric hospital. The sample included 44 child and adolescent patients, aged 9-18 years and their guardian, and 27 adult patients. All patients completed questionnaires and interviews. Results of this preliminary study suggest that many individuals with CF are unaware of or unconcerned with the risks involved in infection transmission via social contact with other CF patients. Further, most participants reported that they could benefit from friendships with other CF patients. Health belief variables were found to be predictive of compliance with both IC guidelines and traditional medical treatments in the adult and parent sample, but not in the child sample. Possible explanations for study findings are discussed and recommendations for future research on IC compliance are highlighted.

Diagnostic multiplex PCR assay for the identification of the Liverpool, Midlands 1 and Manchester CF epidemic strains of Pseudomonas aeruginosa

Individual PCR amplification tests have been developed for three UK CF epidemic strains, the Liverpool epidemic strain (LES), Midlands 1 and the Manchester epidemic strain (MES). We report a simple diagnostic multiplex PCR test that can be used to screen for all three of these strains. To evaluate the test, we screened collections of LES, MES and Midlands 1 isolates, along with various CF and non-CF non-epidemic Pseudomonas aeruginosa strains. The test was 100% sensitive and 100% specific in the identification of these UK CF epidemic strains.

High genotypic diversity of Pseudomonas aeruginosa strains isolated from patients with cystic fibrosis in the Czech Republic

Over the last decade, epidemic and frequently multidrug-resistant Pseudomonas aeruginosa has increasingly been found among European cystic fibrosis (CF) patients. In the Czech Republic, more than half of the registered CF patients attend the Prague CF centre. At this centre, a Burkholderia cenocepacia strain was recently found to have spread among the patients. The aim of the present study was to assess whether P. aeruginosa isolates from patients at this centre were also genetically related and, if so, whether they were multidrug-resistant. We investigated a collection of 69 isolates from as many patients who represented 80% of the total number of P. aeruginosa-positive patients in 2004. The organisms were typed by AFLP and SpeI macrorestriction analyses (PFGE). Using these methods, 44 unique strains and nine groups of two to five isolates each were distinguished. Among these groups, two each had a prevalence of 7% in the patient population, while others had a prevalence of < or =3%. The diversity observed with PFGE was largely in agreement with the diversity found by AFLP analysis. All isolates were susceptible to colistin; 94-96% were susceptible to piperacillin, ceftazidime, cefepime, meropenem, amikacin or tobramycin; and 84-87% were susceptible to ciprofloxacin, gentamicin or netilmicin. In conclusion, the organisms recovered from Czech CF patients showed high genotypic diversity and good susceptibility to antipseudomonal agents. The absence of highly epidemic P. aeruginosa strains may result from infection control measures taken upon recognition of the epidemic B. cenocepacia.

Molecular epidemiology and dynamics of Pseudomonas aeruginosa populations in lungs of cystic fibrosis patients

The ability to establish lifelong persistent infections is a fundamental aspect of the interactions between many pathogenic microorganisms and their mammalian hosts. One example is chronic lung infections by the opportunistic pathogen Pseudomonas aeruginosa in cystic fibrosis (CF) patients. This infection process is associated with extensive genetic adaptation and microevolution of the infecting bacteria. Through investigations of P. aeruginosa populations and infection dynamics in a group of CF patients followed at the Danish CF Clinic in Copenhagen, we have identified two distinct and dominant clones that have evolved into highly successful colonizers of CF patient airways. A significant component of the evolutionary success of these two clones has been their efficient transmissibility among the CF patients. The two clones have been present and transmitted among different CF patients for more than 2 decades. Our data also suggest that the P. aeruginosa population structure in the CF patient airways has been influenced by competition between different clones and that the two dominant clones have been particularly competitive within the lungs, which may add to their overall establishment success. In contrast, we show that adaptive traits commonly associated with establishment of chronic P. aeruginosa infections of CF patients, such as transition to the mucoid phenotype and production of virulence factors, play minor roles in the ability of the two dominant clones to spread among patients and cause long-term chronic infections. These findings suggest that hitherto-unrecognized evolutionary pathways may be involved in the development of successful and persistent P. aeruginosa colonizers of CF patient lungs.

