Comparative hygienic surveillance of contamination with pseudomonads in a cystic fibrosis ward over a 4-year period.

In order to study the long-term distribution and population dynamics of Pseudomonas aeruginosa strains in a highly contaminated hospital environment, two 4-week epidemiological studies, with an interval of 4 years, were carried out in the cystic fibrosis (CF) ward of the Paediatric Clinic of the Medical School of Hannover. Out of the 1948 specimens taken, P. aeruginosa was mainly identified in those from moist, inanimate sources (200 isolates) and hospitalized CF patients (168 isolates). A correlation was established between the frequency with which P. aeruginosa-positive patients came into contact with hospital facilities and the rate of contamination of these facilities. Rooms reserved for colonized patients were more frequently contaminated with P. aeruginosa in contrast to function rooms in the same ward and the outpatient clinic. However, no direct exchange between patients' strains and the inanimate hospital environment was detected. Out of the 11 genotypes of P. aeruginosa found in 1989 and the 13 genotypes found in 1993, four genotypes were present on both occasions. The most predominant clone was found in tap-water, sinks, wash-basins and creams with an incidence of 34 and 68% in the environmental isolates. The strains seemed to have spread into the adjacent control ward during the 4-year interval. Thus, the separation of colonized and non-colonized patients was undermined through the transfer of strains from a highly contaminated environment without additional hygiene precautions.

Direct sputum analysis of Pseudomonas aeruginosa macrorestriction fragment genotypes in patients with cystic fibrosis.

The distribution of bacterial populations in the airways of 13 patients with cystic fibrosis who were colonized for 6-23 years with Pseudomonas aeruginosa was investigated by genotyping of bacterial chromosomes directly isolated from 21 sputa. After removal of host material from sputum by hypotonic cell lysis and repetitive washing and centrifugation steps, agarose-embedded bacterial cells were lysed, residual eukaryotic DNA separated by field inversion gel electrophoresis, and the purified bacterial chromosomes subjected to macrorestriction fragment pattern and Southern analyses. Bacterial populations consisted of a single P. aeruginosa clone in 17 sputa, of which more than one clonal variant was apparent in two SpeI fragment fingerprints. Two clones of P. aeruginosa and another species co-existed in four samples. Genomically homogeneous populations of P. aeruginosa are characteristic for chronically colonized lungs in most cases of cystic fibrosis.

Epidemiology of chronic Pseudomonas aeruginosa infections in the airways of lung transplant recipients with cystic fibrosis.

BACKGROUND: The source of airway colonisation with Pseudomonas aeruginosa is not well defined in patients with cystic fibrosis after lung transplantation. Using a DNA-based typing system a study was undertaken to investigate whether lung transplant recipients acquired new strains of P aeruginosa or retained those they had before transplantation. METHODS: Seventy four P aeruginosa isolates taken before and after transplantation were analysed from 11 patients with cystic fibrosis who had undergone lung transplantation in the Medical School of Hannover between 1988 and 1994. The genetic relatedness of the 74 P aeruginosa strains was evaluated from macrorestriction fragment pattern similarity. RESULTS: Each of the 11 lung transplant recipients harboured one identical P aeruginosa clone before and after transplantation. The airways of four of the 11 patients were preoperatively colonised by two or three different clones, but six months after transplantation only one clone was detectable. CONCLUSIONS: These results show that there is no change in the P aeruginosa population in the airways of lung transplant recipients before and after transplantation and it is assumed that the chronic drainage of P aeruginosa into the lung allografts is caused by the bacterial reservoir in the paranasal sinuses and the trachea.

Epidemiology of chronic Pseudomonas aeruginosa infections in cystic fibrosis.

The epidemiology of chronic colonization of airways with Pseudomonas aeruginosa was monitored in 44 patients with cystic fibrosis (CF) by DraI/SpeI macrorestriction analyses of 489 isolates. Sequential P. aeruginosa isolates (144) that had been collected from 32 CF patients over < or = 2.5 years were investigated, and 12 patients were followed for 8 years after onset of colonization. Forty-eight different genotypes were uncovered from 481 typeable isolates. Ten genotypes were found in > 1 unrelated CF patient. The 6 most frequent clones were identified in 58% of isolates. Ten of the 12 patients monitored for 8 years were harboring their initially acquired P. aeruginosa clone at all times, with subtle shifts of fragment patterns indicating subclonal variation. During colonization, the bacteria gradually lost pyocin and phage typing responses, supporting the view that genotypically discordant P. aeruginosa strains develop a common phenotype.

Detection of more than 50 different CFTR mutations in a large group of German cystic fibrosis patients.

We have conducted a comprehensive study of the molecular basis of cystic fibrosis (CF) in 350 German CF patients. A screening approach based on single-strand conformation analysis and direct sequencing of genomic polymerase chain reaction products has allowed us to detect the molecular defects on 95.4% of the CF chromosomes within the coding region and splice sites of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The spectrum of sequence changes comprises 54 different mutations, including 17 missense mutations, 14 nonsense mutations, 11 frameshift mutations, 10 splice site variants and two amino acid deletions. Eleven of these mutations have not previously been described. Our results reflect the marked mutational heterogeneity of CF in a large sample of patients from a non-isolated population.

Infections with Pseudomonas aeruginosa in patients with cystic fibrosis.

The lung infection with Pseudomonas aeruginosa is regarded as one of the major causes of health decline in patients with cystic fibrosis (CF). The CF host response to the persistent bacterial antigen load in the endobronchiolar lumen is characterized by a pronounced humoral response, local production of cytokines, influx of neutrophils into the lung and a protease-protease inhibitor imbalance predominantly sustained by released neutrophil elastase. CF is an autosomal recessive disease, and we could demonstrate for our local patient population that the age-dependent risk to become chronically colonized with P. aeruginosa can be differentiated by the disease-causing CFTR mutation genotype. The age-specific colonisation rates were significantly lower in pancreas sufficient than in pancreas insufficient patients. P. aeruginosa is occasionally detected in throat swabs already in infancy or early childhood in most patients although there is a lapse of several years amenable to preventive measures such as vaccination until onset of persistent colonization. The epidemiology of the infection with P. aeruginosa was investigated by quantitative macrorestriction fragment pattern analysis. The distribution and frequency of clones found in CF patients match that found in other clinical and environmental aquatic habitats, but the over-representation of specific clones at a CF clinic indicates a significant impact of nosocomial transmission for the prevalence of P. aeruginosa-positive patients at a particular center. Most patients remain colonized with the initially acquired P. aeruginosa clone. According to direct sputum analysis the majority of patients is carrying a single clonal variant at a concentration of 10(7)-10(9) CFU. Co-colonization with other species or other clones is infrequent. Independent of the underlying genotype, the CF lung habitat triggers a uniform, genetically fixed conversion of bacterial phenotype. Most CFP, aeruginosa strains become non-motile, mucoid, LPS-, pyocin- and phage-deficient, secrete less virulence determinants and shift the production of cytokines evoked in neutrophils. On the other hand, other properties such as antimicrobial susceptibility or adherence to bronchial mucins remain highly variable reflecting the capacity of P. aeruginosa to adapt to ongoing changes in the CF lung habitat.