Marie Johannesson

Investigation of the algT operon sequence in mucoid and non-mucoid Pseudomonas aeruginosa isolates from 115 Scandinavian patients with cystic fibrosis and in 88 in vitro non-mucoid revertants

Pseudomonas aeruginosa is the dominant pathogen causing chronic lung infections in patients with cystic fibrosis (CF). After an initial phase characterized by intermittent colonizations, a chronic infection is established upon conversion of P. aeruginosa from the non-mucoid to the mucoid, alginate-overproducing phenotype. During the chronic infection the isolation of both mucoid and non-mucoid isolates in CF sputum samples is very common. The purpose of the present study was to establish, by sequence analysis, the types of mutations present in the algTmucABD operon in a large number of mucoid and non-mucoid P. aeruginosa isolates from Scandinavian CF patients and in in vitro-derived non-mucoid revertants. Mucoid (83) and non-mucoid isolates (103) from 91 Scandinavian patients with chronic P. aeruginosa infection and 24 non-mucoid isolates from intermittently colonized CF patients were investigated. In addition, 88 spontaneous non-mucoid revertants obtained in vitro from nine mucoid CF isolates were also included in the study. Mutations in mucA were found in 92 % of the mucoid and in up to 70 % of the non-mucoid isolates from chronically infected patients, indicating that the majority of non-mucoid isolates are revertants. None of the non-mucoid isolates from intermittently colonized CF patients harboured mucA mutations. Although algT has been considered an important gene for secondary-site mutations responsible for reversion to non-mucoidy, only 30 % of the mucA-mutated non-mucoid CF isolates had mutations in algT. In contrast, 83 % of the in vitro-derived spontaneous non-mucoid revertants had mutations in algT, showing that in the CF lung there is a selection for non-mucoid revertants with secondary-site mutations in genes other than algT. In addition, we report, to our knowledge for the first time, loss-of-function mutations in the negative regulators mucB and mucD in CF clinical isolates. In some of the CF isolates these mutations are associated with moderate alginate production. In conclusion, most non-mucoid isolates from chronically infected CF patients are revertants and the mechanism of revertance is algT-independent in the CF lung.

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

BACKGROUNDnChronic 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?nnnMETHODSn989 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.nnnRESULTSnIn 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.nnnCONCLUSIONSnIt 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.

Prevalence and outcome of pregnancies in Norwegian and Swedish women with cystic fibrosis

Background:u2003 As patients with cystic fibrosis now live longer, more women with cystic fibrosis wish to become mothers. We looked at the prevalence and outcome of pregnancies in women with cystic fibrosis who were alive in Norway and Sweden in the year 2000.

AZITHROMYCIN INCREASES CHLORIDE EFFLUX FROM CYSTIC FIBROSIS AIRWAY EPITHELIAL CELLS

It was investigated whether azithromycin (AZM) stimulates chloride (Cl−) efflux from cystic fibrosis (CF) and non-CF airway epithelial cells, possibly secondary to up-regulation of the multidrug resistance protein (MDR). CF and non-CF human airway epithelial cell lines (CFBE and 16HBE) were treated with 0.4, 4, and 40 μ g/mL AZM for 4 days. Cl− efflux was explored in the presence or absence of specific inhibitors of CFTR and alternative Cl− channels. Six CF patients received AZM (500 mg daily) for 6 months. The percentage of predicted forced vital capacity (FVC%), forced expiratory volume (FEV1%), and the number of acute exacerbations were compared before and after treatment. Nasal biopsies were taken before and after treatment, and mRNA expression of MDR and CFTR was determined by in situ hybridization. A significant dose-dependent increase of Cl− efflux from CFBE cells (but not from 16HBE cells) was observed after AZM treatment. A CFTR inhibitor significantly reduced AZM-stimulated Cl− efflux from CFBE cells. A significant improvement in FEV1%, and fewer exacerbations were observed. AZM treatment did not affect mRNA expression of MDR and CFTR. The stimulation of Cl− efflux could be part of the explanation for the clinical improvement seen among the patients.

Effects of pregnancy on health: certain aspects of importance for women with cystic fibrosis

More women with cystic fibrosis (CF) now reach reproductive age and wish to become pregnant. Although women with CF have reduced fertility, many of them can become mothers. A pregnancy ought to be carefully planned since several studies have shown that pregnancy is well tolerated if good medical care is provided, and the CF woman is in a stable good condition. A short review of the implications of pregnancy for women with CF is presented. A suggested schedule for pregnant women with CF is given.

Survival against the odds.

While the majority of patients with cystic fibrosis (CF) survive well into adulthood, some do so against the odds. The severity of their illness, their psychosocial environment, or their failure to adhere to treatment are such that survival could not have been predicted. It appears that some patients are more resilient than others. Some specific components of resilience include comprehensibility, manageability and meaningfulness. These are defined and case examples provided to illustrate their significance.

Maternal and fetal morbidity in pregnancies of Norwegian and Swedish women with cystic fibrosis.

BACKGROUNDnThe survival of patients with cystic fibrosis has increased. More women with cystic fibrosis reach reproductive age and wish to become pregnant. The aim of this work was to study the outcome of completed pregnancies in women with cystic fibrosis in Norway and Sweden.nnnMETHODSnA retrospective audit from medical records was performed for 33 successful pregnancies in 23 women from the cystic fibrosis center in Norway and two cystic fibrosis centers in Sweden. Lung function, body weight and use of antibiotics together with other medical data were related to the complications and outcomes of the pregnancies.nnnRESULTSnThe most frequent complication of the pregnancies was preterm delivery, which occurred in 24% of cases. The lung function of the women was significantly lower in the preterm group than in those delivering at term. Those who went on to deliver preterm were more likely to have other cystic fibrosis complications including diabetes, asthma or liver disease. The weight gain of the women with cystic fibrosis delivering preterm was less than in the term group (corrected for gestation), but the frequency of pulmonary infections did not differ. As for the total group, lung function did not deteriorate during pregnancy, even though the need for intravenous antibiotics was doubled compared with the year before and after pregnancy. Weight gain in pregnancy was on average 10.3 kg, and almost half of the women needed supplementary nutrition. Gestational diabetes developed in four of the 23 patients. Caesarean sections were performed in eight of the 33 deliveries (24%), and 26 of the babies (79%) were breast-fed. None of the 33 children suffered from cystic fibrosis.nnnCONCLUSIONnWomen with cystic fibrosis with mild to moderate disease may safely go through pregnancy. In those with severe disease, preterm delivery is common. A team approach is necessary to provide the best medical care for pregnant women with cystic fibrosis.