T. Qvist

Epidemiology of nontuberculous mycobacteria among patients with cystic fibrosis in Scandinavia

Background Nontuberculous mycobacteria (NTM) are an emerging threat to cystic fibrosis (CF) patients but their epidemiology is not well described. Methods In this retrospective observational study we identified all Scandinavian CF patients with a positive NTM culture from airway secretions from 2000 to the end of 2012 and used national CF databases to describe microbiological and clinical characteristics. Results During the 13-year period 157 (11%) CF patients were culture positive for NTM at least once. Mycobacterium abscessus complex (MABSC) (45%) and Mycobacterium avium complex (MAC) (32%) were the predominant species with geographical differences in distribution. Younger patients were more prone to MABSC (p < 0.01). Despite treatment, less than one-third of MABSC patients with repeated positive cultures cleared their infection and a quarter had a lung transplant or died. Conclusion NTM are significant CF pathogens and are becoming more prevalent in Scandinavia. MABSC and MAC appear to target distinct patient groups. Having multiple positive cultures despite treatment conveys a poor outcome.

Shifting paradigms of nontuberculous mycobacteria in cystic fibrosis

Important paradigms of pulmonary disease with nontuberculous mycobacteria (NTM) are currently shifting based on an increasing attention within the field of cystic fibrosis (CF). These shifts are likely to benefit the management of all patients with pulmonary NTM, regardless of underlying pathology. Currently several key areas are being revised: The first outbreak of human NTM transmission has been proven and new evidence of biofilm growth in vivo has been demonstrated. A better understanding of the clinical impact of NTM infection has led to increased diagnostic vigilance and new recommendations for lung transplantation are under way. While recent changes have reinvigorated the interest in NTM disease, the challenge remains, whether such advances can be successfully translated into improved management and care.

Nontuberculous Mycobacterial Disease Is Not a Contraindication to Lung Transplantation in Patients With Cystic Fibrosis: A Retrospective Analysis in a Danish Patient Population

Whether nontuberculous mycobacterial (NTM) disease is a contraindication to lung transplantation remains controversial. We conducted a nationwide study to evaluate the clinical importance of NTM infection among lung transplant patients with cystic fibrosis (CF) in Denmark and to determine if NTM infection poses a contraindication to lung transplantation. All CF patients with current or prior NTM who had undergone lung transplantation were identified. Out of 52 lung transplant patients with CF 9 (17%) had NTM disease. Five patients had known infection at the time of transplantation. Two of these died of non-NTM-related causes whereas two developed deep Mycobacterium abscessus wound infections and one was transiently culture negative until M abscessus was reactivated. One patient was subsequently cured; the other two remained on therapy with good performance status. The study supports the contention that CF patients with prior or active NTM can undergo lung transplantation although postoperative complications can be expected.

Comparing the harmful effects of nontuberculous mycobacteria and Gram negative bacteria on lung function in patients with cystic fibrosis

Background To better understand the relative effects of infection with nontuberculous mycobacteria and Gram negative bacteria on lung function decline in cystic fibrosis, we assessed the impact of each infection in a Danish setting. Methods Longitudinal registry study of 432 patients with cystic fibrosis contributing 53,771 lung function measures between 1974 and 2014. We used a mixed effects model with longitudinally structured correlation, while adjusting for clinically important covariates. Results Infections with a significant impact on rate of decline in %FEV1 were Mycobacterium abscessus complex with − 2.22% points per year (95% CI − 3.21 to − 1.23), Burkholderia cepacia complex − 1.95% (95% CI − 2.51 to − 1.39), Achromobacterxylosoxidans − 1.55% (95% CI − 2.21 to − 0.90), and Pseudomonas aeruginosa − 0.95% (95% CI − 1.24 to − 0.66). Clearing M. abscessus complex was associated with a change to a slower decline, similar in magnitude to the pre-infection slope. Conclusions In a national population we have demonstrated the impact on lung function of each chronic CF pathogen. M. abscessus complex was associated with the worst impact on lung function. Eradication of M. abscessus complex may significantly improve lung function.