Anti-neutrophil cytoplasmatic antibodies and lung disease in cystic fibrosis

BACKGROUND

Bactericidal-permeability-increasing protein (BPI) is a potent anti-microbial protein produced by neutrophil granulocytes. Anti-neutrophil cytoplasmatic antibodies (ANCA) directed against BPI have been detected in up to 91% in patients with cystic fibrosis (CF). We aimed to evaluate the prevalence of BPI-ANCA in our CF patients and to determine whether presence of BPI-ANCA is correlated with organ damage.

METHODS

Twenty-four patients performed respiratory function testing and pulmonary high-resolution computed tomography (HRCT). HRCT was scored by using a modified Bhalla method. Serum samples were analysed by direct binding enzyme-linked immunosorbent assay for BPI-ANCA.

RESULTS

The prevalence of anti-BPI-IgG was 71% and anti-BPI-IgA 33%. Twenty-nine percent of our patients were positive for both BPI-ANCA isotypes. Mean HRCT score was 8.0 ranging from 0 to 22, bronchiectasis presented the most common finding (79%). There was a significant correlation between BPI-ANCA and both HRCT score and FEV(1) (p < 0.01). High levels of BPI-ANCA were correlated to chronic Pseudomonas aeruginosa lung infection (p < 0.01).

CONCLUSIONS

BPI-ANCA was common in our study group. Highly significant correlations between BPI-ANCA and parameters to evaluate lung disease in CF may be a consequence of the inflammation process, or it may indicate a pathogenic role of BPI-ANCA levels in the development of lung disease. More research is needed and the clinical significance of our findings needs further evaluation.

Early intervention and prevention of lung disease in cystic fibrosis: a European consensus

In patients with cystic fibrosis (CF), early intervention and prevention of lung disease is of paramount importance. Principles to achieve this aim include early diagnosis of CF, regular monitoring of the clinical status, various hygienic measures to prevent infection and cross-infection, early use of antibiotic courses in patients with recurrent or continuous bacterial colonisation and appropriate use of chest physiotherapy.

Infection control in cystic fibrosis

Over the past 20 years there has been a greater interest in infection control in cystic fibrosis (CF) as patient-to-patient transmission of pathogens has been increasingly demonstrated in this unique patient population. The CF Foundation sponsored a consensus conference to craft recommendations for infection control practices for CF care providers. This review provides a summary of the literature addressing infection control in CF. Burkholderia cepacia complex, Pseudomonas aeruginosa, and Staphylococcus aureus have all been shown to spread between patients with CF. Standard precautions, transmission-based precautions including contact and droplet precautions, appropriate hand hygiene for health care workers, patients, and their families, and care of respiratory tract equipment to prevent the transmission of infectious agents serve as the foundations of infection control and prevent the acquisition of potential pathogens by patients with CF. The respiratory secretions of all CF patients potentially harbor clinically and epidemiologically important microorganisms, even if they have not yet been detected in cultures from the respiratory tract. CF patients should be educated to contain their secretions and maintain a distance of >3 ft from other CF patients to avoid the transmission of potential pathogens, even if culture results are unavailable or negative. To prevent the acquisition of pathogens from respiratory therapy equipment used in health care settings as well as in the home, such equipment should be cleaned and disinfected. It will be critical to measure the dissemination, implementation, and potential impact of these guidelines to monitor changes in practice and reduction in infections.

Evaluation of an impedance method for subtyping of P seudomonas aeruginosa

Eight isolates (no. 1 to 8) of Pseudomonas aeruginosa isolated from 8 burn patients were typed by pulsed-field gel electrophoresis (PFGE), arbitrarily primed polymerase chain reaction (PCR) (AP-PCR), biotyping, antimicrobial susceptibility testing, and a newly developed technique-impedance method. By both PFGE and AP-PCR, isolates 1 and 2 were designated type A, while isolates 3 to 8 were designated type B. However, isolates 3 to 8 could be further divided into three distinct subtypes (B, C, and D) by the impedance method. Four antibiograms were obtained by testing the 8 isolates against six antimicrobial agents and designation of antibiogram to each of the 8 isolates was in accordance with those obtained by the impedance method. The results of biotyping did not agree with any of the above typing methods. In conclusion, the impedance technique had a high discriminatory ability to differentiate genetically related clones into subtypes. The method is simple, reproducible, and has a high typeability.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.