Chronic pulmonary disease with Mycobacterium abscessus complex is a biofilm infection

Direct evidence of Mycobacterium abscessus complex (MABSC) biofilm in the human lung has not previously been demonstrated. Biofilms are microcolonies of bacteria, imbedded in extracellular matrix, providing stability and tolerance to antibiotics and the bodys innate and adaptive defences [1]. This mode of growth is an inherent feature of chronic infections and is particularly well studied for Pseudomonas aeruginosa and other Gram-negative infections [1], but also some Staphylococcus aureus infections [2]. Mycobacterial infections have also been shown to be capable of biofilm formation, most notably Mycobacterium tuberculosis (tuberculosis), which under the right conditions, can self-assemble into highly organised matrix-encapsulated biofilm [3]. Among the nontuberculous mycobacteria (NTM), Mycobacterium avium complex (MAC) and the rapidly growing mycobacteria, including MABSC, have been shown to grow as biofilms either in vitro or in environmental reservoirs [4, 5], but in vivo conditions have not been studied. MABSC is an emerging threat to patients with cystic fibrosis [6], who become infected at an early age and deteriorate clinically [7] as the persistent infection causes inflammation and tissue damage. We wanted to explore how MABSC grows in the antibiotic-rich, end-stage lungs of patients with cystic fibrosis. The aim was to describe the localisation and growth patterns of MABSC in vivo from freshly explanted lungs of patients with cystic fibrosis and a history of MASBC. We simultaneously performed histological and mycobacterial sampling from the same areas, from multiple pulmonary sites. Mycobacterial culture was performed by inoculation on at least one solid (Middlebrooke 7H10 or Löwenstein–Jensen slopes; SSI Diagnostica, Hilleroed, Denmark) and in one liquid culture medium (BACTEC 12B or MGIT; Becton Dickinson Microbiology Systems, Sparks, MD, USA), and a reverse hybridisation DNA assay was performed (InnoLiPA; Fujirebio Europe, Brondby, Denmark), as previously described [7]. Culture morphology was determined by direct visual inspection of colonies and control microscopy used Ziehl–Neelsen staining. Concomitant culture for Gram-negative and -positive bacteria was also performed. Patient files were reviewed to determine the clinical course of their end-stage lung disease and their history of other chronic bacterial infections. The NTM collection and clinical data collection was approved by the Committee on Health Research Ethics in the Capital Region of Denmark (Copenhagen, Denmark) (H-3-2012-098). The explanted lungs were collected by the transplantation team, microbiological samples were sent for NTM culture and histological samples were transferred to 4% formaldehyde before further preparation for microscopic investigation. The biopsy material was embedded in paraffin, cut into 4-μm sections and mounted on glass slides. Prior to microscopy, paraffin was removed and the tissue sections were analysed by means of conventional haematoxylin and eosin (H&E) staining, Ziehl–Neelsen staining (acid-fast stain), auramine dye (fluorescent stain), and fluorescent in situ hybridisation (FISH) with peptide nucleic acid (PNA) probes: a uniBac probe (red) and a NTM-specific probe (green) (AdvanDx, Inc., Woburn, MA, USA). We used 4′,6′-diamidino-2-phenylindole (Vector Laboratories) as a counterstain for DNA. Microscopic observations were performed with Zeiss 710 Confocal Laser Scanning Microscope (Leica Microsystems, Mannheim, Germany). Mycobacterium abscessus complex can establish a biofilm infection in the lung, which has implications for treatment http://ow.ly/RSjGZ

The effect of short-term, high-dose oral N-acetylcysteine treatment on oxidative stress markers in cystic fibrosis patients with chronic P-aeruginosa infection - A pilot study

BACKGROUND Patients with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa lung infection have increased oxidative stress as a result of an imbalance between the production of reactive oxygen species caused by inflammation and their inactivation by the impaired antioxidant systems. Supplementation with anti-oxidants is potentially beneficial for CF patients. METHODS The effect of 4 weeks of oral N-acetylcysteine (NAC) treatment (2400 mg/day divided into two doses) on biochemical parameters of oxidative stress was investigated in an open-label, controlled, randomized trial on 21 patients; 11 patients in the NAC group and 10 in the control group. Biochemical parameters of oxidative burden and plasma levels of antioxidants were assessed at the end of the study and compared to the baseline values in the two groups. RESULTS A significant increase in the plasma levels of the antioxidant ascorbic acid (p=0.037) and a significant decrease in the levels of the oxidized form of ascorbic acid (dehydroascorbate) (p=0.004) compared to baseline were achieved after NAC treatment. No significant differences were observed in the control group. The parameters of oxidative burden did not change significantly compared to baseline in either of the groups. A better lung function was observed in the NAC treated group with a mean (SD) change compared to baseline of FEV1% predicted of 2.11 (4.6), while a decrease was observed in the control group (change -1.4 (4.6)), though not statistically significant. CONCLUSION Treatment with N-acetylcysteine 1200 mg×2/day for 30 days significantly decreased the level of oxidized vitamin C and increased the level of vitamin C (primary end-points) and a not statistically significant improvement of lung function was observed in this group of patients.

Serodiagnosis of Mycobacterium abscessus complex infection in cystic fibrosis

Early signs of pulmonary disease with Mycobacterium abscessus complex (MABSC) can be missed in patients with cystic fibrosis (CF). A serological method could help stratify patients according to risk. The objective of this study was to test the diagnostic accuracy of a novel method for investigating IgG activity against MABSC. A prospective study of all patients attending the Copenhagen CF Centre was conducted by culturing for MABSC during a 22-month period and then screening patients with an anti-MABSC IgG ELISA. Culture-positive patients had stored serum examined for antibody kinetics before and after culture conversion. 307 patients had 3480 respiratory samples cultured and were then tested with the anti-MABSC IgG ELISA. Patients with MABSC pulmonary disease had median anti-MABSC IgG levels six-fold higher than patients with no history of infection (434 versus 64 ELISA units; p<0.001). The test sensitivity was 95% (95% CI 74–99%) and the specificity was 73% (95% CI 67–78%). A diagnostic algorithm was constructed to stratify patients according to risk. The test accurately identified patients with pulmonary disease caused by MABSC and was suited to be used as a complement to mycobacterial culture. Measuring antibodies against Mycobacterium abscessus can identify patients who harbour this emerging threat to health http://ow.ly/LlRYw

Urine lipoarabinomannan point-of-care testing in patients affected by pulmonary nontuberculous mycobacteria – experiences from the Danish Cystic Fibrosis cohort study

BackgroundThe urine lipoarabinomannan (LAM) strip test has been suggested as a new point-of-care test for active tuberculosis (TB) among human immunodeficiency virus (HIV) infected individuals. It has been questioned if infections with nontuberculous mycobacteria (NTM) affect assay specificity. We set forth to investigate if the test detects LAM in urine from a Danish cystic fibrosis (CF) population characterized by a high NTM prevalence and negligible TB exposure.MethodPatients followed at the Copenhagen CF Center were comprehensively screened for pulmonary NTM infection between May 2012 and December 2013. Urine samples were tested for LAM using the 2013 Determine™ TB LAM Ag strip test.ResultsThree-hundred and six patients had a total of 3,322 respiratory samples cultured for NTM and 198 had urine collected (65%). A total of 23/198 (12%) had active pulmonary NTM infection. None had active TB. The TB-LAM test had an overall positive rate of 2.5% applying a grade 2 cut-point as positivity threshold, increasing to 10.6% (21/198) if a grade 1 cut-point was applied. Among patients with NTM infection 2/23 (8.7%) had a positive LAM test result at the grade 2 cut-point and 9/23 (39.1%) at the grade 1 cut -point. Test specificity for NTM diagnosis was 98.3% and 93.1 for grade 2 and 1 cut-point respectively.ConclusionsThis is the first study to assess urine LAM detection in patients with confirmed NTM infection. The study demonstrated low cross-reactivity due to NTM infection when using the recommended grade 2 cut-point as positivity threshold. This is reassuring in regards to interpretation of the LAM test for TB diagnosis in a TB prevalent setting. The test was not found suitable for NTM detection among patients with CF.

Diagnosis of biofilm infections in cystic fibrosis patients.

Chronic Pseudomonas aeruginosa biofilm lung infection in cystic fibrosis patients is the best described biofilm infection in medicine. The initial focus can be the paranasal sinuses and then follows repeated colonization and infection of the lungs by aspiration. The matrix of the biofilms is dominated by alginate and the pathogenesis of tissue damage is immune complex‐mediated chronic inflammation dominated by polymorphonuclear leukocytes and their products (DNA, oxygen radicals and proteases). The P. aeruginosa biofilm infection can be diagnosed by microscopy of lung tissue, sputum and mucus from the paranasal sinuses, where aggregates of the bacteria are found surrounded by the abundant alginate matrix. Specific PNA‐FISH probes can be used to identify P. aeruginosa and other pathogens in situ in the biofilms. Growth of mucoid colonies from the locations mentioned above is also diagnostic for biofilm infection. Rise of specific anti‐P. aeruginosa antibodies is likewise diagnostic, IgG in serum in case of lung infection, sIgA in saliva or nasal secretions in case of paranasal sinus infection. Similar approaches have been developed to diagnose chronic biofilm infections in cystic fibrosis caused by other pathogens e.g., Stenotrophomonas, Burkholderia multivorans, Achromobacter xylosoxidans and Mycobacterium abscessus complex.

Risk of high‐level viraemia in HIV‐infected patients on successful antiretroviral treatment for more than 6 months

According to the Swiss Federal Commission for HIV/AIDS, HIV‐infected patients on successful antiretroviral treatment have a negligible risk of transmitting HIV sexually. We estimated the risk that patients considered to have an undetectable viral load (VL) are actually viraemic.